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  • how to make datagrid Visibility is Collapsed in codebehind

    - by prince23
    hi i have data grid. now here i am checking the condition if Companyrows.count is zero . if count is zero make data grid.visible is false. List<Employee> Companyrows = new List<Employee>(); if (Companyrows.Count == 0) { dgrdRowDetail.Visibility = "Collapsed"; // getting error // convert type 'string' to 'System.Windows.Visibility' } else { dgrdRowDetail.ItemsSource = Companyrows; } any help how to solve this issue would be great thank you

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  • empty base class optimization

    - by FredOverflow
    Two quotes from the C++ standard, §1.8: An object is a region of storage. Base class subobjects may have zero size. I don't think a region of storage can be of size zero. That would mean that some base class subobjects aren't actually objects. Opinions?

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  • ffmpeg: create a video from images

    - by vailen
    Is it possible to use ffmpeg create a video from a set of sequences, where the number does not start from zero? For example, I have some images [test_100.jpg, test_101.jpg, test_102.jpg, ..., test_200.jpg], and I want to convert them to a video. I tried the following command, but it didn't work (it seems the number should start from zero): ffmpeg -i test_%d.jpg -vcodec mpeg4 test.avi Any advise?

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  • Why closed contours are guaranteed here?

    - by user198729
    Quoted from here: BW = edge(I,'zerocross',thresh,h) specifies the zero-cross method, using the filter h. thresh is the sensitivity threshold; if the argument is empty ([]), edge chooses the sensitivity threshold automatically. If you specify a threshold of 0, the output image has closed contours, because it includes all the zero crossings in the input image. I don't understand it,can someone elaborate?

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  • how can I create macro definitions for the lines commented in the code.

    - by yaprak
    #include <stdio.h> //Here use a macro definition that assigns a value to SIZE (for example 5) int main() { int i; int array[SIZE]; int sum=0; for(i=0; i<SIZE; i++) { //Here use a macro definition named as CALCSUM to make the //following addition operation for the array printf("Enter a[%d] = ",i); scanf("%d", &array[i]); sum+=array[i]; //Here use a macro definition named as VERBOSE to print //what program does to the screen printf("The user entered %d\n", array[i]); // // //If the macro definition CALCSUM is not used, the program //should assign 0 to the i-th element of the array array[i]=0; //Here, again use VERBOSE to print what program does to the screen printf("a[%d] is assigned to zero\n", i); // // } //If CALCSUM is defined, print the summation of the array elements to the screen printf("Summation of the array is %d\n",sum); // //If CALCSUM is not defined, but VERBOSE mode is used, print the following printf("All the elements in the array are assigned to zero\n"); // printf("Program terminated\n"); return 0; } When CALCSUM is defined, the program will sum up the values of each element in the given array. If CALCSUM is not defined, each array element will be assigned to zero. Besides, when VERBOSE mode is defined, the program will make print statements pointed out active. [root@linux55]# gcc code.c [root@linux55]# ./a.out Program terminated [root@linux55]# gcc code.c -D CALCSUM [root@linux55]# ./a.out Enter a[0] = 3 Enter a[1] = 0 Enter a[2] = 2 Enter a[3] = 5 Enter a[4] = 9 Summation of the array is 19 Program terminated [root@linux55]# gcc code.c -D CALCSUM -D VERBOSE [root@linux55]# ./a.out Enter a[0] = 2 The user entered 2 Enter a[1] = 10 The user entered 10 Enter a[2] = 3 The user entered 3 Enter a[3] = 8 The user entered 8 Enter a[4] = 1 The user entered 1 Summation of the array is 24 Program terminated [root@linux55]# gcc code.c -D VERBOSE [root@linux55]# ./a.out a[0] is assigned to 0 a[1] is assigned to 0 a[2] is assigned to 0 a[3] is assigned to 0 a[4] is assigned to 0 All the elements in the array is assigned to zero Program terminated

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  • Fun with Aggregates

    - by Paul White
    There are interesting things to be learned from even the simplest queries.  For example, imagine you are given the task of writing a query to list AdventureWorks product names where the product has at least one entry in the transaction history table, but fewer than ten. One possible query to meet that specification is: SELECT p.Name FROM Production.Product AS p JOIN Production.TransactionHistory AS th ON p.ProductID = th.ProductID GROUP BY p.ProductID, p.Name HAVING COUNT_BIG(*) < 10; That query correctly returns 23 rows (execution plan and data sample shown below): The execution plan looks a bit different from the written form of the query: the base tables are accessed in reverse order, and the aggregation is performed before the join.  The general idea is to read all rows from the history table, compute the count of rows grouped by ProductID, merge join the results to the Product table on ProductID, and finally filter to only return rows where the count is less than ten. This ‘fully-optimized’ plan has an estimated cost of around 0.33 units.  The reason for the quote marks there is that this plan is not quite as optimal as it could be – surely it would make sense to push the Filter down past the join too?  To answer that, let’s look at some other ways to formulate this query.  This being SQL, there are any number of ways to write logically-equivalent query specifications, so we’ll just look at a couple of interesting ones.  The first query is an attempt to reverse-engineer T-SQL from the optimized query plan shown above.  It joins the result of pre-aggregating the history table to the Product table before filtering: SELECT p.Name FROM ( SELECT th.ProductID, cnt = COUNT_BIG(*) FROM Production.TransactionHistory AS th GROUP BY th.ProductID ) AS q1 JOIN Production.Product AS p ON p.ProductID = q1.ProductID WHERE q1.cnt < 10; Perhaps a little surprisingly, we get a slightly different execution plan: The results are the same (23 rows) but this time the Filter is pushed below the join!  The optimizer chooses nested loops for the join, because the cardinality estimate for rows passing the Filter is a bit low (estimate 1 versus 23 actual), though you can force a merge join with a hint and the Filter still appears below the join.  In yet another variation, the < 10 predicate can be ‘manually pushed’ by specifying it in a HAVING clause in the “q1” sub-query instead of in the WHERE clause as written above. The reason this predicate can be pushed past the join in this query form, but not in the original formulation is simply an optimizer limitation – it does make efforts (primarily during the simplification phase) to encourage logically-equivalent query specifications to produce the same execution plan, but the implementation is not completely comprehensive. Moving on to a second example, the following query specification results from phrasing the requirement as “list the products where there exists fewer than ten correlated rows in the history table”: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) < 10 ); Unfortunately, this query produces an incorrect result (86 rows): The problem is that it lists products with no history rows, though the reasons are interesting.  The COUNT_BIG(*) in the EXISTS clause is a scalar aggregate (meaning there is no GROUP BY clause) and scalar aggregates always produce a value, even when the input is an empty set.  In the case of the COUNT aggregate, the result of aggregating the empty set is zero (the other standard aggregates produce a NULL).  To make the point really clear, let’s look at product 709, which happens to be one for which no history rows exist: -- Scalar aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709;   -- Vector aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709 GROUP BY th.ProductID; The estimated execution plans for these two statements are almost identical: You might expect the Stream Aggregate to have a Group By for the second statement, but this is not the case.  The query includes an equality comparison to a constant value (709), so all qualified rows are guaranteed to have the same value for ProductID and the Group By is optimized away. In fact there are some minor differences between the two plans (the first is auto-parameterized and qualifies for trivial plan, whereas the second is not auto-parameterized and requires cost-based optimization), but there is nothing to indicate that one is a scalar aggregate and the other is a vector aggregate.  This is something I would like to see exposed in show plan so I suggested it on Connect.  Anyway, the results of running the two queries show the difference at runtime: The scalar aggregate (no GROUP BY) returns a result of zero, whereas the vector aggregate (with a GROUP BY clause) returns nothing at all.  Returning to our EXISTS query, we could ‘fix’ it by changing the HAVING clause to reject rows where the scalar aggregate returns zero: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) BETWEEN 1 AND 9 ); The query now returns the correct 23 rows: Unfortunately, the execution plan is less efficient now – it has an estimated cost of 0.78 compared to 0.33 for the earlier plans.  Let’s try adding a redundant GROUP BY instead of changing the HAVING clause: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY th.ProductID HAVING COUNT_BIG(*) < 10 ); Not only do we now get correct results (23 rows), this is the execution plan: I like to compare that plan to quantum physics: if you don’t find it shocking, you haven’t understood it properly :)  The simple addition of a redundant GROUP BY has resulted in the EXISTS form of the query being transformed into exactly the same optimal plan we found earlier.  What’s more, in SQL Server 2008 and later, we can replace the odd-looking GROUP BY with an explicit GROUP BY on the empty set: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ); I offer that as an alternative because some people find it more intuitive (and it perhaps has more geek value too).  Whichever way you prefer, it’s rather satisfying to note that the result of the sub-query does not exist for a particular correlated value where a vector aggregate is used (the scalar COUNT aggregate always returns a value, even if zero, so it always ‘EXISTS’ regardless which ProductID is logically being evaluated). The following query forms also produce the optimal plan and correct results, so long as a vector aggregate is used (you can probably find more equivalent query forms): WHERE Clause SELECT p.Name FROM Production.Product AS p WHERE ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) < 10; APPLY SELECT p.Name FROM Production.Product AS p CROSS APPLY ( SELECT NULL FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ) AS ca (dummy); FROM Clause SELECT q1.Name FROM ( SELECT p.Name, cnt = ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) FROM Production.Product AS p ) AS q1 WHERE q1.cnt < 10; This last example uses SUM(1) instead of COUNT and does not require a vector aggregate…you should be able to work out why :) SELECT q.Name FROM ( SELECT p.Name, cnt = ( SELECT SUM(1) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID ) FROM Production.Product AS p ) AS q WHERE q.cnt < 10; The semantics of SQL aggregates are rather odd in places.  It definitely pays to get to know the rules, and to be careful to check whether your queries are using scalar or vector aggregates.  As we have seen, query plans do not show in which ‘mode’ an aggregate is running and getting it wrong can cause poor performance, wrong results, or both. © 2012 Paul White Twitter: @SQL_Kiwi email: [email protected]

