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Make DeflaterEngine disposable

af/merge-core
James Jackson-South 6 years ago
parent
95636933ae
commit
3079574c3c
2 changed files with 129 additions and 184 deletions
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  1. 40
      src/ImageSharp/Formats/Png/Zlib/Deflater.cs
  2. 273
      src/ImageSharp/Formats/Png/Zlib/DeflaterEngine.cs

40
src/ImageSharp/Formats/Png/Zlib/Deflater.cs
View File

@ -54,7 +54,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
private DeflaterEngine engine;
private bool isDisposed;
private const int IsSetDict = 0x01;
private const int IsFlushing = 0x04;
private const int IsFinishing = 0x08;
private const int BusyState = 0x10;
@ -82,8 +81,10 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
}
this.pending = new DeflaterPendingBuffer(memoryAllocator);
this.engine = new DeflaterEngine(this.pending, true);
this.engine.Strategy = DeflateStrategy.Default;
// TODO: Possibly provide DeflateStrategy as an option.
this.engine = new DeflaterEngine(memoryAllocator, this.pending, DeflateStrategy.Default);
this.SetLevel(level);
this.Reset();
}
@ -233,37 +234,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
DeflateThrowHelper.ThrowAlreadyClosed();
}
if (this.state < BusyState)
{
// Output header
int header = (Deflated + ((DeflaterConstants.MAX_WBITS - 8) << 4)) << 8;
int levelFlags = (this.level - 1) >> 1;
if (levelFlags < 0 || levelFlags > 3)
{
levelFlags = 3;
}
header |= levelFlags << 6;
if ((this.state & IsSetDict) != 0)
{
// Dictionary was set
header |= DeflaterConstants.PRESET_DICT;
}
header += 31 - (header % 31);
this.pending.WriteShortMSB(header);
if ((this.state & IsSetDict) != 0)
{
int chksum = this.engine.Adler;
this.engine.ResetAdler();
this.pending.WriteShortMSB(chksum >> 16);
this.pending.WriteShortMSB(chksum & 0xffff);
}
this.state = BusyState | (this.state & (IsFlushing | IsFinishing));
}
while (true)
{
int count = this.pending.Flush(output, offset, length);
@ -326,9 +296,11 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
if (disposing)
{
this.pending.Dispose();
this.engine.Dispose();
}
this.pending = null;
this.engine = null;
this.isDisposed = true;
}
}

273
src/ImageSharp/Formats/Png/Zlib/DeflaterEngine.cs
View File

@ -2,8 +2,9 @@
// Licensed under the Apache License, Version 2.0.
using System;
using System.Collections.Generic;
using System.Text;
using System.Buffers;
using System.Runtime.CompilerServices;
using SixLabors.Memory;
namespace SixLabors.ImageSharp.Formats.Png.Zlib
{
@ -48,30 +49,13 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
/// Low level compression engine for deflate algorithm which uses a 32K sliding window
/// with secondary compression from Huffman/Shannon-Fano codes.
/// </summary>
public class DeflaterEngine
public sealed unsafe class DeflaterEngine : IDisposable
{
private const int TooFar = 4096;
// Hash index of string to be inserted
private int insertHashIndex;
/// <summary>
/// Hashtable, hashing three characters to an index for window, so
/// that window[index]..window[index+2] have this hash code.
/// Note that the array should really be unsigned short, so you need
/// to and the values with 0xFFFF.
/// </summary>
private short[] head;
/// <summary>
/// <code>prev[index &amp; WMASK]</code> points to the previous index that has the
/// same hash code as the string starting at index. This way
/// entries with the same hash code are in a linked list.
/// Note that the array should really be unsigned short, so you need
/// to and the values with 0xFFFF.
/// </summary>
private short[] prev;
private int matchStart;
// Length of best match
@ -95,16 +79,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
/// </summary>
private int lookahead;
/// <summary>
/// This array contains the part of the uncompressed stream that
/// is of relevance. The current character is indexed by strstart.
/// </summary>
private byte[] window;
private int maxChain;
private int maxLazy;
private int niceLength;
private int goodLength;
/// <summary>
/// The current compression function.
