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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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 org.apache.dubbo.rpc.protocol.tri.frame;
import org.apache.dubbo.rpc.RpcException;
import org.apache.dubbo.rpc.protocol.tri.compressor.DeCompressor;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.CompositeByteBuf;
import io.netty.buffer.Unpooled;
public class TriDecoder implements Deframer {
private static final int HEADER_LENGTH = 5;
private static final int COMPRESSED_FLAG_MASK = 1;
private static final int RESERVED_MASK = 0xFE;
private final CompositeByteBuf accumulate = Unpooled.compositeBuffer();
private final Listener listener;
private final DeCompressor decompressor;
private boolean compressedFlag;
private long pendingDeliveries;
private boolean inDelivery = false;
private boolean closing;
private boolean closed;
private int requiredLength = HEADER_LENGTH;
private GrpcDecodeState state = GrpcDecodeState.HEADER;
public TriDecoder(DeCompressor decompressor, Listener listener) {
this.decompressor = decompressor;
this.listener = listener;
}
@Override
public void deframe(ByteBuf data) {
if (closing || closed) {
// ignored
return;
}
accumulate.addComponent(true, data);
deliver();
}
public void request(int numMessages) {
pendingDeliveries += numMessages;
deliver();
}
@Override
public void close() {
closing = true;
deliver();
}
private void deliver() {
// We can have reentrancy here when using a direct executor, triggered by calls to
// request more messages. This is safe as we simply loop until pendingDelivers = 0
if (inDelivery) {
return;
}
inDelivery = true;
try {
// Process the uncompressed bytes.
while (pendingDeliveries > 0 && hasEnoughBytes()) {
switch (state) {
case HEADER:
processHeader();
break;
case PAYLOAD:
// Read the body and deliver the message.
processBody();
// Since we've delivered a message, decrement the number of pending
// deliveries remaining.
pendingDeliveries--;
break;
default:
throw new AssertionError("Invalid state: " + state);
}
}
if (closing) {
if (!closed) {
closed = true;
accumulate.clear();
accumulate.release();
listener.close();
}
}
} finally {
inDelivery = false;
}
}
private boolean hasEnoughBytes() {
return requiredLength - accumulate.readableBytes() <= 0;
}
/**
* Processes the GRPC compression header which is composed of the compression flag and the outer
* frame length.
*/
private void processHeader() {
int type = accumulate.readUnsignedByte();
if ((type & RESERVED_MASK) != 0) {
throw new RpcException("gRPC frame header malformed: reserved bits not zero");
}
compressedFlag = (type & COMPRESSED_FLAG_MASK) != 0;
requiredLength = accumulate.readInt();
// Continue reading the frame body.
state = GrpcDecodeState.PAYLOAD;
}
/**
* Processes the GRPC message body, which depending on frame header flags may be compressed.
*/
private void processBody() {
// There is no reliable way to get the uncompressed size per message when it's compressed,
// because the uncompressed bytes are provided through an InputStream whose total size is
// unknown until all bytes are read, and we don't know when it happens.
byte[] stream = compressedFlag ? getCompressedBody() : getUncompressedBody();
listener.onRawMessage(stream);
// Done with this frame, begin processing the next header.
state = GrpcDecodeState.HEADER;
requiredLength = HEADER_LENGTH;
}
private byte[] getCompressedBody() {
final byte[] compressedBody = getUncompressedBody();
return decompressor.decompress(compressedBody);
}
private byte[] getUncompressedBody() {
byte[] data = new byte[requiredLength];
accumulate.readBytes(data);
return data;
}
private enum GrpcDecodeState {
HEADER,
PAYLOAD
}
public interface Listener {
void onRawMessage(byte[] data);
void close();
}
}