private void WriteModuleContent(OciArtifactModuleReference reference, OciArtifactResult result)
{
/*
* this should be kept in sync with the IsModuleRestoreRequired() implementation
*/
// write main.bicep
this.fileResolver.Write(this.GetModuleFileUri(reference, ModuleFileType.ModuleMain), result.ModuleStream);
// write manifest
// it's important to write the original stream here rather than serialize the manifest object
// this way we guarantee the manifest hash will match
this.fileResolver.Write(this.GetModuleFileUri(reference, ModuleFileType.Manifest), result.ManifestStream);
// write metadata
var metadata = new ModuleMetadata(result.ManifestDigest);
using var metadataStream = new MemoryStream();
OciSerialization.Serialize(metadataStream, metadata);
metadataStream.Position = 0;
this.fileResolver.Write(this.GetModuleFileUri(reference, ModuleFileType.Metadata), metadataStream);
}
private async Task TryWriteModuleContentAsync(OciArtifactModuleReference reference, OciArtifactResult result)
{
// this has to be after downloading the manifest so we don't create directories for non-existent modules
string modulePath = GetModuleDirectoryPath(reference);
// creating the directory doesn't require locking
CreateModuleDirectory(modulePath);
/*
* We have already downloaded the module content from the registry.
* The following sections will attempt to synchronize the module write with other
* instances of the language server running on the same machine.
*
* We are not trying to prevent tampering with the module cache by the user.
*/
Uri lockFileUri = GetModuleFileUri(reference, ModuleFileType.Lock);
var sw = Stopwatch.StartNew();
while (sw.Elapsed < ModuleDirectoryContentionTimeout)
{
var @lock = this.fileResolver.TryAcquireFileLock(lockFileUri);
using (@lock)
{
// the placement of "if" inside "using" guarantees that even an exception thrown by the condition results in the lock being released
// (current condition can't throw, but this potentially avoids future regression)
if (@lock is not null)
{
// we have acquired the lock
if (!this.IsModuleRestoreRequired(reference))
{
// the other instance has already written out the content to disk - we can discard the content we downloaded
return;
}
// write the contents to disk
this.WriteModuleContent(reference, result);
return;
}
}
// we have not acquired the lock - let's give the instance that has the lock some time to finish writing the content to the directory
// (the operation involves only writing the already downloaded content to disk, so it "should" complete fairly quickly)
await Task.Delay(ModuleDirectoryContentionRetryInterval);
}
// we have exceeded the timeout
throw new OciModuleRegistryException($"Exceeded the timeout of \"{ModuleDirectoryContentionTimeout}\" to acquire the lock on file \"{lockFileUri}\".");
}