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• Wireless internet connection connects but internet does not work (no packets received). Wired does.

  - by Rodney

  When I connect my PC via ethernet cable to my ADSL router it works fine. When I connect via Wireless it connects and the internet will work for a random amount of time and then stop working. It stays connected with a strong signal but no packets are received. My laptop/iphone are right next to it and wireless works fine. If I open the Wireless USB status, it says it is connected to my SSID with full strength (54 mps - I am 3 meteres away from my router) and the activty shows as Packets 594 SENT and 105 RECEIVED (this goes up VERY slowly) I have tried the following: Turned off anitvirus and firewall completely. Tested the wifi signal- I am writing this on my laptop which is next to my PC and also has full wifi strength. Tried a different wireless adapter - I dug out an old PCI wireless card - it does the exact same thing. Compared all wireless settings to my laptop. I can ping google.com and it replies (sometimes with packet loss) When I reboot the PC it will connect for a minute or two (random time) and then just stops again. I tried Firefox, IE etc. no joy I have updated all latest versions (Netgear WG111v2) and drivers Checked Event Log - nothing unusual Ping the router (and even connect as admin for the few minutes when the internet does work) Changed the MTU down to 1200 using DrTCP Checked Device Manager for conflicts - none. I ping the router from the PC (192.168.0.10 - 192.168.0.1) and it replies with 4 packets. BUT, on my router admin page (which I access via http on my laptop wirelessly) - if I ping 192.168.0.10 all packets timeout (pinging my laptop 192.168.0.12 works fine) My router admin page shows the leased IP address for 192.168.0.10 (ie it is definitely talking to the router initially) Now I am out of ideas - please help. I think it is an OS/Software issue as I have tried 2 different wireless adapaters (PCI and USB) with the same result but all other wireless devices work fine around mine). It's not the firewall. It is getting assigned an IP address correctly (my PC gets 192.168.0.10, my laptop is .12) It is assigned by DHCP. As soon as I plug in the ethernet cable it all works fine. Repairing the adapter sometimes helps but it will always stop working after a random time. The wireless adapter always shows as connected with Excellent signal but the internet does not work. I am running Windows XP SP3 and have tried a Netgear WG111v2 USB adapter. Thanks in advance! UPDATE: The internet seems to be working, it is just either sending packets too small or slow to work (some small pages load bits of them very slowly but then hang). XP seems to have a networking diagnostic app - here is the output: Last diagnostic run time: 08/30/10 08:16:38 IP Configuration Diagnostic Invalid IP address info Valid IP address detected: 192.168.0.10 IP Layer Diagnostic Corrupted IP routing table info The default route is valid info The loopback route is valid info The local host route is valid info The local subnet route is valid Invalid ARP cache entries action The ARP cache has been flushed Gateway Diagnostic Gateway info The following proxy configuration is being used by IE: Automatically Detect Settings:Disabled Automatic Configuration Script: Proxy Server: Proxy Bypass list: info This computer has the following default gateway entry(ies): 192.168.0.1 info This computer has the following IP address(es): 192.168.0.10 info The default gateway is in the same subnet as this computer info The default gateway entry is a valid unicast address info The default gateway address was resolved via ARP in 1 try(ies) info The default gateway was reached via ICMP Ping in 1 try(ies) info TCP port 80 on host 65.55.12.249 was successfully reached info The Internet host www.microsoft.com was successfully reached info The default gateway is OK DNS Client Diagnostic DNS - Not a home user scenario info Using Web Proxy: no info Resolving name ok for (www.microsoft.com): yes No DNS servers DNS failure HTTP, HTTPS, FTP Diagnostic HTTP, HTTPS, FTP connectivity info FTP (Passive): Successfully connected to ftp.microsoft.com. info HTTP: Successfully connected to www.microsoft.com. warn HTTPS: Error 12002 connecting to www.microsoft.com: The operation timed out warn HTTPS: Error 12002 connecting to www.passport.net: The operation timed out error Could not make an HTTPS connection. info Redirecting user to support call WinSock Diagnostic WinSock status info All base service provider entries are present in the Winsock catalog. info The Winsock Service provider chains are valid. info Provider entry MSAFD Tcpip [TCP/IP] passed the loopback communication test. info Provider entry MSAFD Tcpip [UDP/IP] passed the loopback communication test. info Provider entry RSVP UDP Service Provider passed the loopback communication test. info Provider entry RSVP TCP Service Provider passed the loopback communication test. info Connectivity is valid for all Winsock service providers. Wireless Diagnostic Wireless - Service disabled Wireless - User SSID action User input required: Specify network name or SSID Wireless - First time setup info The Wireless Network name (SSID) to which the user would like to connect = RodSof Wifi. Wireless - Radio off info Valid IP address detected: 192.168.0.10 Wireless - Out of range Wireless - Hardware issue Wireless - Novice user Wireless - Ad-hoc network Wireless - Less preferred Wireless - 802.1x enabled Wireless - Configuration mismatch Wireless - Low SNR Network Adapter Diagnostic Network location detection info Using home Internet connection Network adapter identification info Network connection: Name=Local Area Connection 2, Device=Realtek RTL8168C(P)/8111C(P) PCI-E Gigabit Ethernet NIC, MediaType=LAN, SubMediaType=LAN info Network connection: Name=Wireless USB, Device=NETGEAR WG111v2 54Mbps Wireless USB 2.0 Adapter, MediaType=LAN, SubMediaType=WIRELESS info Both Ethernet and Wireless connections available, prompting user for selection action User input required: Select network connection info Wireless connection selected Network adapter status info Network connection status: Connected HTTP, HTTPS, FTP Diagnostic HTTP, HTTPS, FTP connectivity info FTP (Active): Successfully connected to ftp.microsoft.com. warn HTTP: Error 12007 connecting to www.microsoft.com: The server name or address could not be resolved warn HTTP: Error 12002 connecting to www.hotmail.com: The operation timed out warn HTTPS: Error 12002 connecting to www.passport.net: The operation timed out warn HTTPS: Error 12002 connecting to www.microsoft.com: The operation timed out error Could not make an HTTP connection. error Could not make an HTTPS connection.

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• Bug in CF9: values for unique struct keys referenced and overwritten by other keys.

  - by Gin Doe

  We've run into a serious issue with CF9 wherein values for certain struct keys can be referenced by other keys, despite those other keys never being set. See the following examples: Edit: Looks like it isn't just something our servers ate. This is Adobe bug-track ticket 81884: http://cfbugs.adobe.com/cfbugreport/flexbugui/cfbugtracker/main.html#bugId=81884. <cfset a = { AO = "foo" } /> <cfset b = { AO = "foo", B0 = "bar" } /> <cfoutput> The following should throw an error. Instead both keys refer to the same value. <br />Struct a: <cfdump var="#a#" /> <br />a.AO: #a.AO# <br />a.B0: #a.B0# <hr /> The following should show a struct with 2 distinct keys and values. Instead it contains a single key, "AO", with a value of "bar". <br />Struct b: <cfdump var="#b#" /> This is obviously a complete show-stopper for us. I'd be curious to know if anyone has encountered this or can reproduce this in their environment. For us, it happens 100% of the time on Apache/CF9 running on Linux, both RH4 and RH5. We're using the default JRun install on Java 1.6.0_14. To see the extent of the problem, we ran a quick loop to find other naming sequences that are affected and found hundreds of matches for 2 letter key names. A similar loop found more conflicts in 3 letter names. <cfoutput>Testing a range of affected key combinations. This found hundreds of cases on our platform. Aborting after 50 here.</cfoutput> <cfscript> teststring = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; stringlen = len(teststring); matchesfound = 0; matches = ""; for (i1 = 1; i1 <= stringlen; i1++) { symbol1 = mid(teststring, i1, 1); for (i2 = 1; i2 <= stringlen; i2++) { teststruct = structnew(); symbol2 = mid(teststring, i2, 1); symbolwhole = symbol1 & symbol2; teststruct[ symbolwhole ] = "a string"; for (q1 = 1; q1 <= stringlen; q1++) { innersymbol1 = mid(teststring, q1, 1); for (q2 = 1; q2 <= stringlen; q2++) { innersymbol2 = mid(teststring, q2, 1); innersymbolwhole = innersymbol1 & innersymbol2; if ((i1 != q1 || i2 != q2) && structkeyexists(teststruct, innersymbolwhole)) { // another affected pair of keys! writeoutput ("<br />#symbolwhole# = #innersymbolwhole#"); if (matchesfound++ > 50) { // we've seen enough abort; } } } } } } </cfscript> And edit again: This doesn't just affect struct keys but names in the variables scope as well. At least the variables scope has the presence of mind to throw an error, "can't load a null": <cfset test_b0 = "foo" /> <cfset test_ao = "bar" /> <cfoutput> test_b0: #test_b0# <br />test_ao: #test_ao# </cfoutput>

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• Google App Engine + Form Validation

  - by Iwona

  Hi, I would like to do google app engine form validation but I dont know how to do it? I tried like this: from google.appengine.ext.db import djangoforms from django import newforms as forms class SurveyForm(forms.Form): occupations_choices = ( ('1', ""), ('2', "Undergraduate student"), ('3', "Postgraduate student (MSc)"), ('4', "Postgraduate student (PhD)"), ('5', "Lab assistant"), ('6', "Technician"), ('7', "Lecturer"), ('8', "Other" ) ) howreach_choices = ( ('1', ""), ('2', "Typed the URL directly"), ('3', "Site is bookmarked"), ('4', "A search engine"), ('5', "A link from another site"), ('6', "From a book"), ('7', "Other") ) boxes_choices = ( ("des", "Website Design"), ("svr", "Web Server Administration"), ("com", "Electronic Commerce"), ("mkt", "Web Marketing/Advertising"), ("edu", "Web-Related Education") ) name = forms.CharField(label='Name', max_length=100, required=True) email = forms.EmailField(label='Your Email Address:') occupations = forms.ChoiceField(choices=occupations_choices, label='What is your occupation?') howreach = forms.ChoiceField(choices=howreach_choices, label='How did you reach this site?') # radio buttons 1-5 rating = forms.ChoiceField(choices=range(1,6), label='What is your occupation?', widget=forms.RadioSelect) boxes = forms.ChoiceField(choices=boxes_choices, label='Are you involved in any of the following? (check all that apply):', widget=forms.CheckboxInput) comment = forms.CharField(widget=forms.Textarea, required=False) And I wanted to display it like this: template_values = { 'url' : url, 'url_linktext' : url_linktext, 'userName' : userName, 'item1' : SurveyForm() } And I have this error message: Traceback (most recent call last): File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp_init_.py", line 515, in call handler.get(*groups) File "C:\Program Files\Google\google_appengine\demos\b00213576\main.py", line 144, in get self.response.out.write(template.render(path, template_values)) File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp\template.py", line 143, in render return t.render(Context(template_dict)) File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp\template.py", line 183, in wrap_render return orig_render(context) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 168, in render return self.nodelist.render(context) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 705, in render bits.append(self.render_node(node, context)) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 718, in render_node return(node.render(context)) File "C:\Program Files\Google\google_appengine\lib\django\django\template\defaulttags.py", line 209, in render return self.nodelist_true.render(context) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 705, in render bits.append(self.render_node(node, context)) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 718, in render_node return(node.render(context)) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 768, in render return self.encode_output(output) File "C:\Program Files\Google\google_appengine\lib\django\django\template_init_.py", line 757, in encode_output return str(output) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\util.py", line 26, in str return self.unicode().encode(settings.DEFAULT_CHARSET) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\forms.py", line 73, in unicode return self.as_table() File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\forms.py", line 144, in as_table return self._html_output(u'%(label)s%(errors)s%(field)s%(help_text)s', u'%s', '', u'%s', False) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\forms.py", line 129, in _html_output output.append(normal_row % {'errors': bf_errors, 'label': label, 'field': unicode(bf), 'help_text': help_text}) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\forms.py", line 232, in unicode value = value.str() File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\util.py", line 26, in str return self.unicode().encode(settings.DEFAULT_CHARSET) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\widgets.py", line 246, in unicode return u'\n%s\n' % u'\n'.join([u'%s' % w for w in self]) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\widgets.py", line 238, in iter yield RadioInput(self.name, self.value, self.attrs.copy(), choice, i) File "C:\Program Files\Google\google_appengine\lib\django\django\newforms\widgets.py", line 212, in init self.choice_value = smart_unicode(choice[0]) TypeError: 'int' object is unsubscriptable Do You have any idea how I can do this validation in different case? I have tried to do it using this kind of: class ItemUserAnswer(djangoforms.ModelForm): class Meta: model = UserAnswer But I dont know how to add extra labels to this form and it is displayed in one line. Do You have any suggestions? Thanks a lot as it making me crazy why it is still not working:/

