| /** |
| * 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.hadoop.hbase.client; |
| |
| import static org.apache.hadoop.hbase.client.ConnectionUtils.calcEstimatedSize; |
| |
| import java.io.IOException; |
| import java.io.InterruptedIOException; |
| import java.util.ArrayDeque; |
| import java.util.Queue; |
| import org.apache.hadoop.hbase.client.metrics.ScanMetrics; |
| import org.apache.hadoop.hbase.util.FutureUtils; |
| import org.apache.yetus.audience.InterfaceAudience; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * The {@link ResultScanner} implementation for {@link AsyncTable}. It will fetch data automatically |
| * in background and cache it in memory. Typically the {@link #maxCacheSize} will be |
| * {@code 2 * scan.getMaxResultSize()}. |
| */ |
| @InterfaceAudience.Private |
| class AsyncTableResultScanner implements ResultScanner, AdvancedScanResultConsumer { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(AsyncTableResultScanner.class); |
| |
| private final AsyncTable<AdvancedScanResultConsumer> rawTable; |
| |
| private final long maxCacheSize; |
| |
| private final Scan scan; |
| |
| private final Queue<Result> queue = new ArrayDeque<>(); |
| |
| private ScanMetrics scanMetrics; |
| |
| private long cacheSize; |
| |
| private boolean closed = false; |
| |
| private Throwable error; |
| |
| private ScanResumer resumer; |
| |
| public AsyncTableResultScanner(AsyncTable<AdvancedScanResultConsumer> table, Scan scan, |
| long maxCacheSize) { |
| this.rawTable = table; |
| this.maxCacheSize = maxCacheSize; |
| this.scan = scan; |
| table.scan(scan, this); |
| } |
| |
| private void addToCache(Result result) { |
| queue.add(result); |
| cacheSize += calcEstimatedSize(result); |
| } |
| |
| private void stopPrefetch(ScanController controller) { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug(String.format("0x%x", System.identityHashCode(this)) + |
| " stop prefetching when scanning " + rawTable.getName() + " as the cache size " + |
| cacheSize + " is greater than the maxCacheSize " + maxCacheSize); |
| } |
| resumer = controller.suspend(); |
| } |
| |
| @Override |
| public synchronized void onNext(Result[] results, ScanController controller) { |
| assert results.length > 0; |
| if (closed) { |
| controller.terminate(); |
| return; |
| } |
| for (Result result : results) { |
| addToCache(result); |
| } |
| notifyAll(); |
| if (cacheSize >= maxCacheSize) { |
| stopPrefetch(controller); |
| } |
| } |
| |
| @Override |
| public synchronized void onHeartbeat(ScanController controller) { |
| if (closed) { |
| controller.terminate(); |
| return; |
| } |
| if (scan.isNeedCursorResult()) { |
| controller.cursor().ifPresent(c -> queue.add(Result.createCursorResult(c))); |
| } |
| } |
| |
| @Override |
| public synchronized void onError(Throwable error) { |
| this.error = error; |
| notifyAll(); |
| } |
| |
| @Override |
| public synchronized void onComplete() { |
| closed = true; |
| notifyAll(); |
| } |
| |
| @Override |
| public void onScanMetricsCreated(ScanMetrics scanMetrics) { |
| this.scanMetrics = scanMetrics; |
| } |
| |
| private void resumePrefetch() { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug(String.format("0x%x", System.identityHashCode(this)) + " resume prefetching"); |
| } |
| resumer.resume(); |
| resumer = null; |
| } |
| |
| @Override |
| public synchronized Result next() throws IOException { |
| while (queue.isEmpty()) { |
| if (closed) { |
| return null; |
| } |
| if (error != null) { |
| FutureUtils.rethrow(error); |
| } |
| try { |
| wait(); |
| } catch (InterruptedException e) { |
| throw new InterruptedIOException(); |
| } |
| } |
| Result result = queue.poll(); |
| if (!result.isCursor()) { |
| cacheSize -= calcEstimatedSize(result); |
| if (resumer != null && cacheSize <= maxCacheSize / 2) { |
| resumePrefetch(); |
| } |
| } |
| return result; |
| } |
| |
| @Override |
| public synchronized void close() { |
| closed = true; |
| queue.clear(); |
| cacheSize = 0; |
| if (resumer != null) { |
| resumePrefetch(); |
| } |
| notifyAll(); |
| } |
| |
| @Override |
| public boolean renewLease() { |
| // we will do prefetching in the background and if there is no space we will just suspend the |
| // scanner. The renew lease operation will be handled in the background. |
| return false; |
| } |
| |
| // used in tests to test whether the scanner has been suspended |
| synchronized boolean isSuspended() { |
| return resumer != null; |
| } |
| |
| @Override |
| public ScanMetrics getScanMetrics() { |
| return scanMetrics; |
| } |
| |
| int getCacheSize() { |
| return queue.size(); |
| } |
| } |