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.bookkeeper.bookie.storage.directentrylogger;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkState;
  import static org.apache.bookkeeper.common.util.ExceptionMessageHelper.exMsg;
  
  import io.netty.buffer.ByteBuf;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  import org.apache.bookkeeper.common.util.nativeio.NativeIO;
  import org.apache.bookkeeper.common.util.nativeio.NativeIOException;
  import org.apache.bookkeeper.slogger.Slogger;
  import org.apache.commons.lang3.SystemUtils;
  
  class DirectWriter implements LogWriter {
      final NativeIO nativeIO;
      final int fd;
      final int id;
      final String filename;
      final BufferPool bufferPool;
      final ExecutorService writeExecutor;
      final Object bufferLock = new Object();
      final List<Future<?>> outstandingWrites = new ArrayList<Future<?>>();
      final Slogger slog;
      Buffer nativeBuffer;
      long offset;
      private static volatile boolean useFallocate = true;
  
      DirectWriter(int id,
                   String filename,
                   long maxFileSize,
                   ExecutorService writeExecutor,
                   BufferPool bufferPool,
                   NativeIO nativeIO, Slogger slog) throws IOException {
          checkArgument(maxFileSize > 0, "Max file size (%d) must be positive");
          this.id = id;
          this.filename = filename;
          this.writeExecutor = writeExecutor;
          this.nativeIO = nativeIO;
          this.slog = slog.ctx(DirectWriter.class);
  
          offset = 0;
  
          try {
              fd = nativeIO.open(filename,
                                 NativeIO.O_CREAT | NativeIO.O_WRONLY | NativeIO.O_DIRECT,
                                 00644);
              checkState(fd >= 0, "Open should have thrown exception, fd is invalid : %d", fd);
          } catch (NativeIOException ne) {
              throw new IOException(exMsg(ne.getMessage()).kv("file", filename)
                                    .kv("errno", ne.getErrno()).toString(), ne);
          }
  
          if (useFallocate) {
              if (!SystemUtils.IS_OS_LINUX) {
                  disableUseFallocate();
                  this.slog.warn(Events.FALLOCATE_NOT_AVAILABLE);
              } else {
                  try {
                      int ret = nativeIO.fallocate(fd, NativeIO.FALLOC_FL_ZERO_RANGE, 0, maxFileSize);
                      checkState(ret == 0, "Exception should have been thrown on non-zero ret: %d", ret);
                  } catch (NativeIOException ex) {
                      // fallocate(2) is not supported on all filesystems.  Since this is an optimization, disable
                      // subsequent usage instead of failing the operation.
                      disableUseFallocate();
                      this.slog.kv("message", ex.getMessage())
                          .kv("file", filename)
                          .kv("errno", ex.getErrno())
                          .warn(Events.FALLOCATE_NOT_AVAILABLE);
                  }
              }
          }
  
          this.bufferPool = bufferPool;
          this.nativeBuffer = bufferPool.acquire();
      }
  
      private static void disableUseFallocate() {
          DirectWriter.useFallocate = false;
      }
  
      @Override
      public int logId() {
          return id;
      }
  
      @Override
      public void writeAt(long offset, ByteBuf buf) throws IOException {
          checkArgument(Buffer.isAligned(offset),
                        "Offset to writeAt must be aligned to %d: %d is not", Buffer.ALIGNMENT, offset);
          checkArgument(Buffer.isAligned(buf.readableBytes()),
                        "Buffer must write multiple of alignment bytes (%d), %d is not",
                        Buffer.ALIGNMENT, buf.readableBytes());
  
          int bytesToWrite = buf.readableBytes();
          if (bytesToWrite <= 0) {
              return;
          }
  
          Buffer tmpBuffer = bufferPool.acquire();
          tmpBuffer.reset();
          tmpBuffer.writeByteBuf(buf);
          Future<?> f = writeExecutor.submit(() -> {
              writeByteBuf(tmpBuffer, bytesToWrite, offset);
              return null;
              });
          addOutstandingWrite(f);
      }
  
      private void writeByteBuf(Buffer buffer, int bytesToWrite, long offsetToWrite) throws IOException{
          try {
              if (bytesToWrite <= 0) {
                  return;
              }
              int ret = nativeIO.pwrite(fd, buffer.pointer(), bytesToWrite, offsetToWrite);
              if (ret != bytesToWrite) {
                  throw new IOException(exMsg("Incomplete write")
                      .kv("filename", filename)
                      .kv("pointer", buffer.pointer())
                      .kv("offset", offsetToWrite)
                      .kv("writeSize", bytesToWrite)
                      .kv("bytesWritten", ret)
                      .toString());
              }
          } catch (NativeIOException ne) {
              throw new IOException(exMsg("Write error")
                  .kv("filename", filename)
                  .kv("offset", offsetToWrite)
                  .kv("writeSize", bytesToWrite)
                  .kv("pointer", buffer.pointer())
                  .kv("errno", ne.getErrno())
                  .toString());
          } finally {
              bufferPool.release(buffer);
          }
      }
  
