001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.nio;
019
020import com.google.errorprone.annotations.RestrictedApi;
021import java.io.IOException;
022import java.nio.ByteBuffer;
023import java.nio.channels.FileChannel;
024import java.nio.channels.ReadableByteChannel;
025import java.util.List;
026import org.apache.hadoop.hbase.io.ByteBuffAllocator.Recycler;
027import org.apache.hadoop.hbase.util.ByteBufferUtils;
028import org.apache.hadoop.hbase.util.Bytes;
029import org.apache.hadoop.hbase.util.ObjectIntPair;
030import org.apache.yetus.audience.InterfaceAudience;
031
032import org.apache.hbase.thirdparty.io.netty.util.internal.ObjectUtil;
033
034/**
035 * An abstract class that abstracts out as to how the byte buffers are used, either single or
036 * multiple. We have this interface because the java's ByteBuffers cannot be sub-classed. This class
037 * provides APIs similar to the ones provided in java's nio ByteBuffers and allows you to do
038 * positional reads/writes and relative reads and writes on the underlying BB. In addition to it, we
039 * have some additional APIs which helps us in the read path. <br/>
040 * The ByteBuff implement {@link HBaseReferenceCounted} interface which mean need to maintains a
041 * {@link RefCnt} inside, if ensure that the ByteBuff won't be used any more, we must do a
042 * {@link ByteBuff#release()} to recycle its NIO ByteBuffers. when considering the
043 * {@link ByteBuff#duplicate()} or {@link ByteBuff#slice()}, releasing either the duplicated one or
044 * the original one will free its memory, because they share the same NIO ByteBuffers. when you want
045 * to retain the NIO ByteBuffers even if the origin one called {@link ByteBuff#release()}, you can
046 * do like this:
047 *
048 * <pre>
049 *   ByteBuff original = ...;
050 *   ByteBuff dup = original.duplicate();
051 *   dup.retain();
052 *   original.release();
053 *   // The NIO buffers can still be accessed unless you release the duplicated one
054 *   dup.get(...);
055 *   dup.release();
056 *   // Both the original and dup can not access the NIO buffers any more.
057 * </pre>
058 */
059@InterfaceAudience.Private
060public abstract class ByteBuff implements HBaseReferenceCounted {
061  private static final String REFERENCE_COUNT_NAME = "ReferenceCount";
062  private static final int NIO_BUFFER_LIMIT = 64 * 1024; // should not be more than 64KB.
063
064  protected RefCnt refCnt;
065
066  /*************************** Methods for reference count **********************************/
067
068  protected void checkRefCount() {
069    ObjectUtil.checkPositive(refCnt(), REFERENCE_COUNT_NAME);
070  }
071
072  @Override
073  public int refCnt() {
074    return refCnt.refCnt();
075  }
076
077  @Override
078  public boolean release() {
079    return refCnt.release();
080  }
081
082  /******************************* Methods for ByteBuff **************************************/
083
084  /** Returns this ByteBuff's current position */
085  public abstract int position();
086
087  /**
088   * Sets this ByteBuff's position to the given value.
089   * @return this object
090   */
091  public abstract ByteBuff position(int position);
092
093  /**
094   * Jumps the current position of this ByteBuff by specified length.
095   * @param len the length to be skipped
096   */
097  public abstract ByteBuff skip(int len);
098
099  /**
100   * Jumps back the current position of this ByteBuff by specified length.
101   * @param len the length to move back
102   */
103  public abstract ByteBuff moveBack(int len);
104
105  /** Returns the total capacity of this ByteBuff. */
106  public abstract int capacity();
107
108  /** Returns the limit of this ByteBuff */
109  public abstract int limit();
110
111  /** Marks the limit of this ByteBuff */
112  public abstract ByteBuff limit(int limit);
113
114  /** Rewinds this ByteBuff and the position is set to 0 */
115  public abstract ByteBuff rewind();
116
117  /** Marks the current position of the ByteBuff */
118  public abstract ByteBuff mark();
119
120  /**
121   * Returns bytes from current position till length specified, as a single ByteBuffer. When all
122   * these bytes happen to be in a single ByteBuffer, which this object wraps, that ByteBuffer item
123   * as such will be returned. So users are warned not to change the position or limit of this
124   * returned ByteBuffer. The position of the returned byte buffer is at the begin of the required
125   * bytes. When the required bytes happen to span across multiple ByteBuffers, this API will copy
126   * the bytes to a newly created ByteBuffer of required size and return that.
