https://projects.eclipse.org/projects/ee4j.grizzly/grizzly-websockets-server: Grizzly Bill of Materials (BOM) (Oracle Corporation) 
/*
 * Copyright (c) 2012, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.http2;

import static org.glassfish.grizzly.http2.Termination.CLOSED_BY_PEER_STRING;
import static org.glassfish.grizzly.http2.Termination.LOCAL_CLOSE_TERMINATION;
import static org.glassfish.grizzly.http2.Termination.PEER_CLOSE_TERMINATION;
import static org.glassfish.grizzly.http2.Termination.RESET_TERMINATION;
import static org.glassfish.grizzly.http2.Termination.UNEXPECTED_FRAME_TERMINATION;

import java.io.IOException;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.glassfish.grizzly.Buffer;
import org.glassfish.grizzly.CloseListener;
import org.glassfish.grizzly.CloseReason;
import org.glassfish.grizzly.CloseType;
import org.glassfish.grizzly.Closeable;
import org.glassfish.grizzly.CompletionHandler;
import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.GrizzlyFuture;
import org.glassfish.grizzly.ICloseType;
import org.glassfish.grizzly.OutputSink;
import org.glassfish.grizzly.WriteHandler;
import org.glassfish.grizzly.attributes.Attribute;
import org.glassfish.grizzly.attributes.AttributeBuilder;
import org.glassfish.grizzly.attributes.AttributeHolder;
import org.glassfish.grizzly.attributes.AttributeStorage;
import org.glassfish.grizzly.http.HttpContent;
import org.glassfish.grizzly.http.HttpHeader;
import org.glassfish.grizzly.http.HttpRequestPacket;
import org.glassfish.grizzly.http.HttpResponsePacket;
import org.glassfish.grizzly.http2.Termination.TerminationType;
import org.glassfish.grizzly.http2.frames.ErrorCode;
import org.glassfish.grizzly.impl.FutureImpl;
import org.glassfish.grizzly.memory.Buffers;
import org.glassfish.grizzly.memory.CompositeBuffer;
import org.glassfish.grizzly.memory.CompositeBuffer.DisposeOrder;
import org.glassfish.grizzly.utils.Futures;


The abstraction representing HTTP2 stream.

Author:Grizzly team
/**
 * The abstraction representing HTTP2 stream.
 *
 * @author Grizzly team
 */
public class Http2Stream implements AttributeStorage, OutputSink, Closeable {

    public enum State {
        IDLE, OPEN, RESERVED_LOCAL, RESERVED_REMOTE, HALF_CLOSED_LOCAL, HALF_CLOSED_REMOTE, CLOSED
    }

    private static final Logger LOGGER = Grizzly.logger(Http2Stream.class);

    public static final String HTTP2_STREAM_ATTRIBUTE = HttpRequestPacket.READ_ONLY_ATTR_PREFIX + Http2Stream.class.getName();
    public static final String HTTP2_PARENT_STREAM_ATTRIBUTE = HttpRequestPacket.READ_ONLY_ATTR_PREFIX + "parent." + Http2Stream.class.getName();

    static final int UPGRADE_STREAM_ID = 1;

    private static final Attribute<Http2Stream> HTTP_RQST_HTTP2_STREAM_ATTR
        = AttributeBuilder.DEFAULT_ATTRIBUTE_BUILDER.createAttribute("http2.request.stream");

    State state = State.IDLE;

    private final HttpRequestPacket request;
    private final int streamId;
    private final int parentStreamId;
    private final int priority;
    private final boolean exclusive;

    private final Http2Session http2Session;

    private final AttributeHolder attributes = AttributeBuilder.DEFAULT_ATTRIBUTE_BUILDER.createSafeAttributeHolder();

    final StreamInputBuffer inputBuffer;
    final StreamOutputSink outputSink;

    // number of bytes reported to be read, but still unacked to the peer
    static final AtomicIntegerFieldUpdater<Http2Stream> unackedReadBytesUpdater
        = AtomicIntegerFieldUpdater.newUpdater(Http2Stream.class, "unackedReadBytes");
    @SuppressWarnings("unused")
    private volatile int unackedReadBytes;

