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Micro-optimizations and comment fixes on the mem5.c memory allocator module.

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FossilOrigin-Name: 8bf5e056eb8beb6e0ed5874fb24d7fe9f0b66d2b
This commit is contained in:
drh
2015-12-18 16:29:47 +00:00
parent 1db0a72be2
commit d319b8c143
3 changed files with 17 additions and 26 deletions
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12
manifest
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@@ -1,5 +1,5 @@
C Fix\sthe\sspellfix1_scriptcode()\sfunction\sto\signore\swhitespace\sand\spunctuation,\nand\sto\srecognize\shebrew\sand\sarabic\sscripts. C Micro-optimizations\sand\scomment\sfixes\son\sthe\smem5.c\smemory\sallocator\smodule.
D 2015-12-17T14:18:21.904 D 2015-12-18T16:29:47.912
F Makefile.in 28bcd6149e050dff35d4dcfd97e890cd387a499d F Makefile.in 28bcd6149e050dff35d4dcfd97e890cd387a499d
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc 5fff077fcc46de7714ed6eebb6159a4c00eab751 F Makefile.msc 5fff077fcc46de7714ed6eebb6159a4c00eab751
@@ -304,7 +304,7 @@ F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
F src/mem1.c 6919bcf12f221868ea066eec27e579fed95ce98b F src/mem1.c 6919bcf12f221868ea066eec27e579fed95ce98b
F src/mem2.c f1940d9e91948dd6a908fbb9ce3835c36b5d83c3 F src/mem2.c f1940d9e91948dd6a908fbb9ce3835c36b5d83c3
F src/mem3.c 8768ac94694f31ffaf8b4d0ea5dc08af7010a35a F src/mem3.c 8768ac94694f31ffaf8b4d0ea5dc08af7010a35a
F src/mem5.c 5c267678ba9f745a2ee58102a9f482d64a58577a F src/mem5.c 262055c242fa7db59c5f07ad77fdc4e97888c054
F src/memjournal.c 3eb2c0b51adbd869cb6a44780323f05fa904dc85 F src/memjournal.c 3eb2c0b51adbd869cb6a44780323f05fa904dc85
F src/msvc.h d9ba56c6851227ab44b3f228a35f3f5772296495 F src/msvc.h d9ba56c6851227ab44b3f228a35f3f5772296495
F src/mutex.c 8e45800ee78e0cd1f1f3fe8e398853307f4a085c F src/mutex.c 8e45800ee78e0cd1f1f3fe8e398853307f4a085c
@@ -1405,7 +1405,7 @@ F tool/vdbe_profile.tcl 246d0da094856d72d2c12efec03250d71639d19f
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P 85ebd46c701e0a094a4690cd8f1d0cbae9aa257c P 7adfa4a5794e47f97491c08abeaaac90e826b331
R 70cdc580d7d9b92b032d33f5e0d50f2e R 1b3cde8c2a6658c08ed08e4868245c5a
U drh U drh
Z 6d4b5ed9cd1870281d7d851922f323d8 Z 526b8930cb4e95afc320a389b1027b99

2
manifest.uuid
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@@ -1 +1 @@
7adfa4a5794e47f97491c08abeaaac90e826b331 8bf5e056eb8beb6e0ed5874fb24d7fe9f0b66d2b

29
src/mem5.c
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@@ -25,7 +25,7 @@
** **
** This memory allocator uses the following algorithm: ** This memory allocator uses the following algorithm:
** **
** 1. All memory allocations sizes are rounded up to a power of 2. ** 1. All memory allocation sizes are rounded up to a power of 2.
** **
** 2. If two adjacent free blocks are the halves of a larger block, ** 2. If two adjacent free blocks are the halves of a larger block,
** then the two blocks are coalesced into the single larger block. ** then the two blocks are coalesced into the single larger block.
@@ -117,7 +117,7 @@ static SQLITE_WSD struct Mem5Global {
/* /*
** Lists of free blocks. aiFreelist[0] is a list of free blocks of ** Lists of free blocks. aiFreelist[0] is a list of free blocks of
** size mem5.szAtom. aiFreelist[1] holds blocks of size szAtom*2. ** size mem5.szAtom. aiFreelist[1] holds blocks of size szAtom*2.
** and so forth. ** aiFreelist[2] holds free blocks of size szAtom*4. And so forth.
*/ */
int aiFreelist[LOGMAX+1]; int aiFreelist[LOGMAX+1];
@@ -183,9 +183,7 @@ static void memsys5Link(int i, int iLogsize){
} }
/* /*
** If the STATIC_MEM mutex is not already held, obtain it now. The mutex ** Obtain or release the mutex needed to access global data structures.
** will already be held (obtained by code in malloc.c) if
** sqlite3GlobalConfig.bMemStat is true.
*/ */
static void memsys5Enter(void){ static void memsys5Enter(void){
sqlite3_mutex_enter(mem5.mutex); sqlite3_mutex_enter(mem5.mutex);
@@ -195,9 +193,8 @@ static void memsys5Leave(void){
} }
/* /*
** Return the size of an outstanding allocation, in bytes. The ** Return the size of an outstanding allocation, in bytes.
** size returned omits the 8-byte header overhead. This only ** This only works for chunks that are currently checked out.
** works for chunks that are currently checked out.
*/ */
static int memsys5Size(void *p){ static int memsys5Size(void *p){
int iSize, i; int iSize, i;
@@ -230,14 +227,10 @@ static void *memsys5MallocUnsafe(int nByte){
/* Keep track of the maximum allocation request. Even unfulfilled /* Keep track of the maximum allocation request. Even unfulfilled
** requests are counted */ ** requests are counted */
if( (u32)nByte>mem5.maxRequest ){ if( (u32)nByte>mem5.maxRequest ){
mem5.maxRequest = nByte;
}
/* Abort if the requested allocation size is larger than the largest /* Abort if the requested allocation size is larger than the largest
** power of two that we can represent using 32-bit signed integers. ** power of two that we can represent using 32-bit signed integers. */
*/ if( nByte > 0x40000000 ) return 0;
if( nByte > 0x40000000 ){ mem5.maxRequest = nByte;
return 0;
} }
/* Round nByte up to the next valid power of two */ /* Round nByte up to the next valid power of two */
@@ -398,13 +391,11 @@ static void *memsys5Realloc(void *pPrior, int nBytes){
if( nBytes<=nOld ){ if( nBytes<=nOld ){
return pPrior; return pPrior;
} }
memsys5Enter(); p = memsys5Malloc(nBytes);
p = memsys5MallocUnsafe(nBytes);
if( p ){ if( p ){
memcpy(p, pPrior, nOld); memcpy(p, pPrior, nOld);
memsys5FreeUnsafe(pPrior); memsys5Free(pPrior);
} }
memsys5Leave();
return p; return p;
} }