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• FreeBSD high load loopback interface

  - by user1740915

  I have a problem with a FreeBSD server. There is a FreeBSD 9.0 amd64, two network cards em1 (internet), em0 (local network) configured firewall ipfw, natd, squid (not transparent), the server acts as a gateway for access to the Internet. Next problem: upload via squid is very low. At this moment I see next: natd, dhcpd load the cpu at that time when uploading through squid and there are a lot of traffic through the loopback interface. ipfw show output 0100 655389684 36707144666 allow ip from any to any via lo0 00200 0 0 deny ip from any to 127.0.0.0/8 00300 0 0 deny ip from 127.0.0.0/8 to any 00400 0 0 deny ip from any to ::1 00500 0 0 deny ip from ::1 to any 00600 4 292 allow ipv6-icmp from :: to ff02::/16 00700 0 0 allow ipv6-icmp from fe80::/10 to fe80::/10 00800 1 76 allow ipv6-icmp from fe80::/10 to ff02::/16 00900 0 0 allow ipv6-icmp from any to any ip6 icmp6types 1 01000 0 0 allow ipv6-icmp from any to any ip6 icmp6types 2,135,136 01100 1615 76160 deny ip from 192.168.1.1 to any in via em1 01200 0 0 deny ip from 199.69.99.11 to any in via em0 01300 46652 3705426 deny ip from any to 172.16.0.0/12 via em1 01400 3936404 345618870 deny ip from any to 192.168.0.0/16 via em1 01500 4 336 deny ip from any to 0.0.0.0/8 via em1 01600 4129 387621 deny ip from any to 169.254.0.0/16 via em1 01700 0 0 deny ip from any to 192.0.2.0/24 via em1 01800 917566 33777571 deny ip from any to 224.0.0.0/4 via em1 01900 147872 22029252 deny ip from any to 240.0.0.0/4 via em1 02000 1132194739 1190981955947 divert 8668 ip4 from any to any via em1 02100 3 248 deny ip from 172.16.0.0/12 to any via em1 02200 35925 2281289 deny ip from 192.168.0.0/16 to any via em1 02300 1808 122494 deny ip from 0.0.0.0/8 to any via em1 02400 3 174 deny ip from 169.254.0.0/16 to any via em1 02500 0 0 deny ip from 192.0.2.0/24 to any via em1 02600 0 0 deny ip from 224.0.0.0/4 to any via em1 02700 0 0 deny ip from 240.0.0.0/4 to any via em1 02800 960156249 1095316736582 allow tcp from any to any established 02900 64236062 8243196577 allow ip from any to any frag 03000 34 1756 allow tcp from any to me dst-port 25 setup 03100 193 11580 allow tcp from any to me dst-port 53 setup 03200 63 4222 allow udp from any to me dst-port 53 03300 64 8350 allow udp from me 53 to any 03400 417 24140 allow tcp from any to me dst-port 80 setup 03500 211 10472 allow ip from any to me dst-port 3389 setup 05300 77 4488 allow ip from any to me dst-port 1723 setup 05400 3 156 allow ip from any to me dst-port 8443 setup 05500 9882 590596 allow tcp from any to me dst-port 22 setup 05600 1 60 allow ip from any to me dst-port 2000 setup 05700 0 0 allow ip from any to me dst-port 2201 setup 07400 4241779 216690096 deny log logamount 1000 ip4 from any to any in via em1 setup proto tcp 07500 21135656 1048824936 allow tcp from any to any setup 07600 474447 35298081 allow udp from me to any dst-port 53 keep-state 07700 532 40612 allow udp from me to any dst-port 123 keep-state 65535 1990638432 1122305322718 allow ip from any to any systat -ifstat when uploading via squid Load Average ||| Interface Traffic Peak Total tun0 in 79.507 KB/s 232.479 KB/s 42.314 GB out 2.022 MB/s 2.424 MB/s 59.662 GB lo0 in 4.450 MB/s 4.450 MB/s 43.723 GB out 4.450 MB/s 4.450 MB/s 43.723 GB em1 in 2.629 MB/s 2.982 MB/s 464.533 GB out 2.493 MB/s 2.875 MB/s 484.673 GB em0 in 240.458 KB/s 296.941 KB/s 442.368 GB out 512.508 KB/s 850.857 KB/s 416.122 GB top output PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 66885 root 1 92 0 26672K 2784K CPU3 3 528:43 65.48% natd 9160 dhcpd 1 45 0 31032K 9280K CPU1 1 7:40 32.96% dhcpd 66455 root 1 20 0 18344K 2856K select 1 119:27 1.37% openvpn 16043 squid 1 20 0 44404K 17884K kqread 2 0:22 0.29% squid squid.conf cat /usr/local/etc/squid/squid.conf # # Recommended minimum configuration: # acl manager proto cache_object acl localhost src 127.0.0.1/32 ::1 acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1 # Example rule allowing access from your local networks. # Adapt to list your (internal) IP networks from where browsing # should be allowed acl localnet src 10.0.0.0/8 # RFC1918 possible internal network acl localnet src 172.16.0.0/12 # RFC1918 possible internal network acl localnet src 192.168.0.0/16 # RFC1918 possible internal network acl localnet src fc00::/7 # RFC 4193 local private network range acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines acl SSL_ports port 443 acl Safe_ports port 80 # http acl Safe_ports port 21 # ftp acl Safe_ports port 443 # https acl Safe_ports port 70 # gopher acl Safe_ports port 210 # wais acl Safe_ports port 1025-65535 # unregistered ports acl Safe_ports port 280 # http-mgmt acl Safe_ports port 488 # gss-http acl Safe_ports port 591 # filemaker acl Safe_ports port 777 # multiling http acl CONNECT method CONNECT # # Recommended minimum Access Permission configuration: # # Only allow cachemgr access from localhost http_access allow manager localhost http_access deny manager # Deny requests to certain unsafe ports http_access deny !Safe_ports # Deny CONNECT to other than secure SSL ports http_access deny CONNECT !SSL_ports # We strongly recommend the following be uncommented to protect innocent # web applications running on the proxy server who think the only # one who can access services on "localhost" is a local user http_access deny to_localhost # # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # # Example rule allowing access from your local networks. # Adapt localnet in the ACL section to list your (internal) IP networks # from where browsing should be allowed http_access allow localnet http_access allow localhost # And finally deny all other access to this proxy http_access deny all # Squid normally listens to port 3128 http_port 192.168.1.1:3128 # Uncomment and adjust the following to add a disk cache directory. #cache_dir ufs /var/squid/cache 100 16 256 # Leave coredumps in the first cache dir coredump_dir /var/squid/cache I understand that the traffic passes through the SQUID several times. But can not find why.

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• Business rule validation of hierarchical list of objects ASP.NET MVC

  - by SergeanT

  I have a list of objects that are organized in a tree using a Depth property: public class Quota { [Range(0, int.MaxValue, ErrorMessage = "Please enter an amount above zero.")] public int Amount { get; set; } public int Depth { get; set; } [Required] [RegularExpression("^[a-zA-Z]+$")] public string Origin { get; set; } // ... another properties with validation attributes } For data example (amount - origin) 100 originA 200 originB 50 originC 150 originD the model data looks like: IList<Quota> model = new List<Quota>(); model.Add(new Quota{ Amount = 100, Depth = 0, Origin = "originA"); model.Add(new Quota{ Amount = 200, Depth = 0, Origin = "originB"); model.Add(new Quota{ Amount = 50, Depth = 1, Origin = "originC"); model.Add(new Quota{ Amount = 150, Depth = 1, Orinig = "originD"); Editing of the list Then I use Editing a variable length list, ASP.NET MVC 2-style to raise editing of the list. Controller actions QuotaController.cs: public class QuotaController : Controller { // // GET: /Quota/EditList public ActionResult EditList() { IList<Quota> model = // ... assigments as in example above; return View(viewModel); } // // POST: /Quota/EditList [HttpPost] public ActionResult EditList(IList<Quota> quotas) { if (ModelState.IsValid) { // ... save logic return RedirectToAction("Details"); } return View(quotas); // Redisplay the form with errors } // ... other controller actions } View EditList.aspx: <%@ Page Title="" Language="C#" ... Inherits="System.Web.Mvc.ViewPage<IList<Quota>>" %> ... <h2>Edit Quotas</h2> <%=Html.ValidationSummary("Fix errors:") %> <% using (Html.BeginForm()) { foreach (var quota in Model) { Html.RenderPartial("QuotaEditorRow", quota); } %> <% } %> ... Partial View QuotaEditorRow.ascx: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Quota>" %> <div class="quotas" style="margin-left: <%=Model.Depth*45 %>px"> <% using (Html.BeginCollectionItem("Quotas")) { %> <%=Html.HiddenFor(m=>m.Id) %> <%=Html.HiddenFor(m=>m.Depth) %> <%=Html.TextBoxFor(m=>m.Amount, new {@class = "number", size = 5})%> <%=Html.ValidationMessageFor(m=>m.Amount) %> Origin: <%=Html.TextBoxFor(m=>m.Origin)%> <%=Html.ValidationMessageFor(m=>m.Origin) %> ... <% } %> </div> Business rule validation How do I implement validation of business rule: Amount of quota and sum of amounts of nested quotas should equal (e.a. 200 = 50 + 150 in example)? I want to appropriate inputs Html.TextBoxFor(m=>m.Amount) be highlighted red if the rule is broken for it. In example if user enters not 200, but 201 - it should be red on submit. Using sever validation only. Thanks a lot for any advise.