127   * @param length number of bytes required.
128   * @return bytes from current position till length specified, as a single ByteButter.
129   */
130  public abstract ByteBuffer asSubByteBuffer(int length);
131
132  /**
133   * Returns bytes from given offset till length specified, as a single ByteBuffer. When all these
134   * bytes happen to be in a single ByteBuffer, which this object wraps, that ByteBuffer item as
135   * such will be returned (with offset in this ByteBuffer where the bytes starts). So users are
136   * warned not to change the position or limit of this returned ByteBuffer. When the required bytes
137   * happen to span across multiple ByteBuffers, this API will copy the bytes to a newly created
138   * ByteBuffer of required size and return that.
139   * @param offset the offset in this ByteBuff from where the subBuffer should be created
140   * @param length the length of the subBuffer
141   * @param pair   a pair that will have the bytes from the current position till length specified,
142   *               as a single ByteBuffer and offset in that Buffer where the bytes starts. Since
143   *               this API gets called in a loop we are passing a pair to it which could be created
144   *               outside the loop and the method would set the values on the pair that is passed
145   *               in by the caller. Thus it avoids more object creations that would happen if the
146   *               pair that is returned is created by this method every time.
147   */
148  public abstract void asSubByteBuffer(int offset, int length, ObjectIntPair<ByteBuffer> pair);
149
150  /** Returns the number of elements between the current position and the limit. */
151  public abstract int remaining();
152
153  /** Returns true if there are elements between the current position and the limit. */
154  public abstract boolean hasRemaining();
155
156  /**
157   * Similar to {@link ByteBuffer}.reset(), ensures that this ByteBuff is reset back to last marked
158   * position.
159   * @return This ByteBuff
160   */
161  public abstract ByteBuff reset();
162
163  /**
164   * Returns an ByteBuff which is a sliced version of this ByteBuff. The position, limit and mark of
165   * the new ByteBuff will be independent than that of the original ByteBuff. The content of the new
166   * ByteBuff will start at this ByteBuff's current position
167   * @return a sliced ByteBuff
168   */
169  public abstract ByteBuff slice();
170
171  /**
172   * Returns an ByteBuff which is a duplicate version of this ByteBuff. The position, limit and mark
173   * of the new ByteBuff will be independent than that of the original ByteBuff. The content of the
174   * new ByteBuff will start at this ByteBuff's current position The position, limit and mark of the
175   * new ByteBuff would be identical to this ByteBuff in terms of values.
176   * @return a sliced ByteBuff
177   */
178  public abstract ByteBuff duplicate();
179
180  /**
181   * A relative method that returns byte at the current position. Increments the current position by
182   * the size of a byte.
183   * @return the byte at the current position
184   */
185  public abstract byte get();
186
187  /**
188   * Fetches the byte at the given index. Does not change position of the underlying ByteBuffers
189   * @return the byte at the given index
190   */
191  public abstract byte get(int index);
192
193  /**
194   * Fetches the byte at the given offset from current position. Does not change position of the
195   * underlying ByteBuffers.
196   * @return the byte value at the given index.
197   */
198  public abstract byte getByteAfterPosition(int offset);
199
200  /**
201   * Writes a byte to this ByteBuff at the current position and increments the position
202   * @return this object
203   */
204  public abstract ByteBuff put(byte b);
205
206  /**
207   * Writes a byte to this ByteBuff at the given index
208   * @return this object
209   */
210  public abstract ByteBuff put(int index, byte b);
211
212  /**
213   * Copies the specified number of bytes from this ByteBuff's current position to the byte[]'s
214   * offset. Also advances the position of the ByteBuff by the given length.
