ParallelForEach<T> Class

.NET Framework (current version)
 

Enumerates the elements of a collection and executes an embedded statement for each element of the collection in parallel.

Namespace:   System.Activities.Statements
Assembly:  System.Activities (in System.Activities.dll)

System.Object
  System.Activities.Activity
    System.Activities.NativeActivity
      System.Activities.Statements.ParallelForEach<T>

[ContentPropertyAttribute("Body")]
public sealed class ParallelForEach<T> : NativeActivity

Type Parameters

T

The type of the values provided in the Values collection.

NameDescription
System_CAPS_pubmethodParallelForEach<T>()

Creates a new instance of the ParallelForEach<T> class.

NameDescription
System_CAPS_pubpropertyBody

The ActivityAction that is executed once for every value contained in the Values collection.

System_CAPS_protpropertyCacheId

Gets the identifier of the cache that is unique within the scope of the workflow definition.(Inherited from Activity.)

System_CAPS_pubpropertyCompletionCondition

Evaluated after each iteration completes.

System_CAPS_pubpropertyDisplayName

Gets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking.(Inherited from Activity.)

System_CAPS_pubpropertyId

Gets an identifier that is unique in the scope of the workflow definition.(Inherited from Activity.)

System_CAPS_protpropertyImplementationVersion

Gets or sets the implementation version of the activity.(Inherited from NativeActivity.)

System_CAPS_pubpropertyValues

The collection of values used as parameters for each iteration of the activity contained in the Body.

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodShouldSerializeDisplayName()

Indicates whether the DisplayName property should be serialized.(Inherited from Activity.)

System_CAPS_pubmethodToString()

Returns a String that contains the Id and DisplayName of the Activity.(Inherited from Activity.)

The embedded statements are scheduled together and run asynchronously, but unless the scheduled activites themselves are asynchronous (such as messaging activities, InvokeMethod, or activities that derive from AsyncCodeActivity), they do not run on separate threads, so each successive activity will only execute when the previously scheduled activity completes or goes idle. If none of the child activities of this activity are asynchronous or go idle, this activity execute in the same way that a ForEach<T> activity does.

The following code sample demonstrates creating a ParallelForEach<T> activity. This example is from the Corporate Purchase Process sample.

// invite all vendors and wait for their proposals
new ParallelForEach<Vendor>
{
    DisplayName = "Get vendor proposals",
    Values = new InArgument<IEnumerable<Vendor>>(ctx =>this.Rfp.Get(ctx).InvitedVendors),
    Body = new ActivityAction<Vendor>()
    {                                    
        Argument = iterationVariableVendor,
        Handler = new Sequence
        {
            Variables = { tmpValue },
            Activities =
            {
                // waits for a vendor proposal (creates a bookmark for a vendor)
                new WaitForVendorProposal 
                { 
                    VendorId = new LambdaValue<int>(ctx =>iterationVariableVendor.Get(ctx).Id) ,
                    Result = new OutArgument<double>(tmpValue)
                },

                // after the vendor proposal is received, it is registered in the Request for Proposals
                new InvokeMethod
                {
                    TargetObject = new InArgument<RequestForProposal>(ctx =>this.Rfp.Get(ctx)),
                    MethodName = "RegisterProposal",
                    Parameters = 
                    {
                        new InArgument<Vendor>(iterationVariableVendor),
                        new InArgument<double>(tmpValue)
                    }
                },
            }
        }                        
    }
},

.NET Framework
Available since 4.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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