protected static TextAndVersion LoadTextSynchronously(TextLoader loader, DocumentId documentId, SolutionServices services, bool reportInvalidDataException, CancellationToken cancellationToken)
{
var retries = 0;
while (true)
{
try
{
return(loader.LoadTextAndVersionSynchronously(services.Workspace, documentId, cancellationToken));
}
catch (OperationCanceledException)
{
// if load text is failed due to a cancellation, make sure we propagate it out to the caller
throw;
}
catch (IOException e)
{
if (++retries > MaxRetries)
{
services.Workspace.OnWorkspaceFailed(new DocumentDiagnostic(WorkspaceDiagnosticKind.Failure, e.Message, documentId));
return(TextAndVersion.Create(SourceText.From(string.Empty, Encoding.UTF8), VersionStamp.Default, documentId.GetDebuggerDisplay()));
}
// fall out to try again
}
catch (InvalidDataException e)
{
// TODO: Adjust this behavior in the future if we add support for non-text additional files
if (reportInvalidDataException)
{
services.Workspace.OnWorkspaceFailed(new DocumentDiagnostic(WorkspaceDiagnosticKind.Failure, e.Message, documentId));
}
return(TextAndVersion.Create(SourceText.From(string.Empty, Encoding.UTF8), VersionStamp.Default, documentId.GetDebuggerDisplay()));
}
// try again after a delay
Thread.Sleep(RetryDelay);
}
}
/// <summary>
/// Load a text and a version of the document in the workspace.
/// </summary>
/// <exception cref="IOException"></exception>
public override async Task <TextAndVersion> LoadTextAndVersionAsync(Workspace workspace, DocumentId documentId, CancellationToken cancellationToken)
{
DateTime prevLastWriteTime = FileUtilities.GetFileTimeStamp(_path);
TextAndVersion textAndVersion;
using (var stream = FileUtilities.OpenAsyncRead(_path))
{
var version = VersionStamp.Create(prevLastWriteTime);
Contract.Requires(stream.Position == 0);
// we do this so that we asynchronously read from file. and this should allocate less for IDE case.
// but probably not for command line case where it doesn't use more sophisticated services.
using (var readStream = await SerializableBytes.CreateReadableStreamAsync(stream, cancellationToken: cancellationToken).ConfigureAwait(false))
{
var text = CreateText(readStream, workspace);
textAndVersion = TextAndVersion.Create(text, version, _path);
}
}
// this has a potential to return corrupted state text if someone changed text in the middle of us reading it.
// previously, we attempted to detect such case and return empty string with workspace failed event.
// but that is nothing better or even worse than returning what we have read so far.
//
// I am letting it to return what we have read so far. and hopefully, file change event let us re-read this file.
// (* but again, there is still a chance where file change event happens even before writing has finished which ends up
// let us stay in corrupted state)
DateTime newLastWriteTime = FileUtilities.GetFileTimeStamp(_path);
if (!newLastWriteTime.Equals(prevLastWriteTime))
{
// TODO: remove this once we know how often this can happen.
// I am leaving this here for now for diagnostic purpose.
