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  • Best practice for storing global data in PHP?

    - by user281434
    Hi I'm running a web application that allows a user to log in. The user can add/remove content to his/her 'library' which is displayed on a page called "library.php". Instead of querying the database for the contents of the users library everytime they load "library.php", I want to store it globally for PHP when the user logs in, so that the query is only run once. Is there a best practice for doing this? fx. storing their library in an array in a session? Thanks for your time

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • UIKeyboard turn Caps Lock on

    - by Daniel Granger
    I need my user to input some data like DF-DJSL so I put this in the code: theTextField.autocapitalizationType = UITextAutocapitalizationTypeAllCharacters; But unfortunately what happens is the first to letter type in CAPS but then letter immediately after typing the hyphen will be in lower case and then the rest return to CAPS therefore producing output like this (unless the user manually taps the shift button after typing a hyphen): DF-dJSL How can I fix this? Many Thanks

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  • XSLT Global count of grouped items

    - by Chris
    Hi there, I have a set of items which i am grouping using the muenchian method using keys. This is working great however when i try to do things with the first x number of items it is doing it on the x number of items in each group rather than across the whole set of results. How would i get the individual position of each item accross the whole collection? <xsl:key name="pictures-by-productid" match="/dsQueryResponse/Rows/Row" use="@ProductId" /> <xsl:template match="/"> <div style="border:1px solid red; float:left;"> <xsl:apply-templates select="/" mode="sub"> </xsl:apply-templates> </div> </xsl:template> and the second template <xsl:template match="/" mode="sub"> <xsl:for-each select="/dsQueryResponse/Rows/Row[count(. | key('pictures-by-productid', @ProductId)[1]) = 1]"> <xsl:for-each select="key('pictures-by-productid', @ProductId)"> <xsl:sort select="@PictureType" /> <div style="float:left; margin:2px;"> <img src="{@ThumbNailUrl}" width="58" /> <br /> Download <xsl:number value="position()" format="1. " /> <xsl:value-of select="." /> </div> </xsl:for-each> </xsl:for-each> </xsl:template> Thanks Chris

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  • GLOBAL loading inside each single button with Jquery in ajax calls of asp.net mvc

    - by Ricky
    I have the following scenario: I have a button\link with a image inside like this: <button type="submit" id="myButton" class="button"><img src="../../Content/images/check.png" id="defaultImage" /> SaveData!!!</button> We are OK here! Now what I need to do is: I want on the click that the image change for a loading element that is previously loaded in the page like this: <img id="loadingImage" src="../../Content/images/loader.gif" style="display: none;" alt="loading"/> And then when the load complete turn back the old button image, I ended with this code: function loader() { var $button = $('#myButton'); if (btnState == '1') { $button.find('img').hide(); $button.prepend($('#loadingImage')); $('#loadingImage').css({ 'display': 'inherit' }); btnState = '0'; } else { $button.find('img').hide(); $button.prepend($('#defaultImage')); $('#defaultImage').show(); btnState = '1'; } } This does the trick for ONE SINGLE button(since I pass its ID in the function) but, when I have for example a grid with a button on each line, I found inviable when managing a screen with many buttons do this for each of then. The main question is: How can I make this method general for all buttons/links on one specific class in the page? The goal is: Click a button, get the image and change it and stop(can be manual). I just don't wanna have to Hook ALL buttons.

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  • Crystal Reports: global variable running total not displaying in header

    - by phill
    Using Crystal Reports I'm trying to display the running total of a database field in the header where all the labels are. I've attempted to do this by placing the running total (RTversion) into a formula field with the following: Shared stringvar CurrentVers; CurrentVers := {#CurrentVers}; and then in the page header section I have the following: Shared stringvar CurrentVers; EvaluateAFter({#currentVers}); CurrentVers; with {#CurrentVers} running the 1st largest number. Is this incorrect? Update: The goal is to display the latest version in the header near the labels to show what the current verseion is for comparison.

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  • How to apply global filter on Entity Framework?