    // closeReasonRef, "null" value means the connection is open.
    private static final AtomicReferenceFieldUpdater<Http2Stream, CloseReason> closeReasonUpdater
        = AtomicReferenceFieldUpdater.newUpdater(Http2Stream.class, CloseReason.class, "closeReason");
    @SuppressWarnings("unused")
    private volatile CloseReason closeReason;

    private volatile GrizzlyFuture<CloseReason> closeFuture;

    private final Queue<CloseListener> closeListeners = new ConcurrentLinkedQueue<>();

    private static final AtomicIntegerFieldUpdater<Http2Stream> completeFinalizationCounterUpdater
        = AtomicIntegerFieldUpdater.newUpdater(Http2Stream.class, "completeFinalizationCounter");
    @SuppressWarnings("unused")
    private volatile int completeFinalizationCounter;

    // flag, which is indicating if Http2Stream processing has been marked as complete by external code
    volatile boolean isProcessingComplete;

    // the counter for inbound HeaderFrames
    private int inboundHeaderFramesCounter;

    public static Http2Stream getStreamFor(final HttpHeader httpHeader) {
        final HttpRequestPacket request;

        // noinspection Duplicates
        if (httpHeader.isRequest()) {
            assert httpHeader instanceof HttpRequestPacket;
            request = (HttpRequestPacket) httpHeader;
        } else {
            assert httpHeader instanceof HttpResponsePacket;
            request = ((HttpResponsePacket) httpHeader).getRequest();
        }

        if (request != null) {
            return HTTP_RQST_HTTP2_STREAM_ATTR.get(request);
        }

        return null;
    }

    
Create HTTP2 stream.

Params:
  • http2Session – the Http2Session for this Http2Stream.
  • request – the HttpRequestPacket initiating the stream.
  • streamId – this stream's ID.
  • parentStreamId – the parent stream, if any.
  • priority – the priority of this stream.
/**
     * Create HTTP2 stream.
     *
     * @param http2Session the {@link Http2Session} for this {@link Http2Stream}.
     * @param request the {@link HttpRequestPacket} initiating the stream.
     * @param streamId this stream's ID.
     * @param parentStreamId the parent stream, if any.
     * @param priority the priority of this stream.
     */
    protected Http2Stream(final Http2Session http2Session, final HttpRequestPacket request, final int streamId, final int parentStreamId,
            final boolean exclusive, final int priority) {
        this.http2Session = http2Session;
        this.request = request;
        this.streamId = streamId;
        this.parentStreamId = parentStreamId;
        this.exclusive = exclusive;
        this.priority = priority;
        this.state = State.IDLE;

        inputBuffer = new DefaultInputBuffer(this);
        outputSink = new DefaultOutputSink(this);

        HTTP_RQST_HTTP2_STREAM_ATTR.set(request, this);
    }

    
Construct upgrade stream, which is half HTTP, half HTTP2

Params:
/**
     * Construct upgrade stream, which is half HTTP, half HTTP2
     *
     * @param http2Session the {@link Http2Session} for this {@link Http2Stream}.
     * @param request the {@link HttpRequestPacket} initiating the stream.
     * @param priority the priority of this stream.
     */
    protected Http2Stream(final Http2Session http2Session, final HttpRequestPacket request, final int priority) {
        this.http2Session = http2Session;
        this.request = request;
        this.streamId = UPGRADE_STREAM_ID;
        this.parentStreamId = 0;
        this.priority = priority;

        this.exclusive = false;
        inputBuffer = http2Session.isServer() ? new UpgradeInputBuffer(this) : new DefaultInputBuffer(this);
        outputSink = http2Session.isServer() ? new DefaultOutputSink(this) : new UpgradeOutputSink(http2Session);

