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/*
 * Copyright 2011 LMAX Ltd.
 *
 * 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 com.alipay.disruptor;

/**
 * {@link SequenceBarrier} handed out for gating {@link EventProcessor}s on a cursor sequence and optional dependent {@link EventProcessor}(s),
 * using the given WaitStrategy.
 */
final class ProcessingSequenceBarrier implements SequenceBarrier {
    private final WaitStrategy waitStrategy;
    private final Sequence     dependentSequence;
    private volatile boolean   alerted = false;
    private final Sequence     cursorSequence;
    private final Sequencer    sequencer;

    public ProcessingSequenceBarrier(final Sequencer sequencer, final WaitStrategy waitStrategy,
                                     final Sequence cursorSequence,
                                     final Sequence[] dependentSequences) {
        this.sequencer = sequencer;
        this.waitStrategy = waitStrategy;
        this.cursorSequence = cursorSequence;
        if (0 == dependentSequences.length) {
            dependentSequence = cursorSequence;
        } else {
            dependentSequence = new FixedSequenceGroup(dependentSequences);
        }
    }

    @Override
    public long waitFor(final long sequence) throws AlertException, InterruptedException,
                                            TimeoutException {
        checkAlert();

        long availableSequence = waitStrategy.waitFor(sequence, cursorSequence, dependentSequence,
            this);

        if (availableSequence < sequence) {
            return availableSequence;
        }

        return sequencer.getHighestPublishedSequence(sequence, availableSequence);
    }

    @Override
    public long getCursor() {
        return dependentSequence.get();
    }

    @Override
    public boolean isAlerted() {
        return alerted;
    }

    @Override
    public void alert() {
        alerted = true;
        waitStrategy.signalAllWhenBlocking();
    }

    @Override
    public void clearAlert() {
        alerted = false;
    }

    @Override
    public void checkAlert() throws AlertException {
        if (alerted) {
            throw AlertException.INSTANCE;
        }
    }
}