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• Improving TCP performance over a gigabit network lots of connections and high traffic for storage and streaming services

  - by Linux Guy

  I have two servers, Both servers hardware Specification are Processor : Dual Processor RAM : over 128 G.B Hard disk : SSD Hard disk Outging Traffic bandwidth : 3 Gbps network cards speed : 10 Gbps Server A : for Encoding videos Server B : for storage videos andstream videos over web interface like youtube The inbound bandwidth between two servers is 10Gbps , the outbound bandwidth internet bandwidth is 500Mpbs Both servers using public ip addresses in public and private network Both servers transfer and connection on nginx port , and the server B used for streaming media , like youtube stream videos Both servers in same network , when i do ping from Server A to Server B i got high time latency above 1.0ms , the time range time=52.7 ms to time=215.7 ms - This is the output of iftop utility 353Mb 707Mb 1.04Gb 1.38Gb 1.73Gb mqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqq server.example.com => ip.address 6.36Mb 4.31Mb 1.66Mb <= 158Kb 94.8Kb 35.1Kb server.example.com => ip.address 1.23Mb 4.28Mb 1.12Mb <= 17.1Kb 83.5Kb 21.9Kb server.example.com => ip.address 395Kb 3.89Mb 1.07Mb <= 6.09Kb 109Kb 28.6Kb server.example.com => ip.address 4.55Mb 3.83Mb 1.04Mb <= 55.6Kb 45.4Kb 13.0Kb server.example.com => ip.address 649Kb 3.38Mb 1.47Mb <= 9.00Kb 38.7Kb 16.7Kb server.example.com => ip.address 5.00Mb 3.32Mb 1.80Mb <= 65.7Kb 55.1Kb 29.4Kb server.example.com => ip.address 387Kb 3.13Mb 1.06Mb <= 18.4Kb 39.9Kb 15.0Kb server.example.com => ip.address 3.27Mb 3.11Mb 1.01Mb <= 81.2Kb 64.5Kb 20.9Kb server.example.com => ip.address 1.75Mb 3.08Mb 2.72Mb <= 16.6Kb 35.6Kb 32.5Kb server.example.com => ip.address 1.75Mb 2.90Mb 2.79Mb <= 22.4Kb 32.6Kb 35.6Kb server.example.com => ip.address 3.03Mb 2.78Mb 1.82Mb <= 26.6Kb 27.4Kb 20.2Kb server.example.com => ip.address 2.26Mb 2.66Mb 1.36Mb <= 51.7Kb 49.1Kb 24.4Kb server.example.com => ip.address 586Kb 2.50Mb 1.03Mb <= 4.17Kb 26.1Kb 10.7Kb server.example.com => ip.address 2.42Mb 2.49Mb 2.44Mb <= 31.6Kb 29.7Kb 29.9Kb server.example.com => ip.address 2.41Mb 2.46Mb 2.41Mb <= 26.4Kb 24.5Kb 23.8Kb server.example.com => ip.address 2.37Mb 2.39Mb 2.40Mb <= 28.9Kb 27.0Kb 28.5Kb server.example.com => ip.address 525Kb 2.20Mb 1.05Mb <= 7.03Kb 26.0Kb 12.8Kb qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq TX: cum: 102GB peak: 1.65Gb rates: 1.46Gb 1.44Gb 1.48Gb RX: 1.31GB 24.3Mb 19.5Mb 18.9Mb 20.0Mb TOTAL: 103GB 1.67Gb 1.48Gb 1.46Gb 1.50Gb I check the transfer speed using iperf utility From Server A to Server B # iperf -c 0.0.0.2 -p 8777 ------------------------------------------------------------ Client connecting to 0.0.0.2, TCP port 8777 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ [ 3] local 0.0.0.1 port 38895 connected with 0.0.0.2 port 8777 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.8 sec 528 KBytes 399 Kbits/sec My Current Connections in Server B # netstat -an|grep ":8777"|awk '/tcp/ {print $6}'|sort -nr| uniq -c 2072 TIME_WAIT 28 SYN_RECV 1 LISTEN 189 LAST_ACK 139 FIN_WAIT2 373 FIN_WAIT1 3381 ESTABLISHED 34 CLOSING Server A Network Card Information Settings for eth0: Supported ports: [ TP ] Supported link modes: 100baseT/Full 1000baseT/Full 10000baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes Speed: 10000Mb/s Duplex: Full Port: Twisted Pair PHYAD: 0 Transceiver: external Auto-negotiation: on MDI-X: Unknown Supports Wake-on: d Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes Server B Network Card Information Settings for eth2: Supported ports: [ FIBRE ] Supported link modes: 10000baseT/Full Supported pause frame use: No Supports auto-negotiation: No Advertised link modes: 10000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: No Speed: 10000Mb/s Duplex: Full Port: Direct Attach Copper PHYAD: 0 Transceiver: external Auto-negotiation: off Supports Wake-on: d Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes ifconfig server A eth0 Link encap:Ethernet HWaddr 00:25:90:ED:9E:AA inet addr:0.0.0.1 Bcast:0.0.0.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1202795665 errors:0 dropped:64334 overruns:0 frame:0 TX packets:2313161968 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:893413096188 (832.0 GiB) TX bytes:3360949570454 (3.0 TiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:2207544 errors:0 dropped:0 overruns:0 frame:0 TX packets:2207544 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:247769175 (236.2 MiB) TX bytes:247769175 (236.2 MiB) ifconfig Server B eth2 Link encap:Ethernet HWaddr 00:25:90:82:C4:FE inet addr:0.0.0.2 Bcast:0.0.0.2 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:39973046980 errors:0 dropped:1828387600 overruns:0 frame:0 TX packets:69618752480 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3013976063688 (2.7 TiB) TX bytes:102250230803933 (92.9 TiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:1049495 errors:0 dropped:0 overruns:0 frame:0 TX packets:1049495 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:129012422 (123.0 MiB) TX bytes:129012422 (123.0 MiB) Netstat -i on Server B # netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth2 9000 0 42098629968 0 2131223717 0 73698797854 0 0 0 BMRU lo 65536 0 1077908 0 0 0 1077908 0 0 0 LRU I Turn up send/receive buffers on the network card to 2048 and problem still persist I increase the MTU for server A and problem still persist and i increase the MTU for server B for better connectivity and transfer speed but it couldn't transfer at all The problem is : as you can see from iperf utility, the transfer speed from server A to server B slow when i restart network service in server B the transfer in server A at full speed, after 2 minutes , it's getting slow How could i troubleshoot slow speed issue and fix it in server B ? Notice : if there any other commands i should execute in servers for more information, so it might help resolve the problem , let me know in comments

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• Apache/PHP serving file multiple times

  - by easement

  I have a system with a download.php page. The page takes and id and loads a file based on from the DB Record and then serves it up. I've noticed a couple instances where files are requested multiple times in short time spans (20ms). Times that are too quick for human input. There are plenty of instances where the downloader functions fine. However, in taking a closer look at the downloader’s usage, I did see some interesting behavior. For instance, the IP address xxx.xxx.xxx.xxx (which is one in a range owned by xxxxxx.de in Germany) came to the site through Google. They browsed around and then came to the page http://site.com/xxxx/press+125.php There they issued a request for /download.php?id=/ZZ/n+aH55Y= (a PDF) at 9:04:23AM. That alone is not a big deal. However, what is interesting is that the server seems to have been quite preoccupied with serving that request. In the logs the request first completes between 9:09:48 and 9:10:00. It looks like the user must have gotten tired of waiting during that time and requested the document two more times. Between 09:14:47 and 09:15:00 the same request appears again, except it is from 9:04:43AM, 20ms later than the first request. Then it pops up a third time, with a request that started at 09:05:06 completing between 09:19:55 and 09:19:58! I’m suspicious of that document. In looking through the logs I see other instances where it takes the server a little while to handle that specific file. Check out this list of requests from zzz.zzz.zzz.zzz[different than above] for the file /download.php?id=/ZZ/n+aH55Y= (the same docuemnt as before): Request time Complete Time 04:32:43 04:33:36 04:32:50 04:33:36 04:32:51 04:33:38 04:33:05 04:33:38 04:33:34 04:33:42 04:33:05 04:33:42 So something is definitely going on. Whether it has to do with this specific document tripping up the server, the download.php page’s code, or if we’re just seeing the evidence of some server level overload as it plays out in real time I’m not yet sure. In fairness, there are other instances of people downloading /download.php?id=/ZZ/n+aH55Y= (the same PDF) without error. However, it is interesting that the multiple processes only seem to happen with this one file, and then only when it is accessed through the page http://site.com/press+125.php . It bears further investigation if there’s something amiss inside the code that causes the system to fire off multiple download requests that occupy the server. I don't know if this press+125.php is a rabbit hole, but there is weird consicence. Any ideas? I'm totally out of ideas. Apache maxed out? Things like that. ///DOWNLOAD.php $file = new files(); $file->comparison_filter("id", "=", $id); //sql to load if ($file->load()) { $file->serve(); } //FILES function serve() { if ($this->is_loaded) { if (file_exists($this->get_value("filename"))) { if ($this->get_value("content_type") != "") { header("Content-Type: " . $this->get_value("content_type")); } header("Content-Length: " . filesize($this->get_value("filename"))); if ($this->get_value("flag_image") == 0 || $this->get_value("flag_image") == false) { header("Cache-Control: private"); header("Content-Disposition: attachment; filename=" . urlencode($this->get_value("original_filename"))); } set_time_limit(0); @readfile($this->get_value("filename")); exit; } } }

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• How to design a high-level application protocol for metadata syncing between devices and server?

  - by Jaanus

  I am looking for guidance on how to best think about designing a high-level application protocol to sync metadata between end-user devices and a server. My goal: the user can interact with the application data on any device, or on the web. The purpose of this protocol is to communicate changes made on one endpoint to other endpoints through the server, and ensure all devices maintain a consistent picture of the application data. If user makes changes on one device or on the web, the protocol will push data to the central repository, from where other devices can pull it. Some other design thoughts: I call it "metadata syncing" because the payloads will be quite small, in the form of object IDs and small metadata about those ID-s. When client endpoints retrieve new metadata over this protocol, they will fetch actual object data from an external source based on this metadata. Fetching the "real" object data is out of scope, I'm only talking about metadata syncing here. Using HTTP for transport and JSON for payload container. The question is basically about how to best design the JSON payload schema. I want this to be easy to implement and maintain on the web and across desktop and mobile devices. The best approach feels to be simple timer- or event-based HTTP request/response without any persistent channels. Also, you should not have a PhD to read it, and I want my spec to fit on 2 pages, not 200. Authentication and security are out of scope for this question: assume that the requests are secure and authenticated. The goal is eventual consistency of data on devices, it is not entirely realtime. For example, user can make changes on one device while being offline. When going online again, user would perform "sync" operation to push local changes and retrieve remote changes. Having said that, the protocol should support both of these modes of operation: Starting from scratch on a device, should be able to pull the whole metadata picture "sync as you go". When looking at the data on two devices side by side and making changes, should be easy to push those changes as short individual messages which the other device can receive near-realtime (subject to when it decides to contact server for sync). As a concrete example, you can think of Dropbox (it is not what I'm working on, but it helps to understand the model): on a range of devices, the user can manage a files and folders—move them around, create new ones, remove old ones etc. And in my context the "metadata" would be the file and folder structure, but not the actual file contents. And metadata fields would be something like file/folder name and time of modification (all devices should see the same time of modification). Another example is IMAP. I have not read the protocol, but my goals (minus actual message bodies) are the same. Feels like there are two grand approaches how this is done: transactional messages. Each change in the system is expressed as delta and endpoints communicate with those deltas. Example: DVCS changesets. REST: communicating the object graph as a whole or in part, without worrying so much about the individual atomic changes. What I would like in the answers: Is there anything important I left out above? Constraints, goals? What is some good background reading on this? (I realize this is what many computer science courses talk about at great length and detail... I am hoping to short-circuit it by looking at some crash course or nuggets.) What are some good examples of such protocols that I could model after, or even use out of box? (I mention Dropbox and IMAP above... I should probably read the IMAP RFC.)