        HTTP_RQST_HTTP2_STREAM_ATTR.set(request, this);
    }

    Http2Session getHttp2Session() {
        return http2Session;
    }

    public int getPeerWindowSize() {
        return http2Session.getPeerStreamWindowSize();
    }

    public int getLocalWindowSize() {
        return http2Session.getLocalStreamWindowSize();
    }

    
Returns:the number of writes (not bytes), that haven't reached network layer
/**
     * @return the number of writes (not bytes), that haven't reached network layer
     */
    public int getUnflushedWritesCount() {
        return outputSink.getUnflushedWritesCount();
    }

    public HttpRequestPacket getRequest() {
        return request;
    }

    public HttpResponsePacket getResponse() {
        return request.getResponse();
    }

    @SuppressWarnings("unused")
    public boolean isPushEnabled() {
        return http2Session.isPushEnabled();
    }

    public int getId() {
        return streamId;
    }

    @SuppressWarnings("unused")
    public int getParentStreamId() {
        return parentStreamId;
    }

    @SuppressWarnings("unused")
    public int getPriority() {
        return priority;
    }

    public boolean isPushStream() {
        return (streamId & 1) == 0;
    }

    public boolean isLocallyInitiatedStream() {
        return http2Session.isLocallyInitiatedStream(streamId);
    }

    @Override
    public boolean isOpen() {
        return completeFinalizationCounter < 2;
    }

    @Override
    public void assertOpen() throws IOException {
        if (!isOpen()) {
            final CloseReason cr = this.closeReason;
            assert cr != null;

            throw new IOException("closed", cr.getCause());
        }
    }

    @Override
    public AttributeHolder getAttributes() {
        return attributes;
    }

    @Override
    @Deprecated
    public boolean canWrite(int length) {
        return canWrite();
    }

    @Override
    public boolean canWrite() {
        return outputSink.canWrite();
    }

    @Override
    @Deprecated
    public void notifyCanWrite(final WriteHandler handler, final int length) {
        notifyCanWrite(handler);
    }

    @Override
    public void notifyCanWrite(final WriteHandler writeHandler) {
        outputSink.notifyWritePossible(writeHandler);
    }

    StreamOutputSink getOutputSink() {
        return outputSink;
    }

    @Override
    public GrizzlyFuture<Closeable> terminate() {
        final FutureImpl<Closeable> future = Futures.createSafeFuture();
        close0(Futures.toCompletionHandler(future), CloseType.LOCALLY, null, false);

        return future;
    }

    @Override
    public void terminateSilently() {
        close0(null, CloseType.LOCALLY, null, false);
    }

    @Override
    public void terminateWithReason(final IOException cause) {
        close0(null, CloseType.LOCALLY, cause, false);
    }

    @Override
    public GrizzlyFuture<Closeable> close() {
        final FutureImpl<Closeable> future = Futures.createSafeFuture();
        close0(Futures.toCompletionHandler(future), CloseType.LOCALLY, null, true);

        return future;
    }

    @Override
    public void closeSilently() {
        close0(null, CloseType.LOCALLY, null, true);
    }

    
{@inheritDoc}

Deprecated:please use close() with the following GrizzlyFuture.addCompletionHandler(CompletionHandler) call
/**
     * {@inheritDoc}
     *
     * @deprecated please use {@link #close()} with the following
     * {@link GrizzlyFuture#addCompletionHandler(org.glassfish.grizzly.CompletionHandler)} call
     */
    @Deprecated
    @Override
    public void close(final CompletionHandler<Closeable> completionHandler) {
        close0(completionHandler, CloseType.LOCALLY, null, true);
    }

    @Override
    public void closeWithReason(final IOException cause) {
        close0(null, CloseType.LOCALLY, cause, false);
    }

    void close0(final CompletionHandler<Closeable> completionHandler, final CloseType closeType, final IOException cause,
            final boolean isCloseOutputGracefully) {

        if (closeReasonUpdater.compareAndSet(this, null, new CloseReason(closeType, cause))) {

            final Termination termination = closeType == CloseType.LOCALLY ? LOCAL_CLOSE_TERMINATION : PEER_CLOSE_TERMINATION;

            // Terminate the input, discard already buffered data
            inputBuffer.terminate(termination);

            if (isCloseOutputGracefully) {
                outputSink.close();
            } else {
                // Terminate the output, discard all the pending data in the output buffer
                outputSink.terminate(termination);
            }

            notifyCloseListeners();

            if (completionHandler != null) {
                completionHandler.completed(this);
            }
        }
    }

    
Notifies the Http2Stream that it's been closed remotely.

