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| <h1 id="Apache_Ignite_Core_Compute_IComputeTask_3" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3" class="text-break">Interface IComputeTask<TArg, TJobRes, TRes> |
| </h1> |
| <div class="markdown level0 summary"><p>Ignite task interface defines a task that can be executed on the grid. Ignite task |
| is responsible for splitting business logic into multiple Ignite jobs, receiving |
| results from individual Ignite jobs executing on remote nodes, and reducing |
| (aggregating) received jobs' results into final Ignite task result. |
| <p> |
| Upon request to execute a task, the system will do the following: |
| <ul><li>Inject annotated resources into task instance.</li><li>Apply <a class="xref" href="Apache.Ignite.Core.Compute.IComputeTask-3.html#Apache_Ignite_Core_Compute_IComputeTask_3_Map_System_Collections_Generic_IList_Apache_Ignite_Core_Cluster_IClusterNode___0_">Map(IList<IClusterNode>, TArg)</a>. |
| This method is responsible for splitting business logic into multiple jobs |
| (units of execution) and mapping them to Ignite nodes.</li><li>System will send mapped Ignite jobs to their respective nodes.</li><li>Once job execution results become available, <a class="xref" href="Apache.Ignite.Core.Compute.IComputeTask-3.html#Apache_Ignite_Core_Compute_IComputeTask_3_OnResult_Apache_Ignite_Core_Compute_IComputeJobResult__1__System_Collections_Generic_IList_Apache_Ignite_Core_Compute_IComputeJobResult__1___">OnResult(IComputeJobResult<TJobRes>, IList<IComputeJobResult<TJobRes>>)</a> method |
| will be called for ech received job result. The policy returned by this method will |
| determine the way task reacts to every job result. |
| <p> |
| If <a class="xref" href="Apache.Ignite.Core.Compute.ComputeJobResultPolicy.html#Apache_Ignite_Core_Compute_ComputeJobResultPolicy_Wait">Wait</a> is returned, task will continue to wait |
| for other job results. If this result is the last job result, then reduce phase will be |
| started. |
| <p> |
| If <a class="xref" href="Apache.Ignite.Core.Compute.ComputeJobResultPolicy.html#Apache_Ignite_Core_Compute_ComputeJobResultPolicy_Reduce">Reduce</a> is returned, reduce phase will be started |
| right away without waiting for other jobs completion (all remaining jobs will receive cancel |
| request). |
| <p> |
| If <a class="xref" href="Apache.Ignite.Core.Compute.ComputeJobResultPolicy.html#Apache_Ignite_Core_Compute_ComputeJobResultPolicy_Failover">Failover</a> is returned, job will be failed over to |
| another node for execution. Note that if you use <a class="xref" href="Apache.Ignite.Core.Compute.ComputeTaskAdapter-3.html">ComputeTaskAdapter<TArg, TJobRes, TTaskRes></a>, it will |
| automatically fail jobs to another node for 2 well-known failure cases: 1) job has failed to due |
| to node crash (in this case <a class="xref" href="Apache.Ignite.Core.Compute.IComputeJobResult-1.html#Apache_Ignite_Core_Compute_IComputeJobResult_1_Exception">Exception</a> will return |
| <a class="xref" href="Apache.Ignite.Core.Cluster.ClusterTopologyException.html">ClusterTopologyException</a>); 2) job execution was rejected, i.e. remote node |
| has cancelled job before it got a chance to execute, while it still was on the waiting list. |
| (in this case <a class="xref" href="Apache.Ignite.Core.Compute.IComputeJobResult-1.html#Apache_Ignite_Core_Compute_IComputeJobResult_1_Exception">Exception</a> will return |
| <a class="xref" href="Apache.Ignite.Core.Compute.ComputeExecutionRejectedException.html">ComputeExecutionRejectedException</a>). |
| </li><li>Once all results are received or <a class="xref" href="Apache.Ignite.Core.Compute.IComputeTask-3.html#Apache_Ignite_Core_Compute_IComputeTask_3_OnResult_Apache_Ignite_Core_Compute_IComputeJobResult__1__System_Collections_Generic_IList_Apache_Ignite_Core_Compute_IComputeJobResult__1___">OnResult(IComputeJobResult<TJobRes>, IList<IComputeJobResult<TJobRes>>)</a> |
| method returned <a class="xref" href="Apache.Ignite.Core.Compute.ComputeJobResultPolicy.html#Apache_Ignite_Core_Compute_ComputeJobResultPolicy_Reduce">Reduce</a> policy, method <a class="xref" href="Apache.Ignite.Core.Compute.IComputeTask-3.html#Apache_Ignite_Core_Compute_IComputeTask_3_Reduce_System_Collections_Generic_IList_Apache_Ignite_Core_Compute_IComputeJobResult__1___">Reduce(IList<IComputeJobResult<TJobRes>>)</a> |
| is called to aggregate received results into one final result. Once this method is finished the |
| execution of the Ignite task is complete. This result will be returned to the user through future. |
| </li></ul></p> |
| </div> |
| <div class="markdown level0 conceptual"></div> |
| <h6><strong>Namespace</strong>: <a class="xref" href="Apache.Ignite.Core.Compute.html">Apache.Ignite.Core.Compute</a></h6> |
| <h6><strong>Assembly</strong>: Apache.Ignite.Core.dll</h6> |
| <h5 id="Apache_Ignite_Core_Compute_IComputeTask_3_syntax">Syntax</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public interface IComputeTask<in TArg, TJobRes, out TRes></code></pre> |
| </div> |
| <h5 class="typeParameters">Type Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="parametername">TArg</span></td> |
| <td><p>Argument type.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><span class="parametername">TJobRes</span></td> |
| <td><p>Type of job result.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><span class="parametername">TRes</span></td> |
| <td><p>Type of final task result after reduce.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h3 id="methods">Methods |
| </h3> |
| <a id="Apache_Ignite_Core_Compute_IComputeTask_3_Map_" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3.Map*"></a> |
