private Task <StrongBox <ImmutableArray <DiagnosticData> > > DeserializeAsync(DiagnosticDataSerializer serializer, object documentOrProject, object key, string stateKey, CancellationToken cancellationToken)
{
// when VS is loading new solution, we will try to find out all diagnostics persisted from previous VS session.
// in that situation, it is possible that we have a lot of deserialization returning empty result. previously we used to
// return default(ImmutableArray) for such case, but it turns out async/await framework has allocation issues with returning
// default(value type), so we are using StrongBox to return no data as null. async/await has optimization where it will return
// cached empty task if given value is null for reference type. (see AsyncMethodBuilder.GetTaskForResult)
//
// right now, we can't use Nullable either, since it is not one of value type the async/await will reuse cached task. in future,
// if they do, we can change it to return Nullable<ImmutableArray>
//
// after initial deserialization, we track actual document/project that actually have diagnostics so no data won't be a common
// case.
// check cache first
if (InMemoryStorage.TryGetValue(_owner.Analyzer, (key, stateKey), out var entry) && serializer.Version == entry.Version)
{
if (entry.Diagnostics.Length == 0)
{
// if there is no result, use cached task
return(s_emptyResultTaskCache);
}
return(Task.FromResult(new StrongBox <ImmutableArray <DiagnosticData> >(entry.Diagnostics)));
}
// try to deserialize it
return(serializer.DeserializeAsync(documentOrProject, stateKey, cancellationToken));
}
private ValueTask <ImmutableArray <DiagnosticData> > DeserializeDiagnosticsAsync(
IPersistentStorageService persistentService,
DiagnosticDataSerializer serializer,
Project project,
TextDocument?document,
object key,
string stateKey,
CancellationToken cancellationToken
)
{
Contract.ThrowIfFalse(document == null || document.Project == project);
if (
InMemoryStorage.TryGetValue(_owner.Analyzer, (key, stateKey), out var entry) &&
serializer.Version == entry.Version
)
{
return(ValueTaskFactory.FromResult(entry.Diagnostics));
}
return(serializer.DeserializeAsync(
persistentService,
project,
document,
stateKey,
cancellationToken
));
}
private async Task <ImmutableArray <DiagnosticData> > DeserializeAsync(DiagnosticDataSerializer serializer, object documentOrProject, object key, string stateKey, CancellationToken cancellationToken)
{
// check cache first
CacheEntry entry;
if (InMemoryStorage.TryGetValue(_owner.Analyzer, ValueTuple.Create(key, stateKey), out entry) && serializer.Version == entry.Version)
{
return(entry.Diagnostics);
}
// try to deserialize it
return(await serializer.DeserializeAsync(documentOrProject, stateKey, cancellationToken).ConfigureAwait(false));
}
