public void ProjectSnapshot_CachesTagHelperTask()
{
// Arrange
TagHelperResolver.CompletionSource = new TaskCompletionSource <TagHelperResolutionResult>();
try
{
var state = ProjectState.Create(Workspace.Services, HostProject, WorkspaceProject);
var snapshot = new DefaultProjectSnapshot(state);
// Act
var task1 = snapshot.GetTagHelpersAsync();
var task2 = snapshot.GetTagHelpersAsync();
// Assert
Assert.Same(task1, task2);
}
finally
{
TagHelperResolver.CompletionSource.SetCanceled();
}
}
private async Task <(RazorCodeDocument, VersionStamp, VersionStamp)> GetGeneratedOutputAndVersionCoreAsync(DefaultProjectSnapshot project, DocumentSnapshot document)
{
// We only need to produce the generated code if any of our inputs is newer than the
// previously cached output.
//
// First find the versions that are the inputs:
// - The project + computed state
// - The imports
// - This document
//
// All of these things are cached, so no work is wasted if we do need to generate the code.
var computedStateVersion = await project.State.GetComputedStateVersionAsync(project).ConfigureAwait(false);
var documentCollectionVersion = project.State.DocumentCollectionVersion;
var imports = await GetImportsAsync(project, document).ConfigureAwait(false);
var documentVersion = await document.GetTextVersionAsync().ConfigureAwait(false);
// OK now that have the previous output and all of the versions, we can see if anything
// has changed that would require regenerating the code.
var inputVersion = documentVersion;
if (inputVersion.GetNewerVersion(computedStateVersion) == computedStateVersion)
{
inputVersion = computedStateVersion;
}
if (inputVersion.GetNewerVersion(documentCollectionVersion) == documentCollectionVersion)
{
inputVersion = documentCollectionVersion;
}
for (var i = 0; i < imports.Count; i++)
{
var importVersion = imports[i].Version;
if (inputVersion.GetNewerVersion(importVersion) == importVersion)
{
inputVersion = importVersion;
}
}
RazorCodeDocument olderOutput = null;
var olderInputVersion = default(VersionStamp);
var olderOutputVersion = default(VersionStamp);
if (_older?.TaskUnsafe != null)
{
(olderOutput, olderInputVersion, olderOutputVersion) = await _older.TaskUnsafe.ConfigureAwait(false);
if (inputVersion.GetNewerVersion(olderInputVersion) == olderInputVersion)
{
// Nothing has changed, we can use the cached result.
lock (_lock)
{
TaskUnsafe = _older.TaskUnsafe;
_older = null;
return(olderOutput, olderInputVersion, olderOutputVersion);
}
}
}
// OK we have to generate the code.
var tagHelpers = await project.GetTagHelpersAsync().ConfigureAwait(false);
var importSources = new List <RazorSourceDocument>();
foreach (var item in imports)
{
var sourceDocument = await GetRazorSourceDocumentAsync(item.Document).ConfigureAwait(false);
importSources.Add(sourceDocument);
}
var documentSource = await GetRazorSourceDocumentAsync(document).ConfigureAwait(false);
var projectEngine = project.GetProjectEngine();
var codeDocument = projectEngine.ProcessDesignTime(documentSource, importSources, tagHelpers);
var csharpDocument = codeDocument.GetCSharpDocument();
// OK now we've generated the code. Let's check if the output is actually different. This is
// a valuable optimization for our use cases because lots of changes you could make require
// us to run code generation, but don't change the result.
//
// Note that we're talking about the effect on the generated C# code here (not the other artifacts).
// This is the reason why we have two versions associated with the output.
//
// The INPUT version is related the .cshtml files and tag helpers
// The OUTPUT version is related to the generated C#.
//
// Examples:
//
// A change to a tag helper not used by this document - updates the INPUT version, but not
// the OUTPUT version.
//
// A change in the HTML - updates the INPUT version, but not the OUTPUT version.
//
//
// Razor IDE features should always retrieve the output and party on it regardless. Depending
// on the use cases we may or may not need to synchronize the output.
var outputVersion = inputVersion;
if (olderOutput != null)
{
if (string.Equals(
olderOutput.GetCSharpDocument().GeneratedCode,
csharpDocument.GeneratedCode,
StringComparison.Ordinal))
{
outputVersion = olderOutputVersion;
}
}
if (document is DefaultDocumentSnapshot defaultDocument)
{
defaultDocument.State.HostDocument.GeneratedCodeContainer.SetOutput(
defaultDocument,
csharpDocument,
inputVersion,
outputVersion);
}
return(codeDocument, inputVersion, outputVersion);
}