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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.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Collections;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.Notification;
using Microsoft.CodeAnalysis.Shared.TestHooks;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.Remote
{
/// <summary>
/// This class runs against the in-process workspace, and when it sees changes proactively pushes them to
/// the out-of-process workspace through the <see cref="IRemoteAssetSynchronizationService"/>.
/// </summary>
internal sealed class SolutionChecksumUpdater
{
private readonly Workspace _workspace;
/// <summary>
/// We're not at a layer where we are guaranteed to have an IGlobalOperationNotificationService. So allow for
/// it being null.
/// </summary>
private readonly IGlobalOperationNotificationService? _globalOperationService;
/// <summary>
/// Queue to push out text changes in a batched fashion when we hear about them. Because these should be short
/// operations (only syncing text changes) we don't cancel this when we enter the paused state. We simply don't
/// start queuing more requests into this until we become unpaused.
/// </summary>
private readonly AsyncBatchingWorkQueue<(Document? oldDocument, Document? newDocument)> _textChangeQueue;
/// <summary>
/// Queue for kicking off the work to synchronize the primary workspace's solution.
/// </summary>
private readonly AsyncBatchingWorkQueue _synchronizeWorkspaceQueue;
private readonly object _gate = new();
private bool _isPaused;
public SolutionChecksumUpdater(
Workspace workspace,
IAsynchronousOperationListenerProvider listenerProvider,
CancellationToken shutdownToken)
{
var listener = listenerProvider.GetListener(FeatureAttribute.SolutionChecksumUpdater);
_globalOperationService = workspace.Services.SolutionServices.ExportProvider.GetExports<IGlobalOperationNotificationService>().FirstOrDefault()?.Value;
_workspace = workspace;
_textChangeQueue = new AsyncBatchingWorkQueue<(Document? oldDocument, Document? newDocument)>(
DelayTimeSpan.NearImmediate,
SynchronizeTextChangesAsync,
listener,
shutdownToken);
// Use an equality comparer here as we will commonly get lots of change notifications that will all be
// associated with the same cancellation token controlling that batch of work. No need to enqueue the same
// token a huge number of times when we only need the single value of it when doing the work.
_synchronizeWorkspaceQueue = new AsyncBatchingWorkQueue(
DelayTimeSpan.NearImmediate,
SynchronizePrimaryWorkspaceAsync,
listener,
shutdownToken);
// start listening workspace change event
_workspace.WorkspaceChanged += OnWorkspaceChanged;
if (_globalOperationService != null)
{
_globalOperationService.Started += OnGlobalOperationStarted;
_globalOperationService.Stopped += OnGlobalOperationStopped;
}
// Enqueue the work to sync the initial solution.
ResumeWork();
}
public void Shutdown()
{
// Try to stop any work that is in progress.
PauseWork();
_workspace.WorkspaceChanged -= OnWorkspaceChanged;
if (_globalOperationService != null)
{
_globalOperationService.Started -= OnGlobalOperationStarted;
_globalOperationService.Stopped -= OnGlobalOperationStopped;
}
}
private void OnGlobalOperationStarted(object? sender, EventArgs e)
=> PauseWork();
private void OnGlobalOperationStopped(object? sender, EventArgs e)
=> ResumeWork();
private void PauseWork()
{
// An expensive global operation started (like a build). Pause ourselves and cancel any outstanding work in
// progress to synchronize the solution.
lock (_gate)
{
_synchronizeWorkspaceQueue.CancelExistingWork();
_isPaused = true;
}
}
private void ResumeWork()
{
lock (_gate)
{
_isPaused = false;
_synchronizeWorkspaceQueue.AddWork();
}
}
private void OnWorkspaceChanged(object? sender, WorkspaceChangeEventArgs e)
{
// Check if we're currently paused. If so ignore this notification. We don't want to any work in response
// to whatever the workspace is doing.
lock (_gate)
{
if (_isPaused)
return;
}
if (e.Kind == WorkspaceChangeKind.DocumentChanged)
{
_textChangeQueue.AddWork((e.OldSolution.GetDocument(e.DocumentId), e.NewSolution.GetDocument(e.DocumentId)));
}
_synchronizeWorkspaceQueue.AddWork();
}
private async ValueTask SynchronizePrimaryWorkspaceAsync(CancellationToken cancellationToken)
{
var solution = _workspace.CurrentSolution;
var client = await RemoteHostClient.TryGetClientAsync(_workspace, cancellationToken).ConfigureAwait(false);
if (client == null)
return;
using (Logger.LogBlock(FunctionId.SolutionChecksumUpdater_SynchronizePrimaryWorkspace, cancellationToken))
{
var workspaceVersion = solution.WorkspaceVersion;
await client.TryInvokeAsync<IRemoteAssetSynchronizationService>(
solution,
(service, solution, cancellationToken) => service.SynchronizePrimaryWorkspaceAsync(solution, workspaceVersion, cancellationToken),
cancellationToken).ConfigureAwait(false);
}
}
private async ValueTask SynchronizeTextChangesAsync(
ImmutableSegmentedList<(Document? oldDocument, Document? newDocument)> values,
CancellationToken cancellationToken)
{
foreach (var (oldDocument, newDocument) in values)
{
if (oldDocument is null || newDocument is null)
continue;
cancellationToken.ThrowIfCancellationRequested();
await SynchronizeTextChangesAsync(oldDocument, newDocument, cancellationToken).ConfigureAwait(false);
}
return;
async ValueTask SynchronizeTextChangesAsync(Document oldDocument, Document newDocument, CancellationToken cancellationToken)
{
// this pushes text changes to the remote side if it can.
// this is purely perf optimization. whether this pushing text change
// worked or not doesn't affect feature's functionality.
//
// this basically see whether it can cheaply find out text changes
// between 2 snapshots, if it can, it will send out that text changes to
// remote side.
//
// the remote side, once got the text change, will again see whether
// it can use that text change information without any high cost and
// create new snapshot from it.
//
// otherwise, it will do the normal behavior of getting full text from
// VS side. this optimization saves times we need to do full text
// synchronization for typing scenario.
if ((oldDocument.TryGetText(out var oldText) == false) ||
(newDocument.TryGetText(out var newText) == false))
{
// we only support case where text already exist
return;
}
// get text changes
var textChanges = newText.GetTextChanges(oldText);
if (textChanges.Count == 0)
{
// no changes
return;
}
// whole document case
if (textChanges.Count == 1 && textChanges[0].Span.Length == oldText.Length)
{
// no benefit here. pulling from remote host is more efficient
return;
}
// only cancelled when remote host gets shutdown
var client = await RemoteHostClient.TryGetClientAsync(_workspace, cancellationToken).ConfigureAwait(false);
if (client == null)
return;
var state = await oldDocument.State.GetStateChecksumsAsync(cancellationToken).ConfigureAwait(false);
await client.TryInvokeAsync<IRemoteAssetSynchronizationService>(
(service, cancellationToken) => service.SynchronizeTextAsync(oldDocument.Id, state.Text, textChanges, cancellationToken),
cancellationToken).ConfigureAwait(false);
}
}
}
}
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