/**
     * Notifies the Http2Stream that it's been closed remotely.
     */
    void closedRemotely() {
        // Schedule (add to the stream's input queue) the Termination,
        // which will be invoked once read by the user code.
        // This way we simulate Java Socket behavior
        inputBuffer.terminate(new Termination(TerminationType.PEER_CLOSE, CLOSED_BY_PEER_STRING, true) {
            @Override
            public void doTask() {
                close0(null, CloseType.REMOTELY, null, false);
            }
        });
    }

    
Notify the Http2Stream that peer sent RST_FRAME.

/**
     * Notify the Http2Stream that peer sent RST_FRAME.
     */
    void resetRemotely() {
        if (closeReasonUpdater.compareAndSet(this, null, new CloseReason(CloseType.REMOTELY, null))) {
            onReset();
            // initial graceful shutdown for input, so user is able to read
            // the buffered data
            inputBuffer.terminate(RESET_TERMINATION);

            // forcibly terminate the output, so no more data will be sent
            outputSink.terminate(RESET_TERMINATION);
        }

//        rstAssociatedStreams();
    }

    void onProcessingComplete() {
        isProcessingComplete = true;
        close();
//        if (closeReasonUpdater.compareAndSet(this, null,
//                new CloseReason(CloseType.LOCALLY, null))) {
//
//            inputBuffer.terminate(LOCAL_CLOSE_TERMINATION);
//            outputSink.close();
//
//            notifyCloseListeners();
//        }
    }

    @Override
    @SuppressWarnings("unchecked")
    public void addCloseListener(final CloseListener closeListener) {
        CloseReason cr = closeReason;

        // check if connection is still open
        if (cr == null) {
            // add close listener
            closeListeners.add(closeListener);
            // check the connection state again
            cr = closeReason;
            if (cr != null && closeListeners.remove(closeListener)) {
                // if connection was closed during the method call - notify the listener
                try {
                    closeListener.onClosed(this, cr.getType());
                } catch (IOException ignored) {
                }
            }
        } else { // if connection is closed - notify the listener
            try {
                closeListener.onClosed(this, cr.getType());
            } catch (IOException ignored) {
            }
        }
    }

    @Override
    public boolean removeCloseListener(final CloseListener closeListener) {
        return closeListeners.remove(closeListener);
    }

    @SuppressWarnings("Duplicates")
    @Override
    public GrizzlyFuture<CloseReason> closeFuture() {
        if (closeFuture == null) {
            synchronized (this) {
                if (closeFuture == null) {
                    final CloseReason cr = closeReason;

                    if (cr == null) {
                        final FutureImpl<CloseReason> f = Futures.createSafeFuture();
                        addCloseListener(new org.glassfish.grizzly.CloseListener() {

                            @Override
                            public void onClosed(Closeable closeable, @SuppressWarnings("deprecation") ICloseType type) throws IOException {
                                final CloseReason cr = closeReason;
                                assert cr != null;
                                f.result(cr);
                            }
                        });

                        closeFuture = f;
                    } else {
                        closeFuture = Futures.createReadyFuture(cr);
                    }
                }
            }
        }

        return closeFuture;
    }

    void onInputClosed() {
        if (completeFinalizationCounterUpdater.incrementAndGet(this) == 2) {
            closedStateSwitch();
            closeStream();
        }
    }

    void onOutputClosed() {
        if (completeFinalizationCounterUpdater.incrementAndGet(this) == 2) {
            closedStateSwitch();
            closeStream();
        }
    }

    private void closedStateSwitch() {
        synchronized (this) {
            switch (state) {
                case OPEN:
                    state = State.HALF_CLOSED_LOCAL;
                    break;
                case HALF_CLOSED_REMOTE:
                    state = State.CLOSED;
                    break;
            }
        }
    }

    int getInboundHeaderFramesCounter() {
        return inboundHeaderFramesCounter;
    }

    
The method is called when an inbound headers are decoded for the stream, which means all the header frames arrived
and we're ready to parse the headers.