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• "C variable type sizes are machine dependent." Is it really true? signed & unsigned numbers ;

  - by claws

  Hello, I've been told that C types are machine dependent. Today I wanted to verify it. void legacyTypes() { /* character types */ char k_char = 'a'; //Signedness --> signed & unsigned signed char k_char_s = 'a'; unsigned char k_char_u = 'a'; /* integer types */ int k_int = 1; /* Same as "signed int" */ //Signedness --> signed & unsigned signed int k_int_s = -2; unsigned int k_int_u = 3; //Size --> short, _____, long, long long short int k_s_int = 4; long int k_l_int = 5; long long int k_ll_int = 6; /* real number types */ float k_float = 7; double k_double = 8; } I compiled it on a 32-Bit machine using minGW C compiler _legacyTypes: pushl %ebp movl %esp, %ebp subl $48, %esp movb $97, -1(%ebp) # char movb $97, -2(%ebp) # signed char movb $97, -3(%ebp) # unsigned char movl $1, -8(%ebp) # int movl $-2, -12(%ebp)# signed int movl $3, -16(%ebp) # unsigned int movw $4, -18(%ebp) # short int movl $5, -24(%ebp) # long int movl $6, -32(%ebp) # long long int movl $0, -28(%ebp) movl $0x40e00000, %eax movl %eax, -36(%ebp) fldl LC2 fstpl -48(%ebp) leave ret I compiled the same code on 64-Bit processor (Intel Core 2 Duo) on GCC (linux) legacyTypes: .LFB2: .cfi_startproc pushq %rbp .cfi_def_cfa_offset 16 movq %rsp, %rbp .cfi_offset 6, -16 .cfi_def_cfa_register 6 movb $97, -1(%rbp) # char movb $97, -2(%rbp) # signed char movb $97, -3(%rbp) # unsigned char movl $1, -12(%rbp) # int movl $-2, -16(%rbp)# signed int movl $3, -20(%rbp) # unsigned int movw $4, -6(%rbp) # short int movq $5, -32(%rbp) # long int movq $6, -40(%rbp) # long long int movl $0x40e00000, %eax movl %eax, -24(%rbp) movabsq $4620693217682128896, %rax movq %rax, -48(%rbp) leave ret Observations char, signed char, unsigned char, int, unsigned int, signed int, short int, unsigned short int, signed short int all occupy same no. of bytes on both 32-Bit & 64-Bit Processor. The only change is in long int & long long int both of these occupy 32-bit on 32-bit machine & 64-bit on 64-bit machine. And also the pointers, which take 32-bit on 32-bit CPU & 64-bit on 64-bit CPU. Questions: I cannot say, what the books say is wrong. But I'm missing something here. What exactly does "Variable types are machine dependent mean?" As you can see, There is no difference between instructions for unsigned & signed numbers. Then how come the range of numbers that can be addressed using both is different? I was reading http://stackoverflow.com/questions/2511246/how-to-maintain-fixed-size-of-c-variable-types-over-different-machines I didn't get the purpose of the question or their answers. What maintaining fixed size? They all are the same. I didn't understand how those answers are going to ensure the same size.

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• how to avoid sub-query to gain performance

  - by chun

  hi i have a reporting query which have 2 long sub-query SELECT r1.code_centre, r1.libelle_centre, r1.id_equipe, r1.equipe, r1.id_file_attente, r1.libelle_file_attente,r1.id_date, r1.tranche, r1.id_granularite_de_periode,r1.granularite, r1.ContactsTraites, r1.ContactsenParcage, r1.ContactsenComm, r1.DureeTraitementContacts, r1.DureeComm, r1.DureeParcage, r2.AgentsConnectes, r2.DureeConnexion, r2.DureeTraitementAgents, r2.DureePostTraitement FROM ( SELECT cc.id_centre_contact, cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe, a.id_file_attente, f.libelle_file_attente, a.id_date, g.tranche, g.id_granularite_de_periode, g.granularite, sum(Nb_Contacts_Traites) as ContactsTraites, sum(Nb_Contacts_en_Parcage) as ContactsenParcage, sum(Nb_Contacts_en_Communication) as ContactsenComm, sum(Duree_Traitement/1000) as DureeTraitementContacts, sum(Duree_Communication / 1000 + Duree_Conference / 1000 + Duree_Com_Interagent / 1000) as DureeComm, sum(Duree_Parcage/1000) as DureeParcage FROM agr_synthese_activite_media_fa_agent a, centre_contact cc, direction_contact dc, granularite_de_periode g, media m, file_attente f WHERE m.id_media = a.id_media AND cc.id_centre_contact = a.id_centre_contact AND a.id_direction_contact = dc.id_direction_contact AND dc.direction_contact ='INCOMING' AND a.id_file_attente = f.id_file_attente AND m.media = 'PHONE' AND ( ( g.valeur_min = date_format(a.id_date,'%d/%m') and g.granularite = 'Jour') or ( g.granularite = 'Heure' and a.id_th_heure = g.id_granularite_de_periode) ) GROUP by cc.id_centre_contact, a.id_equipe, a.id_file_attente, a.id_date, g.tranche, g.id_granularite_de_periode) r1, ( (SELECT cc.id_centre_contact,cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe, a.id_date, g.tranche, g.id_granularite_de_periode,g.granularite, count(distinct a.id_agent) as AgentsConnectes, sum(Duree_Connexion / 1000) as DureeConnexion, sum(Duree_en_Traitement / 1000) as DureeTraitementAgents, sum(Duree_en_PostTraitement / 1000) as DureePostTraitement FROM activite_agent a, centre_contact cc, granularite_de_periode g WHERE ( g.valeur_min = date_format(a.id_date,'%d/%m') and g.granularite = 'Jour') AND cc.id_centre_contact = a.id_centre_contact GROUP BY cc.id_centre_contact, a.id_equipe, a.id_date, g.tranche, g.id_granularite_de_periode ) UNION (SELECT cc.id_centre_contact,cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe, a.id_date, g.tranche, g.id_granularite_de_periode,g.granularite, count(distinct a.id_agent) as AgentsConnectes, sum(Duree_Connexion / 1000) as DureeConnexion, sum(Duree_en_Traitement / 1000) as DureeTraitementAgents, sum(Duree_en_PostTraitement / 1000) as DureePostTraitement FROM activite_agent a, centre_contact cc, granularite_de_periode g WHERE ( g.granularite = 'Heure' AND a.id_th_heure = g.id_granularite_de_periode) AND cc.id_centre_contact = a.id_centre_contact GROUP BY cc.id_centre_contact,a.id_equipe, a.id_date, g.tranche, g.id_granularite_de_periode) ) r2 WHERE r1.id_centre_contact = r2.id_centre_contact AND r1.id_equipe = r2.id_equipe AND r1.id_date = r2.id_date AND r1.tranche = r2.tranche AND r1.id_granularite_de_periode = r2.id_granularite_de_periode GROUP BY r1.id_centre_contact , r1.id_equipe, r1.id_file_attente, r1.id_date, r1.tranche, r1.id_granularite_de_periode ORDER BY r1.code_centre, r1.libelle_centre, r1.equipe, r1.libelle_file_attente, r1.id_date, r1.id_granularite_de_periode,r1.tranche the EXPLAIN shows | id | select_type | table | type| possible_keys | key | key_len | ref| rows | Extra | '1', 'PRIMARY', '<derived3>', 'ALL', NULL, NULL, NULL, NULL, '2520', 'Using temporary; Using filesort' '1', 'PRIMARY', '<derived2>', 'ALL', NULL, NULL, NULL, NULL, '4378', 'Using where; Using join buffer' '3', 'DERIVED', 'a', 'ALL', 'fk_Activite_Agent_centre_contact', NULL, NULL, NULL, '83433', 'Using temporary; Using filesort' '3', 'DERIVED', 'g', 'ref', 'Index_granularite,Index_Valeur_min', 'Index_Valeur_min', '23', 'func', '1', 'Using where' '3', 'DERIVED', 'cc', 'ALL', 'PRIMARY', NULL, NULL, NULL, '6', 'Using where; Using join buffer' '4', 'UNION', 'g', 'ref', 'PRIMARY,Index_granularite', 'Index_granularite', '23', '', '24', 'Using where; Using temporary; Using filesort' '4', 'UNION', 'a', 'ref', 'fk_Activite_Agent_centre_contact,fk_activite_agent_TH_heure', 'fk_activite_agent_TH_heure', '5', 'reporting_acd.g.Id_Granularite_de_periode', '2979', 'Using where' '4', 'UNION', 'cc', 'ALL', 'PRIMARY', NULL, NULL, NULL, '6', 'Using where; Using join buffer' NULL, 'UNION RESULT', '<union3,4>', 'ALL', NULL, NULL, NULL, NULL, NULL, '' '2', 'DERIVED', 'g', 'range', 'PRIMARY,Index_granularite,Index_Valeur_min', 'Index_granularite', '23', NULL, '389', 'Using where; Using temporary; Using filesort' '2', 'DERIVED', 'a', 'ALL', 'fk_agr_synthese_activite_media_fa_agent_centre_contact,fk_agr_synthese_activite_media_fa_agent_direction_contact,fk_agr_synthese_activite_media_fa_agent_file_attente,fk_agr_synthese_activite_media_fa_agent_media,fk_agr_synthese_activite_media_fa_agent_th_heure', NULL, NULL, NULL, '20903', 'Using where; Using join buffer' '2', 'DERIVED', 'cc', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Centre_Contact', '1', '' '2', 'DERIVED', 'f', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_File_Attente', '1', '' '2', 'DERIVED', 'dc', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Direction_Contact', '1', 'Using where' '2', 'DERIVED', 'm', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Media', '1', 'Using where' don't know it very clear, but i think is the problem of seems it take full scaning than i change all the sub-query to views(create view as select sub-query), and the result is the same thanks for any advice

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• Data adapter not filling my dataset

  - by Doug Ancil

  I have the following code: Imports System.Data.SqlClient Public Class Main Protected WithEvents DataGridView1 As DataGridView Dim instForm2 As New Exceptions Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles startpayrollButton.Click Dim ssql As String = "select MAX(payrolldate) AS [payrolldate], " & _ "dateadd(dd, ((datediff(dd, '17530107', MAX(payrolldate))/7)*7)+7, '17530107') AS [Sunday]" & _ "from dbo.payroll" & _ " where payrollran = 'no'" Dim oCmd As System.Data.SqlClient.SqlCommand Dim oDr As System.Data.SqlClient.SqlDataReader oCmd = New System.Data.SqlClient.SqlCommand Try With oCmd .Connection = New System.Data.SqlClient.SqlConnection("Initial Catalog=mdr;Data Source=xxxxx;uid=xxxxx;password=xxxxx") .Connection.Open() .CommandType = CommandType.Text .CommandText = ssql oDr = .ExecuteReader() End With If oDr.Read Then payperiodstartdate = oDr.GetDateTime(1) payperiodenddate = payperiodstartdate.AddSeconds(604799) Dim ButtonDialogResult As DialogResult ButtonDialogResult = MessageBox.Show(" The Next Payroll Start Date is: " & payperiodstartdate.ToString() & System.Environment.NewLine & " Through End Date: " & payperiodenddate.ToString()) If ButtonDialogResult = Windows.Forms.DialogResult.OK Then exceptionsButton.Enabled = True startpayrollButton.Enabled = False End If End If oDr.Close() oCmd.Connection.Close() Catch ex As Exception MessageBox.Show(ex.Message) oCmd.Connection.Close() End Try End Sub Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exceptionsButton.Click Dim connection As System.Data.SqlClient.SqlConnection Dim adapter As System.Data.SqlClient.SqlDataAdapter = New System.Data.SqlClient.SqlDataAdapter Dim connectionString As String = "Initial Catalog=mdr;Data Source=xxxxx;uid=xxxxx;password=xxxxx" Dim ds As New DataSet Dim _sql As String = "SELECT [Exceptions].Employeenumber,[Exceptions].exceptiondate, [Exceptions].starttime, [exceptions].endtime, [Exceptions].code, datediff(minute, starttime, endtime) as duration INTO scratchpad3" & _ " FROM Employees INNER JOIN Exceptions ON [Exceptions].EmployeeNumber = [Exceptions].Employeenumber" & _ " where [Exceptions].exceptiondate between @payperiodstartdate and @payperiodenddate" & _ " GROUP BY [Exceptions].Employeenumber, [Exceptions].Exceptiondate, [Exceptions].starttime, [exceptions].endtime," & _ " [Exceptions].code, [Exceptions].exceptiondate" connection = New SqlConnection(connectionString) connection.Open() Dim _CMD As SqlCommand = New SqlCommand(_sql, connection) _CMD.Parameters.AddWithValue("@payperiodstartdate", payperiodstartdate) _CMD.Parameters.AddWithValue("@payperiodenddate", payperiodenddate) adapter.SelectCommand = _CMD Try adapter.Fill(ds) If ds Is Nothing OrElse ds.Tables.Count = 0 OrElse ds.Tables(0).Rows.Count = 0 Then 'it's empty MessageBox.Show("There was no data for this time period. Press Ok to continue", "No Data") connection.Close() Exceptions.saveButton.Enabled = False Exceptions.Hide() Else connection.Close() End If Catch ex As Exception MessageBox.Show(ex.ToString) connection.Close() End Try Exceptions.Show() End Sub Private Sub payrollButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles payrollButton.Click Payrollfinal.Show() End Sub End Class and when I run my program and press this button Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exceptionsButton.Click I have my date range within a time that I know that my dataset should produce a result, but when I put a line break in my code here: adapter.Fill(ds) and look at it in debug, I show a table value of 0. If I run the same query that I have to produce these results in sql analyser, I see 1 result. Can someone see why my query on my form produces a different result than the sql analyser does? Also here is my schema for my two tables: Exceptions employeenumber varchar no 50 yes no no SQL_Latin1_General_CP1_CI_AS exceptiondate datetime no 8 yes (n/a) (n/a) NULL starttime datetime no 8 yes (n/a) (n/a) NULL endtime datetime no 8 yes (n/a) (n/a) NULL duration varchar no 50 yes no no SQL_Latin1_General_CP1_CI_AS code varchar no 50 yes no no SQL_Latin1_General_CP1_CI_AS approvedby varchar no 50 yes no no SQL_Latin1_General_CP1_CI_AS approved varchar no 50 yes no no SQL_Latin1_General_CP1_CI_AS time timestamp no 8 yes (n/a) (n/a) NULL employees employeenumber varchar no 50 no no no SQL_Latin1_General_CP1_CI_AS name varchar no 50 no no no SQL_Latin1_General_CP1_CI_AS initials varchar no 50 no no no SQL_Latin1_General_CP1_CI_AS loginname1 varchar no 50 yes no no SQL_Latin1_General_CP1_CI_AS

