| /* |
| * 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.cassandra.hints; |
| |
| import java.util.UUID; |
| import java.util.concurrent.BlockingQueue; |
| import java.util.concurrent.LinkedBlockingQueue; |
| |
| import org.apache.cassandra.config.Config; |
| import org.apache.cassandra.net.MessagingService; |
| |
| /** |
| * A primitive pool of {@link HintsBuffer} buffers. Under normal conditions should only hold two buffers - the currently |
| * written to one, and a reserve buffer to switch to when the first one is beyond capacity. |
| */ |
| final class HintsBufferPool |
| { |
| interface FlushCallback |
| { |
| void flush(HintsBuffer buffer, HintsBufferPool pool); |
| } |
| |
| static final int MAX_ALLOCATED_BUFFERS = Integer.getInteger(Config.PROPERTY_PREFIX + "MAX_HINT_BUFFERS", 3); |
| private volatile HintsBuffer currentBuffer; |
| private final BlockingQueue<HintsBuffer> reserveBuffers; |
| private final int bufferSize; |
| private final FlushCallback flushCallback; |
| private int allocatedBuffers = 0; |
| |
| HintsBufferPool(int bufferSize, FlushCallback flushCallback) |
| { |
| reserveBuffers = new LinkedBlockingQueue<>(); |
| this.bufferSize = bufferSize; |
| this.flushCallback = flushCallback; |
| } |
| |
| /** |
| * @param hostIds host ids of the hint's target nodes |
| * @param hint the hint to store |
| */ |
| void write(Iterable<UUID> hostIds, Hint hint) |
| { |
| int hintSize = (int) Hint.serializer.serializedSize(hint, MessagingService.current_version); |
| try (HintsBuffer.Allocation allocation = allocate(hintSize)) |
| { |
| allocation.write(hostIds, hint); |
| } |
| } |
| |
| private HintsBuffer.Allocation allocate(int hintSize) |
| { |
| HintsBuffer current = currentBuffer(); |
| |
| while (true) |
| { |
| HintsBuffer.Allocation allocation = current.allocate(hintSize); |
| if (allocation != null) |
| return allocation; |
| |
| // allocation failed due to insufficient size remaining in the buffer |
| if (switchCurrentBuffer(current)) |
| flushCallback.flush(current, this); |
| |
| current = currentBuffer; |
| } |
| } |
| |
| void offer(HintsBuffer buffer) |
| { |
| if (!reserveBuffers.offer(buffer)) |
| throw new RuntimeException("Failed to store buffer"); |
| } |
| |
| // A wrapper to ensure a non-null currentBuffer value on the first call. |
| HintsBuffer currentBuffer() |
| { |
| if (currentBuffer == null) |
| initializeCurrentBuffer(); |
| |
| return currentBuffer; |
| } |
| |
| private synchronized void initializeCurrentBuffer() |
| { |
| if (currentBuffer == null) |
| currentBuffer = createBuffer(); |
| } |
| |
| private synchronized boolean switchCurrentBuffer(HintsBuffer previous) |
| { |
| if (currentBuffer != previous) |
| return false; |
| |
| HintsBuffer buffer = reserveBuffers.poll(); |
| if (buffer == null && allocatedBuffers >= MAX_ALLOCATED_BUFFERS) |
| { |
| try |
| { |
| //This BlockingQueue.take is a target for byteman in HintsBufferPoolTest |
| buffer = reserveBuffers.take(); |
| } |
| catch (InterruptedException e) |
| { |
| throw new RuntimeException(e); |
| } |
| } |
| currentBuffer = buffer == null ? createBuffer() : buffer; |
| |
| return true; |
| } |
| |
| private HintsBuffer createBuffer() |
| { |
| allocatedBuffers++; |
| return HintsBuffer.create(bufferSize); |
| } |
| } |