Params:
  • isEOS – flag indicating if the end-of-stream has been reached
Throws:
/**
     * The method is called when an inbound headers are decoded for the stream, which means all the header frames arrived
     * and we're ready to parse the headers.
     *
     * @param isEOS flag indicating if the end-of-stream has been reached
     *
     * @throws Http2StreamException if an error occurs processing the headers frame
     */
    void onRcvHeaders(final boolean isEOS) throws Http2StreamException {

        inboundHeaderFramesCounter++;

        switch (inboundHeaderFramesCounter) {
        case 1: // first header block to process

            // change the state
            onReceiveHeaders();
            if (isEOS) {
                onReceiveEndOfStream();
            }

            break;
        case 2: { // might be a trailing headers, which is ok
            if (isEOS) {
                break; // trailing headers
            }

            // otherwise goto "default" and throw an error
        }
        default: { // WHAT?
            inputBuffer.close(UNEXPECTED_FRAME_TERMINATION);
            throw new Http2StreamException(getId(), ErrorCode.PROTOCOL_ERROR, "Unexpected headers frame");
        }
        }
    }

    
The method is called when an outbound headers are about to be sent to the peer.

Params:
  • isEOS – flag indicating if the end-of-stream has been reached
/**
     * The method is called when an outbound headers are about to be sent to the peer.
     *
     * @param isEOS flag indicating if the end-of-stream has been reached
     */
    void onSndHeaders(final boolean isEOS) {
        // change the state
        onSendHeaders();
        if (isEOS) {
            onSendEndOfStream();
        }
    }

    private Buffer cachedInputBuffer;
    private boolean cachedIsLast;

    private IOException assertCanAcceptData(final boolean fin) {
        if (isPushStream() && isLocallyInitiatedStream()) {
            return new Http2StreamException(getId(), ErrorCode.PROTOCOL_ERROR, "Data frame received on a push-stream");
        }

        final Http2Stream.State state = getState();
        if (state == State.HALF_CLOSED_REMOTE || getState() == State.CLOSED) {

            close0(null, CloseType.LOCALLY, new IOException("Received DATA frame on " + state + " stream."), false);
            return fin ? new Http2SessionException(ErrorCode.STREAM_CLOSED)
                    : new Http2StreamException(getId(), ErrorCode.STREAM_CLOSED, "Received DATA frame on " + state + " stream.");
        }

        if (inboundHeaderFramesCounter != 1) { // we accept data only if we received one HeadersFrame
            close0(null, CloseType.LOCALLY, new IOException("DATA frame came before HEADERS frame."), false);

            return new Http2StreamException(getId(), ErrorCode.PROTOCOL_ERROR, "DATA frame came before HEADERS frame.");
        }

        return null;
    }

    IOException assertCanAcceptHeader(final boolean fin) {
        final Http2Stream.State state = getState();
        if (state == State.HALF_CLOSED_REMOTE || getState() == State.CLOSED) {

            close0(null, CloseType.LOCALLY, new IOException("Received HEADER frame on " + state + " stream."), false);
            return fin ? new Http2SessionException(ErrorCode.STREAM_CLOSED)
                    : new Http2StreamException(getId(), ErrorCode.STREAM_CLOSED, "Received HEADER frame on " + state + " stream.");
        }

        return null;
    }

    void offerInputData(final Buffer data, final boolean fin) throws IOException {
        IOException ex = assertCanAcceptData(fin);
        if (ex != null) {
            throw ex;
        }
        final boolean isFirstBufferCached = cachedInputBuffer == null;
        cachedIsLast |= fin;
        cachedInputBuffer = Buffers.appendBuffers(http2Session.getMemoryManager(), cachedInputBuffer, data);

        if (isFirstBufferCached) {
            http2Session.streamsToFlushInput.add(this);
        }
    }

    void flushInputData() throws Http2SessionException {
        final Buffer cachedInputBufferLocal = cachedInputBuffer;
        final boolean cachedIsLastLocal = cachedIsLast;
        cachedInputBuffer = null;
        cachedIsLast = false;

