content: /*
   * 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.asterix.replication.logging;
  
  import java.nio.ByteBuffer;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.apache.asterix.common.transactions.ILogRecord;
  import org.apache.asterix.replication.management.LogReplicationManager;
  
  public class ReplicationLogBuffer {
  
      private final int logBufferSize;
      private final AtomicBoolean full;
      private int appendOffset;
      private int replicationOffset;
      private final ByteBuffer appendBuffer;
      private final ByteBuffer replicationBuffer;
      private boolean stop;
      private final LogReplicationManager replicationManager;
      private final int batchSize;
  
      public ReplicationLogBuffer(LogReplicationManager replicationManager, int logBufferSize, int batchSize) {
          this.replicationManager = replicationManager;
          this.logBufferSize = logBufferSize;
          this.batchSize = batchSize;
          appendBuffer = ByteBuffer.allocate(logBufferSize);
          replicationBuffer = appendBuffer.duplicate();
          full = new AtomicBoolean(false);
          appendOffset = 0;
          replicationOffset = 0;
      }
  
      public void append(ILogRecord logRecord) {
          appendBuffer.putInt(logRecord.getRemoteLogSize());
          logRecord.writeRemoteLogRecord(appendBuffer);
  
          synchronized (this) {
              appendOffset += getLogReplicationSize(logRecord);
              this.notify();
          }
      }
  
      public synchronized void setFull(boolean full) {
          this.full.set(full);
          this.notify();
      }
  
      public boolean hasSpace(ILogRecord logRecord) {
          return appendOffset + getLogReplicationSize(logRecord) <= logBufferSize;
      }
  
      private static int getLogReplicationSize(ILogRecord logRecord) {
          //log length (4 bytes) + remote log size
          return Integer.BYTES + logRecord.getRemoteLogSize();
      }
  
      public void reset() {
          appendBuffer.position(0);
          appendBuffer.limit(logBufferSize);
          replicationBuffer.position(0);
          replicationBuffer.limit(logBufferSize);
          full.set(false);
          appendOffset = 0;
          replicationOffset = 0;
          stop = false;
      }
  
      public void flush() {
          int endOffset;
          while (!full.get()) {
              synchronized (this) {
                  if (appendOffset - replicationOffset == 0 && !full.get()) {
                      try {
                          if (stop) {
                              break;
                          }
                          this.wait();
                      } catch (InterruptedException e) {
                          Thread.currentThread().interrupt();
                          continue;
                      }
                  }
                  endOffset = appendOffset;
              }
              internalFlush(replicationOffset, endOffset);
          }
          internalFlush(replicationOffset, appendOffset);
      }
  
      private void internalFlush(int beginOffset, int endOffset) {
          if (endOffset > beginOffset) {
              int begingPos = replicationBuffer.position();
              replicationBuffer.limit(endOffset);
              transferBuffer(replicationBuffer);
              replicationBuffer.position(begingPos + (endOffset - beginOffset));
              replicationOffset = endOffset;
          }
      }
  
      private void transferBuffer(ByteBuffer buffer) {
          if (buffer.remaining() <= batchSize) {
              //the current batch can be sent as it is
              replicationManager.transferBatch(buffer);
              return;
          }
          /**
           * break the batch into smaller batches
           */
          int totalTransferLimit = buffer.limit();
          while (buffer.hasRemaining()) {
              if (buffer.remaining() > batchSize) {
  
                  //mark the beginning of this batch
                  buffer.mark();
                  int currentBatchSize = 0;
                  while (currentBatchSize < batchSize) {
                      int logSize = replicationBuffer.getInt();
                      //add the size of the log record itself + 4 bytes for its size
                      currentBatchSize += logSize + Integer.BYTES;
                      //go to the beginning of the next log
                      buffer.position(buffer.position() + logSize);
                  }
                  //set the limit to the end of this batch
                  buffer.limit(buffer.position());
                  //return to the beginning of the batch position
                  buffer.reset();
              }
              replicationManager.transferBatch(buffer);
              //return the original limit to check the new remaining size
              buffer.limit(totalTransferLimit);
          }
      }
  
      public boolean isStop() {
          return stop;
      }
  
      public void isStop(boolean stop) {
          this.stop = stop;
      }
  
      public int getLogBufferSize() {
          return logBufferSize;
      }
  
      public LogReplicationManager getReplicationManager() {
          return replicationManager;
      }
  }
  