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  • My vertex shader doesn't affect texture coords or diffuse info but works for position

    - by tina nyaa
    I am new to 3D and DirectX - in the past I have only used abstractions for 2D drawing. Over the past month I've been studying really hard and I'm trying to modify and adapt some of the shaders as part of my personal 'study project'. Below I have a shader, modified from one of the Microsoft samples. I set diffuse and tex0 vertex shader outputs to zero, but my model still shows the full texture and lighting as if I hadn't changed the values from the vertex buffer. Changing the position of the model works, but nothing else. Why is this? // // Skinned Mesh Effect file // Copyright (c) 2000-2002 Microsoft Corporation. All rights reserved. // float4 lhtDir = {0.0f, 0.0f, -1.0f, 1.0f}; //light Direction float4 lightDiffuse = {0.6f, 0.6f, 0.6f, 1.0f}; // Light Diffuse float4 MaterialAmbient : MATERIALAMBIENT = {0.1f, 0.1f, 0.1f, 1.0f}; float4 MaterialDiffuse : MATERIALDIFFUSE = {0.8f, 0.8f, 0.8f, 1.0f}; // Matrix Pallette static const int MAX_MATRICES = 100; float4x3 mWorldMatrixArray[MAX_MATRICES] : WORLDMATRIXARRAY; float4x4 mViewProj : VIEWPROJECTION; /////////////////////////////////////////////////////// struct VS_INPUT { float4 Pos : POSITION; float4 BlendWeights : BLENDWEIGHT; float4 BlendIndices : BLENDINDICES; float3 Normal : NORMAL; float3 Tex0 : TEXCOORD0; }; struct VS_OUTPUT { float4 Pos : POSITION; float4 Diffuse : COLOR; float2 Tex0 : TEXCOORD0; }; float3 Diffuse(float3 Normal) { float CosTheta; // N.L Clamped CosTheta = max(0.0f, dot(Normal, lhtDir.xyz)); // propogate scalar result to vector return (CosTheta); } VS_OUTPUT VShade(VS_INPUT i, uniform int NumBones) { VS_OUTPUT o; float3 Pos = 0.0f; float3 Normal = 0.0f; float LastWeight = 0.0f; // Compensate for lack of UBYTE4 on Geforce3 int4 IndexVector = D3DCOLORtoUBYTE4(i.BlendIndices); // cast the vectors to arrays for use in the for loop below float BlendWeightsArray[4] = (float[4])i.BlendWeights; int IndexArray[4] = (int[4])IndexVector; // calculate the pos/normal using the "normal" weights // and accumulate the weights to calculate the last weight for (int iBone = 0; iBone < NumBones-1; iBone++) { LastWeight = LastWeight + BlendWeightsArray[iBone]; Pos += mul(i.Pos, mWorldMatrixArray[IndexArray[iBone]]) * BlendWeightsArray[iBone]; Normal += mul(i.Normal, mWorldMatrixArray[IndexArray[iBone]]) * BlendWeightsArray[iBone]; } LastWeight = 1.0f - LastWeight; // Now that we have the calculated weight, add in the final influence Pos += (mul(i.Pos, mWorldMatrixArray[IndexArray[NumBones-1]]) * LastWeight); Normal += (mul(i.Normal, mWorldMatrixArray[IndexArray[NumBones-1]]) * LastWeight); // transform position from world space into view and then projection space //o.Pos = mul(float4(Pos.xyz, 1.0f), mViewProj); o.Pos = mul(float4(Pos.xyz, 1.0f), mViewProj); o.Diffuse.x = 0.0f; o.Diffuse.y = 0.0f; o.Diffuse.z = 0.0f; o.Diffuse.w = 0.0f; o.Tex0 = float2(0,0); return o; } technique t0 { pass p0 { VertexShader = compile vs_3_0 VShade(4); } } I am currently using the SlimDX .NET wrapper around DirectX, but the API is extremely similar: public void Draw() { var device = vertexBuffer.Device; device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.White, 1.0f, 0); device.SetRenderState(RenderState.Lighting, true); device.SetRenderState(RenderState.DitherEnable, true); device.SetRenderState(RenderState.ZEnable, true); device.SetRenderState(RenderState.CullMode, Cull.Counterclockwise); device.SetRenderState(RenderState.NormalizeNormals, true); device.SetSamplerState(0, SamplerState.MagFilter, TextureFilter.Anisotropic); device.SetSamplerState(0, SamplerState.MinFilter, TextureFilter.Anisotropic); device.SetTransform(TransformState.World, Matrix.Identity * Matrix.Translation(0, -50, 0)); device.SetTransform(TransformState.View, Matrix.LookAtLH(new Vector3(-200, 0, 0), Vector3.Zero, Vector3.UnitY)); device.SetTransform(TransformState.Projection, Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)device.Viewport.Width / device.Viewport.Height, 10, 10000000)); var material = new Material(); material.Ambient = material.Diffuse = material.Emissive = material.Specular = new Color4(Color.White); material.Power = 1f; device.SetStreamSource(0, vertexBuffer, 0, vertexSize); device.VertexDeclaration = vertexDeclaration; device.Indices = indexBuffer; device.Material = material; device.SetTexture(0, texture); var param = effect.GetParameter(null, "mWorldMatrixArray"); var boneWorldTransforms = bones.OrderedBones.OrderBy(x => x.Id).Select(x => x.CombinedTransformation).ToArray(); effect.SetValue(param, boneWorldTransforms); effect.SetValue(effect.GetParameter(null, "mViewProj"), Matrix.Identity);// Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)device.Viewport.Width / device.Viewport.Height, 10, 10000000)); effect.SetValue(effect.GetParameter(null, "MaterialDiffuse"), material.Diffuse); effect.SetValue(effect.GetParameter(null, "MaterialAmbient"), material.Ambient); effect.Technique = effect.GetTechnique(0); var passes = effect.Begin(FX.DoNotSaveState); for (var i = 0; i < passes; i++) { effect.BeginPass(i); device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, skin.Vertices.Length, 0, skin.Indicies.Length / 3); effect.EndPass(); } effect.End(); } Again, I set diffuse and tex0 vertex shader outputs to zero, but my model still shows the full texture and lighting as if I hadn't changed the values from the vertex buffer. Changing the position of the model works, but nothing else. Why is this? Also, whatever I set in the bone transformation matrices doesn't seem to have an effect on my model. If I set every bone transformation to a zero matrix, the model still shows up as if nothing had happened, but changing the Pos field in shader output makes the model disappear. I don't understand why I'm getting this kind of behaviour. Thank you!