    - by Hernan
    I have a table in my model named Customers with a field IsActive. Whenever I run a query on Customers, only the active customers should be retrieved. I can include the filter in every query, but that doesn't look very. I would like to be able to override the Customers property at the Object Context lever, but I am not sure if this is possible. Any help would be very appreciated! Thanks

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  • BDE, Delphi, ODBC, SQL Native Client & Dead lock

    - by EspenS
    Hi. We have some Delphi code that uses the BDE to Access SQL Server 2008 through the SQL Server Native Client ODBC driver (2005 version). Our issue is that we're experiencing some deadlock issues in a loop doing inserts to multiple tables. The whole loop is done within a [TDatabase].StartTransaction. Looking at the SQL Server Profiler we clearly see that at one point during the loop the SPID (Session ID?) change, and then we naturally end up with a deadlock. (Both SPID doing inserts to the same table) It seems like the BDE at some point does a second connection to the DB... (Although I would love to skip the BDE, it's currently not possible. ) Anyone with experiences to share?

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  • JPA optimistic lock - setting @Version to entity class cause query to include VERSION as column

    - by masato-san
    I'm using JPA Toplink Essential, Netbean6.8, GlassFish v3 In my Entity class I added @Version annotation to enable optimistic locking at transaction commit however after I added the annotation, my query started including VERSION as column thus throwing SQL exception. None of this is mentioned in any tutorial I've seen so far. What could be wrong? Snippet public class MasatosanTest2 implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @Column(name = "id") private Integer id; @Column(name = "username") private String username; @Column(name = "note") private String note; //here adding Version @Version int version; query used: SELECT m FROM MasatosanTest2 m Internal Exception: com.microsoft.sqlserver.jdbc.SQLServerException Call: SELECT id, username, note, VERSION FROM MasatosanTest2

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  • Populate javascript template at startup global.asax

    - by Andrew Florko
    Hello, everybody I use asp.net mvc & going to build javascript files at application startup depending on site configuration. I am going to have some javascript file templates that will be populated with appropriate constants and put into /scripts folder. Please, suggest me the best way to do that. I want to have something like: application_startup() { string populatedFile = Html.RenderPartial("/scripts/script.template.js"); write populatedFile into /scripts folder... } Thank you in advance !

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  • SQLite as an App Queue, Exclusive Row Lock?

    - by ScSub
    I am considering using SQLite as a "job queue container", and was wondering how I could do so, using custom C# (with ADO.NET) to work the database. If this was SQL Server, I would setup a serializable transaction to make sure the parent row and child rows were exclusively mine until I was done. I'm not sure how that would work in SQLite, can anyone offer any assistance? Or if there are any other existing implementations of message queueing with SQLite, I'd appreciate any pointers in that direction as well. Thanks!

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  • SQL Server lock/hang issue

    - by mattwoberts
    Hi, I'm using SQL Server 2008 on Windows Server 2008 R2, all sp'd up. I'm getting occasional issues with SQL Server hanging with the CPU usage on 100% on our live server. It seems all the wait time on SQL Sever when this happens is given to SOS_SCHEDULER_YIELD. Here is the Stored Proc that causes the hang. I've added the "WITH (NOLOCK)" in an attempt to fix what seems to be a locking issue. ALTER PROCEDURE [dbo].[MostPopularRead] AS BEGIN SET NOCOUNT ON; SELECT c.ForeignId , ct.ContentSource as ContentSource , sum(ch.HitCount * hw.Weight) as Popularity , (sum(ch.HitCount * hw.Weight) * 100) / @Total as Percent , @Total as TotalHits from ContentHit ch WITH (NOLOCK) join [Content] c WITH (NOLOCK) on ch.ContentId = c.ContentId join HitWeight hw WITH (NOLOCK) on ch.HitWeightId = hw.HitWeightId join ContentType ct WITH (NOLOCK) on c.ContentTypeId = ct.ContentTypeId where ch.CreatedDate between @Then and @Now group by c.ForeignId , ct.ContentSource order by sum(ch.HitCount * hw.HitWeightMultiplier) desc END The stored proc reads from the table "ContentHit", which is a table that tracks when content on the site is clicked (it gets hit quite frequently - anything from 4 to 20 hits a minute). So its pretty clear that this table is the source of the problem. There is a stored proc that is called to add hit tracks to the ContentHit table, its pretty trivial, it just builds up a string from the params passed in, which involves a few selects from some lookup tables, followed by the main insert: BEGIN TRAN insert into [ContentHit] (ContentId, HitCount, HitWeightId, ContentHitComment) values (@ContentId, isnull(@HitCount,1), isnull(@HitWeightId,1), @ContentHitComment) COMMIT TRAN The ContentHit table has a clustered index on its ID column, and I've added another index on CreatedDate since that is used in the select. When I profile the issue, I see the Stored proc executes for exactly 30 seconds, then the SQL timeout exception occurs. If it makes a difference the web application using it is ASP.NET, and I'm using Subsonic (3) to execute these stored procs. Can someone please advise how best I can solve this problem? I don't care about reading dirty data... Thanks

