org.vertx.java.core.impl.FlowControlHandler.java Source code

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Here is the source code for org.vertx.java.core.impl.FlowControlHandler.java

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/*
 * Copyright 2013 the original author or authors.
 *
 * Licensed 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.vertx.java.core.impl;

import io.netty.buffer.BufType;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelOperationHandlerAdapter;
import io.netty.channel.ChannelPromise;

/**
 * @author <a href="mailto:nmaurer@redhat.com">Norman Maurer</a>
 */
public class FlowControlHandler extends ChannelOperationHandlerAdapter {

    private final FlowControlStateEvent state = new FlowControlStateEvent();
    private final ChannelFutureListener listener = new ChannelFutureListener() {
        @Override
        public void operationComplete(ChannelFuture future) throws Exception {
            if (!state.isWritable()) {
                if (!outboundBuf.isReadable(lowMark)) {
                    state.updateWritable(true);
                    ctx.fireUserEventTriggered(state);
                } else {
                    if (future.isSuccess() && outboundBuf.isReadable()) {
                        // there is something left to flush so try to flush it now!
                        ctx.flush().addListener(this);
                    }
                }
            }
        }
    };
    private volatile int lowMark;
    private ChannelHandlerContext ctx;
    private ByteBuf outboundBuf;
    private volatile int highMark;

    /**
     * Create a new instance
     */
    public FlowControlHandler(int lowMark, int highMark) {
        if (lowMark < 1) {
            throw new IllegalArgumentException("minWritable must be >= 1");
        }
        if (lowMark > highMark) {
            throw new IllegalArgumentException("lowMark must be >= highMark");
        }
        this.lowMark = lowMark;
        this.highMark = highMark;
    }

    public FlowControlHandler() {
        this(32 * 1024, 64 * 1024);
    }

    public void setLimit(int lowMark, int highMark) {
        if (lowMark < 1) {
            throw new IllegalArgumentException("minWritable must be >= 1");
        }
        if (lowMark > highMark) {
            throw new IllegalArgumentException("lowMark must be >= highMark");
        }
        this.lowMark = lowMark;
        this.highMark = highMark;

        ctx.executor().execute(new Runnable() {
            @Override
            public void run() {
                if (state.isWritable() && outboundBuf.isReadable(FlowControlHandler.this.highMark)) {
                    state.updateWritable(false);
                    ctx.fireUserEventTriggered(state);
                } else if (!state.isWritable() && outboundBuf.isReadable(FlowControlHandler.this.lowMark)) {
                    state.updateWritable(true);
                    ctx.fireUserEventTriggered(state);
                }
            }
        });
    }

    @Override
    public void flush(final ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
        boolean writable = state.isWritable();
        if (writable) {
            writable = !outboundBuf.isReadable(highMark);
        }
        if (!writable) {
            if (state.isWritable()) {
                state.updateWritable(false);
                ctx.fireUserEventTriggered(state);
            }
            promise.addListener(listener);

        }
        ctx.flush(promise);
    }

    @Override
    public void beforeAdd(final ChannelHandlerContext ctx) throws Exception {
        this.ctx = ctx;
        Channel channel = ctx.channel();
        if (channel.metadata().bufferType() == BufType.BYTE) {
            outboundBuf = channel.unsafe().directOutboundContext().outboundByteBuffer();
        } else {
            throw new IllegalStateException("Only supported for Channels which handle bytes");
        }
        super.beforeAdd(ctx);
    }
}