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/*
 * Copyright (c) 2010-2017, KolibriFX AS. Licensed under the Apache License, version 2.0.
 */

package com.kolibrifx.plovercrest.server.internal.protocol;

import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;
import org.apache.log4j.Logger;
import com.kolibrifx.plovercrest.server.internal.streams.RuntimeReadContinuation;
import com.kolibrifx.plovercrest.server.streams.ReaderPosition;

public class ReadContinuationCache {
    private static final Logger log = Logger.getLogger(ReadContinuationCache.class);

    private final Map> map = new HashMap<>();

    public void register(final String tableName, final RuntimeReadContinuation continuation) {
        if (log.isDebugEnabled() && map.containsKey(tableName)) {
            log.debug("Overwriting continuation for table: " + tableName);
        }
        map.put(tableName, continuation);
    }

    public RuntimeReadContinuation tryGetAndRemove(final String tableName, final ReaderPosition position) {
        final RuntimeReadContinuation continuation = map.get(tableName);
        if (continuation == null) {
            return null;
        }
        final ReaderPosition readerPosition = continuation.getReader().getReaderPosition();
        if (!readerPosition.equals(position)) {
            if (log.isDebugEnabled()) {
                log.debug("Performance note: found continuation for " + tableName + ", but its position ("
                        + readerPosition + ") does not match the request: " + position);
            }
            return null;
        }
        // Remove the continuation: it will normally be registered again when the read request (chunk) is finished.
        map.remove(tableName);
        return continuation;
    }
}