var message = string.Format(WorkspacesResources.FileWasExternallyModified, _path);
workspace.OnWorkspaceFailed(new DocumentDiagnostic(WorkspaceDiagnosticKind.Failure, message, documentId));
}
return(textAndVersion);
}
public Document AddDocument(ProjectId projectId, string name, SourceText text)
{
if (projectId == null)
{
throw new ArgumentNullException(nameof(projectId));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
if (text == null)
{
throw new ArgumentNullException(nameof(text));
}
var id = DocumentId.CreateNewId(projectId);
var loader = TextLoader.From(TextAndVersion.Create(text, VersionStamp.Create()));
return(this.AddDocument(DocumentInfo.Create(id, name, loader: loader)));
}
private static async Task <TextAndVersion> LoadTextAsync(TextLoader loader, DocumentId documentId, SolutionServices services, CancellationToken cancellationToken)
{
try
{
using (ExceptionHelpers.SuppressFailFast())
{
var result = await loader.LoadTextAndVersionAsync(services.Workspace, documentId, cancellationToken).ConfigureAwait(continueOnCapturedContext: false);
return(result);
}
}
catch (OperationCanceledException)
{
// if load text is failed due to a cancellation, make sure we propagate it out to the caller
throw;
}
catch (IOException e)
{
services.Workspace.OnWorkspaceFailed(new DocumentDiagnostic(WorkspaceDiagnosticKind.FileAccessFailure, e.Message, documentId));
return(TextAndVersion.Create(SourceText.From(string.Empty, Encoding.UTF8), VersionStamp.Default, documentId.GetDebuggerDisplay()));
}
}
public static AdhocWorkspace WithFakeDocument(
this AdhocWorkspace workspace,
string name,
string filePath,
string text)
{
if (workspace.CurrentSolution.ProjectIds.Count == 0)
{
workspace.WithFakeProject(
"FakeProject",
"FakeProjectAssembly");
}
workspace.AddDocument(DocumentInfo.Create(
id: DocumentId.CreateNewId(workspace.CurrentSolution.ProjectIds[0]),
name: name,
filePath: filePath,
loader: TextLoader.From(TextAndVersion.Create(
version: VersionStamp.Default,
text: SourceText.From(text)))));
return(workspace);
}
protected internal void OnAdditionalDocumentOpened(DocumentId documentId, SourceTextContainer textContainer, bool isCurrentContext = true)
{
CheckAdditionalDocumentIsInCurrentSolution(documentId);
CheckDocumentIsClosed(documentId);
using (_serializationLock.DisposableWait())
{
var oldSolution = this.CurrentSolution;
var oldDocument = oldSolution.GetAdditionalDocument(documentId);
var oldText = oldDocument.GetTextAsync(CancellationToken.None).WaitAndGetResult(CancellationToken.None);
// keep open document text alive by using PreserveIdentity
var newText = textContainer.CurrentText;
var currentSolution = oldSolution;
if (oldText == newText || oldText.ContentEquals(newText))
{
// if the supplied text is the same as the previous text, then also use same version
var version = oldDocument.GetTextVersionAsync(CancellationToken.None).WaitAndGetResult(CancellationToken.None);
var newTextAndVersion = TextAndVersion.Create(newText, version, oldDocument.FilePath);
currentSolution = oldSolution.WithAdditionalDocumentText(documentId, newTextAndVersion, PreservationMode.PreserveIdentity);
}
else
{
currentSolution = oldSolution.WithAdditionalDocumentText(documentId, newText, PreservationMode.PreserveIdentity);
}
var newSolution = this.SetCurrentSolution(currentSolution);
SignupForTextChanges(documentId, textContainer, isCurrentContext, (w, id, text, mode) => w.OnAdditionalDocumentTextChanged(id, text, mode));
this.RaiseWorkspaceChangedEventAsync(WorkspaceChangeKind.AdditionalDocumentChanged, oldSolution, newSolution, documentId: documentId);
}
// register outside of lock since it may call user code.
this.RegisterText(textContainer);
}
/// <exception cref="IOException"></exception>
public override async Task <TextAndVersion> LoadTextAndVersionAsync(Workspace workspace, DocumentId documentId, CancellationToken cancellationToken)
{
DateTime prevLastWriteTime = FileUtilities.GetFileTimeStamp(this.path);
// Open file for reading with FileShare mode read/write/delete so that we do not lock this file.
// Allowing other theads/processes to write or delete the file is essential for scenarios such as
// Rename refactoring where File.Replace API is invoked for updating the modified file.
TextAndVersion textAndVersion;
using (var stream = FileUtilities.OpenRead(this.path))
{
var version = VersionStamp.Create(prevLastWriteTime);
var memoryStream = await this.ReadStreamAsync(stream, cancellationToken : cancellationToken).ConfigureAwait(false);
var text = CreateText(memoryStream, workspace);
textAndVersion = TextAndVersion.Create(text, version, path);
}
// this has a potential to return corrupted state text if someone changed text in the middle of us reading it.
