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Defer the check for error check Pgno zero until after the page fetch misses,

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to gain a few CPU cycles and a small size reduction.

FossilOrigin-Name: ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a
This commit is contained in:
drh 2022-02-23 17:16:30 +00:00
parent 584bfcaeb6
commit eac750e9a6
3 changed files with 10 additions and 11 deletions
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12
manifest
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@ -1,5 +1,5 @@
C Store\sthe\spage\snumber\sfor\sthe\sPENDING_BYTE\spage\sin\sthe\sPager\sobject,\srather\nthan\scomputing\sthe\spage\snumber\severy\stime\sit\sis\sneeded,\sbecause\sit\sturns\sout\nthat\snumber\sis\sneeded\squite\sfrequently.\s\sThis\ssaves\sa\sfew\shundred\sthousand\nCPU\scycles\sand\sa\sfew\sbytes\sof\scode\sspace.
D 2022-02-23T17:00:44.801
C Defer\sthe\scheck\sfor\serror\scheck\sPgno\szero\suntil\safter\sthe\spage\sfetch\smisses,\nto\sgain\sa\sfew\sCPU\scycles\sand\sa\ssmall\ssize\sreduction.
D 2022-02-23T17:16:30.735
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -539,7 +539,7 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
F src/os_unix.c f5ad51cfd024116db8531feab9efd831c2621436dca1464e4ff1e8af9bf3252e
F src/os_win.c 77d39873836f1831a9b0b91894fec45ab0e9ca8e067dc8c549e1d1eca1566fe9
F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
F src/pager.c 198e037aa1f945e19cc4b4e89a80a40c31fc6beafacfe068fb3ca88cb602b523
F src/pager.c 90a3721b4ab007a835c751a441c1b1fc68bfe68d99dd298f28d91cc163730194
F src/pager.h f82e9844166e1585f5786837ddc7709966138ced17f568c16af7ccf946c2baa3
F src/parse.y 0f02b27cdaa334441463153fff3ceb780fea006ab53ffd6ef566d4468f93e924
F src/pcache.c 084e638432c610f95aea72b8509f0845d2791293f39d1b82f0c0a7e089c3bb6b
@ -1944,8 +1944,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 710de6a2137c872812effa43ea888aa77d339362ca0b6c8990d4426c8fb20689
R 31db230ec1e00447c3c5dedc2a12edf4
P 5aa9c3eb45514d5eb7b32696d25a9aeb7dad485e1ea5adb833fac6d1f2105f1a
R 4a7be174abec3b1bd75c937cba4c1ec2
U drh
Z d8442a86814fe9e42893b593cc0d0a34
Z 8b433f90acbe3d610b55829e1edc78df
# Remove this line to create a well-formed Fossil manifest.

2
manifest.uuid
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@ -1 +1 @@
5aa9c3eb45514d5eb7b32696d25a9aeb7dad485e1ea5adb833fac6d1f2105f1a
ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a

7
src/pager.c
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@ -5491,7 +5491,6 @@ static int getPageNormal(
assert( assert_pager_state(pPager) );
assert( pPager->hasHeldSharedLock==1 );
if( pgno==0 ) return SQLITE_CORRUPT_BKPT;
pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
if( pBase==0 ){
pPg = 0;
@ -5519,10 +5518,10 @@ static int getPageNormal(
/* The pager cache has created a new page. Its content needs to
** be initialized. But first some error checks:
**
** (*) obsolete. Was: maximum page number is 2^31
** (2) Never try to fetch the locking page
** (1) Never try to fetch the locking page
** (2) Never try to fetch page 0, which does not exist
*/
if( pgno==PAGER_SJ_PGNO(pPager) ){
if( pgno==PAGER_SJ_PGNO(pPager) || pgno==0 ){
rc = SQLITE_CORRUPT_BKPT;
goto pager_acquire_err;
}