nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.DefaultHttp2LocalFlowController Maven / Gradle / Ivy
/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License, version 2.0 (the
* "License"); you may not use this file except in compliance with the License. You may obtain a
* copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package nl.topicus.jdbc.shaded.io.netty.handler.codec.http2;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2CodecUtil.CONNECTION_STREAM_ID;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_WINDOW_SIZE;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2CodecUtil.MAX_INITIAL_WINDOW_SIZE;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2CodecUtil.MIN_INITIAL_WINDOW_SIZE;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2Error.FLOW_CONTROL_ERROR;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2Error.INTERNAL_ERROR;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2Exception.connectionError;
import static nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2Exception.streamError;
import static nl.topicus.jdbc.shaded.io.netty.util.internal.ObjectUtil.checkNotNull;
import static java.lang.Math.max;
import static java.lang.Math.min;
import nl.topicus.jdbc.shaded.io.netty.buffer.ByteBuf;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelHandlerContext;
import nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2Exception.CompositeStreamException;
import nl.topicus.jdbc.shaded.io.netty.handler.codec.http2.Http2Exception.StreamException;
import nl.topicus.jdbc.shaded.io.netty.util.internal.PlatformDependent;
import nl.topicus.jdbc.shaded.io.netty.util.internal.UnstableApi;
/**
* Basic implementation of {@link Http2LocalFlowController}.
*
* This class is NOT thread safe. The assumption is all methods must be invoked from a single thread.
* Typically this thread is the event loop thread for the {@link ChannelHandlerContext} managed by this class.
*/
@UnstableApi
public class DefaultHttp2LocalFlowController implements Http2LocalFlowController {
/**
* The default ratio of window size to initial window size below which a {@code WINDOW_UPDATE}
* is sent to expand the window.
*/
public static final float DEFAULT_WINDOW_UPDATE_RATIO = 0.5f;
private final Http2Connection connection;
private final Http2Connection.PropertyKey stateKey;
private Http2FrameWriter frameWriter;
private ChannelHandlerContext ctx;
private float windowUpdateRatio;
private int initialWindowSize = DEFAULT_WINDOW_SIZE;
public DefaultHttp2LocalFlowController(Http2Connection connection) {
this(connection, DEFAULT_WINDOW_UPDATE_RATIO, false);
}
/**
* Constructs a controller with the given settings.
*
* @param connection the connection state.
* @param windowUpdateRatio the window percentage below which to send a {@code WINDOW_UPDATE}.
* @param autoRefillConnectionWindow if {@code true}, effectively disables the connection window
* in the flow control algorithm as they will always refill automatically without requiring the
* application to consume the bytes. When enabled, the maximum bytes you must be prepared to
* queue is proportional to {@code maximum number of concurrent streams * the initial window
* size per stream}
* (SETTINGS_MAX_CONCURRENT_STREAMS
* SETTINGS_INITIAL_WINDOW_SIZE).
*/
public DefaultHttp2LocalFlowController(Http2Connection connection,
float windowUpdateRatio,
boolean autoRefillConnectionWindow) {
this.connection = checkNotNull(connection, "connection");
windowUpdateRatio(windowUpdateRatio);
// Add a flow state for the connection.
stateKey = connection.newKey();
FlowState connectionState = autoRefillConnectionWindow ?
new AutoRefillState(connection.connectionStream(), initialWindowSize) :
new DefaultState(connection.connectionStream(), initialWindowSize);
connection.connectionStream().setProperty(stateKey, connectionState);
// Register for notification of new streams.
connection.addListener(new Http2ConnectionAdapter() {
@Override
public void onStreamAdded(Http2Stream stream) {
// Unconditionally used the reduced flow control state because it requires no object allocation
// and the DefaultFlowState will be allocated in onStreamActive.
stream.setProperty(stateKey, REDUCED_FLOW_STATE);
}
@Override
public void onStreamActive(Http2Stream stream) {
// Need to be sure the stream's initial window is adjusted for SETTINGS
// frames which may have been exchanged while it was in IDLE
stream.setProperty(stateKey, new DefaultState(stream, initialWindowSize));
}
@Override
public void onStreamClosed(Http2Stream stream) {
try {
// When a stream is closed, consume any remaining bytes so that they
// are restored to the connection window.