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  • Fun with Aggregates

    - by Paul White
    There are interesting things to be learned from even the simplest queries.  For example, imagine you are given the task of writing a query to list AdventureWorks product names where the product has at least one entry in the transaction history table, but fewer than ten. One possible query to meet that specification is: SELECT p.Name FROM Production.Product AS p JOIN Production.TransactionHistory AS th ON p.ProductID = th.ProductID GROUP BY p.ProductID, p.Name HAVING COUNT_BIG(*) < 10; That query correctly returns 23 rows (execution plan and data sample shown below): The execution plan looks a bit different from the written form of the query: the base tables are accessed in reverse order, and the aggregation is performed before the join.  The general idea is to read all rows from the history table, compute the count of rows grouped by ProductID, merge join the results to the Product table on ProductID, and finally filter to only return rows where the count is less than ten. This ‘fully-optimized’ plan has an estimated cost of around 0.33 units.  The reason for the quote marks there is that this plan is not quite as optimal as it could be – surely it would make sense to push the Filter down past the join too?  To answer that, let’s look at some other ways to formulate this query.  This being SQL, there are any number of ways to write logically-equivalent query specifications, so we’ll just look at a couple of interesting ones.  The first query is an attempt to reverse-engineer T-SQL from the optimized query plan shown above.  It joins the result of pre-aggregating the history table to the Product table before filtering: SELECT p.Name FROM ( SELECT th.ProductID, cnt = COUNT_BIG(*) FROM Production.TransactionHistory AS th GROUP BY th.ProductID ) AS q1 JOIN Production.Product AS p ON p.ProductID = q1.ProductID WHERE q1.cnt < 10; Perhaps a little surprisingly, we get a slightly different execution plan: The results are the same (23 rows) but this time the Filter is pushed below the join!  The optimizer chooses nested loops for the join, because the cardinality estimate for rows passing the Filter is a bit low (estimate 1 versus 23 actual), though you can force a merge join with a hint and the Filter still appears below the join.  In yet another variation, the < 10 predicate can be ‘manually pushed’ by specifying it in a HAVING clause in the “q1” sub-query instead of in the WHERE clause as written above. The reason this predicate can be pushed past the join in this query form, but not in the original formulation is simply an optimizer limitation – it does make efforts (primarily during the simplification phase) to encourage logically-equivalent query specifications to produce the same execution plan, but the implementation is not completely comprehensive. Moving on to a second example, the following query specification results from phrasing the requirement as “list the products where there exists fewer than ten correlated rows in the history table”: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) < 10 ); Unfortunately, this query produces an incorrect result (86 rows): The problem is that it lists products with no history rows, though the reasons are interesting.  The COUNT_BIG(*) in the EXISTS clause is a scalar aggregate (meaning there is no GROUP BY clause) and scalar aggregates always produce a value, even when the input is an empty set.  In the case of the COUNT aggregate, the result of aggregating the empty set is zero (the other standard aggregates produce a NULL).  To make the point really clear, let’s look at product 709, which happens to be one for which no history rows exist: -- Scalar aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709;   -- Vector aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709 GROUP BY th.ProductID; The estimated execution plans for these two statements are almost identical: You might expect the Stream Aggregate to have a Group By for the second statement, but this is not the case.  The query includes an equality comparison to a constant value (709), so all qualified rows are guaranteed to have the same value for ProductID and the Group By is optimized away. In fact there are some minor differences between the two plans (the first is auto-parameterized and qualifies for trivial plan, whereas the second is not auto-parameterized and requires cost-based optimization), but there is nothing to indicate that one is a scalar aggregate and the other is a vector aggregate.  This is something I would like to see exposed in show plan so I suggested it on Connect.  Anyway, the results of running the two queries show the difference at runtime: The scalar aggregate (no GROUP BY) returns a result of zero, whereas the vector aggregate (with a GROUP BY clause) returns nothing at all.  Returning to our EXISTS query, we could ‘fix’ it by changing the HAVING clause to reject rows where the scalar aggregate returns zero: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) BETWEEN 1 AND 9 ); The query now returns the correct 23 rows: Unfortunately, the execution plan is less efficient now – it has an estimated cost of 0.78 compared to 0.33 for the earlier plans.  Let’s try adding a redundant GROUP BY instead of changing the HAVING clause: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY th.ProductID HAVING COUNT_BIG(*) < 10 ); Not only do we now get correct results (23 rows), this is the execution plan: I like to compare that plan to quantum physics: if you don’t find it shocking, you haven’t understood it properly :)  The simple addition of a redundant GROUP BY has resulted in the EXISTS form of the query being transformed into exactly the same optimal plan we found earlier.  What’s more, in SQL Server 2008 and later, we can replace the odd-looking GROUP BY with an explicit GROUP BY on the empty set: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ); I offer that as an alternative because some people find it more intuitive (and it perhaps has more geek value too).  Whichever way you prefer, it’s rather satisfying to note that the result of the sub-query does not exist for a particular correlated value where a vector aggregate is used (the scalar COUNT aggregate always returns a value, even if zero, so it always ‘EXISTS’ regardless which ProductID is logically being evaluated). The following query forms also produce the optimal plan and correct results, so long as a vector aggregate is used (you can probably find more equivalent query forms): WHERE Clause SELECT p.Name FROM Production.Product AS p WHERE ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) < 10; APPLY SELECT p.Name FROM Production.Product AS p CROSS APPLY ( SELECT NULL FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ) AS ca (dummy); FROM Clause SELECT q1.Name FROM ( SELECT p.Name, cnt = ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) FROM Production.Product AS p ) AS q1 WHERE q1.cnt < 10; This last example uses SUM(1) instead of COUNT and does not require a vector aggregate…you should be able to work out why :) SELECT q.Name FROM ( SELECT p.Name, cnt = ( SELECT SUM(1) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID ) FROM Production.Product AS p ) AS q WHERE q.cnt < 10; The semantics of SQL aggregates are rather odd in places.  It definitely pays to get to know the rules, and to be careful to check whether your queries are using scalar or vector aggregates.  As we have seen, query plans do not show in which ‘mode’ an aggregate is running and getting it wrong can cause poor performance, wrong results, or both. © 2012 Paul White Twitter: @SQL_Kiwi email: [email protected]