215   * @param dst    the byte[] to which the ByteBuff's content is to be copied
216   * @param offset within the current array
217   * @param length upto which the bytes to be copied
218   */
219  public abstract void get(byte[] dst, int offset, int length);
220
221  /**
222   * Copies the specified number of bytes from this ByteBuff's given position to the byte[]'s
223   * offset. The position of the ByteBuff remains in the current position only
224   * @param sourceOffset the offset in this ByteBuff from where the copy should happen
225   * @param dst          the byte[] to which the ByteBuff's content is to be copied
226   * @param offset       within the current array
227   * @param length       upto which the bytes to be copied
228   */
229  public abstract void get(int sourceOffset, byte[] dst, int offset, int length);
230
231  /**
232   * Copies the content from this ByteBuff's current position to the byte array and fills it. Also
233   * advances the position of the ByteBuff by the length of the byte[].
234   * @param dst the byte[] to which the ByteBuff's content is to be copied
235   */
236  public abstract void get(byte[] dst);
237
238  /**
239   * Copies from the given byte[] to this ByteBuff
240   * @param src    source byte array
241   * @param offset the position in the byte array from which the copy should be done
242   * @param length the length upto which the copy should happen
243   * @return this ByteBuff
244   */
245  public abstract ByteBuff put(byte[] src, int offset, int length);
246
247  /**
248   * Copies from the given byte[] to this ByteBuff
249   * @return this ByteBuff
250   * @param src source byte array
251   * @return this ByteBuff
252   */
253  public abstract ByteBuff put(byte[] src);
254
255  /** Returns true or false if the underlying BB support hasArray */
256  public abstract boolean hasArray();
257
258  /** Returns the byte[] if the underlying BB has single BB and hasArray true */
259  public abstract byte[] array();
260
261  /** Returns the arrayOffset of the byte[] incase of a single BB backed ByteBuff */
262  public abstract int arrayOffset();
263
264  /**
265   * Returns the short value at the current position. Also advances the position by the size of
266   * short.
267   */
268  public abstract short getShort();
269
270  /**
271   * Fetches the short value at the given index. Does not change position of the underlying
272   * ByteBuffers. The caller is sure that the index will be after the current position of this
273   * ByteBuff. So even if the current short does not fit in the current item we can safely move to
274   * the next item and fetch the remaining bytes forming the short
275   * @return the short value at the given index
276   */
277  public abstract short getShort(int index);
278
279  /**
280   * Fetches the short value at the given offset from current position. Does not change position of
281   * the underlying ByteBuffers.
282   * @return the short value at the given index.
283   */
284  public abstract short getShortAfterPosition(int offset);
285
286  /**
287   * Returns the int value at the current position. Also advances the position by the size of int.
288   */
289  public abstract int getInt();
290
291  /**
292   * Writes an int to this ByteBuff at its current position. Also advances the position by size of
293   * int.
294   */
295  public abstract ByteBuff putInt(int value);
296
297  /**
298   * Fetches the int at the given index. Does not change position of the underlying ByteBuffers.
299   * Even if the current int does not fit in the current item we can safely move to the next item
300   * and fetch the remaining bytes forming the int.
301   */
302  public abstract int getInt(int index);
303
304  /**
305   * Fetches the int value at the given offset from current position. Does not change position of
306   * the underlying ByteBuffers.
307   */
308  public abstract int getIntAfterPosition(int offset);
309
310  /**
311   * Returns the long value at the current position. Also advances the position by the size of long.
312   */
313  public abstract long getLong();
314
315  /**
316   * Writes a long to this ByteBuff at its current position. Also advances the position by size of
317   * long.
318   */
319  public abstract ByteBuff putLong(long value);
320
321  /**
322   * Fetches the long at the given index. Does not change position of the underlying ByteBuffers.
323   * The caller is sure that the index will be after the current position of this ByteBuff. So even
324   * if the current long does not fit in the current item we can safely move to the next item and
325   * fetch the remaining bytes forming the long
326   * @return the long value at the given index
327   */
328  public abstract long getLong(int index);
329
330  /**
331   * Fetches the long value at the given offset from current position. Does not change position of
332   * the underlying ByteBuffers.
333   * @return the long value at the given index.
334   */
335  public abstract long getLongAfterPosition(int offset);
336
337  /**
338   * Copy the content from this ByteBuff to a byte[].
339   */
340  public byte[] toBytes() {
341    return toBytes(0, this.limit());
342  }
343
344  /**
345   * Copy the content from this ByteBuff to a byte[] based on the given offset and length.