/// </summary>
@ -115,11 +89,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
/// </summary>
private byte[] inputBuf;
/// <summary>
/// The total bytes of input read.
/// </summary>
private long totalIn;
/// <summary>
/// The offset into inputBuf, where input data starts.
/// </summary>
@ -130,31 +99,59 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
/// </summary>
private int inputEnd;
private DeflateStrategy strategy;
private DeflaterPendingBuffer pending;
private DeflaterHuffman huffman;
private bool isDisposed;
/// <summary>
/// The adler checksum
/// Hashtable, hashing three characters to an index for window, so
/// that window[index]..window[index+2] have this hash code.
/// Note that the array should really be unsigned short, so you need
/// to and the values with 0xFFFF.
/// </summary>
private Adler32 adler;
private short[] head;
/// <summary>
/// <code>prev[index &amp; WMASK]</code> points to the previous index that has the
/// same hash code as the string starting at index. This way
/// entries with the same hash code are in a linked list.
/// Note that the array should really be unsigned short, so you need
/// to and the values with 0xFFFF.
/// </summary>
private short[] prev;
/// <summary>
/// This array contains the part of the uncompressed stream that
/// is of relevance. The current character is indexed by strstart.
/// </summary>
private readonly IManagedByteBuffer windowBuffer;
private MemoryHandle windowBufferHandle;
private byte[] window;
private readonly byte* pinnedWindowPointer;
private int maxChain;
private int maxLazy;
private int niceLength;
private int goodLength;
/// <summary>
/// Initializes a new instance of the <see cref="DeflaterEngine"/> class.
/// </summary>
/// <param name="memoryAllocator">The memory allocator to use for buffer allocations.</param>
/// <param name="pending">The pending buffer to use.</param>
/// <param name="noAdlerCalculation">
/// If no adler calculation should be performed
/// </param>
public DeflaterEngine(DeflaterPendingBuffer pending, bool noAdlerCalculation)
/// <param name="strategy">The deflate strategy to use.</param>
public DeflaterEngine(MemoryAllocator memoryAllocator, DeflaterPendingBuffer pending, DeflateStrategy strategy)
{
this.pending = pending;
this.huffman = new DeflaterHuffman(pending);
if (!noAdlerCalculation)
{
this.adler = new Adler32();
}
this.strategy = strategy;
this.windowBuffer = memoryAllocator.AllocateManagedByteBuffer(2 * DeflaterConstants.WSIZE);
this.window = this.windowBuffer.Array;
this.windowBufferHandle = this.windowBuffer.Memory.Pin();
this.pinnedWindowPointer = (byte*)this.windowBufferHandle.Pointer;
this.window = new byte[2 * DeflaterConstants.WSIZE];
this.head = new short[DeflaterConstants.HASH_SIZE];
this.prev = new short[DeflaterConstants.WSIZE];
@ -163,33 +160,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
this.blockStart = this.strstart = 1;
}
/// <summary>
/// Gets the current value of Adler checksum
/// </summary>
public int Adler
{
get
{
return (this.adler != null) ? unchecked((int)this.adler.Value) : 0;
}
}
/// <summary>
/// Gets the total data processed
/// </summary>
public long TotalIn
{
get
{
return this.totalIn;
}
}
/// <summary>
/// Gets or sets the <see cref="DeflateStrategy">deflate strategy</see>
/// </summary>
public DeflateStrategy Strategy { get; set; }
/// <summary>
/// Deflate drives actual compression of data
/// </summary>
@ -286,7 +256,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
/// <param name="length">The length of the dictionary data.</param>
public void SetDictionary(byte[] buffer, int offset, int length)
{
this.adler?.Update(new ArraySegment<byte>(buffer, offset, length));
if (length < DeflaterConstants.MIN_MATCH)
{
return;
@ -318,10 +287,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
public void Reset()
{
this.huffman.Reset();
this.adler?.Reset();
this.blockStart = this.strstart = 1;
this.lookahead = 0;
this.totalIn = 0;
this.prevAvailable = false;
this.matchLen = DeflaterConstants.MIN_MATCH - 1;
@ -336,14 +303,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
}
}
/// <summary>
/// Reset Adler checksum
/// </summary>
public void ResetAdler()
{
this.adler?.Reset();
}
/// <summary>
/// Set the deflate level (0-9)
/// </summary>
@ -386,7 +345,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
case DeflaterConstants.DEFLATE_SLOW:
if (this.prevAvailable)
{
this.huffman.TallyLit(this.window[this.strstart - 1] & 0xff);
this.huffman.TallyLit(this.pinnedWindowPointer[this.strstart - 1] & 0xFF);
}
if (this.strstart > this.blockStart)
@ -427,10 +386,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
}
Array.Copy(this.inputBuf, this.inputOff, this.window, this.strstart + this.lookahead, more);
this.adler?.Update(new ArraySegment<byte>(this.inputBuf, this.inputOff, more));
this.inputOff += more;
this.totalIn += more;
this.lookahead += more;
}
@ -440,9 +397,19 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
}
}
/// <inheritdoc/>
public void Dispose()
{
// Do not change this code. Put cleanup code in Dispose(bool disposing) above.
