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Restrict two-phase graceful HTTP/2 shutdown to server-side connections #661

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Restrict two-phase graceful HTTP/2 shutdown to server-side connections #661

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147 changes: 108 additions & 39 deletions ...ore5-h2/src/main/java/org/apache/hc/core5/http2/impl/nio/AbstractH2StreamMultiplexer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -106,11 +106,11 @@ abstract class AbstractH2StreamMultiplexer implements Identifiable, HttpConnecti

private static final long CONNECTION_WINDOW_LOW_MARK = 10 * 1024 * 1024;

enum ConnectionHandshake { READY, ACTIVE, GRACEFUL_SHUTDOWN, SHUTDOWN }
enum ConnectionHandshake { READY, ACTIVE, DRAINING, GRACEFUL_SHUTDOWN, SHUTDOWN }
enum SettingsHandshake { READY, TRANSMITTED, ACKED }

private final ProtocolIOSession ioSession;
private final FrameFactory frameFactory;
final FrameFactory frameFactory;
private final HttpProcessor httpProcessor;
private final H2Config localConfig;
private final BasicH2TransportMetrics inputMetrics;
Expand All @@ -121,14 +121,14 @@ enum SettingsHandshake { READY, TRANSMITTED, ACKED }
private final Deque<RawFrame> outputQueue;
private final HPackEncoder hPackEncoder;
private final HPackDecoder hPackDecoder;
private final H2Streams streams;
final H2Streams streams;
private final Queue<AsyncPingHandler> pingHandlers;
private final AtomicInteger connInputWindow;
private final AtomicInteger connOutputWindow;
private final AtomicInteger outputRequests;
private final H2StreamListener streamListener;

private ConnectionHandshake connState = ConnectionHandshake.READY;
ConnectionHandshake connState = ConnectionHandshake.READY;
private SettingsHandshake localSettingState = SettingsHandshake.READY;
private SettingsHandshake remoteSettingState = SettingsHandshake.READY;

Expand Down Expand Up @@ -297,7 +297,7 @@ private void commitFrameInternal(final RawFrame frame) throws IOException {
ioSession.setEvent(SelectionKey.OP_WRITE);
}

private void commitFrame(final RawFrame frame) throws IOException {
void commitFrame(final RawFrame frame) throws IOException {
Args.notNull(frame, "Frame");
ioSession.getLock().lock();
try {
Expand Down Expand Up @@ -506,6 +506,10 @@ public final void onOutput() throws HttpException, IOException {
ioSession.getLock().unlock();
}

if (beforeOutputProcessing()) {
return;
}

if (connState.compareTo(ConnectionHandshake.SHUTDOWN) < 0) {

if (connOutputWindow.get() > 0 && remoteSettingState == SettingsHandshake.ACKED) {
Expand Down Expand Up @@ -581,23 +585,7 @@ public final void onOutput() throws HttpException, IOException {
validateStreamTimeouts();
}

if (connState.compareTo(ConnectionHandshake.GRACEFUL_SHUTDOWN) == 0) {
int liveStreams = 0;
for (final Iterator<H2Stream> it = streams.iterator(); it.hasNext(); ) {
final H2Stream stream = it.next();
if (stream.isClosedPastLingerDeadline()) {
streams.dropStreamId(stream.getId());
it.remove();
} else {
if (streams.isSameSide(stream.getId()) || stream.getId() <= streams.getLastRemoteId()) {
liveStreams++;
}
}
}
if (liveStreams == 0) {
connState = ConnectionHandshake.SHUTDOWN;
}
}
maybeTransitionFromGracefulShutdown();
if (connState.compareTo(ConnectionHandshake.GRACEFUL_SHUTDOWN) >= 0) {
for (;;) {
final Command command = ioSession.poll();
Expand Down Expand Up @@ -628,6 +616,9 @@ public final void onOutput() throws HttpException, IOException {
}

public final void onTimeout(final Timeout timeout) throws HttpException, IOException {
if (onShutdownTimeout(timeout)) {
return;
}
connState = ConnectionHandshake.SHUTDOWN;

final RawFrame goAway;
Expand Down Expand Up @@ -665,14 +656,100 @@ private void executeShutdown(final ShutdownCommand shutdownCommand) throws IOExc
connState = ConnectionHandshake.SHUTDOWN;
} else {
if (connState.compareTo(ConnectionHandshake.ACTIVE) <= 0) {
final RawFrame goAway = frameFactory.createGoAway(streams.getLastRemoteId(), H2Error.NO_ERROR, "Graceful shutdown");
commitFrame(goAway);
connState = streams.isEmpty() ? ConnectionHandshake.SHUTDOWN : ConnectionHandshake.GRACEFUL_SHUTDOWN;
initiateGracefulShutdown();
}
}
}

/**
* Initiates the graceful shutdown sequence. The default implementation emits a single
* GOAWAY frame carrying the last processed remote stream id and transitions to
* {@code GRACEFUL_SHUTDOWN} (or straight to {@code SHUTDOWN} when no streams are open).
* Subclasses may override to implement alternate shutdown sequences.
*/
void initiateGracefulShutdown() throws IOException {
final RawFrame goAway = frameFactory.createGoAway(streams.getLastRemoteId(), H2Error.NO_ERROR, "Graceful shutdown");
commitFrame(goAway);
connState = streams.isEmpty() ? ConnectionHandshake.SHUTDOWN : ConnectionHandshake.GRACEFUL_SHUTDOWN;
}

