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Change the SHM VFS logic in os_unix.c so that it does not hold an exclusive

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lock n the mapped memory when also holding a CHECKPOINT lock.  This
improves concurrency between readers and checkpointers.

FossilOrigin-Name: 8660cda6f8ef43bd276897ef3b5fc2376b5684dc
This commit is contained in:
drh 2010-04-30 17:47:51 +00:00
parent 1b48aa49a4
commit 6dea3248ae
3 changed files with 19 additions and 13 deletions
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18
manifest
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@ -1,8 +1,8 @@
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
C Remove\ssome\sobsolete\sdebugging\sparameters.
D 2010-04-30T17:28:35
C Change\sthe\sSHM\sVFS\slogic\sin\sos_unix.c\sso\sthat\sit\sdoes\snot\shold\san\sexclusive\nlock\sn\sthe\smapped\smemory\swhen\salso\sholding\sa\sCHECKPOINT\slock.\s\sThis\nimproves\sconcurrency\sbetween\sreaders\sand\scheckpointers.
D 2010-04-30T17:47:51
F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
F Makefile.in d83a0ffef3dcbfb08b410a6c6dd6c009ec9167fb
F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@ -153,7 +153,7 @@ F src/os.c 8bc63cf91e9802e2b807198e54e50227fa889306
F src/os.h 534b082c3cb349ad05fa6fa0b06087e022af282c
F src/os_common.h 0d6ee583b6ee3185eb9d951f890c6dd03021a08d
F src/os_os2.c 8ad77a418630d7dee91d1bb04f79c2096301d3a0
F src/os_unix.c edbc13a32a6b835b5303a444bd7da9404dc17e58
F src/os_unix.c 559f9f18ccd85a6d8da0309753f4be124998bddf
F src/os_win.c a8fc01d8483be472e495793c01064fd87e56a5c1
F src/pager.c 434f9751fc2dfc11ade004282deda5f8560bcba2
F src/pager.h 934b598583a9d936bb13c37d62a2fe68ac48781c
@ -811,14 +811,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
P 79d356fea6008a8adf8ebd4906571375f3cf5213
R 7623f491cc3fe25e6cf1447dc278db34
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R 8c6bff1c20fef6364d82d75506d94733
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2
manifest.uuid
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@ -1 +1 @@
a012aed498bf41a5f6f3006182b0c4c2ab0fe1bb
8660cda6f8ef43bd276897ef3b5fc2376b5684dc

12
src/os_unix.c
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@ -5140,7 +5140,10 @@ static int unixShmGet(
unixShmFile *pFile = p->pFile;
int rc = SQLITE_OK;
sqlite3_mutex_enter(pFile->mutexBuf);
if( p->lockState!=SQLITE_SHM_CHECKPOINT ){
sqlite3_mutex_enter(pFile->mutexBuf);
p->hasMutexBuf = 1;
}
sqlite3_mutex_enter(pFile->mutex);
if( pFile->szMap==0 || reqMapSize>pFile->szMap ){
int actualSize;
@ -5168,8 +5171,11 @@ static int unixShmGet(
*/
static int unixShmRelease(sqlite3_shm *pSharedMem){
unixShm *p = (unixShm*)pSharedMem;
unixShmFile *pFile = p->pFile;
sqlite3_mutex_leave(pFile->mutexBuf);
if( p->hasMutexBuf ){
unixShmFile *pFile = p->pFile;
sqlite3_mutex_leave(pFile->mutexBuf);
p->hasMutexBuf = 0;
}
return SQLITE_OK;
}