FlowState state = state(stream);
int unconsumedBytes = state.unconsumedBytes();
if (ctx != null && unconsumedBytes > 0) {
connectionState().consumeBytes(unconsumedBytes);
state.consumeBytes(unconsumedBytes);
}
} catch (Http2Exception e) {
PlatformDependent.throwException(e);
} finally {
// Unconditionally reduce the amount of memory required for flow control because there is no
// object allocation costs associated with doing so and the stream will not have any more
// local flow control state to keep track of anymore.
stream.setProperty(stateKey, REDUCED_FLOW_STATE);
}
}
});
}
@Override
public DefaultHttp2LocalFlowController frameWriter(Http2FrameWriter frameWriter) {
this.frameWriter = checkNotNull(frameWriter, "frameWriter");
return this;
}
@Override
public void channelHandlerContext(ChannelHandlerContext ctx) {
this.ctx = checkNotNull(ctx, "ctx");
}
@Override
public void initialWindowSize(int newWindowSize) throws Http2Exception {
assert ctx == null || ctx.executor().inEventLoop();
int delta = newWindowSize - initialWindowSize;
initialWindowSize = newWindowSize;
WindowUpdateVisitor visitor = new WindowUpdateVisitor(delta);
connection.forEachActiveStream(visitor);
visitor.throwIfError();
}
@Override
public int initialWindowSize() {
return initialWindowSize;
}
@Override
public int windowSize(Http2Stream stream) {
return state(stream).windowSize();
}
@Override
public int initialWindowSize(Http2Stream stream) {
return state(stream).initialWindowSize();
}
@Override
public void incrementWindowSize(Http2Stream stream, int delta) throws Http2Exception {
assert ctx != null && ctx.executor().inEventLoop();
FlowState state = state(stream);
// Just add the delta to the stream-specific initial window size so that the next time the window
// expands it will grow to the new initial size.
state.incrementInitialStreamWindow(delta);
state.writeWindowUpdateIfNeeded();
}
@Override
public boolean consumeBytes(Http2Stream stream, int numBytes) throws Http2Exception {
assert ctx != null && ctx.executor().inEventLoop();
if (numBytes < 0) {
throw new IllegalArgumentException("numBytes must not be negative");
}
if (numBytes == 0) {
return false;
}
// Streams automatically consume all remaining bytes when they are closed, so just ignore
// if already closed.
if (stream != null && !isClosed(stream)) {
if (stream.id() == CONNECTION_STREAM_ID) {
throw new UnsupportedOperationException("Returning bytes for the connection window is not supported");
}
boolean windowUpdateSent = connectionState().consumeBytes(numBytes);
windowUpdateSent |= state(stream).consumeBytes(numBytes);
return windowUpdateSent;
}
return false;
}
@Override
public int unconsumedBytes(Http2Stream stream) {
return state(stream).unconsumedBytes();
}
private static void checkValidRatio(float ratio) {
if (Double.compare(ratio, 0.0) <= 0 || Double.compare(ratio, 1.0) >= 0) {
throw new IllegalArgumentException("Invalid ratio: " + ratio);
}
}
/**
* The window update ratio is used to determine when a window update must be sent. If the ratio
* of bytes processed since the last update has meet or exceeded this ratio then a window update will
* be sent. This is the global window update ratio that will be used for new streams.
* @param ratio the ratio to use when checking if a {@code WINDOW_UPDATE} is determined necessary for new streams.
* @throws IllegalArgumentException If the ratio is out of bounds (0, 1).
*/
public void windowUpdateRatio(float ratio) {
assert ctx == null || ctx.executor().inEventLoop();
checkValidRatio(ratio);
windowUpdateRatio = ratio;
}
/**
* The window update ratio is used to determine when a window update must be sent. If the ratio
* of bytes processed since the last update has meet or exceeded this ratio then a window update will
* be sent. This is the global window update ratio that will be used for new streams.
