X-Git-Url: https://git.mdrn.pl/pylucene.git/blobdiff_plain/a2e61f0c04805cfcb8706176758d1283c7e3a55c..aaeed5504b982cf3545252ab528713250aa33eed:/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/BufferedIndexInput.java?ds=sidebyside

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/BufferedIndexInput.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/BufferedIndexInput.java
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+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/BufferedIndexInput.java
@@ -0,0 +1,310 @@
+package org.apache.lucene.store;
+
+/**
+ * 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.
+ */
+
+import java.io.IOException;
+
+/** Base implementation class for buffered {@link IndexInput}. */
+public abstract class BufferedIndexInput extends IndexInput {
+
+  /** Default buffer size */
+  public static final int BUFFER_SIZE = 1024;
+
+  private int bufferSize = BUFFER_SIZE;
+  
+  protected byte[] buffer;
+  
+  private long bufferStart = 0;			  // position in file of buffer
+  private int bufferLength = 0;			  // end of valid bytes
+  private int bufferPosition = 0;		  // next byte to read
+
+  @Override
+  public byte readByte() throws IOException {
+    if (bufferPosition >= bufferLength)
+      refill();
+    return buffer[bufferPosition++];
+  }
+
+  /** @deprecated please pass resourceDesc */
+  @Deprecated
+  public BufferedIndexInput() {
+    this("anonymous BuffereIndexInput");
+  }
+
+  public BufferedIndexInput(String resourceDesc) {
+    this(resourceDesc, BUFFER_SIZE);
+  }
+
+  /** Inits BufferedIndexInput with a specific bufferSize
+   *  @deprecated please pass resourceDesc */
+  @Deprecated
+  public BufferedIndexInput(int bufferSize) {
+    this("anonymous BuffereIndexInput", bufferSize);
+  }
+
+  /** Inits BufferedIndexInput with a specific bufferSize */
+  public BufferedIndexInput(String resourceDesc, int bufferSize) {
+    super(resourceDesc);
+    checkBufferSize(bufferSize);
+    this.bufferSize = bufferSize;
+  }
+
+  /** Change the buffer size used by this IndexInput */
+  public void setBufferSize(int newSize) {
+    assert buffer == null || bufferSize == buffer.length: "buffer=" + buffer + " bufferSize=" + bufferSize + " buffer.length=" + (buffer != null ? buffer.length : 0);
+    if (newSize != bufferSize) {
+      checkBufferSize(newSize);
+      bufferSize = newSize;
+      if (buffer != null) {
+        // Resize the existing buffer and carefully save as
+        // many bytes as possible starting from the current
+        // bufferPosition
+        byte[] newBuffer = new byte[newSize];
+        final int leftInBuffer = bufferLength-bufferPosition;
+        final int numToCopy;
+        if (leftInBuffer > newSize)
+          numToCopy = newSize;
+        else
+          numToCopy = leftInBuffer;
+        System.arraycopy(buffer, bufferPosition, newBuffer, 0, numToCopy);
+        bufferStart += bufferPosition;
+        bufferPosition = 0;
+        bufferLength = numToCopy;
+        newBuffer(newBuffer);
+      }
+    }
+  }
+
+  protected void newBuffer(byte[] newBuffer) {
+    // Subclasses can do something here
+    buffer = newBuffer;
+  }
+
+  /** Returns buffer size.  @see #setBufferSize */
+  public int getBufferSize() {
+    return bufferSize;
+  }
+
+  private void checkBufferSize(int bufferSize) {
+    if (bufferSize <= 0)
+      throw new IllegalArgumentException("bufferSize must be greater than 0 (got " + bufferSize + ")");
+  }
+
+  @Override
+  public void readBytes(byte[] b, int offset, int len) throws IOException {
+    readBytes(b, offset, len, true);
+  }
+
+  @Override
+  public void readBytes(byte[] b, int offset, int len, boolean useBuffer) throws IOException {
+
+    if(len <= (bufferLength-bufferPosition)){
+      // the buffer contains enough data to satisfy this request
+      if(len>0) // to allow b to be null if len is 0...
+        System.arraycopy(buffer, bufferPosition, b, offset, len);
+      bufferPosition+=len;
+    } else {
+      // the buffer does not have enough data. First serve all we've got.
+      int available = bufferLength - bufferPosition;
+      if(available > 0){
+        System.arraycopy(buffer, bufferPosition, b, offset, available);
+        offset += available;
+        len -= available;
+        bufferPosition += available;
+      }
+      // and now, read the remaining 'len' bytes:
+      if (useBuffer && len<bufferSize){
+        // If the amount left to read is small enough, and
+        // we are allowed to use our buffer, do it in the usual
+        // buffered way: fill the buffer and copy from it:
+        refill();
+        if(bufferLength<len){
+          // Throw an exception when refill() could not read len bytes:
+          System.arraycopy(buffer, 0, b, offset, bufferLength);
+          throw new IOException("read past EOF");
+        } else {
+          System.arraycopy(buffer, 0, b, offset, len);
+          bufferPosition=len;
+        }
+      } else {
+        // The amount left to read is larger than the buffer
+        // or we've been asked to not use our buffer -
+        // there's no performance reason not to read it all
+        // at once. Note that unlike the previous code of
+        // this function, there is no need to do a seek
+        // here, because there's no need to reread what we
+        // had in the buffer.
