ceph/src/rocksdb/java/src/main/java/org/rocksdb/WriteOptions.java

   1 // Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 // This source code is licensed under the BSD-style license found in the
   3 // LICENSE file in the root directory of this source tree. An additional grant
   4 // of patent rights can be found in the PATENTS file in the same directory.
   5
   6 package org.rocksdb;
   7
   8 /**
   9  * Options that control write operations.
  10  *
  11  * Note that developers should call WriteOptions.dispose() to release the
  12  * c++ side memory before a WriteOptions instance runs out of scope.
  13  */
  14 public class WriteOptions extends RocksObject {
  15   /**
  16    * Construct WriteOptions instance.
  17    */
  18   public WriteOptions() {
  19     super(newWriteOptions());
  20
  21   }
  22
  23   /**
  24    * If true, the write will be flushed from the operating system
  25    * buffer cache (by calling WritableFile::Sync()) before the write
  26    * is considered complete.  If this flag is true, writes will be
  27    * slower.
  28    *
  29    * If this flag is false, and the machine crashes, some recent
  30    * writes may be lost.  Note that if it is just the process that
  31    * crashes (i.e., the machine does not reboot), no writes will be
  32    * lost even if sync==false.
  33    *
  34    * In other words, a DB write with sync==false has similar
  35    * crash semantics as the "write()" system call.  A DB write
  36    * with sync==true has similar crash semantics to a "write()"
  37    * system call followed by "fdatasync()".
  38    *
  39    * Default: false
  40    *
  41    * @param flag a boolean flag to indicate whether a write
  42    *     should be synchronized.
  43    * @return the instance of the current WriteOptions.
  44    */
  45   public WriteOptions setSync(final boolean flag) {
  46     setSync(nativeHandle_, flag);
  47     return this;
  48   }
  49
  50   /**
  51    * If true, the write will be flushed from the operating system
  52    * buffer cache (by calling WritableFile::Sync()) before the write
  53    * is considered complete.  If this flag is true, writes will be
  54    * slower.
  55    *
  56    * If this flag is false, and the machine crashes, some recent
  57    * writes may be lost.  Note that if it is just the process that
  58    * crashes (i.e., the machine does not reboot), no writes will be
  59    * lost even if sync==false.
  60    *
  61    * In other words, a DB write with sync==false has similar
  62    * crash semantics as the "write()" system call.  A DB write
  63    * with sync==true has similar crash semantics to a "write()"
  64    * system call followed by "fdatasync()".
  65    *
  66    * @return boolean value indicating if sync is active.
  67    */
  68   public boolean sync() {
  69     return sync(nativeHandle_);
  70   }
  71
  72   /**
  73    * If true, writes will not first go to the write ahead log,
  74    * and the write may got lost after a crash.
  75    *
  76    * @param flag a boolean flag to specify whether to disable
  77    *     write-ahead-log on writes.
  78    * @return the instance of the current WriteOptions.
  79    */
  80   public WriteOptions setDisableWAL(final boolean flag) {
  81     setDisableWAL(nativeHandle_, flag);
  82     return this;
  83   }
  84
  85   /**
  86    * If true, writes will not first go to the write ahead log,
  87    * and the write may got lost after a crash.
  88    *
  89    * @return boolean value indicating if WAL is disabled.
  90    */
  91   public boolean disableWAL() {
  92     return disableWAL(nativeHandle_);
  93   }
  94
  95   /**
  96    * If true and if user is trying to write to column families that don't exist
  97    * (they were dropped), ignore the write (don't return an error). If there
  98    * are multiple writes in a WriteBatch, other writes will succeed.
  99    *
 100    * Default: false
 101    *
 102    * @param ignoreMissingColumnFamilies true to ignore writes to column families
 103    *     which don't exist
 104    * @return the instance of the current WriteOptions.
 105    */
 106   public WriteOptions setIgnoreMissingColumnFamilies(
 107       final boolean ignoreMissingColumnFamilies) {
 108     setIgnoreMissingColumnFamilies(nativeHandle_, ignoreMissingColumnFamilies);
 109     return this;
 110   }
 111
 112   /**
 113    * If true and if user is trying to write to column families that don't exist
 114    * (they were dropped), ignore the write (don't return an error). If there
 115    * are multiple writes in a WriteBatch, other writes will succeed.
 116    *
 117    * Default: false
 118    *
 119    * @return true if writes to column families which don't exist are ignored
 120    */
 121   public boolean ignoreMissingColumnFamilies() {
 122     return ignoreMissingColumnFamilies(nativeHandle_);
 123   }
 124
 125   /**
 126    * If true and we need to wait or sleep for the write request, fails
 127    * immediately with {@link Status.Code#Incomplete}.
 128    *
 129    * @param noSlowdown true to fail write requests if we need to wait or sleep
 130    * @return the instance of the current WriteOptions.
 131    */
 132   public WriteOptions setNoSlowdown(final boolean noSlowdown) {
 133     setNoSlowdown(nativeHandle_, noSlowdown);
 134     return this;
 135   }
 136
 137   /**
 138    * If true and we need to wait or sleep for the write request, fails
 139    * immediately with {@link Status.Code#Incomplete}.
 140    *
 141    * @return true when write requests are failed if we need to wait or sleep
 142    */
 143   public boolean noSlowdown() {
 144     return noSlowdown(nativeHandle_);
 145   }
 146
 147   private native static long newWriteOptions();
 148   private native void setSync(long handle, boolean flag);
 149   private native boolean sync(long handle);
 150   private native void setDisableWAL(long handle, boolean flag);
 151   private native boolean disableWAL(long handle);
 152   private native void setIgnoreMissingColumnFamilies(final long handle,
 153       final boolean ignoreMissingColumnFamilies);
 154   private native boolean ignoreMissingColumnFamilies(final long handle);
 155   private native void setNoSlowdown(final long handle,
 156       final boolean noSlowdown);
 157   private native boolean noSlowdown(final long handle);
 158   @Override protected final native void disposeInternal(final long handle);
 159 }