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  • SQLAuthority News – Monthly list of Puzzles and Solutions on SQLAuthority.com

    - by pinaldave
    This month has been very interesting month for SQLAuthority.com we had multiple and various puzzles which everybody participated and lots of interesting conversation which we have shared. Let us start in latest puzzles and continue going down. There are few answers also posted on facebook as well. SQL SERVER – Puzzle Involving NULL – Resolve – Error – Operand data type void type is invalid for sum operator This puzzle involves NULL and throws an error. The challenge is to resolve the error. There are multiple ways to resolve this error. Readers has contributed various methods. Few of them even have supplied the answer why this error is showing up. NULL are very important part of the database and if one of the column has NULL the result can be totally different than the one expected. SQL SERVER – T-SQL Scripts to Find Maximum between Two Numbers I modified script provided by friend to find greatest number between two number. My script has small bug in it. However, lots of readers have suggested better scripts. Madhivanan has written blog post on the subject over here. SQL SERVER – BI Quiz Hint – Performance Tuning Cubes – Hints This quiz is hosted on my friend Jacob‘s site. I have written many hints how one can tune cubes. Now one can take part here and win exciting prizes. SQL SERVER – Solution – Generating Zero Without using Any Numbers in T-SQL Madhivanan has asked very interesting question on his blog about How to Generate Zero without using Any Numbers in T-SQL. He has demonstrated various methods how one can generate Zero. I asked the same question on blog and got many interesting answers which I have shared. SQL SERVER – Solution – Puzzle – Statistics are not Updated but are Created Once I have to accept that this was most difficult puzzle. In this puzzle I have asked even though settings are correct, why statistics of the tables are not getting updated. In this puzzle one is tested with various concepts 1) Indexes, 2) Statistics, 3) database settings etc. There are multiple ways of solving this puzzles. It was interesting as many took interest but only few got it right. SQL SERVER – Question to You – When to use Function and When to use Stored Procedure This is rather straight forward question and not the typical puzzle. The answers from readers are great however, still there is chance of more detailed answers. SQL SERVER – Selecting Domain from Email Address I wrote on selecting domains from email addresses. Madhivanan makes puzzle out of a simple question. He wrote a follow-up post over here. In his post he writes various way how one can find email addresses from list of domains. Well, this is not a puzzle but amazing Guest Post by Feodor Georgiev who has written on subject Job Interviewing the Right Way (and for the Right Reasons). An article which everyone should read. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • Randomly placing items script not working - sometimes items spawn in walls, sometimes items spawn in weird locations

    - by Timothy Williams
    I'm trying to figure out a way to randomly spawn items throughout my level, however I need to make sure they won't spawn inside another object (walls, etc.) Here's the code I'm currently using, it's based on the Physics.CheckSphere(); function. This runs OnLevelWasLoaded(); It spawns the items perfectly fine, but sometimes items spawn partway in walls. And sometimes items will spawn outside of the SpawnBox range (no clue why it does that.) //This is what randomly generates all the items. void SpawnItems () { if (Application.loadedLevelName == "Menu" || Application.loadedLevelName == "End Demo") return; //The bottom corner of the box we want to spawn items in. Vector3 spawnBoxBot = Vector3.zero; //Top corner. Vector3 spawnBoxTop = Vector3.zero; //If we're in the dungeon, set the box to the dungeon box and tell the items we want to spawn. if (Application.loadedLevelName == "dungeonScene") { spawnBoxBot = new Vector3 (8.857f, 0, 9.06f); spawnBoxTop = new Vector3 (-27.98f, 2.4f, -15); itemSpawn = dungeonSpawn; } //Spawn all the items. for (i = 0; i != itemSpawn.Length; i ++) { spawnedItem = null; //Zeroes out our random location Vector3 randomLocation = Vector3.zero; //Gets the meshfilter of the item we'll be spawning MeshFilter mf = itemSpawn[i].GetComponent<MeshFilter>(); //Gets it's bounds (see how big it is) Bounds bounds = mf.sharedMesh.bounds; //Get it's radius float maxRadius = new Vector3 (bounds.extents.x + 10f, bounds.extents.y + 10f, bounds.extents.z + 10f).magnitude * 5f; //Set which layer is the no walls layer var NoWallsLayer = 1 << LayerMask.NameToLayer("NoWallsLayer"); //Use that layer as your layermask. LayerMask layerMask = ~(1 << NoWallsLayer); //If we're in the dungeon, certain items need to spawn on certain halves. if (Application.loadedLevelName == "dungeonScene") { if (itemSpawn[i].name == "key2" || itemSpawn[i].name == "teddyBearLW" || itemSpawn[i].name == "teddyBearLW_Admiration" || itemSpawn[i].name == "radio") randomLocation = new Vector3(Random.Range(spawnBoxBot.x, -26.96f), Random.Range(spawnBoxBot.y, spawnBoxTop.y), Random.Range(spawnBoxBot.z, -2.141f)); else randomLocation = new Vector3(Random.Range(spawnBoxBot.x, spawnBoxTop.x), Random.Range(spawnBoxBot.y, spawnBoxTop.y), Random.Range(-2.374f, spawnBoxTop.z)); } //Otherwise just spawn them in the box. else randomLocation = new Vector3(Random.Range(spawnBoxBot.x, spawnBoxTop.x), Random.Range(spawnBoxBot.y, spawnBoxTop.y), Random.Range(spawnBoxBot.z, spawnBoxTop.z)); //This is what actually spawns the item. It checks to see if the spot where we want to instantiate it is clear, and if so it instatiates it. Otherwise we have to repeat the whole process again. if (Physics.CheckSphere(randomLocation, maxRadius, layerMask)) spawnedItem = Instantiate(itemSpawn[i], randomLocation, Random.rotation); else i --; //If we spawned something, set it's name to what it's supposed to be. Removes the (clone) addon. if (spawnedItem != null) spawnedItem.name = itemSpawn[i].name; } } What I'm asking for is if you know what's going wrong with this code that it would spawn stuff in walls. Or, if you could provide me with links/code/ideas of a better way to check if an item will spawn in a wall (some other function than Physics.CheckSphere). I've been working on this for a long time, and nothing I try seems to work. Any help is appreciated.