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  • Should an NSLock instance be "global"?

    - by Alex Reynolds
    Should I make a single NSLock instance in the application delegate, to be used by all classes? Or is it advisable to have each class instantiate its own NSLock instance as needed? Would the locking work in the second case, if I, for example, had access to a managed object context that is spread across two view controllers?

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  • IOException: Unable To Delete Images Due To File Lock

    - by Arslan Pervaiz
    I am Unable To Delete Image File From My Server Path It Gaves Error That The Process Cannot Access The File "FileName" Because it is being Used By Another Process. I Tried Many Methods But Still All In Vain. Please Help me Out in This Issue. Here is My Code Snippet. using System; using System.Data; using System.Web; using System.Data.SqlClient; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Globalization; using System.Web.Security; using System.Text; using System.DirectoryServices; using System.Collections; using System.IO; using System.Drawing; using System.Drawing.Imaging; using System.Drawing.Drawing2D; //============ Main Block ================= byte[] data = (byte[])ds.Tables[0].Rows[0][0]; MemoryStream ms = new MemoryStream(data); Image returnImage = Image.FromStream(ms); returnImage.Save(Server.MapPath(".\\TmpImages\\SavedImage.jpg"), System.Drawing.Imaging.ImageFormat.Jpeg); returnImage.Dispose(); \\ I Tried this Dispose Method To Unlock The File But Nothing Done. ms.Close(); \\ I Tried The Memory Stream Close Method Also But Its Also Not Worked For Me. watermark(); \\ Here is My Water Mark Method That Print Water Mark Image on My Saved Image (Image That is Converted From Byte Array) DeleteImages(); \\ Here is My Delete Method That I Call To Delete The Images //===== ==== My Delete Method To Delete Files================== public void DeleteImages() { try { File.Delete(Server.MapPath(".\\TmpImages\\WaterMark.jpg")); \\This Image Deleted Fine. File.Delete(Server.MapPath(".\\TmpImages\\SavedImage.jpg")); \\ Exception Thrown On Deleting of This Image. } catch (Exception ex) { LogManager.LogException(ex, "Error in Deleting Images."); Master.ShowMessage(ex.Message, true); } } \ ==== Method Declartion That Make Watermark of One Image On Another Image.======= public void watermark() { //create a image object containing the photograph to watermark Image imgPhoto = Image.FromFile(Server.MapPath(".\\TmpImages\\SavedImage.jpg")); int phWidth = imgPhoto.Width; int phHeight = imgPhoto.Height; //create a Bitmap the Size of the original photograph Bitmap bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb); bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); //load the Bitmap into a Graphics object Graphics grPhoto = Graphics.FromImage(bmPhoto); //create a image object containing the watermark Image imgWatermark = new Bitmap(Server.MapPath(".\\TmpImages\\PrintasWatermark.jpg")); int wmWidth = imgWatermark.Width; int wmHeight = imgWatermark.Height; //Set the rendering quality for this Graphics object grPhoto.SmoothingMode = SmoothingMode.AntiAlias; //Draws the photo Image object at original size to the graphics object. grPhoto.DrawImage( imgPhoto, // Photo Image object new Rectangle(0, 0, phWidth, phHeight), // Rectangle structure 0, // x-coordinate of the portion of the source image to draw. 0, // y-coordinate of the portion of the source image to draw. phWidth, // Width of the portion of the source image to draw. phHeight, // Height of the portion of the source image to draw. GraphicsUnit.Pixel); // Units of measure //------------------------------------------------------- //to maximize the size of the Copyright message we will //test multiple Font sizes to determine the largest posible //font we can use for the width of the Photograph //define an array of point sizes you would like to consider as possiblities //------------------------------------------------------- //Define the text layout by setting the text alignment to centered StringFormat StrFormat = new StringFormat(); StrFormat.Alignment = StringAlignment.Center; //define a Brush which is semi trasparent black (Alpha set to 153) SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(153, 0, 0, 0)); //define a Brush which is semi trasparent white (Alpha set to 153) SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255)); //------------------------------------------------------------ //Step #2 - Insert Watermark image //------------------------------------------------------------ //Create a Bitmap based on the previously modified photograph Bitmap Bitmap bmWatermark = new Bitmap(bmPhoto); bmWatermark.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); //Load this Bitmap into a new Graphic Object Graphics grWatermark = Graphics.FromImage(bmWatermark); //To achieve a transulcent watermark we will apply (2) color //manipulations by defineing a ImageAttributes object and //seting (2) of its properties. ImageAttributes imageAttributes = new ImageAttributes(); //The first step in manipulating the watermark image is to replace //the background color with one that is trasparent (Alpha=0, R=0, G=0, B=0) //to do this we will use a Colormap and use this to define a RemapTable ColorMap colorMap = new ColorMap(); //My watermark was defined with a background of 100% Green this will //be the color we search for and replace with transparency colorMap.OldColor = Color.FromArgb(255, 0, 255, 0); colorMap.NewColor = Color.FromArgb(0, 0, 0, 0); ColorMap[] remapTable = { colorMap }; imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap); //The second color manipulation is used to change the opacity of the //watermark. This is done by applying a 5x5 matrix that contains the //coordinates for the RGBA space. By setting the 3rd row and 3rd column //to 0.3f we achive a level of opacity float[][] colorMatrixElements = { new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f}, new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f}, new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f}, new float[] {0.0f, 0.0f, 0.0f, 0.3f, 0.0f}, new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}}; ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements); imageAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap); //For this example we will place the watermark in the upper right //hand corner of the photograph. offset down 10 pixels and to the //left 10 pixles int xPosOfWm = ((phWidth - wmWidth) - 10); int yPosOfWm = 10; grWatermark.DrawImage(imgWatermark, new Rectangle(xPosOfWm, yPosOfWm, wmWidth, wmHeight), //Set the detination Position 0, // x-coordinate of the portion of the source image to draw. 0, // y-coordinate of the portion of the source image to draw. wmWidth, // Watermark Width wmHeight, // Watermark Height GraphicsUnit.Pixel, // Unit of measurment imageAttributes); //ImageAttributes Object //Replace the original photgraphs bitmap with the new Bitmap imgPhoto = bmWatermark; grPhoto.Dispose(); grWatermark.Dispose(); //save new image to file system. imgPhoto.Save(Server.MapPath(".\\TmpImages\\WaterMark.jpg"), ImageFormat.Jpeg); imgPhoto.Dispose(); imgWatermark.Dispose(); }

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  • A lock could not obtained within the time requested issue