*/
public float windowUpdateRatio() {
return windowUpdateRatio;
}
/**
* The window update ratio is used to determine when a window update must be sent. If the ratio
* of bytes processed since the last update has meet or exceeded this ratio then a window update will
* be sent. This window update ratio will only be applied to {@code streamId}.
*
* Note it is the responsibly of the caller to ensure that the the
* initial {@code SETTINGS} frame is sent before this is called. It would
* be considered a {@link Http2Error#PROTOCOL_ERROR} if a {@code WINDOW_UPDATE}
* was generated by this method before the initial {@code SETTINGS} frame is sent.
* @param stream the stream for which {@code ratio} applies to.
* @param ratio the ratio to use when checking if a {@code WINDOW_UPDATE} is determined necessary.
* @throws Http2Exception If a protocol-error occurs while generating {@code WINDOW_UPDATE} frames
*/
public void windowUpdateRatio(Http2Stream stream, float ratio) throws Http2Exception {
assert ctx != null && ctx.executor().inEventLoop();
checkValidRatio(ratio);
FlowState state = state(stream);
state.windowUpdateRatio(ratio);
state.writeWindowUpdateIfNeeded();
}
/**
* The window update ratio is used to determine when a window update must be sent. If the ratio
* of bytes processed since the last update has meet or exceeded this ratio then a window update will
* be sent. This window update ratio will only be applied to {@code streamId}.
* @throws Http2Exception If no stream corresponding to {@code stream} could be found.
*/
public float windowUpdateRatio(Http2Stream stream) throws Http2Exception {
return state(stream).windowUpdateRatio();
}
@Override
public void receiveFlowControlledFrame(Http2Stream stream, ByteBuf data, int padding,
boolean endOfStream) throws Http2Exception {
assert ctx != null && ctx.executor().inEventLoop();
int dataLength = data.readableBytes() + padding;
// Apply the connection-level flow control
FlowState connectionState = connectionState();
connectionState.receiveFlowControlledFrame(dataLength);
if (stream != null && !isClosed(stream)) {
// Apply the stream-level flow control
FlowState state = state(stream);
state.endOfStream(endOfStream);
state.receiveFlowControlledFrame(dataLength);
} else if (dataLength > 0) {
// Immediately consume the bytes for the connection window.
connectionState.consumeBytes(dataLength);
}
}
private FlowState connectionState() {
return connection.connectionStream().getProperty(stateKey);
}
private FlowState state(Http2Stream stream) {
return stream.getProperty(stateKey);
}
private static boolean isClosed(Http2Stream stream) {
return stream.state() == Http2Stream.State.CLOSED;
}
/**
* Flow control state that does autorefill of the flow control window when the data is
* received.
*/
private final class AutoRefillState extends DefaultState {
public AutoRefillState(Http2Stream stream, int initialWindowSize) {
super(stream, initialWindowSize);
}
@Override
public void receiveFlowControlledFrame(int dataLength) throws Http2Exception {
super.receiveFlowControlledFrame(dataLength);
// Need to call the super to consume the bytes, since this.consumeBytes does nothing.
super.consumeBytes(dataLength);
}
@Override
public boolean consumeBytes(int numBytes) throws Http2Exception {
// Do nothing, since the bytes are already consumed upon receiving the data.
return false;
}
}
/**
* Flow control window state for an individual stream.
*/
private class DefaultState implements FlowState {
private final Http2Stream stream;
/**
* The actual flow control window that is decremented as soon as {@code DATA} arrives.
*/
private int window;
/**
* A view of {@link #window} that is used to determine when to send {@code WINDOW_UPDATE}
* frames. Decrementing this window for received {@code DATA} frames is delayed until the
* application has indicated that the data has been fully processed. This prevents sending
* a {@code WINDOW_UPDATE} until the number of processed bytes drops below the threshold.
*/
private int processedWindow;
/**
* This is what is used to determine how many bytes need to be returned relative to {@link #processedWindow}.
* Each stream has their own initial window size.
