Update System.Threading.Tasks.Task for NET4.5/4.6 #296

yaakov-h · 2015-11-08T23:47:15Z

Adds contract for missing .NET 4.5 API Task.FromResult<TResult>
Adds contracts for new .NET 4.6 APIs to build on top of Producing contract reference assemblies for .NET Framework 4.6 #291:
- Task.FromCanceled
- Task.FromCanceled<TResult>
- Task.FromException
- Task.FromException<TResult>
- Task.CompletedTask

Adds missing .NET 4.5 API Task.FromResult<TResult>, and adds new .NET 4.6 APIs FromCanceled, FromCanceled<TResult>, FromException, FromException<TResult> and CompletedTask.

yaakov-h · 2015-11-19T02:02:21Z

Any other suggestions?

yaakov-h · 2015-11-19T02:36:49Z

Getting this error now when running buildCC.bat, but no idea why:

Build FAILED.

"C:\Workspace\Git\CodeContracts\Microsoft.Research\ManagedContract.Setup\buildMSI10.xml" (All target) (1) ->
"C:\Workspace\Git\CodeContracts\CodeContracts.sln" (Clean;Rebuild target) (2) ->
"C:\Workspace\Git\CodeContracts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj.metaproj" (Rebuild ta
rget) (41:3) ->
"C:\Workspace\Git\CodeContracts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj" (Rebuild target) (42
:3) ->
(BuildMultiTargets target) ->
  System.Threading.Tasks.Task.cs(1567,57): error CS1061: 'System.Threading.Tasks.Task<TResult>' does not contain a defi
nition for 'Exception' and no extension method 'Exception' accepting a first argument of type 'System.Threading.Tasks.T
ask<TResult>' could be found (are you missing a using directive or an assembly reference?) [C:\Workspace\Git\CodeContra
cts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]
  System.Threading.Tasks.Task.cs(1568,58): error CS1061: 'System.Threading.Tasks.Task<TResult>' does not contain a defi
nition for 'IsCanceled' and no extension method 'IsCanceled' accepting a first argument of type 'System.Threading.Tasks
.Task<TResult>' could be found (are you missing a using directive or an assembly reference?) [C:\Workspace\Git\CodeCont
racts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]
  System.Threading.Tasks.Task.cs(1569,57): error CS1061: 'System.Threading.Tasks.Task<TResult>' does not contain a defi
nition for 'IsCompleted' and no extension method 'IsCompleted' accepting a first argument of type 'System.Threading.Tas
ks.Task<TResult>' could be found (are you missing a using directive or an assembly reference?) [C:\Workspace\Git\CodeCo
ntracts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]
  System.Threading.Tasks.Task.cs(1570,58): error CS1061: 'System.Threading.Tasks.Task<TResult>' does not contain a defi
nition for 'IsFaulted' and no extension method 'IsFaulted' accepting a first argument of type 'System.Threading.Tasks.T
ask<TResult>' could be found (are you missing a using directive or an assembly reference?) [C:\Workspace\Git\CodeContra
cts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]
  System.Threading.Tasks.Task.cs(1571,57): error CS1061: 'System.Threading.Tasks.Task<TResult>' does not contain a defi
nition for 'Status' and no extension method 'Status' accepting a first argument of type 'System.Threading.Tasks.Task<TR
esult>' could be found (are you missing a using directive or an assembly reference?) [C:\Workspace\Git\CodeContracts\Mi
crosoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]
  System.Threading.Tasks.Task.cs(1571,67): error CS0103: The name 'TaskStatus' does not exist in the current context [C
:\Workspace\Git\CodeContracts\Microsoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]
  System.Threading.Tasks.Task.cs(1572,57): error CS1061: 'System.Threading.Tasks.Task<TResult>' does not contain a defi
nition for 'Result' and no extension method 'Result' accepting a first argument of type 'System.Threading.Tasks.Task<TR
esult>' could be found (are you missing a using directive or an assembly reference?) [C:\Workspace\Git\CodeContracts\Mi
crosoft.Research\Contracts\MsCorlib\MsCorlib.Contracts10.csproj]

    0 Warning(s)
    7 Error(s)

Time Elapsed 00:00:36.03
.
****************************************************
Build FAILED
****************************************************

Do I need to define those properties and the enum in the Contracts project?

fedotovalex · 2015-11-19T04:05:28Z

Do I need to define those properties and the enum in the Contracts project?