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• trie reg exp parse step over char and continue

  - by forest.peterson

  Setup: 1) a string trie database formed from linked nodes and a vector array linking to the next node terminating in a leaf, 2) a recursive regular expression function that if A) char '*' continues down all paths until string length limit is reached, then continues down remaining string paths if valid, and B) char '?' continues down all paths for 1 char and then continues down remaining string paths if valid. 3) after reg expression the candidate strings are measured for edit distance against the 'try' string. Problem: the reg expression works fine for adding chars or swapping ? for a char but if the remaining string has an error then there is not a valid path to a terminating leaf; making the matching function redundant. I tried adding a 'step-over' ? char if the end of the node vector was reached and then followed every path of that node - allowing this step-over only once; resulted in a memory exception; I cannot find logically why it is accessing the vector out of range - bactracking? Questions: 1) how can the regular expression step over an invalid char and continue with the path? 2) why is swapping the 'sticking' char for '?' resulting in an overflow? Function: void Ontology::matchRegExpHelper(nodeT *w, string inWild, Set<string> &matchSet, string out, int level, int pos, int stepover) { if (inWild=="") { matchSet.add(out); } else { if (w->alpha.size() == pos) { int testLength = out.length() + inWild.length(); if (stepover == 0 && matchSet.size() == 0 && out.length() > 8 && testLength == tokenLength) {//candidate generator inWild[0] = '?'; matchRegExpHelper(w, inWild, matchSet, out, level, 0, stepover+1); } else return; //giveup on this path } if (inWild[0] == '?' || (inWild[0] == '*' && (out.length() + inWild.length() ) == level ) ) { //wild matchRegExpHelper(w->alpha[pos].next, inWild.substr(1), matchSet, out+w->alpha[pos].letter, level, 0, stepover);//follow path -> if ontology is full, treat '*' like a '?' } else if (inWild[0] == '*') matchRegExpHelper(w->alpha[pos].next, '*'+inWild.substr(1), matchSet, out+w->alpha[pos].letter, level, 0, stepover); //keep adding chars if (inWild[0] == w->alpha[pos].letter) //follow self matchRegExpHelper(w->alpha[pos].next, inWild.substr(1), matchSet, out+w->alpha[pos].letter, level, 0, stepover); //follow char matchRegExpHelper(w, inWild, matchSet, out, level, pos+1, stepover);//check next path } } Error Message: +str "Attempt to access index 1 in a vector of size 1." std::basic_string<char,std::char_traits<char>,std::allocator<char> > +err {msg="Attempt to access index 1 in a vector of size 1." } ErrorException Note: this function works fine for hundreds of test strings with '*' wilds if the extra stepover gate is not used Semi-Solved: I place a pos < w->alpha.size() condition on each path that calls w->alpha[pos]... - this prevented the backtrack calls from attempting to access the vector with an out of bounds index value. Still have other issues to work out - it loops infinitely adding the ? and backtracking to remove it, then repeat. But, moving forward now. Revised question: why during backtracking is the position index accumulating and/or not deincrementing - so at somepoint it calls w->alpha[pos]... with an invalid position that is either remaining from the next node or somehow incremented pos+1 when passing upward?

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• Push notification not received in ios5 device

  - by Surender Rathore

  I am sending push notification on device which has iOS 5.0.1, but notification is not received on iOS5 device. If i try to send notification on iOS4.3.3 device, it received on this device. My server is developed in c# and apple push notification certificate is used in .p12 format. My code to register the notification is - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { // Override point for customization after application launch. // Set the navigation controller as the window's root view controller and display. deviceToken = nil; self.window.rootViewController = self.navigationController; [self.window makeKeyAndVisible]; [[UIApplication sharedApplication] enabledRemoteNotificationTypes]; [[UIApplication sharedApplication] registerForRemoteNotificationTypes: UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound | UIRemoteNotificationTypeAlert]; return YES; } - (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)devToken { UIAlertView *alertView=[[UIAlertView alloc]initWithTitle:@"Succeeded in registering for APNS" message:@"Sucess" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alertView show]; [alertView release]; deviceToken = [devToken retain]; NSMutableString *dev = [[NSMutableString alloc] init]; NSRange r; r.length = 1; unsigned char c; for (int i = 0; i < [deviceToken length]; i++) { r.location = i; [deviceToken getBytes:&c range:r]; if (c < 10) { [dev appendFormat:@"0%x", c]; } else { [dev appendFormat:@"%x", c]; } } NSUserDefaults *def = [NSUserDefaults standardUserDefaults]; [def setObject:dev forKey:@"DeviceToken"]; [def synchronize]; NSLog(@"Registered for APNS %@\n%@", deviceToken, dev); [dev release]; } - (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error { NSLog(@"Failed to register %@", [error localizedDescription]); UIAlertView *alertView=[[UIAlertView alloc]initWithTitle:@"FAILED" message:@"Fail" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alertView show]; [alertView release]; deviceToken = nil; } - (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo { NSLog(@"Recieved Remote Notification %@", userInfo); NSDictionary *aps = [userInfo objectForKey:@"aps"]; NSDictionary *alert = [aps objectForKey:@"alert"]; //NSString *actionLocKey = [alert objectForKey:@"action-loc-key"]; NSString *body = [alert objectForKey:@"body"]; // NSMutableArray *viewControllers = [NSMutableArray arrayWithArray:[self.navigationController viewControllers]]; // // if ([viewControllers count] > 2) { // NSRange r; // r.length = [viewControllers count] - 2; // r.location = 2; // [viewControllers removeObjectsInRange:r]; // // MapViewController *map = (MapViewController*)[viewControllers objectAtIndex:1]; // [map askDriver]; // } // // [self.navigationController setViewControllers:viewControllers]; // [viewControllers release]; //NewBooking,"BookingId",Passenger_latitude,Passenger_longitude,Destination_latitude,Destination_longitude,Distance,Time,comments NSArray *arr = [body componentsSeparatedByString:@","]; if ([arr count]>0) { MapViewController *map = (MapViewController*)[[self.navigationController viewControllers] objectAtIndex:1]; [map askDriver:arr]; [self.navigationController popToViewController:[[self.navigationController viewControllers] objectAtIndex:1] animated:YES]; } //NSString *sound = [userInfo objectForKey:@"sound"]; //UIAlertView *alertV = [[UIAlertView alloc] initWithTitle:actionLocKey // message:body delegate:nil // cancelButtonTitle:@"Reject" // otherButtonTitles:@"Accept", nil]; // // [alertV show]; // [alertV release]; } Can anyone help me out with this issue. Why notification received on iOS4.3 device but not on iOS5? Thank you very much!!! in advance

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• Java code optimization leads to numerical inaccuracies and errors

  - by rano

  I'm trying to implement a version of the Fuzzy C-Means algorithm in Java and I'm trying to do some optimization by computing just once everything that can be computed just once. This is an iterative algorithm and regarding the updating of a matrix, the clusters x pixels membership matrix U, this is the update rule I want to optimize: where the x are the element of a matrix X (pixels x features) and v belongs to the matrix V (clusters x features). And m is a parameter that ranges from 1.1 to infinity. The distance used is the euclidean norm. If I had to implement this formula in a banal way I'd do: for(int i = 0; i < X.length; i++) { int count = 0; for(int j = 0; j < V.length; j++) { double num = D[i][j]; double sumTerms = 0; for(int k = 0; k < V.length; k++) { double thisDistance = D[i][k]; sumTerms += Math.pow(num / thisDistance, (1.0 / (m - 1.0))); } U[i][j] = (float) (1f / sumTerms); } } In this way some optimization is already done, I precomputed all the possible squared distances between X and V and stored them in a matrix D but that is not enough, since I'm cycling througn the elements of V two times resulting in two nested loops. Looking at the formula the numerator of the fraction is independent of the sum so I can compute numerator and denominator independently and the denominator can be computed just once for each pixel. So I came to a solution like this: int nClusters = V.length; double exp = (1.0 / (m - 1.0)); for(int i = 0; i < X.length; i++) { int count = 0; for(int j = 0; j < nClusters; j++) { double distance = D[i][j]; double denominator = D[i][nClusters]; double numerator = Math.pow(distance, exp); U[i][j] = (float) (1f / (numerator * denominator)); } } Where I precomputed the denominator into an additional column of the matrix D while I was computing the distances: for (int i = 0; i < X.length; i++) { for (int j = 0; j < V.length; j++) { double sum = 0; for (int k = 0; k < nDims; k++) { final double d = X[i][k] - V[j][k]; sum += d * d; } D[i][j] = sum; D[i][B.length] += Math.pow(1 / D[i][j], exp); } } By doing so I encounter numerical differences between the 'banal' computation and the second one that leads to different numerical value in U (not in the first iterates but soon enough). I guess that the problem is that exponentiate very small numbers to high values (the elements of U can range from 0.0 to 1.0 and exp , for m = 1.1, is 10) leads to ver y small values, whereas by dividing the numerator and the denominator and THEN exponentiating the result seems to be better numerically. The problem is it involves much more operations. Am I doing something wrong? Is there a possible solution to get both the code optimized and numerically stable? Any suggestion or criticism will be appreciated.

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• How to reduce virtual memory by optimising my PHP code?