/**
* Whether the multiplexer is currently accepting new remote-initiated streams.
* The default allows new streams while the connection is in {@code READY} or {@code ACTIVE}.
*/
boolean canAcceptNewRemoteStream() {
return connState.compareTo(ConnectionHandshake.ACTIVE) <= 0;
}

/**
* Notification hook fired right after a remote-initiated stream has been created.
* The default is a no-op.
*/
void onRemoteStreamAccepted(final int streamId) {
}

/**
* Timeout hook that lets subclasses intercept inactivity-driven shutdowns.
* Returning {@code true} signals that the subclass has handled the timeout and the
* default full-shutdown path should be skipped.
*/
boolean onShutdownTimeout(final Timeout timeout) throws HttpException, IOException {
return false;
}

/**
* Early {@code onOutput} hook fired after the output buffer has been flushed and before
* the main state-machine processing. Returning {@code true} aborts the rest of the
* {@code onOutput} cycle, allowing subclasses to interleave additional frames between
* flush and further work.
*/
boolean beforeOutputProcessing() throws HttpException, IOException {
return false;
}

void applyRemoteGracefulGoAway(final int processedLocalStreamId) {
if (connState.compareTo(ConnectionHandshake.ACTIVE) <= 0) {
for (final Iterator<H2Stream> it = streams.iterator(); it.hasNext(); ) {
final H2Stream stream = it.next();
final int activeStreamId = stream.getId();
if (!streams.isSameSide(activeStreamId) && activeStreamId > processedLocalStreamId) {
stream.fail(new RequestNotExecutedException());
it.remove();
}
}
}
connState = streams.isEmpty() ? ConnectionHandshake.SHUTDOWN : ConnectionHandshake.GRACEFUL_SHUTDOWN;
}

/**
* Evaluates whether the {@code GRACEFUL_SHUTDOWN} state can be promoted to
* {@code SHUTDOWN}. The default transitions once no live streams remain.
*/
void maybeTransitionFromGracefulShutdown() {
if (connState.compareTo(ConnectionHandshake.GRACEFUL_SHUTDOWN) == 0) {
int liveStreams = 0;
for (final Iterator<H2Stream> it = streams.iterator(); it.hasNext(); ) {
final H2Stream stream = it.next();
if (stream.isClosedPastLingerDeadline()) {
streams.dropStreamId(stream.getId());
it.remove();
} else {
if (streams.isSameSide(stream.getId()) || stream.getId() <= streams.getLastRemoteId()) {
liveStreams++;
}
}
}
if (liveStreams == 0) {
connState = ConnectionHandshake.SHUTDOWN;
}
}
}

private void executePing(final PingCommand pingCommand) throws IOException {
boolean hasPendingOutput() {
return !outputBuffer.isEmpty() || !outputQueue.isEmpty();
}

void executePing(final PingCommand pingCommand) throws IOException {
final AsyncPingHandler handler = pingCommand.getHandler();
pingHandlers.add(handler);
final RawFrame ping = frameFactory.createPing(handler.getData());
Expand Down Expand Up @@ -817,8 +894,9 @@ private void consumeFrame(final RawFrame frame) throws HttpException, IOExceptio
}

final H2StreamChannel channel = createChannel(streamId);
if (connState.compareTo(ConnectionHandshake.ACTIVE) <= 0) {
if (canAcceptNewRemoteStream()) {
stream = streams.createActive(channel, incomingRequest(channel));
onRemoteStreamAccepted(streamId);
streams.resetIfExceedsMaxConcurrentLimit(stream, localConfig.getMaxConcurrentStreams());
} else {
channel.localReset(H2Error.REFUSED_STREAM);
Expand Down Expand Up @@ -1026,8 +1104,9 @@ private void consumeFrame(final RawFrame frame) throws HttpException, IOExceptio

final H2StreamChannel channel = createChannel(promisedStreamId);
final H2Stream promisedStream;
if (connState.compareTo(ConnectionHandshake.ACTIVE) <= 0) {
if (canAcceptNewRemoteStream()) {
promisedStream = streams.createReserved(channel, incomingPushPromise(channel, stream.getPushHandlerFactory()));
onRemoteStreamAccepted(promisedStreamId);
} else {
channel.localReset(H2Error.REFUSED_STREAM);
promisedStream = streams.createActive(channel, NoopH2StreamHandler.INSTANCE);
Expand All @@ -1053,17 +1132,7 @@ private void consumeFrame(final RawFrame frame) throws HttpException, IOExceptio
final int errorCode = payload.getInt();
goAwayReceived = true;
if (errorCode == H2Error.NO_ERROR.getCode()) {
if (connState.compareTo(ConnectionHandshake.ACTIVE) <= 0) {
for (final Iterator<H2Stream> it = streams.iterator(); it.hasNext(); ) {
final H2Stream stream = it.next();
final int activeStreamId = stream.getId();
if (!streams.isSameSide(activeStreamId) && activeStreamId > processedLocalStreamId) {
stream.fail(new RequestNotExecutedException());
it.remove();
}
}
}
connState = streams.isEmpty() ? ConnectionHandshake.SHUTDOWN : ConnectionHandshake.GRACEFUL_SHUTDOWN;
applyRemoteGracefulGoAway(processedLocalStreamId);
} else {
for (final Iterator<H2Stream> it = streams.iterator(); it.hasNext(); ) {
final H2Stream stream = it.next();
Expand Down
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