// previously, we attempted to detect such case and return empty string with workspace failed event.
// but that is nothing better or even worse than returning what we have read so far.
//
// I am letting it to return what we have read so far. and hopefully, file change event let us re-read this file.
// (* but again, there is still a chance where file change event happens even before writing has finished which ends up
// let us stay in corrupted state)
DateTime newLastWriteTime = FileUtilities.GetFileTimeStamp(this.path);
if (!newLastWriteTime.Equals(prevLastWriteTime))
{
// TODO: remove this once we know how often this can happen.
// I am leaving this here for now for diagnostic purpose.
var message = string.Format(WorkspacesResources.FileWasExternallyModified, this.path);
workspace.OnWorkspaceFailed(new DocumentDiagnostic(WorkspaceDiagnosticKind.FileAccessFailure, message, documentId));
}
return(textAndVersion);
}
/// <summary>
/// Adds a document to the workspace.
/// </summary>
public DocumentId AddDocument(ProjectId projectId, string name, string text)
{
if (projectId == null)
{
throw new ArgumentNullException("projectId");
}
if (name == null)
{
throw new ArgumentNullException("name");
}
if (text == null)
{
throw new ArgumentNullException("text");
}
var id = DocumentId.CreateNewId(projectId);
this.AddDocument(
DocumentInfo.Create(id, name, loader: TextLoader.From(TextAndVersion.Create(SourceText.From(text), VersionStamp.Create()))));
return(id);
}
public override async Task <TextAndVersion> LoadTextAndVersionAsync(Workspace workspace, DocumentId documentId, CancellationToken cancellationToken)
{
ValidateFileLength(workspace, Path);
var prevLastWriteTime = FileUtilities.GetFileTimeStamp(Path);
TextAndVersion textAndVersion;
// In many .NET Framework versions (specifically the 4.5.* series, but probably much earlier
// and also later) there is this particularly interesting bit in FileStream.BeginReadAsync:
//
// // [ed: full comment clipped for brevity]
// //
// // If we did a sync read to fill the buffer, we could avoid the
// // problem, and any async read less than 64K gets turned into a
// // synchronous read by NT anyways...
// if (numBytes < _bufferSize)
// {
// if (_buffer == null) _buffer = new byte[_bufferSize];
// IAsyncResult bufferRead = BeginReadCore(_buffer, 0, _bufferSize, null, null, 0);
// _readLen = EndRead(bufferRead);
//
// In English, this means that if you do a asynchronous read for smaller than _bufferSize,
// this is implemented by the framework by starting an asynchronous read, and then
// blocking your thread until that read is completed. The comment implies this is "fine"
// because the asynchronous read will actually be synchronous and thus EndRead won't do
// any blocking -- it'll be an effective no-op. In theory, everything is fine here.
//
// In reality, this can end very poorly. That read in fact can be asynchronous, which means the
// EndRead will enter a wait and block the thread. If we are running that call to ReadAsync on a
// thread pool thread that completed a previous piece of IO, it means there has to be another
// thread available to service the completion of that request in order for our thread to make
// progress. Why is this worse than the claim about the operating system turning an
// asynchronous read into a synchronous one? If the underlying native ReadFile completes
// synchronously, that would mean just our thread is being blocked, and will be unblocked once
// the kernel gets done with our work. In this case, if the OS does do the read asynchronously
// we are now dependent on another thread being available to unblock us.
//
// So how does ths manifest itself? We have seen dumps from customers reporting hangs where
// we have over a hundred thread pool threads all blocked on EndRead() calls as we read this stream.
// In these cases, the user had just completed a build that had a bunch of XAML files, and
// this resulted in many .g.i.cs files being written and updated. As a result, Roslyn is trying to
// re-read them to provide a new compilation to the XAML language service that is asking for it.