  - by iCeR

  My current code (see below) uses 147MB of virtual memory! My provider has allocated 100MB by default and the process is killed once run, causing an internal error. The code is utilising curl multi and must be able to loop with more than 150 iterations whilst still minimizing the virtual memory. The code below is only set at 150 iterations and still causes the internal server error. At 90 iterations the issue does not occur. How can I adjust my code to lower the resource use / virtual memory? Thanks! <?php function udate($format, $utimestamp = null) { if ($utimestamp === null) $utimestamp = microtime(true); $timestamp = floor($utimestamp); $milliseconds = round(($utimestamp - $timestamp) * 1000); return date(preg_replace('`(?<!\\\\)u`', $milliseconds, $format), $timestamp); } $url = 'https://www.testdomain.com/'; $curl_arr = array(); $master = curl_multi_init(); for($i=0; $i<150; $i++) { $curl_arr[$i] = curl_init(); curl_setopt($curl_arr[$i], CURLOPT_URL, $url); curl_setopt($curl_arr[$i], CURLOPT_RETURNTRANSFER, 1); curl_setopt($curl_arr[$i], CURLOPT_SSL_VERIFYHOST, FALSE); curl_setopt($curl_arr[$i], CURLOPT_SSL_VERIFYPEER, FALSE); curl_multi_add_handle($master, $curl_arr[$i]); } do { curl_multi_exec($master,$running); } while($running > 0); for($i=0; $i<150; $i++) { $results = curl_multi_getcontent ($curl_arr[$i]); $results = explode("<br>", $results); echo $results[0]; echo "<br>"; echo $results[1]; echo "<br>"; echo udate('H:i:s:u'); echo "<br><br>"; usleep(100000); } ?> Processor Information Total processors: 8 Processor #1 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #2 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #3 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #4 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #5 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #6 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #7 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Processor #8 Vendor GenuineIntel Name Intel(R) Xeon(R) CPU E5405 @ 2.00GHz Speed 1995.120 MHz Cache 6144 KB Memory Information Memory for crash kernel (0x0 to 0x0) notwithin permissible range Memory: 8302344k/9175040k available (2176k kernel code, 80272k reserved, 901k data, 228k init, 7466304k highmem) System Information Linux server3.server.com 2.6.18-194.17.1.el5PAE #1 SMP Wed Sep 29 13:31:51 EDT 2010 i686 i686 i386 GNU/Linux Physical Disks SCSI device sda: 1952448512 512-byte hdwr sectors (999654 MB) sda: Write Protect is off sda: Mode Sense: 03 00 00 08 SCSI device sda: drive cache: write back SCSI device sda: 1952448512 512-byte hdwr sectors (999654 MB) sda: Write Protect is off sda: Mode Sense: 03 00 00 08 SCSI device sda: drive cache: write back sd 0:1:0:0: Attached scsi disk sda sd 4:0:0:0: Attached scsi removable disk sdb sd 0:1:0:0: Attached scsi generic sg4 type 0 sd 4:0:0:0: Attached scsi generic sg7 type 0 Current Memory Usage total used free shared buffers cached Mem: 8306672 7847384 459288 0 487912 6444548 -/+ buffers/cache: 914924 7391748 Swap: 4095992 496 4095496 Total: 12402664 7847880 4554784 Current Disk Usage Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 898G 307G 546G 36% / /dev/sda1 99M 19M 76M 20% /boot none 4.0G 0 4.0G 0% /dev/shm /var/tmpMnt 4.0G 1.8G 2.0G 48% /tmp

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• shop by brand name in magento

  - by Jyotiranjan

  This is brand.php file having directory local/Vilpjsc/brand/Block.I want the brand name with logo(image) sholud display on home page .But I am getting the error i.e Fatal error: Call to a member function getCollection() on a non-object in /var/www/magentodemo/app/code/local/Vilpjsc/Brand/Block/Brand.php on line 25 <?php class Vilpjsc_Brand_Block_Brand extends Mage_Core_Block_Template { public function _prepareLayout() { return parent::_prepareLayout(); } //Get Collection from Brand Controller public function getBrand() { if (!$this->hasData('brand')) { $this->setData('brand', Mage::registry('brand')); } return $this->getData('brand'); } //Get Brand Featured Collection public function getFeaturedBrand() { return $this->getBrand()->getCollection()->setPageSize(12)->addFilter('status', '1'); } public function resizeImage($img,$width=100, $height=60) { if (!file_exists("./media/brand/resized")) mkdir("./media/brand/resized", 0777); $imageResized = Mage::getBaseDir('media') . DS . "brand" . DS . "resized" . DS . $width."x".$height.$img; if (!file_exists($imageResized) && file_exists("./media/brand/" . $img)) { $imageObj = new Varien_Image("./media/brand/" . $img); $imageObj->constrainOnly(TRUE); $imageObj->keepAspectRatio(TRUE); $imageObj->keepFrame(FALSE); $imageObj->resize($width, $height); $imageObj->save($imageResized); } $newImageUrl = Mage::getBaseUrl('media')."brand/resized/".$width."x".$height.$img; return $newImageUrl; } public function getNormalBrand() { return $this->getBrand()->getCollection()->addFilter('status', '0'); } public function getBrandChar() { extract($this->getBrandKey()); return $this->getBrand()->getCollection()->saveBrandcollection($char); } //Create Alphabet navigation public function navigation() { extract($this->getBrandKey()); $alphas = range('A', 'Z'); $navigation = ""; $digitClass = ""; foreach ($alphas as $key) { if ($char == $key) $class_key = "current_char"; else $class_key=""; $navigation .= "<li class='key_item " . $class_key . "'><a href='" . Mage::getBaseUrl() . "brand/index/index/brand_key/" . $key . "'>" . $key . "</a></li>"; } if ($char == "digit") { $digitClass = "current_char"; } elseif ($char == "all") $allClass = "current_char"; $navigation = "<li class='key_item " . $digitClass . "'><a href='" . Mage::getBaseUrl() . "brand/index/index/brand_key/digit'>#</a></li>" . $navigation; return $navigation; } //Get request for brand block public function getBrandKey() { $brand_key = Mage::registry('brand_key'); if ($brand_key) { $char = $brand_key->getParam('brand_key') ? $brand_key->getParam('brand_key') : 'A'; $option_id = $brand_key->getParam('option_id') ? $brand_key->getParam('option_id') : '1'; $brand = $brand_key->getParam('brand') ? $brand_key->getParam('brand') : 'Nike'; } else { $char = 'digit'; $option_id = '544'; } return compact('char', 'option_id', 'brand'); } }

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• Control XML serialization of Dictionary<K, T>

  - by Luca

  I'm investigating about XML serialization, and since I use lot of dictionary, I would like to serialize them as well. I found the following solution for that (I'm quite proud of it! :) ). [XmlInclude(typeof(Foo))] public class XmlDictionary<TKey, TValue> { /// <summary> /// Key/value pair. /// </summary> public struct DictionaryItem { /// <summary> /// Dictionary item key. /// </summary> public TKey Key; /// <summary> /// Dictionary item value. /// </summary> public TValue Value; } /// <summary> /// Dictionary items. /// </summary> public DictionaryItem[] Items { get { List<DictionaryItem> items = new List<DictionaryItem>(ItemsDictionary.Count); foreach (KeyValuePair<TKey, TValue> pair in ItemsDictionary) { DictionaryItem item; item.Key = pair.Key; item.Value = pair.Value; items.Add(item); } return (items.ToArray()); } set { ItemsDictionary = new Dictionary<TKey,TValue>(); foreach (DictionaryItem item in value) ItemsDictionary.Add(item.Key, item.Value); } } /// <summary> /// Indexer base on dictionary key. /// </summary> /// <param name="key"></param> /// <returns></returns> public TValue this[TKey key] { get { return (ItemsDictionary[key]); } set { Debug.Assert(value != null); ItemsDictionary[key] = value; } } /// <summary> /// Delegate for get key from a dictionary value. /// </summary> /// <param name="value"></param> /// <returns></returns> public delegate TKey GetItemKeyDelegate(TValue value); /// <summary> /// Add a range of values automatically determining the associated keys. /// </summary> /// <param name="values"></param> /// <param name="keygen"></param> public void AddRange(IEnumerable<TValue> values, GetItemKeyDelegate keygen) { foreach (TValue v in values) ItemsDictionary.Add(keygen(v), v); } /// <summary> /// Items dictionary. /// </summary> [XmlIgnore] public Dictionary<TKey, TValue> ItemsDictionary = new Dictionary<TKey,TValue>(); } The classes deriving from this class are serialized in the following way: <FooDictionary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Items> <DictionaryItemOfInt32Foo> <Key/> <Value/> </DictionaryItemOfInt32XmlProcess> <Items> This give me a good solution, but: How can I control the name of the element DictionaryItemOfInt32Foo What happens if I define a Dictionary<FooInt32, Int32> and I have the classes Foo and FooInt32? Is it possible to optimize the class above? THank you very much!

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• Control XML serialization of generic types

  - by Luca

  I'm investigating about XML serialization, and since I use lot of dictionary, I would like to serialize them as well. I found the following solution for that (I'm quite proud of it! :) ). [XmlInclude(typeof(Foo))] public class XmlDictionary<TKey, TValue> { /// <summary> /// Key/value pair. /// </summary> public struct DictionaryItem { /// <summary> /// Dictionary item key. /// </summary> public TKey Key; /// <summary> /// Dictionary item value. /// </summary> public TValue Value; } /// <summary> /// Dictionary items. /// </summary> public DictionaryItem[] Items { get { List<DictionaryItem> items = new List<DictionaryItem>(ItemsDictionary.Count); foreach (KeyValuePair<TKey, TValue> pair in ItemsDictionary) { DictionaryItem item; item.Key = pair.Key; item.Value = pair.Value; items.Add(item); } return (items.ToArray()); } set { ItemsDictionary = new Dictionary<TKey,TValue>(); foreach (DictionaryItem item in value) ItemsDictionary.Add(item.Key, item.Value); } } /// <summary> /// Indexer base on dictionary key. /// </summary> /// <param name="key"></param> /// <returns></returns> public TValue this[TKey key] { get { return (ItemsDictionary[key]); } set { Debug.Assert(value != null); ItemsDictionary[key] = value; } } /// <summary> /// Delegate for get key from a dictionary value. /// </summary> /// <param name="value"></param> /// <returns></returns> public delegate TKey GetItemKeyDelegate(TValue value); /// <summary> /// Add a range of values automatically determining the associated keys. /// </summary> /// <param name="values"></param> /// <param name="keygen"></param> public void AddRange(IEnumerable<TValue> values, GetItemKeyDelegate keygen) { foreach (TValue v in values) ItemsDictionary.Add(keygen(v), v); } /// <summary> /// Items dictionary. /// </summary> [XmlIgnore] public Dictionary<TKey, TValue> ItemsDictionary = new Dictionary<TKey,TValue>(); } The classes deriving from this class are serialized in the following way: <XmlProcessList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Items> <DictionaryItemOfInt32Foo> <Key/> <Value/> </DictionaryItemOfInt32XmlProcess> <Items> This give me a good solution, but: How can I control the name of the element DictionaryItemOfInt32Foo What happens if I define a Dictionary<FooInt32, Int32> and I have the classes Foo and FooInt32? Is it possible to optimize the class above? THank you very much!

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• SQL - date variable isn't being parsed correctly?