*/
private int initialStreamWindowSize;
/**
* This is used to determine when {@link #processedWindow} is sufficiently far away from
* {@link #initialStreamWindowSize} such that a {@code WINDOW_UPDATE} should be sent.
* Each stream has their own window update ratio.
*/
private float streamWindowUpdateRatio;
private int lowerBound;
private boolean endOfStream;
public DefaultState(Http2Stream stream, int initialWindowSize) {
this.stream = stream;
window(initialWindowSize);
streamWindowUpdateRatio = windowUpdateRatio;
}
@Override
public void window(int initialWindowSize) {
assert ctx == null || ctx.executor().inEventLoop();
window = processedWindow = initialStreamWindowSize = initialWindowSize;
}
@Override
public int windowSize() {
return window;
}
@Override
public int initialWindowSize() {
return initialStreamWindowSize;
}
@Override
public void endOfStream(boolean endOfStream) {
this.endOfStream = endOfStream;
}
@Override
public float windowUpdateRatio() {
return streamWindowUpdateRatio;
}
@Override
public void windowUpdateRatio(float ratio) {
assert ctx == null || ctx.executor().inEventLoop();
streamWindowUpdateRatio = ratio;
}
@Override
public void incrementInitialStreamWindow(int delta) {
// Clip the delta so that the resulting initialStreamWindowSize falls within the allowed range.
int newValue = (int) min(MAX_INITIAL_WINDOW_SIZE,
max(MIN_INITIAL_WINDOW_SIZE, initialStreamWindowSize + (long) delta));
delta = newValue - initialStreamWindowSize;
initialStreamWindowSize += delta;
}
@Override
public void incrementFlowControlWindows(int delta) throws Http2Exception {
if (delta > 0 && window > MAX_INITIAL_WINDOW_SIZE - delta) {
throw streamError(stream.id(), FLOW_CONTROL_ERROR,
"Flow control window overflowed for stream: %d", stream.id());
}
window += delta;
processedWindow += delta;
lowerBound = delta < 0 ? delta : 0;
}
@Override
public void receiveFlowControlledFrame(int dataLength) throws Http2Exception {
assert dataLength >= 0;
// Apply the delta. Even if we throw an exception we want to have taken this delta into account.
window -= dataLength;
// Window size can become negative if we sent a SETTINGS frame that reduces the
// size of the transfer window after the peer has written data frames.
// The value is bounded by the length that SETTINGS frame decrease the window.
// This difference is stored for the connection when writing the SETTINGS frame
// and is cleared once we send a WINDOW_UPDATE frame.
if (window < lowerBound) {
throw streamError(stream.id(), FLOW_CONTROL_ERROR,
"Flow control window exceeded for stream: %d", stream.id());
}
}
private void returnProcessedBytes(int delta) throws Http2Exception {
if (processedWindow - delta < window) {
throw streamError(stream.id(), INTERNAL_ERROR,
"Attempting to return too many bytes for stream %d", stream.id());
}
processedWindow -= delta;
}
@Override
public boolean consumeBytes(int numBytes) throws Http2Exception {
// Return the bytes processed and update the window.
returnProcessedBytes(numBytes);
return writeWindowUpdateIfNeeded();
}
@Override
public int unconsumedBytes() {
return processedWindow - window;
}
@Override
public boolean writeWindowUpdateIfNeeded() throws Http2Exception {
if (endOfStream || initialStreamWindowSize <= 0) {
return false;
}
int threshold = (int) (initialStreamWindowSize * streamWindowUpdateRatio);
if (processedWindow <= threshold) {
writeWindowUpdate();
return true;
}
return false;
}
/**
* Called to perform a window update for this stream (or connection). Updates the window size back
* to the size of the initial window and sends a window update frame to the remote endpoint.
*/
private void writeWindowUpdate() throws Http2Exception {
// Expand the window for this stream back to the size of the initial window.
int deltaWindowSize = initialStreamWindowSize - processedWindow;
try {
incrementFlowControlWindows(deltaWindowSize);
} catch (Throwable t) {
throw connectionError(INTERNAL_ERROR, t,
"Attempting to return too many bytes for stream %d", stream.id());
}
// Send a window update for the stream/connection.
frameWriter.writeWindowUpdate(ctx, stream.id(), deltaWindowSize, ctx.newPromise());
}
}
/**
* The local flow control state for a single stream that is not in a state where flow controlled frames cannot
* be exchanged.