      @Override
      public int writeDelimited(ByteBuf buf) throws IOException {
          synchronized (bufferLock) {
              if (!nativeBuffer.hasSpace(serializedSize(buf))) {
                  flushBuffer();
              }
  
              int readable = buf.readableBytes();
              long bufferPosition = position() + Integer.BYTES;
              if (bufferPosition > Integer.MAX_VALUE) {
                  throw new IOException(exMsg("Cannot write past max int")
                                        .kv("filename", filename)
                                        .kv("writeSize", readable)
                                        .kv("position", bufferPosition)
                                        .toString());
              }
              nativeBuffer.writeInt(readable);
              nativeBuffer.writeByteBuf(buf);
              return (int) bufferPosition;
          }
      }
  
      @Override
      public void position(long offset) throws IOException {
          synchronized (bufferLock) {
              if (nativeBuffer != null && nativeBuffer.position() > 0) {
                  flushBuffer();
              }
              if ((offset % Buffer.ALIGNMENT) != 0) {
                  throw new IOException(exMsg("offset must be multiple of alignment")
                                        .kv("offset", offset)
                                        .kv("alignment", Buffer.ALIGNMENT)
                                        .toString());
              }
              this.offset = offset;
          }
      }
  
      @Override
      public long position() {
          synchronized (bufferLock) {
              return this.offset + (nativeBuffer != null ? nativeBuffer.position() : 0);
          }
      }
  
      @Override
      public void flush() throws IOException {
          flushBuffer();
  
          waitForOutstandingWrites();
  
          try {
              int ret = nativeIO.fsync(fd);
              checkState(ret == 0, "Fsync should throw exception on non-zero return (%d)", ret);
          } catch (NativeIOException ne) {
              throw new IOException(exMsg(ne.getMessage())
                                    .kv("file", filename)
                                    .kv("errno", ne.getErrno()).toString());
          }
      }
  
      @Override
      public void close() throws IOException {
          synchronized (bufferLock) {
              if (nativeBuffer != null && nativeBuffer.position() > 0) {
                  flush();
              }
          }
  
          try {
              int ret = nativeIO.close(fd);
              checkState(ret == 0, "Close should throw exception on non-zero return (%d)", ret);
          } catch (NativeIOException ne) {
              throw new IOException(exMsg(ne.getMessage())
                                    .kv("file", filename)
                                    .kv("errno", ne.getErrno()).toString());
          } finally {
              synchronized (bufferLock) {
                  bufferPool.release(nativeBuffer);
                  nativeBuffer = null;
              }
          }
      }
  
      private void addOutstandingWrite(Future<?> toAdd) throws IOException {
          synchronized (outstandingWrites) {
              outstandingWrites.add(toAdd);
  
              Iterator<Future<?>> iter = outstandingWrites.iterator();
              while (iter.hasNext()) { // clear out completed futures
                  Future<?> f = iter.next();
                  if (f.isDone()) {
                      waitForFuture(f);
                      iter.remove();
                  } else {
                      break;
                  }
              }
          }
      }
  
      private void waitForOutstandingWrites() throws IOException {
          synchronized (outstandingWrites) {
              Iterator<Future<?>> iter = outstandingWrites.iterator();
              while (iter.hasNext()) { // clear out completed futures
                  Future<?> f = iter.next();
                  waitForFuture(f);
                  iter.remove();
              }
          }
      }
  
      private void waitForFuture(Future<?> f) throws IOException {
          try {
              f.get();
          } catch (InterruptedException ie) {
              Thread.currentThread().interrupt();
              throw new IOException(ie);
          } catch (Throwable t) {
              if (t.getCause() instanceof IOException) {
                  throw (IOException) t.getCause();
              } else {
                  throw new IOException(t);
              }
          }
      }
  
      private void flushBuffer() throws IOException {
          synchronized (bufferLock) {
              if (this.nativeBuffer != null) {
                  int bytesToWrite = this.nativeBuffer.padToAlignment();
                  if (bytesToWrite == 0) {
                      return;
                  }
  
                  Buffer bufferToFlush = this.nativeBuffer;
                  this.nativeBuffer = null;
  
                  long offsetToWrite = offset;
                  offset += bytesToWrite;
  
                  Future<?> f = writeExecutor.submit(() -> {
                      writeByteBuf(bufferToFlush, bytesToWrite, offsetToWrite);
                      return null;
                  });
                  addOutstandingWrite(f);
  
                  // must acquire after triggering the write
                  // otherwise it could try to acquire a buffer without kicking off
                  // a subroutine that will free another
                  this.nativeBuffer = bufferPool.acquire();
              }
          }
      }
  
      @Override
      public int serializedSize(ByteBuf buf) {
          return buf.readableBytes() + Integer.BYTES;
      }
  }
  