  - by Bill Sambrone

  I am pulling a list of invoices filtered by a starting and ending date, and further filtered by type of invoice from a SQL table. When I specify a range of 2013-07-01 through 2013-09-30 I am receiving 2 invoices per company when I expect 3. When I use the built in select top 1000 query in SSMS and add my date filters, all the expected invoices appear. Here is my fancy query that I'm using that utilizing variables that are fed in: DECLARE @ReportStart datetime DECLARE @ReportStop datetime SET @ReportStart = '2013-07-01' SET @ReportStop = '2013-09-30' SELECT Entity_Company.CompanyName, Reporting_AgreementTypes.Description, Reporting_Invoices.InvoiceAmount, ISNULL(Reporting_ProductCost.ProductCost,0), (Reporting_Invoices.InvoiceAmount - ISNULL(Reporting_ProductCost.ProductCost,0)), (Reporting_AgreementTypes.Description + Entity_Company.CompanyName), Reporting_Invoices.InvoiceDate FROM Reporting_Invoices JOIN Entity_Company ON Entity_Company.ClientID = Reporting_Invoices.ClientID LEFT JOIN Reporting_ProductCost ON Reporting_ProductCost.InvoiceNumber =Reporting_Invoices.InvoiceNumber JOIN Reporting_AgreementTypes ON Reporting_AgreementTypes.AgreementTypeID = Reporting_Invoices.AgreementTypeID WHERE Reporting_Invoices.AgreementTypeID = (SELECT AgreementTypeID FROM Reporting_AgreementTypes WHERE Description = 'Resold Services') AND Reporting_Invoices.InvoiceDate >= @ReportStart AND Reporting_Invoices.InvoiceDate <= @ReportStop ORDER BY CompanyName,InvoiceDate The above only returns 2 invoices per company. When I run a much more basic query through SSMS I get 3 as expected, which looks like: SELECT TOP 1000 [InvoiceID] ,[AgreementID] ,[AgreementTypeID] ,[InvoiceDate] ,[Comment] ,[InvoiceAmount] ,[InvoiceNumber] ,[TicketID] ,Entity_Company.CompanyName FROM Reporting_Invoices JOIN Entity_Company ON Entity_Company.ClientID = Reporting_Invoices.ClientID WHERE Entity_Company.ClientID = '9' AND AgreementTypeID = (SELECT AgreementTypeID FROM Reporting_AgreementTypes WHERE Description = 'Resold Services') AND Reporting_Invoices.InvoiceDate >= '2013-07-01' AND Reporting_Invoices.InvoiceDate <= '2013-09-30' ORDER BY InvoiceDate DESC I've tried stripping down the 1st query to include only a client ID on the original invoice table, the invoice date, and nothing else. Still only get 2 invoices instead of the expected 3. I've also tried manually entering the dates instead of the @ variables, same result. I confirmed that InvoiceDate is defined as a datetime in the table. I've tried making all JOIN's a FULL JOIN to see if anything is hiding, but no change. Here is how I stripped down the original query to keep all other tables out of the mix and yet I'm still getting only 2 invoices per client ID instead of 3 (I manually entered the ID for the type filter): --DECLARE @ReportStart datetime --DECLARE @ReportStop datetime --SET @ReportStart = '2013-07-01' --SET @ReportStop = '2013-09-30' SELECT --Entity_Company.CompanyName, --Reporting_AgreementTypes.Description, Reporting_Invoices.ClientID, Reporting_Invoices.InvoiceAmount, --ISNULL(Reporting_ProductCost.ProductCost,0), --(Reporting_Invoices.InvoiceAmount - ISNULL(Reporting_ProductCost.ProductCost,0)), --(Reporting_AgreementTypes.Description + Entity_Company.CompanyName), Reporting_Invoices.InvoiceDate FROM Reporting_Invoices --JOIN Entity_Company ON Entity_Company.ClientID = Reporting_Invoices.ClientID --LEFT JOIN Reporting_ProductCost ON Reporting_ProductCost.InvoiceNumber = Reporting_Invoices.InvoiceNumber --JOIN Reporting_AgreementTypes ON Reporting_AgreementTypes.AgreementTypeID = Reporting_Invoices.AgreementTypeID WHERE Reporting_Invoices.AgreementTypeID = '22'-- (SELECT AgreementTypeID FROM Reporting_AgreementTypes WHERE Description = 'Resold Services') AND Reporting_Invoices.InvoiceDate >= '2013-07-01' AND Reporting_Invoices.InvoiceDate <= '2013-09-30' ORDER BY ClientID,InvoiceDate This strikes me as really weird as it is pretty much the same query as the SSMS generated one that returns correct results. What am I overlooking? UPDATE I've further refined my "test query" that is returning only 2 invoices per company to help troubleshoot this. Below is the query and a relevant subset of data for 1 company from the appropriate tables: SELECT Reporting_Invoices.ClientID, Reporting_AgreementTypes.Description, Reporting_Invoices.InvoiceAmount, Reporting_Invoices.InvoiceDate FROM Reporting_Invoices JOIN Reporting_AgreementTypes ON Reporting_AgreementTypes.AgreementTypeID = Reporting_Invoices.AgreementTypeID WHERE Reporting_Invoices.AgreementTypeID = (SELECT AgreementTypeID FROM Reporting_AgreementTypes WHERE Description = 'Resold Services') AND Reporting_Invoices.InvoiceDate >= '2013-07-01T00:00:00' AND Reporting_Invoices.InvoiceDate <= '2013-09-30T00:00:00' ORDER BY Reporting_Invoices.ClientID,InvoiceDate The above only returns 2 invoices. Here is the relevant table data: Relevant data from Reporting_AgreementTypes AgreementTypeID Description 22 Resold Services Relevant data from Reporting_Invoices InvoiceID ClientID AgreementID AgreementTypeID InvoiceDate 16111 9 757 22 2013-09-30 00:00:00.000 15790 9 757 22 2013-08-30 00:00:00.000 15517 9 757 22 2013-07-31 00:00:00.000 Actual results from my new modified query ClientID Description InvoiceAmount InvoiceDate 9 Resold Services 3513.79 7/31/13 00:00:00 9 Resold Services 3570.49 8/30/13 00:00:00

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• Why would Linux VM in vSphere ESXi 5.5 show dramatically increased disk i/o latency?

  - by mhucka

  I'm stumped and I hope someone else will recognize the symptoms of this problem. Hardware: new Dell T110 II, dual-core Pentium G860 2.9 GHz, onboard SATA controller, one new 500 GB 7200 RPM cabled hard drive inside the box, other drives inside but not mounted yet. No RAID. Software: fresh CentOS 6.5 virtual machine under VMware ESXi 5.5.0 (build 174 + vSphere Client). 2.5 GB RAM allocated. The disk is how CentOS offered to set it up, namely as a volume inside an LVM Volume Group, except that I skipped having a separate /home and simply have / and /boot. CentOS is patched up, ESXi patched up, latest VMware tools installed in the VM. No users on the system, no services running, no files on the disk but the OS installation. I'm interacting with the VM via the VM virtual console in vSphere Client. Before going further, I wanted to check that I configured things more or less reasonably. I ran the following command as root in a shell on the VM: for i in 1 2 3 4 5 6 7 8 9 10; do dd if=/dev/zero of=/test.img bs=8k count=256k conv=fdatasync done I.e., just repeat the dd command 10 times, which results in printing the transfer rate each time. The results are disturbing. It starts off well: 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 20.451 s, 105 MB/s 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 20.4202 s, 105 MB/s ... but after 7-8 of these, it then prints 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GG) copied, 82.9779 s, 25.9 MB/s 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 84.0396 s, 25.6 MB/s 262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 103.42 s, 20.8 MB/s If I wait a significant amount of time, say 30-45 minutes, and run it again, it again goes back to 105 MB/s, and after several rounds (sometimes a few, sometimes 10+), it drops to ~20-25 MB/s again. Plotting the disk latency in vSphere's interface, it shows periods of high disk latency hitting 1.2-1.5 seconds during the times that dd reports the low throughput. (And yes, things get pretty unresponsive while that's happening.) What could be causing this? I'm comfortable that it is not due to the disk failing, because I also had configured two other disks as an additional volume in the same system. At first I thought I did something wrong with that volume, but after commenting the volume out from /etc/fstab and rebooting, and trying the tests on / as shown above, it became clear that the problem is elsewhere. It is probably an ESXi configuration problem, but I'm not very experienced with ESXi. It's probably something stupid, but after trying to figure this out for many hours over multiple days, I can't find the problem, so I hope someone can point me in the right direction. (P.S.: yes, I know this hardware combo won't win any speed awards as a server, and I have reasons for using this low-end hardware and running a single VM, but I think that's besides the point for this question [unless it's actually a hardware problem].) ADDENDUM #1: Reading other answers such as this one made me try adding oflag=direct to dd. However, it makes no difference in the pattern of results: initially the numbers are higher for many rounds, then they drop to 20-25 MB/s. (The initial absolute numbers are in the 50 MB/s range.) ADDENDUM #2: Adding sync ; echo 3 > /proc/sys/vm/drop_caches into the loop does not make a difference at all. ADDENDUM #3: To take out further variables, I now run dd such that the file it creates is larger than the amount of RAM on the system. The new command is dd if=/dev/zero of=/test.img bs=16k count=256k conv=fdatasync oflag=direct. Initial throughput numbers with this version of the command are ~50 MB/s. They drop to 20-25 MB/s when things go south. ADDENDUM #4: Here is the output of iostat -d -m -x 1 running in another terminal window while performance is "good" and then again when it's "bad". (While this is going on, I'm running dd if=/dev/zero of=/test.img bs=16k count=256k conv=fdatasync oflag=direct.) First, when things are "good", it shows this: When things go "bad", iostat -d -m -x 1 shows this:

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• How to make MySQL utilize available system resources, or find "the real problem"?

  - by anonymous coward

  This is a MySQL 5.0.26 server, running on SuSE Enterprise 10. This may be a Serverfault question. The web user interface that uses these particular queries (below) is showing sometimes 30+, even up to 120+ seconds at the worst, to generate the pages involved. On development, when the queries are run alone, they take up to 20 seconds on the first run (with no query cache enabled) but anywhere from 2 to 7 seconds after that - I assume because the tables and indexes involved have been placed into ram. From what I can tell, the longest load times are caused by Read/Update Locking. These are MyISAM tables. So it looks like a long update comes in, followed by a couple 7 second queries, and they're just adding up. And I'm fine with that explanation. What I'm not fine with is that MySQL doesn't appear to be utilizing the hardware it's on, and while the bottleneck seems to be the database, I can't understand why. I would say "throw more hardware at it", but we did and it doesn't appear to have changed the situation. Viewing a 'top' during the slowest times never shows much cpu or memory utilization by mysqld, as if the server is having no trouble at all - but then, why are the queries taking so long? How can I make MySQL use the crap out of this hardware, or find out what I'm doing wrong? Extra Details: On the "Memory Health" tab in the MySQL Administrator (for Windows), the Key Buffer is less than 1/8th used - so all the indexes should be in RAM. I can provide a screen shot of any graphs that might help. So desperate to fix this issue. Suffice it to say, there is legacy code "generating" these queries, and they're pretty much stuck the way they are. I have tried every combination of Indexes on the tables involved, but any suggestions are welcome. Here's the current Create Table statement from development (the 'experimental' key I have added, seems to help a little, for the example query only): CREATE TABLE `registration_task` ( `id` varchar(36) NOT NULL default '', `date_entered` datetime NOT NULL default '0000-00-00 00:00:00', `date_modified` datetime NOT NULL default '0000-00-00 00:00:00', `assigned_user_id` varchar(36) default NULL, `modified_user_id` varchar(36) default NULL, `created_by` varchar(36) default NULL, `name` varchar(80) NOT NULL default '', `status` varchar(255) default NULL, `date_due` date default NULL, `time_due` time default NULL, `date_start` date default NULL, `time_start` time default NULL, `parent_id` varchar(36) NOT NULL default '', `priority` varchar(255) NOT NULL default '9', `description` text, `order_number` int(11) default '1', `task_number` int(11) default NULL, `depends_on_id` varchar(36) default NULL, `milestone_flag` varchar(255) default NULL, `estimated_effort` int(11) default NULL, `actual_effort` int(11) default NULL, `utilization` int(11) default '100', `percent_complete` int(11) default '0', `deleted` tinyint(1) NOT NULL default '0', `wf_task_id` varchar(36) default '0', `reg_field` varchar(8) default '', `date_offset` int(11) default '0', `date_source` varchar(10) default '', `date_completed` date default '0000-00-00', `completed_id` varchar(36) default NULL, `original_name` varchar(80) default NULL, PRIMARY KEY (`id`), KEY `idx_reg_task_p` (`deleted`,`parent_id`), KEY `By_Assignee` (`assigned_user_id`,`deleted`), KEY `status_assignee` (`status`,`deleted`), KEY `experimental` (`deleted`,`status`,`assigned_user_id`,`parent_id`,`date_due`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 And one of the ridiculous queries in question: SELECT users.user_name assigned_user_name, registration.FIELD001 parent_name, registration_task.status status, registration_task.date_modified date_modified, registration_task.date_due date_due, registration.FIELD240 assigned_wf, if(LENGTH(registration_task.description)>0,1,0) has_description, registration_task.* FROM registration_task LEFT JOIN users ON registration_task.assigned_user_id=users.id LEFT JOIN registration ON registration_task.parent_id=registration.id where (registration_task.status != 'Completed' AND registration.FIELD001 LIKE '%' AND registration_task.name LIKE '%' AND registration.FIELD060 LIKE 'GN001472%') AND registration_task.deleted=0 ORDER BY date_due asc LIMIT 0,20; my.cnf - '[mysqld]' section. [mysqld] port = 3306 socket = /var/lib/mysql/mysql.sock skip-locking key_buffer = 384M max_allowed_packet = 100M table_cache = 2048 sort_buffer_size = 2M net_buffer_length = 100M read_buffer_size = 2M read_rnd_buffer_size = 160M myisam_sort_buffer_size = 128M query_cache_size = 16M query_cache_limit = 1M EXPLAIN above query, without additional index: +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ | 1 | SIMPLE | registration_task | ref | idx_reg_task_p,status_assignee | idx_reg_task_p | 1 | const | 1067354 | Using where; Using filesort | | 1 | SIMPLE | registration | eq_ref | PRIMARY,gbl | PRIMARY | 8 | sugarcrm401.registration_task.parent_id | 1 | Using where | | 1 | SIMPLE | users | ref | PRIMARY | PRIMARY | 38 | sugarcrm401.registration_task.assigned_user_id | 1 | | +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ EXPLAIN above query, with 'experimental' index: +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+ | 1 | SIMPLE | registration_task | range | idx_reg_task_p,status_assignee,NewIndex1,tcg_experimental | tcg_experimental | 259 | NULL | 103345 | Using where; Using filesort | | 1 | SIMPLE | registration | eq_ref | PRIMARY,gbl | PRIMARY | 8 | sugarcrm401.registration_task.parent_id | 1 | Using where | | 1 | SIMPLE | users | ref | PRIMARY | PRIMARY | 38 | sugarcrm401.registration_task.assigned_user_id | 1 | | +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+