*/
private static final FlowState REDUCED_FLOW_STATE = new FlowState() {
@Override
public int windowSize() {
return 0;
}
@Override
public int initialWindowSize() {
return 0;
}
@Override
public void window(int initialWindowSize) {
throw new UnsupportedOperationException();
}
@Override
public void incrementInitialStreamWindow(int delta) {
// This operation needs to be supported during the initial settings exchange when
// the peer has not yet acknowledged this peer being activated.
}
@Override
public boolean writeWindowUpdateIfNeeded() throws Http2Exception {
throw new UnsupportedOperationException();
}
@Override
public boolean consumeBytes(int numBytes) throws Http2Exception {
return false;
}
@Override
public int unconsumedBytes() {
return 0;
}
@Override
public float windowUpdateRatio() {
throw new UnsupportedOperationException();
}
@Override
public void windowUpdateRatio(float ratio) {
throw new UnsupportedOperationException();
}
@Override
public void receiveFlowControlledFrame(int dataLength) throws Http2Exception {
throw new UnsupportedOperationException();
}
@Override
public void incrementFlowControlWindows(int delta) throws Http2Exception {
// This operation needs to be supported during the initial settings exchange when
// the peer has not yet acknowledged this peer being activated.
}
@Override
public void endOfStream(boolean endOfStream) {
throw new UnsupportedOperationException();
}
};
/**
* An abstraction which provides specific extensions used by local flow control.
*/
private interface FlowState {
int windowSize();
int initialWindowSize();
void window(int initialWindowSize);
/**
* Increment the initial window size for this stream.
* @param delta The amount to increase the initial window size by.
*/
void incrementInitialStreamWindow(int delta);
/**
* Updates the flow control window for this stream if it is appropriate.
*
* @return true if {@code WINDOW_UPDATE} was written, false otherwise.
*/
boolean writeWindowUpdateIfNeeded() throws Http2Exception;
/**
* Indicates that the application has consumed {@code numBytes} from the connection or stream and is
* ready to receive more data.
*
* @param numBytes the number of bytes to be returned to the flow control window.
* @return true if {@code WINDOW_UPDATE} was written, false otherwise.
* @throws Http2Exception
*/
boolean consumeBytes(int numBytes) throws Http2Exception;
int unconsumedBytes();
float windowUpdateRatio();
void windowUpdateRatio(float ratio);
/**
* A flow control event has occurred and we should decrement the amount of available bytes for this stream.
* @param dataLength The amount of data to for which this stream is no longer eligible to use for flow control.
* @throws Http2Exception If too much data is used relative to how much is available.
*/
void receiveFlowControlledFrame(int dataLength) throws Http2Exception;
/**
* Increment the windows which are used to determine many bytes have been processed.
* @param delta The amount to increment the window by.
* @throws Http2Exception if integer overflow occurs on the window.
*/
void incrementFlowControlWindows(int delta) throws Http2Exception;
void endOfStream(boolean endOfStream);
}
/**
* Provides a means to iterate over all active streams and increment the flow control windows.
*/
private final class WindowUpdateVisitor implements Http2StreamVisitor {
private CompositeStreamException compositeException;
private final int delta;
public WindowUpdateVisitor(int delta) {
this.delta = delta;
}
@Override
public boolean visit(Http2Stream stream) throws Http2Exception {
try {
// Increment flow control window first so state will be consistent if overflow is detected.
FlowState state = state(stream);
state.incrementFlowControlWindows(delta);
state.incrementInitialStreamWindow(delta);
} catch (StreamException e) {
if (compositeException == null) {
compositeException = new CompositeStreamException(e.error(), 4);
}
compositeException.add(e);
}
return true;
}
public void throwIfError() throws CompositeStreamException {
if (compositeException != null) {
throw compositeException;
}
}
}
}