346   */
347  public abstract byte[] toBytes(int offset, int length);
348
349  /**
350   * Copies the content from this ByteBuff to a ByteBuffer Note : This will advance the position
351   * marker of {@code out} but not change the position maker for this ByteBuff
352   * @param out          the ByteBuffer to which the copy has to happen
353   * @param sourceOffset the offset in the ByteBuff from which the elements has to be copied
354   * @param length       the length in this ByteBuff upto which the elements has to be copied
355   */
356  public abstract void get(ByteBuffer out, int sourceOffset, int length);
357
358  /**
359   * Copies the contents from the src ByteBuff to this ByteBuff. This will be absolute positional
360   * copying and won't affect the position of any of the buffers.
361   * @param offset    the position in this ByteBuff to which the copy should happen
362   * @param src       the src ByteBuff
363   * @param srcOffset the offset in the src ByteBuff from where the elements should be read
364   * @param length    the length up to which the copy should happen
365   */
366  public abstract ByteBuff put(int offset, ByteBuff src, int srcOffset, int length);
367
368  /** Reads bytes from the given channel into this ByteBuf. */
369  public abstract int read(ReadableByteChannel channel) throws IOException;
370
371  /** Reads bytes from FileChannel into this ByteBuff */
372  public abstract int read(FileChannel channel, long offset) throws IOException;
373
374  /** Write this ByteBuff's data into target file */
375  public abstract int write(FileChannel channel, long offset) throws IOException;
376
377  /** Functional interface for Channel read */
378  @FunctionalInterface
379  interface ChannelReader {
380    int read(ReadableByteChannel channel, ByteBuffer buf, long offset) throws IOException;
381  }
382
383  static final ChannelReader CHANNEL_READER = (channel, buf, offset) -> {
384    return channel.read(buf);
385  };
386
387  static final ChannelReader FILE_READER = (channel, buf, offset) -> {
388    return ((FileChannel) channel).read(buf, offset);
389  };
390
391  // static helper methods
392  public static int read(ReadableByteChannel channel, ByteBuffer buf, long offset,
393    ChannelReader reader) throws IOException {
394    if (buf.remaining() <= NIO_BUFFER_LIMIT) {
395      return reader.read(channel, buf, offset);
396    }
397    int originalLimit = buf.limit();
398    int initialRemaining = buf.remaining();
399    int ret = 0;
400
401    while (buf.remaining() > 0) {
402      try {
403        int ioSize = Math.min(buf.remaining(), NIO_BUFFER_LIMIT);
404        buf.limit(buf.position() + ioSize);
405        offset += ret;
406        ret = reader.read(channel, buf, offset);
407        if (ret < ioSize) {
408          break;
409        }
410      } finally {
411        buf.limit(originalLimit);
412      }
413    }
414    int nBytes = initialRemaining - buf.remaining();
415    return (nBytes > 0) ? nBytes : ret;
416  }
417
418  /** Read integer from ByteBuff coded in 7 bits and increment position. */
419  public static int readCompressedInt(ByteBuff buf) {
420    byte b = buf.get();
421    if ((b & ByteBufferUtils.NEXT_BIT_MASK) != 0) {
422      return (b & ByteBufferUtils.VALUE_MASK)
423        + (readCompressedInt(buf) << ByteBufferUtils.NEXT_BIT_SHIFT);
424    }
425    return b & ByteBufferUtils.VALUE_MASK;
426  }
427
428  /**
429   * Compares two ByteBuffs
430   * @param buf1 the first ByteBuff
431   * @param o1   the offset in the first ByteBuff from where the compare has to happen
432   * @param len1 the length in the first ByteBuff upto which the compare has to happen
433   * @param buf2 the second ByteBuff
434   * @param o2   the offset in the second ByteBuff from where the compare has to happen
435   * @param len2 the length in the second ByteBuff upto which the compare has to happen
436   * @return Positive if buf1 is bigger than buf2, 0 if they are equal, and negative if buf1 is
437   *         smaller than buf2.