    - by Wayne Daly
    The title is the error I'm getting, when I click load my program freezes. I assume its because I'm doing a statement inside a statement, but from what I see its the only solution to my issue. By loading I want to just repopulate the list of patients, but to do so I need to do their conditions also. The code works, the bottom method is what I'm trying to fix. I think the issue is that I have 2 statements open but I am not sure. load: public void DatabaseLoad() { try { String Name = "Wayne"; String Pass= "Wayne"; String Host = "jdbc:derby://localhost:1527/Patients"; Connection con = DriverManager.getConnection( Host,Name, Pass); PatientList.clear(); Statement stmt8 = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); String SQL8 = "SELECT * FROM PATIENTS"; ResultSet rs8 = stmt8.executeQuery( SQL8 ); ArrayList<PatientCondition> PatientConditions1 = new ArrayList(); while(rs8.next()) { PatientConditions1 = LoadPatientConditions(); } Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); String SQL = "SELECT * FROM PATIENTS"; ResultSet rs = stmt.executeQuery( SQL ); while(rs.next()) { int id = (rs.getInt("ID")); String name = (rs.getString("NAME")); int age = (rs.getInt("AGE")); String address = (rs.getString("ADDRESS")); String sex = (rs.getString("SEX")); String phone = (rs.getString("PHONE")); Patient p = new Patient(id, name, age, address, sex, phone, PatientConditions1); PatientList.add(p); } UpdateTable(); UpdateAllViews(); DefaultListModel PatientListModel = new DefaultListModel(); for (Patient s : PatientList) { PatientListModel.addElement(s.getAccountNumber() + "-" + s.getName()); } PatientJList.setModel(PatientListModel); } catch(SQLException err) { System.out.println(err.getMessage()); } } This is the method that returns the arraylist of patient conditions public ArrayList LoadPatientConditions() { ArrayList<PatientCondition> PatientConditionsTemp = new ArrayList(); try { String Name = "Wayne"; String Pass= "Wayne"; String Host = "jdbc:derby://localhost:1527/Patients"; Connection con = DriverManager.getConnection( Host,Name, Pass); Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); String SQL = "SELECT * FROM PATIENTCONDITIONS"; ResultSet rs5 = stmt.executeQuery( SQL ); int e = 0; while(rs5.next()) { e++; String ConName = (rs5.getString("CONDITION")); PatientCondition k = new PatientCondition(e,ConName); PatientConditionsTemp.add(k); } } catch(SQLException err) { System.out.println(err.getMessage()); } return PatientConditionsTemp; }

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  • Qwt setAxisScale() seems to lock up application when given numbers with greater precision than 2e-07

    - by Dane Larsen
    I'm using Qwt for some scientific graphing, and I'm working with some fairly small numbers, the smallest being around 1.0e-22. I'm trying to call setAxisScale(xaxis, xmin, xmax) //xmin = 0, xmax = 2.0e-10 But when I do, the application locks up. I haven't found anything in the documentation that refers to a minimum value. Xmin and xmax are both doubles, so that shouldn't be a problem. Is this a bug in Qwt, or am I doing something wrong? Thanks in advance

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  • C# Serialization lock out

    - by Greycrow
    When I try to Serialize a class to an xml file I get the exception: The process cannot access the file 'C:\settings.xml' because it is being used by another process. Settings currentSettings = new Settings(); public void LoadSettings() { //Load Settings from XML file try { Stream stream = File.Open("settings.xml", FileMode.Open); XmlSerializer s = new XmlSerializer(typeof(Settings)); currentSettings = (Settings)s.Deserialize(stream); stream.Close(); } catch //Can't read XML - use default settings { currentSettings.Name = GameSelect.Items[0].ToString(); currentSettings.City = MapSelect.Items[0].ToString(); currentSettings.Country = RaceSelect.Items[0].ToString(); } } public void SaveSettings() { //Save Settings to XML file try { Stream stream = File.Open("settings.xml", FileMode.Create); XmlSerializer x = new XmlSerializer(typeof(Settings)); x.Serialize(stream, currentSettings); stream.Close(); } catch { MessageBox.Show("Unable to open XML File - File in use by other process"); } It appears that when I Deserialize it locks the file for writing back, even if I closed the stream. Thanks in advance.

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  • Problems with "global" exception handlers for unhandled exceptions in multithreaded WPF

    - by JustABill
    I have a program that, among other things, needs to be able to refresh the contents of a directory when the user tells it to. The actual task doesn't really matter, but this is the simplest way of causing this problem to occur that I know of. If I tell it to open a directory that doesn't exist, I get the "unhandled exception" dialog in VS with a stack trace of, from outer to inner: [External code] Textbox PreviewKeyUp event [External code] ClassA's path property being set ClassA's internal path update function being called A call to the INotifyPropertyChanged event [External code] A call to the getter for ClassB's list of children A call to ClassB's internal directory list function And then it fails inside this internal function. I have the following in my App.xaml.cs: private void Application_Startup(object sender, StartupEventArgs e) { AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException); Application.Current.Dispatcher.UnhandledException += new System.Windows.Threading.DispatcherUnhandledExceptionEventHandler(Dispatcher_UnhandledException); } But neither of their exception handlers are being called. If I run this program from outside VS, I don't get notified of an exception at all, it just breaks because of the invalid input. And yes, the Application_Startup event is being called. How can I properly "trap" this exception so I can provide a friendly error message and kill the program?