        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.log(Level.FINEST, "{0} streamId={1}: flushInputData cachedInputBufferLocal={2}",
                    new Object[] { Thread.currentThread().getName(), getId(), cachedInputBufferLocal != null ? cachedInputBufferLocal.toString() : null });
        }
        if (cachedInputBufferLocal != null) {
            if (cachedInputBufferLocal.isComposite()) {
                ((CompositeBuffer) cachedInputBufferLocal).allowInternalBuffersDispose(true);
                cachedInputBufferLocal.allowBufferDispose(true);
                ((CompositeBuffer) cachedInputBufferLocal).disposeOrder(DisposeOrder.LAST_TO_FIRST);
            }

            final int size = cachedInputBufferLocal.remaining();
            try {
                if (!inputBuffer.offer(cachedInputBufferLocal, cachedIsLastLocal)) {
                    // if we can't add this buffer to the stream input buffer -
                    // we have to release the part of connection window allocated
                    // for the buffer
                    http2Session.ackConsumedData(size);
                }
            } catch (final RuntimeException e) {
                throw new Http2SessionException(ErrorCode.PROTOCOL_ERROR, e.getMessage());
            }
        }
    }

    HttpContent pollInputData() throws IOException {
        return inputBuffer.poll();
    }

    private void closeStream() {
        // TODO ensure stream proper transitions to CLOSED state
        // Http2StreamState.close(this);
        http2Session.deregisterStream();
    }

    HttpHeader getInputHttpHeader() {
        return isLocallyInitiatedStream() ^ isPushStream() ? request.getResponse() : request;
    }

    HttpHeader getOutputHttpHeader() {
        return !isLocallyInitiatedStream() ^ isPushStream() ? request.getResponse() : request;
    }

    
Notify all close listeners

/**
     * Notify all close listeners
     */
    @SuppressWarnings("unchecked")
    private void notifyCloseListeners() {
        final CloseReason cr = closeReason;

        CloseListener closeListener;
        while ((closeListener = closeListeners.poll()) != null) {
            try {
                closeListener.onClosed(this, cr.getType());
            } catch (IOException ignored) {
            }
        }
    }

    
The state of the specified stream.

Returns:the current State.
/**
     * The state of the specified stream.
     *
     * @return the current State.
     */
    State getState() {
        synchronized (this) {
            return state;
        }
    }

    
Checks if the specified stream is closed.

Returns:true if the stream is closed, otherwise false.
/**
     * Checks if the specified stream is closed.
     *
     * @return true if the stream is closed, otherwise false.
     */
    boolean isClosed() {
        synchronized (this) {
            return state == State.CLOSED;
        }
    }

    
Checks if the specified stream is idle.

Returns:true if the stream is idle, otherwise false.
/**
     * Checks if the specified stream is idle.
     *
     * @return true if the stream is idle, otherwise false.
     */

    boolean isIdle() {
        synchronized (this) {
            return state == State.IDLE;
        }
    }

    
Checks if the specified stream is can send frames.

Returns:true if the stream can send frames, otherwise false.
/**
     * Checks if the specified stream is can send frames.
     *
     * @return true if the stream can send frames, otherwise false.
     */
    boolean canSendFrames() {
        synchronized (this) {
            return state != State.CLOSED && state != State.HALF_CLOSED_LOCAL;
        }
    }

    
Checks if the specified stream is can receive frames.