// Inspecting these dumps and sampling some of the threads made some notable discoveries:
//
// 1. When there was a read blocked, it was the _last_ chunk that we were reading in the file in
// the file that we were reading. This leads me to believe that it isn't simply very slow IO
// (like a network drive), because in that case I'd expect to see some threads in different
// places than others.
// 2. Some stacks were starting by the continuation of a ReadAsync, and some were the first read
// of a file from the background parser. In the first case, all of those threads were if the
// files were over 4K in size. The ones with the BackgroundParser still on the stack were files
// less than 4K in size.
// 3. The "time unresponsive" in seconds correlated with roughly the number of threads we had
// blocked, which makes me think we were impacted by the once-per-second hill climbing algorithm
// used by the thread pool.
//
// So what's my analysis? When the XAML language service updated all the files, we kicked off
// background parses for all of them. If the file was over 4K the asynchronous read actually did
// happen (see point #2), but we'd eventually block the thread pool reading the last chunk.
// Point #1 confirms that it was always the last chunk. And in small file cases, we'd block on
// the first chunk. But in either case, we'd be blocking off a thread pool thread until another
// thread pool thread was available. Since we had enough requests going (over a hundred),
// sometimes the user got unlucky and all the threads got blocked. At this point, the CLR
// started slowly kicking off more threads, but each time it'd start a new thread rather than
// starting work that would be needed to unblock a thread, it just handled an IO that resulted
// in another file read hitting the end of the file and another thread would get blocked. The
// CLR then must kick off another thread, rinse, repeat. Eventually it'll make progress once
// there's no more pending IO requests, everything will complete, and life then continues.
//
// To work around this issue, we set bufferSize to 1, which means that all reads should bypass
// this logic. This is tracked by https://github.com/dotnet/corefx/issues/6007, at least in
// corefx. We also open the file for reading with FileShare mode read/write/delete so that
// we do not lock this file.
using (var stream = FileUtilities.RethrowExceptionsAsIOException(() => new FileStream(Path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete, bufferSize: 1, useAsync: true)))
{
var version = VersionStamp.Create(prevLastWriteTime);
// we do this so that we asynchronously read from file. and this should allocate less for IDE case.
// but probably not for command line case where it doesn't use more sophisticated services.
using var readStream = await SerializableBytes.CreateReadableStreamAsync(stream, cancellationToken : cancellationToken).ConfigureAwait(false);
var text = CreateText(readStream, workspace);
textAndVersion = TextAndVersion.Create(text, version, Path);
}
// Check if the file was definitely modified and closed while we were reading. In this case, we know the read we got was
// probably invalid, so throw an IOException which indicates to our caller that we should automatically attempt a re-read.
// If the file hasn't been closed yet and there's another writer, we will rely on file change notifications to notify us
// and reload the file.
var newLastWriteTime = FileUtilities.GetFileTimeStamp(Path);
if (!newLastWriteTime.Equals(prevLastWriteTime))
{
var message = string.Format(WorkspacesResources.File_was_externally_modified_colon_0, Path);
throw new IOException(message);
}
return(textAndVersion);
}
public override Task <TextAndVersion> LoadTextAndVersionAsync(Workspace workspace, DocumentId documentId, CancellationToken cancellationToken)
{
return(Task.FromResult(TextAndVersion.Create(this.container.CurrentText, this.version, this.filePath)));
}
protected internal void OnDocumentOpened(DocumentId documentId, SourceTextContainer textContainer, bool isCurrentContext = true)
{
CheckDocumentIsInCurrentSolution(documentId);