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  • Exploring TCP throughput with DTrace

    - by user12820842
    One key measure to use when assessing TCP throughput is assessing the amount of unacknowledged data in the pipe. This is sometimes termed the Bandwidth Delay Product (BDP) (note that BDP is often used more generally as the product of the link capacity and the end-to-end delay). In DTrace terms, the amount of unacknowledged data in bytes for the connection is the different between the next sequence number to send and the lowest unacknoweldged sequence number (tcps_snxt - tcps_suna). According to the theory, when the number of unacknowledged bytes for the connection is less than the receive window of the peer, the path bandwidth is the limiting factor for throughput. In other words, if we can fill the pipe without the peer TCP complaining (by virtue of its window size reaching 0), we are purely bandwidth-limited. If the peer's receive window is too small however, the sending TCP has to wait for acknowledgements before it can send more data. In this case the round-trip time (RTT) limits throughput. In such cases the effective throughput limit is the window size divided by the RTT, e.g. if the window size is 64K and the RTT is 0.5sec, the throughput is 128K/s. So a neat way to visually determine if the receive window of clients may be too small should be to compare the distribution of BDP values for the server versus the client's advertised receive window. If the BDP distribution overlaps the send window distribution such that it is to the right (or lower down in DTrace since quantizations are displayed vertically), it indicates that the amount of unacknowledged data regularly exceeds the client's receive window, so that it is possible that the sender may have more data to send but is blocked by a zero-window on the client side. In the following example, we compare the distribution of BDP values to the receive window advertised by the receiver (10.175.96.92) for a large file download via http. # dtrace -s tcp_tput.d ^C BDP(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count -1 | 0 0 | 6 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 9 4096 | 14 8192 | 27 16384 | 67 32768 |@@ 1464 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 32396 131072 | 0 SWND(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count 16384 | 0 32768 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 17067 65536 | 0 Here we have a puzzle. We can see that the receiver's advertised window is in the 32768-65535 range, while the amount of unacknowledged data in the pipe is largely in the 65536-131071 range. What's going on here? Surely in a case like this we should see zero-window events, since the amount of data in the pipe regularly exceeds the window size of the receiver. We can see that we don't see any zero-window events since the SWND distribution displays no 0 values - it stays within the 32768-65535 range. The explanation is straightforward enough. TCP Window scaling is in operation for this connection - the Window Scale TCP option is used on connection setup to allow a connection to advertise (and have advertised to it) a window greater than 65536 bytes. In this case the scaling shift is 1, so this explains why the SWND values are clustered in the 32768-65535 range rather than the 65536-131071 range - the SWND value needs to be multiplied by two since the reciever is also scaling its window by a shift factor of 1. Here's the simple script that compares BDP and SWND distributions, fixed to take account of window scaling. #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @bdp["BDP(bytes)", args[2]-ip_daddr, args[4]-tcp_sport] = quantize(args[3]-tcps_snxt - args[3]-tcps_suna); } tcp:::receive / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @swnd["SWND(bytes)", args[2]-ip_saddr, args[4]-tcp_dport] = quantize((args[4]-tcp_window)*(1 tcps_snd_ws)); } And here's the fixed output. # dtrace -s tcp_tput_scaled.d ^C BDP(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count -1 | 0 0 | 39 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 4 4096 | 9 8192 | 22 16384 | 37 32768 |@ 99 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 3858 131072 | 0 SWND(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count 512 | 0 1024 | 1 2048 | 0 4096 | 2 8192 | 4 16384 | 7 32768 | 14 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1956 131072 | 0

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  • Oracle MAA Part 1: When One Size Does Not Fit All

    - by JoeMeeks
    The good news is that Oracle Maximum Availability Architecture (MAA) best practices combined with Oracle Database 12c (see video) introduce first-in-the-industry database capabilities that truly make unplanned outages and planned maintenance transparent to users. The trouble with such good news is that Oracle’s enthusiasm in evangelizing its latest innovations may leave some to wonder if we’ve lost sight of the fact that not all database applications are created equal. Afterall, many databases don’t have the business requirements for high availability and data protection that require all of Oracle’s ‘stuff’. For many real world applications, a controlled amount of downtime and/or data loss is OK if it saves money and effort. Well, not to worry. Oracle knows that enterprises need solutions that address the full continuum of requirements for data protection and availability. Oracle MAA accomplishes this by defining four HA service level tiers: BRONZE, SILVER, GOLD and PLATINUM. The figure below shows the progression in service levels provided by each tier. Each tier uses a different MAA reference architecture to deploy the optimal set of Oracle HA capabilities that reliably achieve a given service level (SLA) at the lowest cost.  Each tier includes all of the capabilities of the previous tier and builds upon the architecture to handle an expanded fault domain. Bronze is appropriate for databases where simple restart or restore from backup is ‘HA enough’. Bronze is based upon a single instance Oracle Database with MAA best practices that use the many capabilities for data protection and HA included with every Oracle Enterprise Edition license. Oracle-optimized backups using Oracle Recovery Manager (RMAN) provide data protection and are used to restore availability should an outage prevent the database from being able to restart. Silver provides an additional level of HA for databases that require minimal or zero downtime in the event of database instance or server failure as well as many types of planned maintenance. Silver adds clustering technology - either Oracle RAC or RAC One Node. RMAN provides database-optimized backups to protect data and restore availability should an outage prevent the cluster from being able to restart. Gold raises the game substantially for business critical applications that can’t accept vulnerability to single points-of-failure. Gold adds database-aware replication technologies, Active Data Guard and Oracle GoldenGate, which synchronize one or more replicas of the production database to provide real time data protection and availability. Database-aware replication greatly increases HA and data protection beyond what is possible with storage replication technologies. It also reduces cost while improving return on investment by actively utilizing all replicas at all times. Platinum introduces all of the sexy new Oracle Database 12c capabilities that Oracle staff will gush over with great enthusiasm. These capabilities include Application Continuity for reliable replay of in-flight transactions that masks outages from users; Active Data Guard Far Sync for zero data loss protection at any distance; new Oracle GoldenGate enhancements for zero downtime upgrades and migrations; and Global Data Services for automated service management and workload balancing in replicated database environments. Each of these technologies requires additional effort to implement. But they deliver substantial value for your most critical applications where downtime and data loss are not an option. The MAA reference architectures are inherently designed to address conflicting realities. On one hand, not every application has the same objectives for availability and data protection – the Not One Size Fits All title of this blog post. On the other hand, standard infrastructure is an operational requirement and a business necessity in order to reduce complexity and cost. MAA reference architectures address both realities by providing a standard infrastructure optimized for Oracle Database that enables you to dial-in the level of HA appropriate for different service level requirements. This makes it simple to move a database from one HA tier to the next should business requirements change, or from one hardware platform to another – whether it’s your favorite non-Oracle vendor or an Oracle Engineered System. Please stay tuned for additional blog posts in this series that dive into the details of each MAA reference architecture. Meanwhile, more information on Oracle HA solutions and the Maximum Availability Architecture can be found at: Oracle Maximum Availability Architecture - Webcast Maximize Availability with Oracle Database 12c - Technical White Paper