Yes, you need to uncomment these properties in the Task class. I see the properties are there, but they were commented out, probably they did not seem relevant for the contracts assembly before (but now they are).

You will also need to add the TaskStatus enum.

yaakov-h · 2015-11-19T04:41:23Z

OK, seems to be compiling now. Thanks for the pointers, @fedotovalex.

yaakov-h · 2015-11-19T04:48:54Z

I should probably add actual contracts for AggregateException, but I'll do that as a separate PR after this.

SergeyTeplyakov · 2016-01-21T20:52:47Z

Microsoft.Research/Contracts/MsCorlib/System.Threading.Tasks.Task.cs

+      Contract.Ensures(!Contract.Result<Task<TResult>>().IsCanceled);
+      Contract.Ensures(Contract.Result<Task<TResult>>().IsCompleted);
+      Contract.Ensures(!Contract.Result<Task<TResult>>().IsFaulted);
+      Contract.Ensures(Contract.Result<Task<TResult>>().Status == TaskStatus.RanToCompletion);


Just curious would it be enough to leave just one postcondition that Status == TaskStatus.RanToCompletion and than express (via postconditions) relationship between Status and IsCanceled, IsCompleted and IsFaulted?

I'm fine with this approach but proposed one could be slightly easier to read, because all those postconditions:

+ Contract.Ensures(Contract.Result<Task<TResult>>().Exception == null); + Contract.Ensures(!Contract.Result<Task<TResult>>().IsCanceled); + Contract.Ensures(Contract.Result<Task<TResult>>().IsCompleted); + Contract.Ensures(!Contract.Result<Task<TResult>>().IsFaulted);

Are just redundant.

SergeyTeplyakov · 2016-01-21T20:55:51Z

Add some minor comments, but everything is LGTM.

yaakov-h · 2016-01-21T22:25:55Z

Thanks. I'll take a shot at addressing your comments early next week.

hubuk · 2016-01-21T22:55:58Z

Microsoft.Research/Contracts/MsCorlib/System.Threading.Tasks.Task.cs

+      Contract.Ensures(Contract.Result<Task>().IsCompleted);
+      Contract.Ensures(!Contract.Result<Task>().IsFaulted);
+      Contract.Ensures(Contract.Result<Task>().Status == TaskStatus.Canceled);
+      Contract.EnsuresOnThrow<ArgumentOutOfRangeException>(true, "Cancellation has not been requested for cancellationToken; its IsCancellationRequested property is false.");


What is the purpose of this kinds of contracts? It never fails at runtime and it seems that it has no value for static analyzer. Is it some kind of documentation?

I believe it actually does help static analyzer. Imagine you have a method

public void HandleCompletedTask(Task task) { Contract.Requires(task.IsCompleted); ... }

With the contracts above, you should be able to write

HandleCompletedTask(Task.FromCanceled(cancellationToken));

and the static checker would not complain. Without the contract, you'll have to add an explicit Assume to keep the static checker quiet.

I thought @hubuk's comment was specifically on the EnsuresOnThrow, in which case I have no idea what it's for, but I've added it purely to be consistent with existing contracts.

Yes, my question was about

Contract.EnsuresOnThrow<ArgumentOutOfRangeException>(true, "Cancellation has not been requested for cancellationToken; its IsCancellationRequested property is false.");

Never saw contracts like this one.

There are quite a handful already.