438   */
439  public static int compareTo(ByteBuff buf1, int o1, int len1, ByteBuff buf2, int o2, int len2) {
440    if (buf1.hasArray() && buf2.hasArray()) {
441      return Bytes.compareTo(buf1.array(), buf1.arrayOffset() + o1, len1, buf2.array(),
442        buf2.arrayOffset() + o2, len2);
443    }
444    int end1 = o1 + len1;
445    int end2 = o2 + len2;
446    for (int i = o1, j = o2; i < end1 && j < end2; i++, j++) {
447      int a = buf1.get(i) & 0xFF;
448      int b = buf2.get(j) & 0xFF;
449      if (a != b) {
450        return a - b;
451      }
452    }
453    return len1 - len2;
454  }
455
456  /**
457   * Read long which was written to fitInBytes bytes and increment position.
458   * @param fitInBytes In how many bytes given long is stored.
459   * @return The value of parsed long.
460   */
461  public static long readLong(ByteBuff in, final int fitInBytes) {
462    long tmpLength = 0;
463    for (int i = 0; i < fitInBytes; ++i) {
464      tmpLength |= (in.get() & 0xffl) << (8l * i);
465    }
466    return tmpLength;
467  }
468
469  public abstract ByteBuffer[] nioByteBuffers();
470
471  @Override
472  public String toString() {
473    return this.getClass().getSimpleName() + "[pos=" + position() + ", lim=" + limit() + ", cap= "
474      + capacity() + "]";
475  }
476
477  /********************************* ByteBuff wrapper methods ***********************************/
478
479  /**
480   * In theory, the upstream should never construct an ByteBuff by passing an given refCnt, so
481   * please don't use this public method in other place. Make the method public here because the
482   * BucketEntry#wrapAsCacheable in hbase-server module will use its own refCnt and ByteBuffers from
483   * IOEngine to composite an HFileBlock's ByteBuff, we didn't find a better way so keep the public
484   * way here.
485   */
486  public static ByteBuff wrap(ByteBuffer[] buffers, RefCnt refCnt) {
487    if (buffers == null || buffers.length == 0) {
488      throw new IllegalArgumentException("buffers shouldn't be null or empty");
489    }
490    return buffers.length == 1
491      ? new SingleByteBuff(refCnt, buffers[0])
492      : new MultiByteBuff(refCnt, buffers);
493  }
494
495  public static ByteBuff wrap(ByteBuffer[] buffers, Recycler recycler) {
496    return wrap(buffers, RefCnt.create(recycler));
497  }
498
499  public static ByteBuff wrap(ByteBuffer[] buffers) {
500    return wrap(buffers, RefCnt.create());
501  }
502
503  public static ByteBuff wrap(List<ByteBuffer> buffers, Recycler recycler) {
504    return wrap(buffers, RefCnt.create(recycler));
505  }
506
507  public static ByteBuff wrap(List<ByteBuffer> buffers) {
508    return wrap(buffers, RefCnt.create());
509  }
510
511  public static ByteBuff wrap(ByteBuffer buffer) {
512    return wrap(buffer, RefCnt.create());
513  }
514
515  /**
516   * Calling this method in strategic locations where ByteBuffs are referenced may help diagnose
517   * potential buffer leaks. We pass the buffer itself as a default hint, but one can use
518   * {@link #touch(Object)} to pass their own hint as well.
519   */
520  @Override
521  public ByteBuff touch() {
522    return touch(this);
523  }
524
525  @Override
526  public ByteBuff touch(Object hint) {
527    refCnt.touch(hint);
528    return this;
529  }
530
531  @RestrictedApi(explanation = "Should only be called in tests", link = "",
532      allowedOnPath = ".*/src/test/.*")
533  public RefCnt getRefCnt() {
534    return refCnt;
535  }
536
537  // Make this private because we don't want to expose the refCnt related wrap method to upstream.
538  private static ByteBuff wrap(List<ByteBuffer> buffers, RefCnt refCnt) {
539    if (buffers == null || buffers.size() == 0) {
540      throw new IllegalArgumentException("buffers shouldn't be null or empty");
541    }
542    return buffers.size() == 1
543      ? new SingleByteBuff(refCnt, buffers.get(0))
544      : new MultiByteBuff(refCnt, buffers.toArray(new ByteBuffer[0]));
545  }
546
547  // Make this private because we don't want to expose the refCnt related wrap method to upstream.
548  private static ByteBuff wrap(ByteBuffer buffer, RefCnt refCnt) {
549    return new SingleByteBuff(refCnt, buffer);
550  }
551}