| <h4 id="Apache_Ignite_Core_Compute_IComputeTask_3_Map_System_Collections_Generic_IList_Apache_Ignite_Core_Cluster_IClusterNode___0_" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3.Map(System.Collections.Generic.IList{Apache.Ignite.Core.Cluster.IClusterNode},`0)">Map(IList<IClusterNode>, TArg)</h4> |
| <div class="markdown level1 summary"><p>This method is called to map or split Ignite task into multiple Ignite jobs. This is the |
| first method that gets called when task execution starts.</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">IDictionary<IComputeJob<TJobRes>, IClusterNode> Map(IList<IClusterNode> subgrid, TArg arg)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Collections.Generic.IList</span><<a class="xref" href="Apache.Ignite.Core.Cluster.IClusterNode.html">IClusterNode</a>></td> |
| <td><span class="parametername">subgrid</span></td> |
| <td><p>Nodes available for this task execution. Note that order of nodes is |
| guaranteed to be randomized by container. This ensures that every time you simply iterate |
| through Ignite nodes, the order of nodes will be random which over time should result into |
| all nodes being used equally.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><span class="xref">TArg</span></td> |
| <td><span class="parametername">arg</span></td> |
| <td><p>Task execution argument. Can be <code>null</code>. This is the same argument |
| as the one passed into <code>ICompute.Execute()</code> methods.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Collections.Generic.IDictionary</span><<a class="xref" href="Apache.Ignite.Core.Compute.IComputeJob-1.html">IComputeJob</a><TJobRes>, <a class="xref" href="Apache.Ignite.Core.Cluster.IClusterNode.html">IClusterNode</a>></td> |
| <td><p>Map of Ignite jobs assigned to subgrid node. If <code>null</code> or empty map is returned, |
| exception will be thrown.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <a id="Apache_Ignite_Core_Compute_IComputeTask_3_OnResult_" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3.OnResult*"></a> |
| <h4 id="Apache_Ignite_Core_Compute_IComputeTask_3_OnResult_Apache_Ignite_Core_Compute_IComputeJobResult__1__System_Collections_Generic_IList_Apache_Ignite_Core_Compute_IComputeJobResult__1___" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3.OnResult(Apache.Ignite.Core.Compute.IComputeJobResult{`1},System.Collections.Generic.IList{Apache.Ignite.Core.Compute.IComputeJobResult{`1}})">OnResult(IComputeJobResult<TJobRes>, IList<IComputeJobResult<TJobRes>>)</h4> |
| <div class="markdown level1 summary"><p>Asynchronous callback invoked every time a result from remote execution is |
| received. It is ultimately upto this method to return a policy based |
| on which the system will either wait for more results, reduce results |
| received so far, or failover this job to another node. See |
| <a class="xref" href="Apache.Ignite.Core.Compute.ComputeJobResultPolicy.html">ComputeJobResultPolicy</a> for more information.</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">ComputeJobResultPolicy OnResult(IComputeJobResult<TJobRes> res, IList<IComputeJobResult<TJobRes>> rcvd)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Apache.Ignite.Core.Compute.IComputeJobResult-1.html">IComputeJobResult</a><TJobRes></td> |
| <td><span class="parametername">res</span></td> |
| <td><p>Received remote Ignite executable result.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><span class="xref">System.Collections.Generic.IList</span><<a class="xref" href="Apache.Ignite.Core.Compute.IComputeJobResult-1.html">IComputeJobResult</a><TJobRes>></td> |
| <td><span class="parametername">rcvd</span></td> |
| <td><p>All previously received results. Note that if task class has |
| <a class="xref" href="Apache.Ignite.Core.Compute.ComputeTaskNoResultCacheAttribute.html">ComputeTaskNoResultCacheAttribute</a> attribute, then this list will be empty.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Apache.Ignite.Core.Compute.ComputeJobResultPolicy.html">ComputeJobResultPolicy</a></td> |
| <td><p>Result policy that dictates how to process further upcoming job results.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <a id="Apache_Ignite_Core_Compute_IComputeTask_3_Reduce_" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3.Reduce*"></a> |
| <h4 id="Apache_Ignite_Core_Compute_IComputeTask_3_Reduce_System_Collections_Generic_IList_Apache_Ignite_Core_Compute_IComputeJobResult__1___" data-uid="Apache.Ignite.Core.Compute.IComputeTask`3.Reduce(System.Collections.Generic.IList{Apache.Ignite.Core.Compute.IComputeJobResult{`1}})">Reduce(IList<IComputeJobResult<TJobRes>>)</h4> |
| <div class="markdown level1 summary"><p>Reduces (or aggregates) results received so far into one compound result to be returned to |
| caller via future. |
| <p> |
| Note, that if some jobs did not succeed and could not be failed over then the list of |
| results passed into this method will include the failed results. Otherwise, failed |
| results will not be in the list.</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">TRes Reduce(IList<IComputeJobResult<TJobRes>> results)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Collections.Generic.IList</span><<a class="xref" href="Apache.Ignite.Core.Compute.IComputeJobResult-1.html">IComputeJobResult</a><TJobRes>></td> |
| <td><span class="parametername">results</span></td> |
| <td><p>Received job results. Note that if task class has |
| <a class="xref" href="Apache.Ignite.Core.Compute.ComputeTaskNoResultCacheAttribute.html">ComputeTaskNoResultCacheAttribute</a> attribute, then this list will be empty.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">TRes</span></td> |
| <td><p>Task result constructed from results of remote executions.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </article> |
| </div> |
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