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  • Problem with sprite direction and rotation

    - by user2236165
    I have a sprite called Tool that moves with a speed represented as a float and in a direction represented as a Vector2. When I click the mouse on the screen the sprite change its direction and starts to move towards the mouseclick. In addition to that I rotate the sprite so that it is facing in the direction it is heading. However, when I add a camera that is suppose to follow the sprite so that the sprite is always centered on the screen, the sprite won't move in the given direction and the rotation isn't accurate anymore. This only happens when I add the Camera.View in the spriteBatch.Begin(). I was hoping anyone could maybe shed a light on what I am missing in my code, that would be highly appreciated. Here is the camera class i use: public class Camera { private const float zoomUpperLimit = 1.5f; private const float zoomLowerLimit = 0.1f; private float _zoom; private Vector2 _pos; private int ViewportWidth, ViewportHeight; #region Properties public float Zoom { get { return _zoom; } set { _zoom = value; if (_zoom < zoomLowerLimit) _zoom = zoomLowerLimit; if (_zoom > zoomUpperLimit) _zoom = zoomUpperLimit; } } public Rectangle Viewport { get { int width = (int)((ViewportWidth / _zoom)); int height = (int)((ViewportHeight / _zoom)); return new Rectangle((int)(_pos.X - width / 2), (int)(_pos.Y - height / 2), width, height); } } public void Move(Vector2 amount) { _pos += amount; } public Vector2 Position { get { return _pos; } set { _pos = value; } } public Matrix View { get { return Matrix.CreateTranslation(new Vector3(-_pos.X, -_pos.Y, 0)) * Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) * Matrix.CreateTranslation(new Vector3(ViewportWidth * 0.5f, ViewportHeight * 0.5f, 0)); } } #endregion public Camera(Viewport viewport, float initialZoom) { _zoom = initialZoom; _pos = Vector2.Zero; ViewportWidth = viewport.Width; ViewportHeight = viewport.Height; } } And here is my Update and Draw-method: protected override void Update (GameTime gameTime) { float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; TouchCollection touchCollection = TouchPanel.GetState (); foreach (TouchLocation tl in touchCollection) { if (tl.State == TouchLocationState.Pressed || tl.State == TouchLocationState.Moved) { //direction the tool shall move towards direction = touchCollection [0].Position - toolPos; if (direction != Vector2.Zero) { direction.Normalize (); } //change the direction the tool is moving and find the rotationangle the texture must rotate to point in given direction toolPos += (direction * speed * elapsed); RotationAngle = (float)Math.Atan2 (direction.Y, direction.X); } } if (direction != Vector2.Zero) { direction.Normalize (); } //move tool in given direction toolPos += (direction * speed * elapsed); //change cameracentre to the tools position Camera.Position = toolPos; base.Update (gameTime); } protected override void Draw (GameTime gameTime) { graphics.GraphicsDevice.Clear (Color.Blue); spriteBatch.Begin (SpriteSortMode.BackToFront, BlendState.AlphaBlend, null, null, null, null, Camera.View); spriteBatch.Draw (tool, new Vector2 (toolPos.X, toolPos.Y), null, Color.White, RotationAngle, originOfToolTexture, 1, SpriteEffects.None, 1); spriteBatch.End (); base.Draw (gameTime); }

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  • Greyscale Image from YUV420p data

    - by fergs
    From what I have read on the internet the Y value is the luminance value and can be used to create a grey scale image. The following link: http://www.bobpowell.net/grayscale.htm, has some C# code on working out the luminance of a bitmap image : { Bitmap bm = new Bitmap(source.Width,source.Height); for(int y=0;y<bm.Height;y++) public Bitmap ConvertToGrayscale(Bitmap source) { for(int x=0;x<bm.Width;x++) { Color c=source.GetPixel(x,y); int luma = (int)(c.R*0.3 + c.G*0.59+ c.B*0.11); bm.SetPixel(x,y,Color.FromArgb(luma,luma,luma)); } } return bm; } I have a method that returns the YUV values and have the Y data in a byte array. I have the current piece of code and it is failing on Marshal.Copy – attempted to read or write protected memory. public Bitmap ConvertToGrayscale2(byte[] yuvData, int width, int height) { Bitmap bmp; IntPtr blue = IntPtr.Zero; int inputOffSet = 0; long[] pixels = new long[width * height]; try { for (int y = 0; y < height; y++) { int outputOffSet = y * width; for (int x = 0; x < width; x++) { int grey = yuvData[inputOffSet + x] & 0xff; unchecked { pixels[outputOffSet + x] = UINT_Constant | (grey * INT_Constant); } } inputOffSet += width; } blue = Marshal.AllocCoTaskMem(pixels.Length); Marshal.Copy(pixels, 0, blue, pixels.Length); // fails here : Attempted to read or write protected memory bmp = new Bitmap(width, height, width, PixelFormat.Format24bppRgb, blue); } catch (Exception) { throw; } finally { if (blue != IntPtr.Zero) { Marshal.FreeHGlobal(blue); blue = IntPtr.Zero; } } return bmp; } Any help would be appreciated?

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  • CreateProcessAsUser doesn't draw the GUI

    - by pavel.tuzov
    Hi, I have a windows service running under "SYSTEM" account that checks if a specific application is running for each logged in user. If the application is not running, the service starts it (under corresponding user name). I'm trying to accomplish my goal using CreateProcessAsUser(). The service does start the application under corresponding user name, but the GUI is not drawn. (Yes, I'm making sure that "Allow service to interact with desktop" check box is enabled). System: XP SP3, labguage: C# Here is some code that might be of interest: PROCESS_INFORMATION processInfo = new PROCESS_INFORMATION(); startInfo.cb = Marshal.SizeOf(startInfo); startInfo.lpDesktop = "winsta0\\default"; bResult = Win32.CreateProcessAsUser(hToken, null, strCommand, IntPtr.Zero, IntPtr.Zero, false, 0, IntPtr.Zero, null, ref startInfo, out processInfo); As far as I understand, setting startInfo.lpDesktop = "winsta0\default"; should have used the desktop of corresponding user. Even contrary to what is stated here: http://support.microsoft.com/kb/165194, I tried setting lpDesktop to null, or not setting it at all, both giving the same result: process was started in the name of expected user and I could see a part of window's title bar. The "invisible" window intercepts mouse click events, handles them as expected. It just doesn't draw itself. Is anyone familiar with such a problem and knows what am I doing wrong?