+        long after = bufferStart+bufferPosition+len;
+        if(after > length())
+          throw new IOException("read past EOF");
+        readInternal(b, offset, len);
+        bufferStart = after;
+        bufferPosition = 0;
+        bufferLength = 0;                    // trigger refill() on read
+      }
+    }
+  }
+  
+  @Override
+  public int readInt() throws IOException {
+    if (4 <= (bufferLength-bufferPosition)) {
+      return ((buffer[bufferPosition++] & 0xFF) << 24) | ((buffer[bufferPosition++] & 0xFF) << 16)
+        | ((buffer[bufferPosition++] & 0xFF) <<  8) |  (buffer[bufferPosition++] & 0xFF);
+    } else {
+      return super.readInt();
+    }
+  }
+  
+  @Override
+  public long readLong() throws IOException {
+    if (8 <= (bufferLength-bufferPosition)) {
+      final int i1 = ((buffer[bufferPosition++] & 0xff) << 24) | ((buffer[bufferPosition++] & 0xff) << 16) |
+        ((buffer[bufferPosition++] & 0xff) << 8) | (buffer[bufferPosition++] & 0xff);
+      final int i2 = ((buffer[bufferPosition++] & 0xff) << 24) | ((buffer[bufferPosition++] & 0xff) << 16) |
+        ((buffer[bufferPosition++] & 0xff) << 8) | (buffer[bufferPosition++] & 0xff);
+      return (((long)i1) << 32) | (i2 & 0xFFFFFFFFL);
+    } else {
+      return super.readLong();
+    }
+  }
+
+  @Override
+  public int readVInt() throws IOException {
+    if (5 <= (bufferLength-bufferPosition)) {
+      byte b = buffer[bufferPosition++];
+      int i = b & 0x7F;
+      for (int shift = 7; (b & 0x80) != 0; shift += 7) {
+        b = buffer[bufferPosition++];
+        i |= (b & 0x7F) << shift;
+      }
+      return i;
+    } else {
+      return super.readVInt();
+    }
+  }
+  
+  @Override
+  public long readVLong() throws IOException {
+    if (9 <= bufferLength-bufferPosition) {
+      byte b = buffer[bufferPosition++];
+      long i = b & 0x7F;
+      for (int shift = 7; (b & 0x80) != 0; shift += 7) {
+        b = buffer[bufferPosition++];
+        i |= (b & 0x7FL) << shift;
+      }
+      return i;
+    } else {
+      return super.readVLong();
+    }
+  }
+  
+  private void refill() throws IOException {
+    long start = bufferStart + bufferPosition;
+    long end = start + bufferSize;
+    if (end > length())				  // don't read past EOF
+      end = length();
+    int newLength = (int)(end - start);
+    if (newLength <= 0)
+      throw new IOException("read past EOF");
+
+    if (buffer == null) {
+      newBuffer(new byte[bufferSize]);  // allocate buffer lazily
+      seekInternal(bufferStart);
+    }
+    readInternal(buffer, 0, newLength);
+    bufferLength = newLength;
+    bufferStart = start;
+    bufferPosition = 0;
+  }
+
+  /** Expert: implements buffer refill.  Reads bytes from the current position
+   * in the input.
+   * @param b the array to read bytes into
+   * @param offset the offset in the array to start storing bytes
+   * @param length the number of bytes to read
+   */
+  protected abstract void readInternal(byte[] b, int offset, int length)
+          throws IOException;
+
+  @Override
+  public long getFilePointer() { return bufferStart + bufferPosition; }
+
+  @Override
+  public void seek(long pos) throws IOException {
+    if (pos >= bufferStart && pos < (bufferStart + bufferLength))
+      bufferPosition = (int)(pos - bufferStart);  // seek within buffer
+    else {
+      bufferStart = pos;
+      bufferPosition = 0;
+      bufferLength = 0;				  // trigger refill() on read()
+      seekInternal(pos);
+    }
+  }
+
+  /** Expert: implements seek.  Sets current position in this file, where the
+   * next {@link #readInternal(byte[],int,int)} will occur.
+   * @see #readInternal(byte[],int,int)
+   */
+  protected abstract void seekInternal(long pos) throws IOException;
+
+  @Override
+  public Object clone() {
+    BufferedIndexInput clone = (BufferedIndexInput)super.clone();
+
+    clone.buffer = null;
+    clone.bufferLength = 0;
+    clone.bufferPosition = 0;
+    clone.bufferStart = getFilePointer();
+
+    return clone;
+  }
+
+  /**
+   * Flushes the in-memory bufer to the given output, copying at most
+   * <code>numBytes</code>.
+   * <p>
+   * <b>NOTE:</b> this method does not refill the buffer, however it does
+   * advance the buffer position.
+   * 
+   * @return the number of bytes actually flushed from the in-memory buffer.
+   */
+  protected int flushBuffer(IndexOutput out, long numBytes) throws IOException {
+    int toCopy = bufferLength - bufferPosition;
+    if (toCopy > numBytes) {
+      toCopy = (int) numBytes;
+    }
+    if (toCopy > 0) {
+      out.writeBytes(buffer, bufferPosition, toCopy);
+      bufferPosition += toCopy;
+    }
+    return toCopy;
+  }
+  
+  @Override
+  public void copyBytes(IndexOutput out, long numBytes) throws IOException {
+    assert numBytes >= 0: "numBytes=" + numBytes;
+
+    while (numBytes > 0) {
+      if (bufferLength == bufferPosition) {
+        refill();
+      }
+      numBytes -= flushBuffer(out, numBytes);
+    }
+  }
+  
+}