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  • iPhone: Using a NSMutableArry in the AppDelegate as a Global Variable

    - by aahrens
    What i'm trying to accomplish is to have an NSMutableArray defined in the AppDelegate. I then have two UIViewControllers. One view is responsible for displaying the array from the AppDelegate. The other view is used to add items to the array. So the array starts out to be empty. View1 doesn't display anything because the array is empty. The User goes to View2 and adds an item to the array in AppDelegate. Then when the user goes back to View1 it now displays one item. Here is how I'm trying to accomplish this @interface CalcAppDelegate : NSObject <UIApplicationDelegate> { UIWindow *window; UITabBarController *tabBarController; NSMutableArray *globalClasses; } @property (nonatomic,retain) NSMutableArray *globalClasses; My other view In the viewDidload I set the array in my View to be the one in the AppDelegate. In an effort to retain values. allCourses = [[NSMutableArray alloc]init]; CalcAppDelegate *appDelegate = (CalcAppDelegate *)[[UIApplication sharedApplication] delegate]; allCourses = appDelegate.globalClasses; Then I would update my allCourses array by adding a new item. Then try to set the array in the AppDelegate to be equal to the modified one. CalcAppDelegate *appDel = (CalcAppDelegate *)[[UIApplication sharedApplication] delegate]; NSLog(@"Size before reset %d",[appDel.globalClasses count]); appDel.globalClasses = allCourses; NSLog(@"Size after reset %d",[appDel.globalClasses count]); What I'm seeing that's returned is 2 in the before, and 2 after. So it doesn't appear to be getting updated properly. Any suggestions?

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  • Make object available within php functions without passing them or making them global

    - by Matt
    Hey all, This requirement is just for simplicity for developers and beautiful code. I'm building a template system and I really would just like an object variable to simply be there in all functions. Here's some code: Librarian.php: $class = "slideshow"; $function = "basic"; $args = array(...); $librarian = $this; // I WOULD LIKE THIS TO BE PRESENT IN CALLED FUNCTION ... return call_user_func($class.'::'.$function, $args); ... Slideshow.php: public static function basic($args) { echo $librarian; // "Librarian Object" } Thanks! Matt Mueller

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  • About fork system call and global variables

    - by lurks
    I have this program in C++ that forks two new processes: #include <pthread.h> #include <iostream> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <cstdlib> using namespace std; int shared; void func(){ extern int shared; for (int i=0; i<10;i++) shared++; cout<<"Process "<<getpid()<<", shared " <<shared<<", &shared " <<&shared<<endl; } int main(){ extern int shared; pid_t p1,p2; int status; shared=0; if ((p1=fork())==0) {func();exit(0);}; if ((p2=fork())==0) {func();exit(0);}; for(int i=0;i<10;i++) shared++; waitpid(p1,&status,0); waitpid(p2,&status,0);; cout<<"shared variable is: "<<shared<<endl; cout<<"Process "<<getpid()<<", shared " <<shared<<", &shared " <<&shared<<endl; } The two forked processes make an increment on the shared variables and the parent process does the same. As the variable belongs to the data segment of each process, the final value is 10 because the increment is independent. However, the memory address of the shared variables is the same, you can try compiling and watching the output of the program. How can that be explained ? I cannot understand that, I thought I knew how the fork() works, but this seems very odd.. I need an explanation on why the address is the same, although they are separate variables.

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  • Is this code thread-safe?

    - by mafutrct
    I've got a class with several properties. On every value update, a Store method is called with stores all fields (in a file). private int _Prop1; public int Prop1 { get { return _Prop1; } set { _Prop1 = value; Store(); } } // more similar properties here... private XmlSerializer _Ser = new ...; private void Store() { lock (_Ser) { using (FileStream fs = new ...) { _Ser.Serialize (fs, this); } } } Is this design thread-safe? (Btw, if you can think of a more appropriate caption, feel free to edit.)

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