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  • Dynamic Programming Recursion and a sprinkle of Memoization

    - by Auburnate
    I have this massive array of ints from 0-4 in this triangle. I am trying to learn dynamic programming with Ruby and would like some assistance in calculating the number of paths in the triangle that meet three criterion: You must start at one of the zero points in the row with 70 elements. Your path can be directly above you one row (if there is a number directly above) or one row up heading diagonal to the left. One of these options is always available The sum of the path you take to get to the zero on the first row must add up to 140. Example, start at the second zero in the bottom row. You can move directly up to the one or diagonal left to the 4. In either case, the number you arrive at must be added to the running count of all the numbers you have visited. From the 1 you can travel to a 2 (running sum = 3) directly above or to the 0 (running sum = 1) diagonal to the left. 0 41 302 2413 13024 024130 4130241 30241302 241302413 1302413024 02413024130 413024130241 3024130241302 24130241302413 130241302413024 0241302413024130 41302413024130241 302413024130241302 2413024130241302413 13024130241302413024 024130241302413024130 4130241302413024130241 30241302413024130241302 241302413024130241302413 1302413024130241302413024 02413024130241302413024130 413024130241302413024130241 3024130241302413024130241302 24130241302413024130241302413 130241302413024130241302413024 0241302413024130241302413024130 41302413024130241302413024130241 302413024130241302413024130241302 2413024130241302413024130241302413 13024130241302413024130241302413024 024130241302413024130241302413024130 4130241302413024130241302413024130241 30241302413024130241302413024130241302 241302413024130241302413024130241302413 1302413024130241302413024130241302413024 02413024130241302413024130241302413024130 413024130241302413024130241302413024130241 3024130241302413024130241302413024130241302 24130241302413024130241302413024130241302413 130241302413024130241302413024130241302413024 0241302413024130241302413024130241302413024130 41302413024130241302413024130241302413024130241 302413024130241302413024130241302413024130241302 2413024130241302413024130241302413024130241302413 13024130241302413024130241302413024130241302413024 024130241302413024130241302413024130241302413024130 4130241302413024130241302413024130241302413024130241 30241302413024130241302413024130241302413024130241302 241302413024130241302413024130241302413024130241302413 1302413024130241302413024130241302413024130241302413024 02413024130241302413024130241302413024130241302413024130 413024130241302413024130241302413024130241302413024130241 3024130241302413024130241302413024130241302413024130241302 24130241302413024130241302413024130241302413024130241302413 130241302413024130241302413024130241302413024130241302413024 0241302413024130241302413024130241302413024130241302413024130 41302413024130241302413024130241302413024130241302413024130241 302413024130241302413024130241302413024130241302413024130241302 2413024130241302413024130241302413024130241302413024130241302413 13024130241302413024130241302413024130241302413024130241302413024 024130241302413024130241302413024130241302413024130241302413024130 4130241302413024130241302413024130241302413024130241302413024130241 30241302413024130241302413024130241302413024130241302413024130241302 241302413024130241302413024130241302413024130241302413024130241302413 1302413024130241302413024130241302413024130241302413024130241302413024 02413024130241302413024130241302413024130241302413024130241302413024130

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  • What are alternatives to Win32 PulseEvent() function?

    - by Bill
    The documentation for the Win32 API PulseEvent() function (kernel32.dll) states that this function is “… unreliable and should not be used by new applications. Instead, use condition variables”. However, condition variables cannot be used across process boundaries like (named) events can. I have a scenario that is cross-process, cross-runtime (native and managed code) in which a single producer occasionally has something interesting to make known to zero or more consumers. Right now, a well-known named event is used (and set to signaled state) by the producer using this PulseEvent function when it needs to make something known. Zero or more consumers wait on that event (WaitForSingleObject()) and perform an action in response. There is no need for two-way communication in my scenario, and the producer does not need to know if the event has any listeners, nor does it need to know if the event was successfully acted upon. On the other hand, I do not want any consumers to ever miss any events. In other words, the system needs to be perfectly reliable – but the producer does not need to know if that is the case or not. The scenario can be thought of as a “clock ticker” – i.e., the producer provides a semi-regular signal for zero or more consumers to count. And all consumers must have the correct count over any given period of time. No polling by consumers is allowed (performance reasons). The ticker is just a few milliseconds (20 or so, but not perfectly regular). Raymen Chen (The Old New Thing) has a blog post pointing out the “fundamentally flawed” nature of the PulseEvent() function, but I do not see an alternative for my scenario from Chen or the posted comments. Can anyone please suggest one? Please keep in mind that the IPC signal must cross process boundries on the machine, not simply threads. And the solution needs to have high performance in that consumers must be able to act within 10ms of each event.

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  • Pseudo code for instruction description

    - by Claus
    Hi, I am just trying to fiddle around what is the best and shortest way to describe two simple instructions with C-like pseudo code. The extract instruction is defined as follows: extract rd, rs, imm This instruction extracts the appropriate byte from the 32-bit source register rs and right justifies it in the destination register. The byte is specified by imm and thus can take the values 0 (for the least-significant byte) and 3 (for the most-significant byte). rd = 0x0; // zero-extend result, ie to make sure bits 31 to 8 are set to zero in the result rd = (rs && (0xff << imm)) >> imm; // this extracts the approriate byte and stores it in rd The insert instruction can be regarded as the inverse operation and it takes a right justified byte from the source register rs and deposits it in the appropriate byte of the destination register rd; again, this byte is determined by the value of imm tmp = 0x0 XOR (rs << imm)) // shift the byte to the appropriate byte determined by imm rd = (rd && (0x00 << imm)) // set appropriate byte to zero in rd rd = rd XOR tmp // XOR the byte into the destination register This looks all a bit horrible, so I wonder if there is a little bit a more elegant way to describe this bahaviour in C-like style ;) Many thanks, Claus

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  • Minimal assembler program for CP/M 3.1 (z80)

    - by Andrew J. Brehm
    I seem to be losing the battle against my stupidity. This site explains the system calls under various versions of CP/M. However, when I try to use call 2 (C_WRITE, console output), nothing much happens. I have the following code. ORG 100h LD E,'a' LD C,2 CALL 5 CALL 0 I recite this here from memory. If there are typos, rest assured they were not in the original since the file did compile and I had a COM file to start. I am thinking the lines mean the following: Make sure this gets loaded at address 100h (0h to FFh being the zero page). Load ASCII 'a' into E register for system call 2. Load integer 2 into C register for system call 2. Make system call (JMP to system call is at address 5 in zero page). End program (Exit command is at address 0 in zero page). The program starts and exits with no problems. If I remove the last command, it hangs the computer (which I guess is also expected and shows that CALL 0 works). However, it does not print the ASCII character. (But it does print an extra new line, but the system might have done that.) How can I get my CP/M program to do what the system call is supposed to do? What am I doing wrong?

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  • How to get around DnsRecordListFree error in .NET Framework 4.0?

