Mercurial > hg4j
diff src/org/tmatesoft/hg/internal/InflaterDataAccess.java @ 576:3c4db86e8c1f
Issue 43: poor performance with InflaterDataAccess. Phase 2: inflate into buffer, effective skip and readByte/readBytes()
author | Artem Tikhomirov <tikhomirov.artem@gmail.com> |
---|---|
date | Tue, 16 Apr 2013 19:31:57 +0200 |
parents | 8bf184c9d733 |
children | ed243b668502 |
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--- a/src/org/tmatesoft/hg/internal/InflaterDataAccess.java Tue Apr 16 16:59:59 2013 +0200 +++ b/src/org/tmatesoft/hg/internal/InflaterDataAccess.java Tue Apr 16 19:31:57 2013 +0200 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2011-2012 TMate Software Ltd + * Copyright (c) 2011-2013 TMate Software Ltd * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -16,8 +16,8 @@ */ package org.tmatesoft.hg.internal; -import java.io.EOFException; import java.io.IOException; +import java.nio.ByteBuffer; import java.util.zip.DataFormatException; import java.util.zip.Inflater; import java.util.zip.ZipException; @@ -32,9 +32,9 @@ public class InflaterDataAccess extends FilterDataAccess { private final Inflater inflater; - private final byte[] buffer; - private final byte[] singleByte = new byte[1]; - private int decompressedPos = 0; + private final byte[] inBuffer; + private final ByteBuffer outBuffer; + private int inflaterPos = 0; private int decompressedLength; public InflaterDataAccess(DataAccess dataAccess, long offset, int compressedLength) { @@ -52,20 +52,23 @@ } this.inflater = inflater; this.decompressedLength = actualLength; - buffer = buf; + inBuffer = buf; + outBuffer = ByteBuffer.allocate(inBuffer.length * 2); + outBuffer.limit(0); // there's nothing to read in the buffer } @Override public InflaterDataAccess reset() throws IOException { super.reset(); inflater.reset(); - decompressedPos = 0; + inflaterPos = 0; + outBuffer.clear().limit(0); // or flip(), to indicate nothing to read return this; } @Override protected int available() throws IOException { - return length() - decompressedPos; + return length() - decompressedPosition(); } @Override @@ -80,29 +83,16 @@ if (decompressedLength != -1) { return decompressedLength; } - decompressedLength = 0; // guard to avoid endless loop in case length() would get invoked from below. - int c = 0; - int oldPos = decompressedPos; - byte[] dummy = new byte[buffer.length]; - try { - int toRead = -1; - do { - while (!inflater.needsInput()) { - c += inflater.inflate(dummy, 0, dummy.length); - } - if (inflater.needsInput() && (toRead = super.available()) > 0) { - // fill: - if (toRead > buffer.length) { - toRead = buffer.length; - } - super.readBytes(buffer, 0, toRead); - inflater.setInput(buffer, 0, toRead); - } - } while(toRead > 0); - } catch (DataFormatException ex) { - throw new IOException(ex.toString()); - } - decompressedLength = c + oldPos; + decompressedLength = 0; // guard to avoid endless loop in case length() would get invoked from below. + final int oldPos = decompressedPosition(); + final int inflatedUpTo = inflaterPos; + int inflatedMore = 0, c; + do { + outBuffer.limit(outBuffer.position()); // pretend the buffer is consumed + c = fillOutBuffer(); + inflatedMore += c; + } while (c == outBuffer.capacity()); // once we unpacked less than capacity, input is over + decompressedLength = inflatedUpTo + inflatedMore; reset(); seek(oldPos); return decompressedLength; @@ -113,8 +103,9 @@ if (localOffset < 0 /* || localOffset >= length() */) { throw new IllegalArgumentException(); } - if (localOffset >= decompressedPos) { - skip(localOffset - decompressedPos); + int currentPos = decompressedPosition(); + if (localOffset >= currentPos) { + skip(localOffset - currentPos); } else { reset(); skip(localOffset); @@ -125,57 +116,122 @@ public void skip(final int bytesToSkip) throws IOException { int bytes = bytesToSkip; if (bytes < 0) { - bytes += decompressedPos; + bytes += decompressedPosition(); if (bytes < 0) { - throw new IOException(String.format("Underflow. Rewind past start of the slice. To skip:%d, decPos:%d, decLen:%d. Left:%d", bytesToSkip, decompressedPos, decompressedLength, bytes)); + throw new IOException(String.format("Underflow. Rewind past start of the slice. To