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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Diagnostics;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.SolutionCrawler
{
internal partial class SolutionCrawlerRegistrationService
{
internal partial class WorkCoordinator
{
private abstract class AsyncWorkItemQueue<TKey> : IDisposable
where TKey : class
{
private readonly object _gate = new();
private readonly SemaphoreSlim _semaphore;
private bool _disposed;
private readonly Workspace _workspace;
private readonly SolutionCrawlerProgressReporter _progressReporter;
// map containing cancellation source for the item given out.
private readonly Dictionary<object, CancellationTokenSource> _cancellationMap = new();
public AsyncWorkItemQueue(SolutionCrawlerProgressReporter progressReporter, Workspace workspace)
{
_semaphore = new SemaphoreSlim(initialCount: 0);
_workspace = workspace;
_progressReporter = progressReporter;
}
protected abstract int WorkItemCount_NoLock { get; }
protected abstract void Dispose_NoLock();
protected abstract bool AddOrReplace_NoLock(WorkItem item);
protected abstract bool TryTake_NoLock(TKey key, out WorkItem workInfo);
protected abstract bool TryTakeAnyWork_NoLock(ProjectId? preferableProjectId, ProjectDependencyGraph dependencyGraph, IDiagnosticAnalyzerService? service, out WorkItem workItem);
public int WorkItemCount
{
get
{
lock (_gate)
{
return WorkItemCount_NoLock;
}
}
}
public bool HasAnyWork
{
get
{
lock (_gate)
{
return WorkItemCount_NoLock > 0;
}
}
}
public virtual Task WaitAsync(CancellationToken cancellationToken)
=> _semaphore.WaitAsync(cancellationToken);
public bool AddOrReplace(WorkItem item)
{
lock (_gate)
{
if (_disposed)
{
// The work queue was shut down, so mark the request as complete and return false to
// indicate the work was not queued.
item.AsyncToken.Dispose();
return false;
}
if (AddOrReplace_NoLock(item))
{
// the item is new item that got added to the queue.
// let solution crawler progress report to know about new item enqueued.
// progress reporter will take care of nested/overlapped works by itself
//
// order of events is as follow
// 1. first item added by AddOrReplace which is the point where progress start.
// 2. bunch of other items added or replaced (workitem in the queue > 0)
// 3. items start dequeued to be processed by TryTake or TryTakeAnyWork
// 4. once item is done processed, it is marked as done by MarkWorkItemDoneFor
// 5. all items in the queue are dequeued (workitem in the queue == 0)
// but there can be still work in progress
// 6. all works are considered done when last item is marked done by MarkWorkItemDoneFor
// and at the point, we will set progress to stop.
_progressReporter.Start();
// increase count
_semaphore.Release();
return true;
}
return false;
}
}
public void MarkWorkItemDoneFor(object key)
{
lock (_gate)
{
// just remove cancellation token from the map.
// the cancellation token might be passed out to other service
// so don't call cancel on the source only because we are done using it.
_cancellationMap.Remove(key);
// every works enqueued by "AddOrReplace" will be processed
// at some point, and when it is processed, this method will be called to mark
// work has been done.
_progressReporter.Stop();
}
}
public void RequestCancellationOnRunningTasks()
{
List<CancellationTokenSource>? cancellations;
lock (_gate)
{
// request to cancel all running works
cancellations = CancelAll_NoLock();
}
RaiseCancellation_NoLock(cancellations);
}
public void Dispose()
{
List<CancellationTokenSource>? cancellations;
lock (_gate)
{
_disposed = true;
// here we don't need to care about progress reporter since
// it will be only called when host is shutting down.
// we do the below since we want to kill any pending tasks
Dispose_NoLock();
cancellations = CancelAll_NoLock();
}
RaiseCancellation_NoLock(cancellations);
}
protected Workspace Workspace => _workspace;
private static void RaiseCancellation_NoLock(List<CancellationTokenSource>? cancellations)
{
if (cancellations == null)
{
return;
}
// cancel can cause outer code to be run inlined, run it outside of the lock.
cancellations.Do(s => s.Cancel());
}
private List<CancellationTokenSource>? CancelAll_NoLock()
{
// nothing to do
if (_cancellationMap.Count == 0)
{
return null;
}
// make a copy
var cancellations = _cancellationMap.Values.ToList();
// clear cancellation map
_cancellationMap.Clear();
return cancellations;
}
protected void Cancel_NoLock(object key)
{
if (_cancellationMap.TryGetValue(key, out var source))
{
source.Cancel();
_cancellationMap.Remove(key);
}
}
public bool TryTake(TKey key, out WorkItem workInfo, out CancellationToken cancellationToken)
{
lock (_gate)
{
if (TryTake_NoLock(key, out workInfo))
{
cancellationToken = GetNewCancellationToken_NoLock(key);
workInfo.AsyncToken.Dispose();
return true;
}
else
{
cancellationToken = CancellationToken.None;
return false;
}
}
}
public bool TryTakeAnyWork(
ProjectId? preferableProjectId,
ProjectDependencyGraph dependencyGraph,
IDiagnosticAnalyzerService? analyzerService,
out WorkItem workItem,
out CancellationToken cancellationToken)
{
lock (_gate)
{
// there must be at least one item in the map when this is called unless host is shutting down.
if (TryTakeAnyWork_NoLock(preferableProjectId, dependencyGraph, analyzerService, out workItem))
{
cancellationToken = GetNewCancellationToken_NoLock(workItem.Key);
workItem.AsyncToken.Dispose();
return true;
}
else
{
cancellationToken = CancellationToken.None;
return false;
}
}
}
protected CancellationToken GetNewCancellationToken_NoLock(object key)
{
Debug.Assert(!_cancellationMap.ContainsKey(key));
var source = new CancellationTokenSource();
_cancellationMap.Add(key, source);
return source.Token;
}
protected ProjectId GetBestProjectId_NoLock<T>(
Dictionary<ProjectId, T> workQueue, ProjectId? projectId,
ProjectDependencyGraph dependencyGraph, IDiagnosticAnalyzerService? analyzerService)
{
if (projectId != null)
{
if (workQueue.ContainsKey(projectId))
{
return projectId;
}
// prefer project that directly depends on the given project and has diagnostics as next project to
// process
foreach (var dependingProjectId in dependencyGraph.GetProjectsThatDirectlyDependOnThisProject(projectId))
{
if (workQueue.ContainsKey(dependingProjectId) && analyzerService?.ContainsDiagnostics(Workspace, dependingProjectId) == true)
{
return dependingProjectId;
}
}
}
// prefer a project that has diagnostics as next project to process.
foreach (var pendingProjectId in workQueue.Keys)
{
if (analyzerService?.ContainsDiagnostics(Workspace, pendingProjectId) == true)
{
return pendingProjectId;
}
}
// explicitly iterate so that we can use struct enumerator
foreach (var pair in workQueue)
{
return pair.Key;
}
throw ExceptionUtilities.Unreachable();
}
}
}
}
}
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