    - by Greg Finzer
    I am doing an MxRecordLookup. I am getting an error when calling the DnsRecordListFree in the .NET Framework 4.0. I am using Windows 7. How do I get around it? Here is the error: System.MethodAccessException: Attempt by security transparent method to call native code through method. Here is my code: [DllImport("dnsapi", EntryPoint = "DnsQuery_W", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true)] private static extern int DnsQuery([MarshalAs(UnmanagedType.VBByRefStr)]ref string pszName, QueryTypes wType, QueryOptions options, int aipServers, ref IntPtr ppQueryResults, int pReserved); [DllImport("dnsapi", CharSet = CharSet.Auto, SetLastError = true)] private static extern void DnsRecordListFree(IntPtr pRecordList, int FreeType); public List<string> GetMXRecords(string domain) { List<string> records = new List<string>(); IntPtr ptr1 = IntPtr.Zero; IntPtr ptr2 = IntPtr.Zero; MXRecord recMx; try { int result = DnsQuery(ref domain, QueryTypes.DNS_TYPE_MX, QueryOptions.DNS_QUERY_BYPASS_CACHE, 0, ref ptr1, 0); if (result != 0) { if (result == 9003) { //No Record Exists } else { //Some other error } } for (ptr2 = ptr1; !ptr2.Equals(IntPtr.Zero); ptr2 = recMx.pNext) { recMx = (MXRecord)Marshal.PtrToStructure(ptr2, typeof(MXRecord)); if (recMx.wType == 15) { records.Add(Marshal.PtrToStringAuto(recMx.pNameExchange)); } } } finally { DnsRecordListFree(ptr1, 0); } return records; }

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  • NHibernate mapping with two special cases

    - by brainimus
    I am using NHibernate to map a class to a database table. The Part table has an ID column (primary key) and a ParentPart column (along with a few others). class Part { public virtual long ID{ get; set; } public virtual Part ParentPart { get; set; } } The ParentPart is normally another valid part in the part table but I have two special cases. I have a case where the ParentPart column can be 0 (zero) and another case where it can be -1. Neither of these cases currently represent another valid Part object. I was thinking I could make 2 subclasses of Part (ZeroPart and NegativeOnePart) that would never persist. I want the zero and -1 values to be entered in the column but not persist the entire ZeroPart or NegativeOnePart objects. I am unsure how to map this (I'm using hbm files) or if this even the correct approach. How can I map this so that normal valid parts are persisted but I can also handle the special cases? As an aside: My current hbm file has the Part.ID's unsaved value as zero but I think I can just change this in the mapping to something different and default it in the class.

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  • Generic validate input data via regex. Input error when match.count == 0

    - by Valamas
    Hi, I have a number of types of data fields on an input form, for example, a web page. Some fields are like, must be an email address, must be a number, must be a number between, must have certain characters. Basically, the list is undefinable. I wish to come up with a generic way of validating the data inputed. I thought I would use regex to validate the data. The fields which need validation would be related to a "regex expression" and a "regex error message" stating what the field should contain. My current mock up has that when the match count is zero, that would signify an error and to display the message. While still a white belt regex designer I have come to understand that in certain situations that it is difficult to write a regex which results in a match count of zero for every case. A complex regex case I looked for help on was Link Here. The forum post was a disaster because I confused people helping me. But one of the statements said that it was difficult to make a regex with a match count of zero meaning the input data was invalid; that the regex was very difficult to write that for. Does anyone have comments or suggestions on this generic validation system I am trying to create? thanks

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  • Save Bitmap image in a location in C#

    - by acadia
    Hello, I have this function to store the bmp image in a desired location as shown below My question is, how do I save the image in C:\temp folder by default, instead of opening the filedialog box? I want to specify sd.fileName=picname+".bmp" and store it in c:\temp by default. I tried to specify Thanks for your help in advance. I tried to public static bool SaveDIBAs( string picname, IntPtr bminfo, IntPtr pixdat ) { SaveFileDialog sd = new SaveFileDialog(); sd.FileName = picname; sd.Title = "Save bitmap as..."; sd.Filter = "Bitmap file (*.bmp)|*.bmp|TIFF file (*.tif)|*.tif|JPEG file (*.jpg)|*.jpg|PNG file (*.png)|*.png|GIF file (*.gif)|*.gif|All files (*.*)|*.*"; sd.FilterIndex = 1; if( sd.ShowDialog() != DialogResult.OK ) return false; Guid clsid; if( ! GetCodecClsid( sd.FileName, out clsid ) ) { MessageBox.Show( "Unknown picture format for extension " + Path.GetExtension( sd.FileName ), "Image Codec", MessageBoxButtons.OK, MessageBoxIcon.Information ); return false; } IntPtr img = IntPtr.Zero; int st = GdipCreateBitmapFromGdiDib( bminfo, pixdat, ref img ); if( (st != 0) || (img == IntPtr.Zero) ) return false; st = GdipSaveImageToFile( img, sd.FileName, ref clsid, IntPtr.Zero ); GdipDisposeImage( img ); return st == 0; }

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  • How to avoid resetting the java Scanner position

    - by Derek
    I have some code that looks more or less like this: while(scanner.hasNext()) { if(scanner.findInLine("Test") !=null) { //do some things }else{ scanner.nextLine(); } } I am using this to parse an ~10MB text file. The problem is, if I put a breakpoint on the while() and the scanner.nextLine(), I can see that sometimes the scanners position (in the debug window) goes back to zero. I think this is causing me some kind of loop blow up, because the regext in findInLine() starts at zero, looks through some amount of text, advancing the position, and then it randomly gets set back to zero, so it has to re-parse all that text again. Any ideas what can be causing that? Am I even doing this the right way? Thanks Some additional info: The Scanner is instantiated from an InputStream. After diubg sine debugging, it appears that there is a HearCharBuffer that Scanner uses and it only allows 1024 characters at a time, and then resets. Is there a way to avoid this, or do things differently? That seems like a small amount of characters to be able to scan. Derek

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  • Why does DeviceIoControl throw error 21 (Device Not Ready) from C# when the equivalent in C works fine?

    - by Ragesh
    I'm trying to send an IOCTL_SERVICE_REFRESH command to the GPS Intermediate Driver service using C# like this: handle = CreateFile("GPD0:", GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero); if (handle.ToInt32() == INVALID_HANDLE_VALUE) { rc = Marshal.GetLastWin32Error(); return rc; } int numBytesReturned = 0; rc = DeviceIoControl( handle, IOCTL_SERVICE_REFRESH, null, 0, null, 0, ref numBytesReturned, IntPtr.Zero); int error = Marshal.GetLastWin32Error(); GetLastWin32Error always gives me error 21 (device not ready). However, the equivalent call when made from C++ works fine: HANDLE hGPS = CreateFile(L"GPD0:", GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); if (hGPS != INVALID_HANDLE_VALUE) { BOOL ret = DeviceIoControl(hGPS,IOCTL_SERVICE_REFRESH,0,0,0,0,0,0); DWORD err = GetLastError(); } I suspected a problem with the PInvoke signatures, but I can't seem to find anything wrong here: [DllImport("coredll.dll", EntryPoint = "DeviceIoControl", SetLastError = true)] public static extern int DeviceIoControl( IntPtr hDevice, uint dwIoControlCode, byte[] lpInBuffer, int nInBufferSize, byte[] lpOutBuffer, int nOutBufferSize, ref int lpBytesReturned, IntPtr lpOverlapped); [DllImport("coredll.dll", SetLastError = true)] public static extern IntPtr CreateFile( String lpFileName, uint dwDesiredAccess, uint dwShareMode, IntPtr attr, uint dwCreationDisposition, uint dwFlagsAndAttributes, IntPtr hTemplateFile); What am I missing here?

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