this.Dispose(true);
GC.SuppressFinalize(this);
}
[MethodImpl(InliningOptions.ShortMethod)]
private void UpdateHash()
{
this.insertHashIndex = (this.window[this.strstart] << DeflaterConstants.HASH_SHIFT) ^ this.window[this.strstart + 1];
byte* pinned = this.pinnedWindowPointer;
this.insertHashIndex = (pinned[this.strstart] << DeflaterConstants.HASH_SHIFT) ^ pinned[this.strstart + 1];
}
/// <summary>
@ -453,7 +420,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
private int InsertString()
{
short match;
int hash = ((this.insertHashIndex << DeflaterConstants.HASH_SHIFT) ^ this.window[this.strstart + (DeflaterConstants.MIN_MATCH - 1)]) & DeflaterConstants.HASH_MASK;
int hash = ((this.insertHashIndex << DeflaterConstants.HASH_SHIFT) ^ this.pinnedWindowPointer[this.strstart + (DeflaterConstants.MIN_MATCH - 1)]) & DeflaterConstants.HASH_MASK;
this.prev[this.strstart & DeflaterConstants.WMASK] = match = this.head[hash];
this.head[hash] = unchecked((short)this.strstart);
@ -463,7 +430,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
private void SlideWindow()
{
Array.Copy(this.window, DeflaterConstants.WSIZE, this.window, 0, DeflaterConstants.WSIZE);
Unsafe.CopyBlockUnaligned(ref this.window[0], ref this.window[DeflaterConstants.WSIZE], DeflaterConstants.WSIZE);
this.matchStart -= DeflaterConstants.WSIZE;
this.strstart -= DeflaterConstants.WSIZE;
this.blockStart -= DeflaterConstants.WSIZE;
@ -518,8 +485,9 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
return false;
}
byte scan_end1 = window[scan + this.matchLen - 1];
byte scan_end = window[scan + this.matchLen];
byte* pinnedWindow = this.pinnedWindowPointer;
byte scan_end1 = pinnedWindow[scan + this.matchLen - 1];
byte scan_end = pinnedWindow[scan + this.matchLen];
// Do not waste too much time if we already have a good match:
if (this.matchLen >= this.goodLength)
@ -532,10 +500,10 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
match = curMatch;
scan = this.strstart;
if (window[match + this.matchLen] != scan_end
|| window[match + this.matchLen - 1] != scan_end1
|| window[match] != window[scan]
|| window[++match] != window[++scan])
if (pinnedWindow[match + this.matchLen] != scan_end
|| pinnedWindow[match + this.matchLen - 1] != scan_end1
|| pinnedWindow[match] != pinnedWindow[scan]
|| pinnedWindow[++match] != pinnedWindow[++scan])
{
continue;
}
@ -547,7 +515,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
switch ((scanMax - scan) % 8)
{
case 1:
if (window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -555,8 +523,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
case 2:
if (window[++scan] == window[++match]
&& window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -564,9 +532,9 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
case 3:
if (window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -574,10 +542,10 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
case 4:
if (window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -585,11 +553,11 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
case 5:
if (window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -597,12 +565,12 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
case 6:
if (window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -610,13 +578,13 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
case 7:
if (window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match])
if (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match])
{
break;
}
@ -624,7 +592,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
}