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• Counting number of times an item occurs in a linked list

  - by HanaCHaN92

  Here is the assignment: Here's the assignment: Implement a method countValue() that counts the number of times an item occurs in a linked list. Remember to use the STL list. int countValue(list front, const int item); Generate 20 random numbers in the range of 0 to 4, and insert each number in the linked list. Output the list by using a method which you would call writeLinkedList which you would add to the ListP.cpp. In a loop, call the method countValue() , and display the number of occurrences of each value from 0 to 4 in the list. Remember that all the above is to be included in the file ListP.ccp Run: 2 3 4 0 1 0 2 4 2 3 3 4 3 3 3 0 0 2 0 2 0 : 5, 1 : 1, 2 : 5, 3 : 6, 4 : 3 and here is what I have so far: #include<iostream> #include<list> #include<tchar.h> int countValue(list<int> front, const int item); using namespace std; int _tmain(int argc, _TCHAR* argv[]){ list<int> front; int listCount; cout << "Enter the size of the list: "; cin >> listCount; for (int i = 1; i <= listCount; i++) front.insert(rand()%5); cout << "Original List of Values: " << endl; //writeLinkedList(front, " "); cout << endl; for(int j=0;j<5;++j) cout << countValue (front,j) << endl; cout << endl; return 0; } int countValue(list<int> front, const int item) { int count0; int count1; int count2; int count3; int count4; list<int> *List; for(list<int>::iterator i = front.begin(); i != front.end(); i++) { if(List->item == 0) { count0++; } if(List->item == 1) { count1++; } if(List->item == 2) { count2++; } if(List->item == 3) { count2++; }if(List->item == 4) { count4++; } } } And here are the errors: error C2065: 'list' : undeclared identifier line 5 error C2062: type 'int' unexpected line 5 error C2661: 'std::list<_Ty>::insert' : no overloaded function takes 1 arguments line 16 error C3861: 'countValue': identifier not found line 21 IntelliSense: no instance of overloaded function "std::list<_Ty, _Ax>::insert [with _Ty=int, _Ax=std::allocator<int>]" matches the argument list line 16 IntelliSense: too few arguments in function call line 16 error C2039: 'item': is not a member of 'std::list<_Ty>' lines 34, 38, 42, 46, 49 IntelliSense: declaration is incompatible with "int countValue" (declared at line 5) line 25 IntelliSense: class "std::list<int, std:: allocator<int>>" has no member "item" lines 34, 38, 42, 46, 49 I just want to know what I've done wrong and how to fix it and also if someone could help me figure out if I'm doing the countValue function wrong or not based on the instructions I would really appreciate it. I've read the chapter in our textbook several times, looked up tutorials on youtube and on Dream in Code, and still I can not figure this out. All helpful information is appreciated!

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• Why can't I sort this container?

  - by Knowing me knowing you

  Please don't mind that there is no insert fnc and that data are hardcoded. The main purpouse of it is to correctly implement iterator for this container. //file Set.h #pragma once template<class T> class Set { template<class T> friend ostream& operator<<(ostream& out, const Set<T>& obj); private: T** myData_; std::size_t mySize_; std::size_t myIndex_; public: Set(); class iterator : public std::iterator<std::random_access_iterator_tag, T*> { private: T** itData_; public: iterator(T** obj) { itData_ = obj; } T operator*() const { return **itData_; } /*Comparing values of two iterators*/ bool operator<(const iterator& obj) { return **itData_ < **obj.itData_; } /*Substracting two iterators*/ difference_type operator-(const iterator& obj) { return itData_ - obj.itData_; } /*Moving iterator backward for value*/ iterator operator-(const int value) { return itData_ - value; } /*Adding two iterators*/ difference_type operator+(const iterator& obj) { return itData_ + obj.itData_; } /*Moving iterator forward for value*/ iterator operator+(const int value) { return itData_ + value; } bool operator!=(const iterator& obj) { return (itData_ != obj.itData_); } bool operator==(const iterator& obj) { return (itData_ == obj.itData_); } T** operator++() { return ++itData_; } T** operator--() { return --itData_; } }; iterator begin() const { return myData_; } iterator end() const { return myData_ + myIndex_; } }; template<class T> ostream& operator<<(ostream& out, const Set<T>& obj) { for (int i = 0;i < 3; ++i) { out << *obj.myData_[i] << "\n"; } return out; } //file Set_impl.h #pragma once #include "stdafx.h" #include "Set.h" template<class T> Set<T>::Set() { mySize_ = 3; myIndex_ = 3; myData_ = new T*[mySize_]; myData_[0] = new T(3); myData_[1] = new T(1); myData_[2] = new T(2); } //main include "stdafx.h" #include "Set_impl.h" int _tmain(int argc, _TCHAR* argv[]) { Set<int> a; Set<int>::iterator beg_ = a.begin(); Set<int>::iterator end_ = a.end(); std::sort(beg_,end_);//WONT SORT THIS RANGE cin.get(); return 0; } Why sort can't accept this iterators even though I've provided all operators needed for sort to work? I think the best way to check what's going on is to paste this code and run it first. Thanks

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• How to reserve public API to internal usage in .NET?

  - by mark

  Dear ladies and sirs. Let me first present the case, which will explain my question. This is going to be a bit long, so I apologize in advance :-). I have objects and collections, which should support the Merge API (it is my custom API, the signature of which is immaterial for this question). This API must be internal, meaning only my framework should be allowed to invoke it. However, derived types should be able to override the basic implementation. The natural way to implement this pattern as I see it, is this: The Merge API is declared as part of some internal interface, let us say IMergeable. Because the interface is internal, derived types would not be able to implement it directly. Rather they must inherit it from a common base type. So, a common base type is introduced, which would implement the IMergeable interface explicitly, where the interface methods delegate to respective protected virtual methods, providing the default implementation. This way the API is only callable by my framework, but derived types may override the default implementation. The following code snippet demonstrates the concept: internal interface IMergeable { void Merge(object obj); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } void IMergeable.Merge(object obj) { Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } All is fine, provided a single common base type suffices, which is usually true for non collection types. The thing is that collections must be mergeable as well. Collections do not play nicely with the presented concept, because developers do not develop collections from the scratch. There are predefined implementations - observable, filtered, compound, read-only, remove-only, ordered, god-knows-what, ... They may be developed from scratch in-house, but once finished, they serve wide range of products and should never be tailored to some specific product. Which means, that either: they do not implement the IMergeable interface at all, because it is internal to some product the scope of the IMergeable interface is raised to public and the API becomes open and callable by all. Let us refer to these collections as standard collections. Anyway, the first option screws my framework, because now each possible standard collection type has to be paired with the respective framework version, augmenting the standard with the IMergeable interface implementation - this is so bad, I am not even considering it. The second option breaks the framework as well, because the IMergeable interface should be internal for a reason (whatever it is) and now this interface has to open to all. So what to do? My solution is this. make IMergeable public API, but add an extra parameter to the Merge method, I call it a security token. The interface implementation may check that the token references some internal object, which is never exposed to the outside. If this is the case, then the method was called from within the framework, otherwise - some outside API consumer attempted to invoke it and so the implementation can blow up with a SecurityException. Here is the modified code snippet demonstrating this concept: internal static class InternalApi { internal static readonly object Token = new object(); } public interface IMergeable { void Merge(object obj, object token); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } public void Merge(object obj, object token) { if (!object.ReferenceEquals(token, InternalApi.Token)) { throw new SecurityException("bla bla bla"); } Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } Of course, this is less explicit than having an internally scoped interface and the check is moved from the compile time to run time, yet this is the best I could come up with. Now, I have a gut feeling that there is a better way to solve the problem I have presented. I do not know, may be using some standard Code Access Security features? I have only vague understanding of it, but can LinkDemand attribute be somehow related to it? Anyway, I would like to hear other opinions. Thanks.

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• Generating strongly biased radom numbers for tests

  - by nobody

  I want to run tests with randomized inputs and need to generate 'sensible' random numbers, that is, numbers that match good enough to pass the tested function's preconditions, but hopefully wreak havoc deeper inside its code. math.random() (I'm using Lua) produces uniformly distributed random numbers. Scaling these up will give far more big numbers than small numbers, and there will be very few integers. I would like to skew the random numbers (or generate new ones using the old function as a randomness source) in a way that strongly favors 'simple' numbers, but will still cover the whole range, I.e. extending up to positive/negative infinity (or ±1e309 for double). This means: numbers up to, say, ten should be most common, integers should be more common than fractions, numbers ending in 0.5 should be the most common fractions, followed by 0.25 and 0.75; then 0.125, and so on. A different description: Fix a base probability x such that probabilities will sum to one and define the probability of a number n as xk where k is the generation in which n is constructed as a surreal number1. That assigns x to 0, x2 to -1 and +1, x3 to -2, -1/2, +1/2 and +2, and so on. This gives a nice description of something close to what I want (it skews a bit too much), but is near-unusable for computing random numbers. The resulting distribution is nowhere continuous (it's fractal!), I'm not sure how to determine the base probability x (I think for infinite precision it would be zero), and computing numbers based on this by iteration is awfully slow (spending near-infinite time to construct large numbers). Does anyone know of a simple approximation that, given a uniformly distributed randomness source, produces random numbers very roughly distributed as described above? I would like to run thousands of randomized tests, quantity/speed is more important than quality. Still, better numbers mean less inputs get rejected. Lua has a JIT, so performance can't be reasonably predicted. Jumps based on randomness will break every prediction, and many calls to math.random() will be slow, too. This means a closed formula will be better than an iterative or recursive one. 1 Wikipedia has an article on surreal numbers, with a nice picture. A surreal number is a pair of two surreal numbers, i.e. x := {n|m}, and its value is the number in the middle of the pair, i.e. (for finite numbers) {n|m} = (n+m)/2 (as rational). If one side of the pair is empty, that's interpreted as increment (or decrement, if right is empty) by one. If both sides are empty, that's zero. Initially, there are no numbers, so the only number one can build is 0 := { | }. In generation two one can build numbers {0| } =: 1 and { |0} =: -1, in three we get {1| } =: 2, {|1} =: -2, {0|1} =: 1/2 and {-1|0} =: -1/2 (plus some more complex representations of known numbers, e.g. {-1|1} ? 0). Note that e.g. 1/3 is never generated by finite numbers because it is an infinite fraction – the same goes for floats, 1/3 is never represented exactly.

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