java/org/apache/coyote/http2/RecycledStream.java

/*
 *  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.coyote.http2;

import java.nio.ByteBuffer;

/**
 * Represents a closed stream and is used to correctly respond to (or ignore) frames for the stream that are processed
 * after the stream has been closed. Used in preference to the full {@link Stream} as has much lower memory usage.
 */
class RecycledStream extends AbstractNonZeroStream {

    private final String connectionId;
    private int remainingFlowControlWindow;

    RecycledStream(String connectionId, Integer identifier, StreamStateMachine state, int remainingFlowControlWindow) {
        super(identifier, state);
        this.connectionId = connectionId;
        this.remainingFlowControlWindow = remainingFlowControlWindow;
    }


    @Override
    String getConnectionId() {
        return connectionId;
    }


    @Override
    void incrementWindowSize(int increment) throws Http2Exception {
        // NO-OP
    }


    @Override
    void receivedData(int dataLength) throws ConnectionException {
        remainingFlowControlWindow -= dataLength;
    }


    /**
     * {@inheritDoc}
     * <p>
     * This implementation will return a zero length ByteBuffer to trigger a flow control error if more DATA frame
     * payload than the remaining flow control window is received for this recycled stream.
     */
    @Override
    ByteBuffer getInputByteBuffer(boolean create) {
        if (remainingFlowControlWindow < 0) {
            return ZERO_LENGTH_BYTEBUFFER;
        } else {
            return null;
        }
    }
}