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authorBo Xu <bo_xu@foxitsoftware.com>2014-12-17 17:51:00 -0800
committerBo Xu <bo_xu@foxitsoftware.com>2014-12-17 17:51:00 -0800
commitbf42dfea544a8ea3269b139e940f3f8eb38f7a27 (patch)
tree2eedf59a9519706f4d1db486b2ee9571770444ae /core/src
parent9f52a10839e62a8b58359d89e6f623cdcb77c71b (diff)
downloadpdfium-bf42dfea544a8ea3269b139e940f3f8eb38f7a27.tar.xz
Add a small LRU cache for the JBIG2 symbol dictionary.
This reduces rendering time on my test document by over 10 seconds. It is super common for a JBIG2 dictionary to span multiple pages, so we don't want to decode the same dictionary over and over again. Original patch from Jeff Breidenbach (breidenbach@gmail.com) BUG=https://code.google.com/p/pdfium/issues/detail?id=85 R=bo_xu@foxitsoftware.com, thestig@chromium.org Review URL: https://codereview.chromium.org/761313004
Diffstat (limited to 'core/src')
-rw-r--r--core/src/fxcodec/jbig2/JBig2_Context.cpp66
-rw-r--r--core/src/fxcodec/jbig2/JBig2_SymbolDict.cpp20
-rw-r--r--core/src/fxcodec/jbig2/JBig2_SymbolDict.h2
3 files changed, 72 insertions, 16 deletions
diff --git a/core/src/fxcodec/jbig2/JBig2_Context.cpp b/core/src/fxcodec/jbig2/JBig2_Context.cpp
index 83ded6fbe1..fec6b5fb68 100644
--- a/core/src/fxcodec/jbig2/JBig2_Context.cpp
+++ b/core/src/fxcodec/jbig2/JBig2_Context.cpp
@@ -4,7 +4,21 @@
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+#include <map>
+#include <list>
#include "JBig2_Context.h"
+
+// Implement a very small least recently used (LRU) cache. It is very
+// common for a JBIG2 dictionary to span multiple pages in a PDF file,
+// and we do not want to decode the same dictionary over and over
+// again. We key off of the memory location of the dictionary. The
+// list keeps track of the freshness of entries, with freshest ones
+// at the front. Even a tiny cache size like 2 makes a dramatic
+// difference for typical JBIG2 documents.
+const int kSymbolDictCacheMaxSize = 2;
+typedef std::pair<FX_BYTE*, CJBig2_SymbolDict*> CJBig2_CachePair;
+static std::list<CJBig2_CachePair> SymbolDictCache;
+
void OutputBitmap(CJBig2_Image* pImage)
{
if(!pImage) {
@@ -614,6 +628,8 @@ FX_INT32 CJBig2_Context::parseSymbolDict(CJBig2_Segment *pSegment, IFX_Pause* pP
JBig2ArithCtx *gbContext = NULL, *grContext = NULL;
CJBig2_ArithDecoder *pArithDecoder;
JBIG2_ALLOC(pSymbolDictDecoder, CJBig2_SDDProc());
+ FX_BYTE *key = pSegment->m_pData;
+ FX_BOOL cache_hit = false;
if(m_pStream->readShortInteger(&wFlags) != 0) {
m_pModule->JBig2_Error("symbol dictionary segment : data header too short.");
nRet = JBIG2_ERROR_TOO_SHORT;
@@ -791,23 +807,43 @@ FX_INT32 CJBig2_Context::parseSymbolDict(CJBig2_Segment *pSegment, IFX_Pause* pP
}
}
pSegment->m_nResultType = JBIG2_SYMBOL_DICT_POINTER;
- if(pSymbolDictDecoder->SDHUFF == 0) {
- JBIG2_ALLOC(pArithDecoder, CJBig2_ArithDecoder(m_pStream));
- pSegment->m_Result.sd = pSymbolDictDecoder->decode_Arith(pArithDecoder, gbContext, grContext);