Update System.Threading.Tasks.Task for NET4.5/4.6

SergeyTeplyakov · 2016-01-26T18:07:09Z

@yaakov-h This PR broke the build. I'm going to revert it to fix the master.

hubuk · 2016-01-26T18:25:18Z

@SergeyTeplyakov It seems as this is not the only one PR that required fixing. There are other problems related to enabling contracts for .Net 4.6. Looking into it right now.
BTW. f0c4d1a already contains fix for this part of problem caused by this PR.

yaakov-h · 2016-01-26T19:17:59Z

Odd, the build appeared to work... I'd guess it's because I only tested this building on top of master, not on top of #291 (I think? Hard to remember) so NETFRAMEWORK_4_6 was never actually defined. Whoops!

yaakov-h added 2 commits November 9, 2015 10:36

Update System.Threading.Tasks.Task for NET45/46

79edddd

Adds missing .NET 4.5 API Task.FromResult<TResult>, and adds new .NET 4.6 APIs FromCanceled, FromCanceled<TResult>, FromException, FromException<TResult> and CompletedTask.

Add [Pure] and more postconditions to newly contracted Task methods

3f3d9a7

Add ArgumentOutOfRangeException on Task.FromCanceled

d174f0f

yaakov-h added 2 commits November 19, 2015 15:26

Add missing Task properties and TaskStatus

9b796e3

Fix compilation

20991bc

SergeyTeplyakov reviewed Jan 21, 2016
View reviewed changes

hubuk reviewed Jan 21, 2016
View reviewed changes

SergeyTeplyakov added a commit that referenced this pull request Jan 26, 2016

Merge pull request #296 from yaakov-h/pr-Net46Task

1064c75

Update System.Threading.Tasks.Task for NET4.5/4.6

SergeyTeplyakov merged commit 1064c75 into microsoft:master Jan 26, 2016

yaakov-h deleted the pr-Net46Task branch April 24, 2018 13:41

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Update System.Threading.Tasks.Task for NET4.5/4.6 #296

Update System.Threading.Tasks.Task for NET4.5/4.6 #296

yaakov-h commented Nov 8, 2015

yaakov-h commented Nov 19, 2015

yaakov-h commented Nov 19, 2015

fedotovalex commented Nov 19, 2015

yaakov-h commented Nov 19, 2015

yaakov-h commented Nov 19, 2015

SergeyTeplyakov Jan 21, 2016

SergeyTeplyakov commented Jan 21, 2016

yaakov-h commented Jan 21, 2016

hubuk Jan 21, 2016

fedotovalex Jan 22, 2016

yaakov-h Jan 22, 2016

hubuk Jan 22, 2016

yaakov-h Jan 22, 2016

SergeyTeplyakov commented Jan 26, 2016

hubuk commented Jan 26, 2016

yaakov-h commented Jan 26, 2016

Update System.Threading.Tasks.Task for NET4.5/4.6 #296

Update System.Threading.Tasks.Task for NET4.5/4.6 #296

Conversation

yaakov-h commented Nov 8, 2015

yaakov-h commented Nov 19, 2015

yaakov-h commented Nov 19, 2015

fedotovalex commented Nov 19, 2015

yaakov-h commented Nov 19, 2015

yaakov-h commented Nov 19, 2015

SergeyTeplyakov Jan 21, 2016

Choose a reason for hiding this comment

SergeyTeplyakov commented Jan 21, 2016

yaakov-h commented Jan 21, 2016

hubuk Jan 21, 2016

Choose a reason for hiding this comment

fedotovalex Jan 22, 2016

Choose a reason for hiding this comment

yaakov-h Jan 22, 2016

Choose a reason for hiding this comment

hubuk Jan 22, 2016

Choose a reason for hiding this comment

yaakov-h Jan 22, 2016

Choose a reason for hiding this comment

SergeyTeplyakov commented Jan 26, 2016

hubuk commented Jan 26, 2016

yaakov-h commented Jan 26, 2016