private static async Task WriteAsyncCore <TValue>(
Stream utf8Json,
TValue value,
Type inputType,
JsonSerializerOptions?options,
CancellationToken cancellationToken)
{
// We flush the Stream when the buffer is >=90% of capacity.
// This threshold is a compromise between buffer utilization and minimizing cases where the buffer
// needs to be expanded\doubled because it is not large enough to write the current property or element.
// We check for flush after each object property and array element is written to the buffer.
// Once the buffer is expanded to contain the largest single element\property, a 90% thresold
// means the buffer may be expanded a maximum of 4 times: 1-(1\(2^4))==.9375.
const float FlushThreshold = .9f;
if (options == null)
{
options = JsonSerializerOptions.s_defaultOptions;
}
JsonWriterOptions writerOptions = options.GetWriterOptions();
using (var bufferWriter = new PooledByteBufferWriter(options.DefaultBufferSize))
using (var writer = new Utf8JsonWriter(bufferWriter, writerOptions))
{
// We treat typeof(object) special and allow polymorphic behavior.
if (inputType == JsonTypeInfo.ObjectType && value != null)
{
inputType = value !.GetType();
}
WriteStack state = new WriteStack {
CancellationToken = cancellationToken
};
JsonConverter converterBase = state.Initialize(inputType, options, supportContinuation: true);
bool isFinalBlock;
try
{
do
{
state.FlushThreshold = (int)(bufferWriter.Capacity * FlushThreshold);
try
{
isFinalBlock = WriteCore(converterBase, writer, value, options, ref state);
}
finally
{
if (state.PendingAsyncDisposables?.Count > 0)
{
await state.DisposePendingAsyncDisposables().ConfigureAwait(false);
}
}
await bufferWriter.WriteToStreamAsync(utf8Json, cancellationToken).ConfigureAwait(false);
bufferWriter.Clear();
if (state.PendingTask is not null)
{
try
{
await state.PendingTask.ConfigureAwait(false);
}
catch
{
// Exceptions will be propagated elsewhere
// TODO https://github.com/dotnet/runtime/issues/22144
}
}
} while (!isFinalBlock);
}
catch
{
await state.DisposePendingDisposablesOnExceptionAsync().ConfigureAwait(false);
throw;
}
}
}
private static async Task WriteStreamAsync <TValue>(
Stream utf8Json,
TValue value,
JsonTypeInfo jsonTypeInfo,
CancellationToken cancellationToken)
{
JsonSerializerOptions options = jsonTypeInfo.Options;
JsonWriterOptions writerOptions = options.GetWriterOptions();
using (var bufferWriter = new PooledByteBufferWriter(options.DefaultBufferSize))
using (var writer = new Utf8JsonWriter(bufferWriter, writerOptions))
{
WriteStack state = new WriteStack {
CancellationToken = cancellationToken
};
JsonConverter converter = state.Initialize(jsonTypeInfo, supportContinuation: true);
bool isFinalBlock;
try
{
do
{
state.FlushThreshold = (int)(bufferWriter.Capacity * FlushThreshold);
try
{
isFinalBlock = WriteCore(converter, writer, value, options, ref state);
await bufferWriter.WriteToStreamAsync(utf8Json, cancellationToken).ConfigureAwait(false);
bufferWriter.Clear();
}
finally
{
// Await any pending resumable converter tasks (currently these can only be IAsyncEnumerator.MoveNextAsync() tasks).
// Note that pending tasks are always awaited, even if an exception has been thrown or the cancellation token has fired.
if (state.PendingTask is not null)
{
try
{
await state.PendingTask.ConfigureAwait(false);
}
catch
{
// Exceptions should only be propagated by the resuming converter
// TODO https://github.com/dotnet/runtime/issues/22144
}
}
// Dispose any pending async disposables (currently these can only be completed IAsyncEnumerators).
if (state.CompletedAsyncDisposables?.Count > 0)
{
await state.DisposeCompletedAsyncDisposables().ConfigureAwait(false);
}
}
} while (!isFinalBlock);
}
catch
{
// On exception, walk the WriteStack for any orphaned disposables and try to dispose them.
await state.DisposePendingDisposablesOnExceptionAsync().ConfigureAwait(false);
throw;
}
}
}