- delete pArithDecoder;
- if(pSegment->m_Result.sd == NULL) {
- nRet = JBIG2_ERROR_FETAL;
- goto failed;
+ for(std::list<CJBig2_CachePair>::iterator it =
+ SymbolDictCache.begin(); it != SymbolDictCache.end(); ++it) {
+ if (it->first == key) {
+ pSegment->m_Result.sd = it->second->DeepCopy();
+ SymbolDictCache.push_front(*it);
+ SymbolDictCache.erase(it);
+ cache_hit = true;
+ break;
}
- m_pStream->alignByte();
- m_pStream->offset(2);
- } else {
- pSegment->m_Result.sd = pSymbolDictDecoder->decode_Huffman(m_pStream, gbContext, grContext, pPause);
- if(pSegment->m_Result.sd == NULL) {
- nRet = JBIG2_ERROR_FETAL;
- goto failed;
+ }
+ if (!cache_hit) {
+ if(pSymbolDictDecoder->SDHUFF == 0) {
+ JBIG2_ALLOC(pArithDecoder, CJBig2_ArithDecoder(m_pStream));
+ pSegment->m_Result.sd = pSymbolDictDecoder->decode_Arith(pArithDecoder, gbContext, grContext);
+ delete pArithDecoder;
+ if(pSegment->m_Result.sd == NULL) {
+ nRet = JBIG2_ERROR_FETAL;
+ goto failed;
+ }
+ m_pStream->alignByte();
+ m_pStream->offset(2);
+ } else {
+ pSegment->m_Result.sd = pSymbolDictDecoder->decode_Huffman(m_pStream, gbContext, grContext, pPause);
+ if(pSegment->m_Result.sd == NULL) {
+ nRet = JBIG2_ERROR_FETAL;
+ goto failed;
+ }
+ m_pStream->alignByte();
+ }
+ CJBig2_SymbolDict *value = pSegment->m_Result.sd->DeepCopy();
+ if (value) {
+ while (SymbolDictCache.size() >= kSymbolDictCacheMaxSize) {
+ delete SymbolDictCache.back().second;
+ SymbolDictCache.pop_back();
+ }
+ SymbolDictCache.push_front(CJBig2_CachePair(key, value));
}
- m_pStream->alignByte();
}
if(wFlags & 0x0200) {
pSegment->m_Result.sd->m_bContextRetained = TRUE;
diff --git a/core/src/fxcodec/jbig2/JBig2_SymbolDict.cpp b/core/src/fxcodec/jbig2/JBig2_SymbolDict.cpp
index 67e54c0cea..bad2fc4bce 100644
--- a/core/src/fxcodec/jbig2/JBig2_SymbolDict.cpp
+++ b/core/src/fxcodec/jbig2/JBig2_SymbolDict.cpp
@@ -13,6 +13,26 @@ CJBig2_SymbolDict::CJBig2_SymbolDict()
m_gbContext = m_grContext = NULL;
}
+CJBig2_SymbolDict *CJBig2_SymbolDict::DeepCopy()
+{
+ CJBig2_SymbolDict *dst = NULL;
+ CJBig2_SymbolDict *src = this;
+ if (src->m_bContextRetained ||
+ src->m_gbContext ||
+ src->m_grContext) {
+ return NULL;
+ }
+ JBIG2_ALLOC(dst, CJBig2_SymbolDict());
+ dst->SDNUMEXSYMS = src->SDNUMEXSYMS;
+ dst->SDEXSYMS = (CJBig2_Image**)m_pModule->JBig2_Malloc2(
+ sizeof(CJBig2_Image*), src->SDNUMEXSYMS);
+ for(FX_DWORD i = 0; i < src->SDNUMEXSYMS; i++) {
+ JBIG2_ALLOC(dst->SDEXSYMS[i],
+ CJBig2_Image(*(src->SDEXSYMS[i])));
+ }
+ return dst;
+}
+
CJBig2_SymbolDict::~CJBig2_SymbolDict()
{
if(SDEXSYMS) {
diff --git a/core/src/fxcodec/jbig2/JBig2_SymbolDict.h b/core/src/fxcodec/jbig2/JBig2_SymbolDict.h
index cfe75db4c9..9156e30ea8 100644
--- a/core/src/fxcodec/jbig2/JBig2_SymbolDict.h
+++ b/core/src/fxcodec/jbig2/JBig2_SymbolDict.h
@@ -14,7 +14,7 @@ class CJBig2_SymbolDict : public CJBig2_Object
public:
CJBig2_SymbolDict();
-
+ CJBig2_SymbolDict *DeepCopy();
~CJBig2_SymbolDict();
public:
FX_DWORD SDNUMEXSYMS;