CheckDocumentIsClosed(documentId);
using (this.serializationLock.DisposableWait())
{
var oldSolution = this.CurrentSolution;
var oldDocument = oldSolution.GetDocument(documentId);
var oldText = oldDocument.GetTextAsync(CancellationToken.None).WaitAndGetResult(CancellationToken.None);
using (this.stateLock.DisposableWrite())
{
var openDocuments = GetProjectOpenDocuments_NoLock(documentId.ProjectId);
if (openDocuments != null)
{
openDocuments.Add(documentId);
}
else
{
this.projectToOpenDocumentsMap.Add(documentId.ProjectId, new HashSet <DocumentId> {
documentId
});
}
}
// keep open document text alive by using PreserveIdentity
var newText = textContainer.CurrentText;
var currentSolution = oldSolution;
if (oldText != newText)
{
if (oldText.ContentEquals(newText))
{
// if the supplied text is the same as the previous text, then add with same version
var version = oldDocument.GetTextVersionAsync(CancellationToken.None).WaitAndGetResult(CancellationToken.None);
var newTextAndVersion = TextAndVersion.Create(newText, version, oldDocument.FilePath);
currentSolution = oldSolution.WithDocumentText(documentId, newTextAndVersion, PreservationMode.PreserveIdentity);
}
else
{
currentSolution = oldSolution.WithDocumentText(documentId, newText, PreservationMode.PreserveIdentity);
}
}
var newSolution = this.SetCurrentSolution(currentSolution);
var tracker = new TextTracker(this, documentId, textContainer);
this.textTrackers.Add(documentId, tracker);
this.AddTextToDocumentIdMapping_NoLock(textContainer, documentId, isCurrentContext);
tracker.Connect();
var newDoc = newSolution.GetDocument(documentId);
this.OnDocumentTextChanged(newDoc);
this.RaiseWorkspaceChangedEventAsync(WorkspaceChangeKind.DocumentChanged, oldSolution, newSolution, documentId: documentId);
var tsk = this.RaiseDocumentOpenedEventAsync(newDoc); // don't await this
}
// register outside of lock since it may call user code.
this.RegisterText(textContainer);
}
public static SourceGeneratedDocumentState Create(
string hintName,
SourceText generatedSourceText,
SyntaxTree generatedSyntaxTree,
DocumentId documentId,
ISourceGenerator sourceGenerator,
HostLanguageServices languageServices,
SolutionServices solutionServices,
CancellationToken cancellationToken
)
{
var options = generatedSyntaxTree.Options;
var filePath = generatedSyntaxTree.FilePath;
var textAndVersion = TextAndVersion.Create(generatedSourceText, VersionStamp.Create());
ValueSource <TextAndVersion> textSource = new ConstantValueSource <TextAndVersion>(
textAndVersion
);
var root = generatedSyntaxTree.GetRoot(cancellationToken);
Contract.ThrowIfNull(
languageServices.SyntaxTreeFactory,
"We should not have a generated syntax tree for a language that doesn't support trees."
);
if (languageServices.SyntaxTreeFactory.CanCreateRecoverableTree(root))
{
// We will only create recoverable text if we can create a recoverable tree; if we created a
// recoverable text but not a new tree, it would mean tree.GetText() could still potentially return
// the non-recoverable text, but asking the document directly for it's text would give a recoverable
// text with a different object identity.
textSource = CreateRecoverableText(textAndVersion, solutionServices);
generatedSyntaxTree = languageServices.SyntaxTreeFactory.CreateRecoverableTree(
documentId.ProjectId,
filePath: generatedSyntaxTree.FilePath,
options,
textSource,
generatedSourceText.Encoding,
root
);
}
var treeAndVersion = TreeAndVersion.Create(generatedSyntaxTree, textAndVersion.Version);
return(new SourceGeneratedDocumentState(
languageServices,
solutionServices,
documentServiceProvider: null,
new DocumentInfo.DocumentAttributes(
documentId,
name: hintName,
folders: SpecializedCollections.EmptyReadOnlyList <string>(),
options.Kind,
filePath: filePath,
isGenerated: true,
designTimeOnly: false
),
options,
sourceText: null, // don't strongly hold the text
textSource,
treeAndVersion,
sourceGenerator,
hintName
));
}
internal override TextAndVersion LoadTextAndVersionSynchronously(Workspace workspace, DocumentId documentId, CancellationToken cancellationToken)
{
return(TextAndVersion.Create(_container.CurrentText, _version, _filePath));
}