skip:%d, decPos:%d, decLen:%d. Left:%d", bytesToSkip, inflaterPos, decompressedLength, bytes)); } reset(); // fall-through } while (!isEmpty() && bytes > 0) { - readByte(); - bytes--; + int fromBuffer = outBuffer.remaining(); + if (fromBuffer > 0) { + if (fromBuffer >= bytes) { + outBuffer.position(outBuffer.position() + bytes); + bytes = 0; + break; + } else { + bytes -= fromBuffer; + outBuffer.limit(outBuffer.position()); // mark consumed + // fall through to fill the buffer + } + } + fillOutBuffer(); } if (bytes != 0) { - throw new IOException(String.format("Underflow. Rewind past end of the slice. To skip:%d, decPos:%d, decLen:%d. Left:%d", bytesToSkip, decompressedPos, decompressedLength, bytes)); + throw new IOException(String.format("Underflow. Rewind past end of the slice. To skip:%d, decPos:%d, decLen:%d. Left:%d", bytesToSkip, inflaterPos, decompressedLength, bytes)); } } @Override public byte readByte() throws IOException { - readBytes(singleByte, 0, 1); - return singleByte[0]; + if (!outBuffer.hasRemaining()) { + fillOutBuffer(); + } + return outBuffer.get(); } @Override public void readBytes(byte[] b, int off, int len) throws IOException { + do { + int fromBuffer = outBuffer.remaining(); + if (fromBuffer > 0) { + if (fromBuffer >= len) { + outBuffer.get(b, off, len); + return; + } else { + outBuffer.get(b, off, fromBuffer); + off += fromBuffer; + len -= fromBuffer; + // fall-through + } + } + fillOutBuffer(); + } while (len > 0); + } + + @Override + public void readBytes(ByteBuffer buf) throws IOException { + int len = Math.min(available(), buf.remaining()); + while (len > 0) { + if (outBuffer.remaining() >= len) { + ByteBuffer slice = outBuffer.slice(); + slice.limit(len); + buf.put(slice); + outBuffer.position(outBuffer.position() + len); + return; + } else { + len -= outBuffer.remaining(); + buf.put(outBuffer); + } + fillOutBuffer(); + } + } + + private int decompressedPosition() { + assert outBuffer.remaining() <= inflaterPos; + return inflaterPos - outBuffer.remaining(); + } + + // after #fillOutBuffer(), outBuffer is ready for read + private int fillOutBuffer() throws IOException { + assert !outBuffer.hasRemaining(); try { - int n; - while (len > 0) { - while ((n = inflater.inflate(b, off, len)) == 0) { + int inflatedBytes = 0; + outBuffer.clear(); + int len = outBuffer.capacity(); + int off = 0; + do { + int n; + while ((n = inflater.inflate(outBuffer.array(), off, len)) == 0) { // XXX few last bytes (checksum?) may be ignored by inflater, thus inflate may return 0 in // perfectly legal conditions (when all data already expanded, but there are still some bytes // in the input stream) int toRead = -1; if (inflater.needsInput() && (toRead = super.available()) > 0) { - // fill: - if (toRead > buffer.length) { - toRead = buffer.length; + // fill + if (toRead > inBuffer.length) { + toRead = inBuffer.length; } - super.readBytes(buffer, 0, toRead); - inflater.setInput(buffer, 0, toRead); + super.readBytes(inBuffer, 0, toRead); + inflater.setInput(inBuffer, 0, toRead); } else { + // inflated nothing and doesn't want any more data (or no date available) - assume we're done + assert inflater.finished(); + assert toRead <= 0; + break; // prevent hang up in this cycle if no more data is available, see Issue 25 - throw new EOFException(String.format("No more compressed data is available to satisfy request for %d bytes. [finished:%b, needDict:%b, needInp:%b, available:%d", len, inflater.finished(), inflater.needsDictionary(), inflater.needsInput(), toRead)); +// throw new EOFException(String.format("No more compressed data is available to satisfy request for %d bytes. [finished:%b, needDict:%b, needInp:%b, available:%d", len, inflater.finished(), inflater.needsDictionary(), inflater.needsInput(), toRead)); } } off += n; len -= n; - decompressedPos += n; - if (len == 0) { - return; // filled - } - } + inflatedBytes += n; + } while (len > 0 && !inflater.finished()); // either the buffer is filled or nothing more to unpack + inflaterPos += inflatedBytes; + outBuffer.limit(inflatedBytes); + assert outBuffer.position() == 0; // didn't change since #clear() above + return inflatedBytes; } catch (DataFormatException e) { String s = e.getMessage(); throw new ZipException(s != null ? s : "Invalid ZLIB data format");