Package io.grpc.servlet

Class AsyncServletOutputStreamWriter

java.lang.Object

io.grpc.servlet.AsyncServletOutputStreamWriter

final class AsyncServletOutputStreamWriter
extends Object

Handles write actions from the container thread and the application thread.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static interface	AsyncServletOutputStreamWriter.ActionItem	Write actions, e.g.
(package private) static interface	AsyncServletOutputStreamWriter.Log
private static final class	AsyncServletOutputStreamWriter.WriteState

Field Summary

Fields

Modifier and Type	Field	Description
private final AsyncServletOutputStreamWriter.ActionItem	completeAction
private final AsyncServletOutputStreamWriter.ActionItem	flushAction
private final BooleanSupplier	isReady
private final AsyncServletOutputStreamWriter.Log	log
private Thread	parkingThread
private final BiFunction<byte[],Integer,AsyncServletOutputStreamWriter.ActionItem>	writeAction
private final Queue<AsyncServletOutputStreamWriter.ActionItem>	writeChain	New write actions will be buffered into this queue if the servlet output stream is not ready or the queue is not drained.
private final AtomicReference<AsyncServletOutputStreamWriter.WriteState>	writeState	Memory boundary for write actions.

Constructor Summary

Constructors

Constructor	Description
AsyncServletOutputStreamWriter(BiFunction<byte[],Integer,AsyncServletOutputStreamWriter.ActionItem> writeAction, AsyncServletOutputStreamWriter.ActionItem flushAction, AsyncServletOutputStreamWriter.ActionItem completeAction, BooleanSupplier isReady, AsyncServletOutputStreamWriter.Log log)	Constructor without java.util.logging and javax.servlet.* dependency, so that Lincheck can run.
AsyncServletOutputStreamWriter(javax.servlet.AsyncContext asyncContext, ServletServerStream.ServletTransportState transportState, InternalLogId logId)

Method Summary

Modifier and Type	Method	Description
private void	assureReadyAndDrainedTurnsFalse()
(package private) void	complete()	Called from application thread.
(package private) void	flush()	Called from application thread.
(package private) void	onWritePossible()	Called from the container thread WriteListener.onWritePossible().
private void	runOrBuffer(AsyncServletOutputStreamWriter.ActionItem actionItem)	Either execute the write action directly, or buffer the action and let the container thread drain it.
(package private) void	writeBytes(byte[] bytes, int numBytes)	Called from application thread.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

writeState

private final AtomicReference<AsyncServletOutputStreamWriter.WriteState> writeState

Memory boundary for write actions.

 WriteState curState = writeState.get();  // mark a boundary
 doSomething();  // do something within the boundary
 boolean successful = writeState.compareAndSet(curState, newState); // try to mark a boundary
 if (successful) {
   // state has not changed since
   return;
 } else {
   // state is changed by another thread while doSomething(), need recompute
 }
 

There are two threads, the container thread (calling onWritePossible()) and the application thread (calling runOrBuffer()) that read and update the writeState. Only onWritePossible() may turn readyAndDrained from false to true, and only runOrBuffer() may turn it from true to false.

log

private final AsyncServletOutputStreamWriter.Log log

writeAction

private final BiFunction<byte[],Integer,AsyncServletOutputStreamWriter.ActionItem> writeAction

flushAction

private final AsyncServletOutputStreamWriter.ActionItem flushAction

completeAction

private final AsyncServletOutputStreamWriter.ActionItem completeAction

isReady

private final BooleanSupplier isReady

writeChain

private final Queue<AsyncServletOutputStreamWriter.ActionItem> writeChain

New write actions will be buffered into this queue if the servlet output stream is not ready or the queue is not drained.

parkingThread

@Nullable
private volatile Thread parkingThread

Constructor Details

AsyncServletOutputStreamWriter

AsyncServletOutputStreamWriter(javax.servlet.AsyncContext asyncContext,
 ServletServerStream.ServletTransportState transportState,
 InternalLogId logId)
                        throws IOException

Throws:

IOException

AsyncServletOutputStreamWriter

AsyncServletOutputStreamWriter(BiFunction<byte[],Integer,AsyncServletOutputStreamWriter.ActionItem> writeAction,
 AsyncServletOutputStreamWriter.ActionItem flushAction,
 AsyncServletOutputStreamWriter.ActionItem completeAction,
 BooleanSupplier isReady,
 AsyncServletOutputStreamWriter.Log log)

Constructor without java.util.logging and javax.servlet.* dependency, so that Lincheck can run.

Parameters:

writeAction - Provides an AsyncServletOutputStreamWriter.ActionItem to write given bytes with specified length.

isReady - Indicates whether the writer can write bytes at the moment (asynchronously).

Method Details

writeBytes

void writeBytes(byte[] bytes,
 int numBytes)
         throws IOException

Called from application thread.

Throws:

IOException

flush

void flush()
    throws IOException

Called from application thread.

Throws:

IOException

complete

void complete()

Called from application thread.

onWritePossible

void onWritePossible()
              throws IOException

Called from the container thread WriteListener.onWritePossible().

Throws:

IOException

assureReadyAndDrainedTurnsFalse

private void assureReadyAndDrainedTurnsFalse()

runOrBuffer

private void runOrBuffer(AsyncServletOutputStreamWriter.ActionItem actionItem)
                  throws IOException

Either execute the write action directly, or buffer the action and let the container thread drain it.

Called from application thread.

Throws:

IOException