if (window[scan] == window[match])
if (pinnedWindow[scan] == pinnedWindow[match])
{
// We check for insufficient lookahead only every 8th comparison;
// the 256th check will be made at strstart + 258 unless lookahead is
@ -639,14 +607,14 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
}
}
while (window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]
&& window[++scan] == window[++match]);
while (pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]
&& pinnedWindow[++scan] == pinnedWindow[++match]);
}
if (scan - this.strstart > this.matchLen)
@ -659,8 +627,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
break;
}
scan_end1 = window[scan - 1];
scan_end = window[scan];
scan_end1 = pinnedWindow[scan - 1];
scan_end = pinnedWindow[scan];
}
}
while ((curMatch = prev[curMatch & DeflaterConstants.WMASK] & 0xFFFF) > limit && --chainLength != 0);
@ -727,7 +695,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
int hashHead;
if (this.lookahead >= DeflaterConstants.MIN_MATCH &&
(hashHead = this.InsertString()) != 0 &&
this.Strategy != DeflateStrategy.HuffmanOnly &&
this.strategy != DeflateStrategy.HuffmanOnly &&
this.strstart - hashHead <= DeflaterConstants.MAX_DIST &&
this.FindLongestMatch(hashHead))
{
@ -763,7 +731,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
else
{
// No match found
this.huffman.TallyLit(this.window[this.strstart] & 0xff);
this.huffman.TallyLit(this.pinnedWindowPointer[this.strstart] & 0xff);
++this.strstart;
--this.lookahead;
}
@ -793,7 +761,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
{
if (this.prevAvailable)
{
this.huffman.TallyLit(this.window[this.strstart - 1] & 0xff);
this.huffman.TallyLit(this.pinnedWindowPointer[this.strstart - 1] & 0xff);
}
this.prevAvailable = false;
@ -818,14 +786,14 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
{
int hashHead = this.InsertString();
if (this.Strategy != DeflateStrategy.HuffmanOnly &&
if (this.strategy != DeflateStrategy.HuffmanOnly &&
hashHead != 0 &&
this.strstart - hashHead <= DeflaterConstants.MAX_DIST &&
this.FindLongestMatch(hashHead))
{
// longestMatch sets matchStart and matchLen
// Discard match if too small and too far away
if (this.matchLen <= 5 && (this.Strategy == DeflateStrategy.Filtered || (this.matchLen == DeflaterConstants.MIN_MATCH && this.strstart - this.matchStart > TooFar)))
if (this.matchLen <= 5 && (this.strategy == DeflateStrategy.Filtered || (this.matchLen == DeflaterConstants.MIN_MATCH && this.strstart - this.matchStart > TooFar)))
{
this.matchLen = DeflaterConstants.MIN_MATCH - 1;
}
@ -835,15 +803,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
// previous match was better
if ((prevLen >= DeflaterConstants.MIN_MATCH) && (this.matchLen <= prevLen))
{
#if DebugDeflation
if (DeflaterConstants.DEBUGGING)
{
for (int i = 0 ; i < matchLen; i++) {
if (window[strstart-1+i] != window[prevMatch + i])
throw new ImageFormatException();
}
}
#endif
this.huffman.TallyDist(this.strstart - 1 - prevMatch, prevLen);
prevLen -= 2;
do
@ -866,7 +825,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
{
if (this.prevAvailable)
{
this.huffman.TallyLit(this.window[this.strstart - 1] & 0xff);
this.huffman.TallyLit(this.pinnedWindowPointer[this.strstart - 1] & 0xff);
}
this.prevAvailable = true;
@ -891,5 +850,19 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
return true;
}
private void Dispose(bool disposing)
{
if (!this.isDisposed)
{
if (disposing)
{
this.windowBufferHandle.Dispose();
this.windowBuffer.Dispose();
}
this.isDisposed = true;
}
}
}
}

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