Returns:true if the stream can receive frames, otherwise false.
/**
     * Checks if the specified stream is can receive frames.
     *
     * @return true if the stream can receive frames, otherwise false.
     */
    boolean canReceiveFrames() {
        synchronized (this) {
            return state != State.CLOSED && state != State.HALF_CLOSED_REMOTE;
        }
    }

    
Transition the stream from IDLE to RESERVED_LOCAL.

/**
     * Transition the stream from IDLE to RESERVED_LOCAL.
     */
    void onSendPushPromise() {
        synchronized (this) {
            if (state == State.IDLE) {
                state = State.RESERVED_LOCAL;
            }
        }
    }

    
Transition the stream from IDLE to RESERVED_REMOTE.

/**
     * Transition the stream from IDLE to RESERVED_REMOTE.
     */
    void onReceivePushPromise() {
        synchronized (this) {
            if (state == State.IDLE) {
                state = State.RESERVED_REMOTE;
            }
        }
    }

    
Transition the stream from: - IDLE -> OPEN - RESERVED_LOCAL -> HALF_CLOSED_REMOTE

/**
     * Transition the stream from: - IDLE -> OPEN - RESERVED_LOCAL -> HALF_CLOSED_REMOTE
     */
    private void onSendHeaders() {
        synchronized (this) {
            switch (state) {
            case IDLE:
                state = State.OPEN;
                break;
            case RESERVED_LOCAL:
                state = State.HALF_CLOSED_REMOTE;
                break;
            }
        }
    }

    
Transition the stream from: - IDLE -> OPEN - RESERVED_REMOTE -> HALF_CLOSED_LOCAL

/**
     * Transition the stream from: - IDLE -> OPEN - RESERVED_REMOTE -> HALF_CLOSED_LOCAL
     */
    private void onReceiveHeaders() {
        synchronized (this) {
            switch (state) {
            case IDLE:
                state = State.OPEN;
                break;
            case RESERVED_REMOTE:
                state = State.HALF_CLOSED_LOCAL;
                break;
            }
        }
    }

    
Transition the stream from: - OPEN -> HALF_CLOSED_LOCAL - HALF_CLOSED_REMOTE -> CLOSED

/**
     * Transition the stream from: - OPEN -> HALF_CLOSED_LOCAL - HALF_CLOSED_REMOTE -> CLOSED
     */
    private void onSendEndOfStream() {
        synchronized (this) {
            switch (state) {
            case OPEN:
                state = State.HALF_CLOSED_LOCAL;
                break;
            case HALF_CLOSED_REMOTE:
                state = State.CLOSED;
                break;
            }
        }
    }

    
Transition the stream from: - OPEN -> HALF_CLOSED_REMOTE - HALF_CLOSED_LOCAL -> CLOSED

/**
     * Transition the stream from: - OPEN -> HALF_CLOSED_REMOTE - HALF_CLOSED_LOCAL -> CLOSED
     */
    private void onReceiveEndOfStream() {
        synchronized (this) {
            switch (state) {
            case OPEN:
                state = State.HALF_CLOSED_REMOTE;
                break;
            case HALF_CLOSED_LOCAL:
                state = State.CLOSED;
                break;
            }
        }
    }

    
Transition the stream from: - OPEN -> CLOSED - RESERVED_LOCAL -> CLOSED - RESERVED_REMOTE -> CLOSED -
HALF_CLOSED_LOCAL -> CLOSED - HALF_CLOSED_REMOTE -> CLOSED

/**
     * Transition the stream from: - OPEN -> CLOSED - RESERVED_LOCAL -> CLOSED - RESERVED_REMOTE -> CLOSED -
     * HALF_CLOSED_LOCAL -> CLOSED - HALF_CLOSED_REMOTE -> CLOSED
     */
    private void onReset() {
        synchronized (this) {
            switch (state) {
            case OPEN:
            case RESERVED_LOCAL:
            case RESERVED_REMOTE:
            case HALF_CLOSED_LOCAL:
            case HALF_CLOSED_REMOTE:
                state = State.CLOSED;
                break;
            }
        }
    }
}