Store the page number for the PENDING_BYTE page in the Pager object, rather

than computing the page number every time it is needed, because it turns out
that number is needed quite frequently.  This saves a few hundred thousand
CPU cycles and a few bytes of code space.

FossilOrigin-Name: 5aa9c3eb45514d5eb7b32696d25a9aeb7dad485e1ea5adb833fac6d1f2105f1a

diff --git a/manifest b/manifest
index 1ee93b5f40aa3c2a45a24582f028a4caf3cacb5a..b39cd4588c498025f5d90a6cb662cdb29d609778 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C For\sthe\s"PRAGMA\sdatabase_list"\sstatement,\sdo\snot\scheck\sto\ssee\sif\sthe\sschema\nis\sup-to-date\sand\sdo\snot\stry\sto\sreload\sthe\sschema.
-D 2022-02-22T20:29:31.035
+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
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -494,7 +494,7 @@ F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
 F src/btree.c 117808943727d27e38c69de4e79237e52c89ee40f6f1a70de4e6e14b5e596cbc
 F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
-F src/btreeInt.h ee9348c4cb9077243b049edc93a82c1f32ca48baeabf2140d41362b9f9139ff7
+F src/btreeInt.h 7282a6e77775f93a6eb78d3a41dab372a01a4ec1d93d3b4728d191d15fda42e2
 F src/build.c 9891c2160886cf7e344d7e8f1f7177f9612916c7c67ffeacd64cb34a92d387a8
 F src/callback.c 4c19af69835787bfe790ac560f3071a824eb629f34e41f97b52ce5235c77de1c
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
@@ -539,8 +539,8 @@ 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 cda9e2d1df7c5fb4d777d09e23e69d78c518550d8873ed08b4a66c41d8cf2543
-F src/pager.h 4bf9b3213a4b2bebbced5eaa8b219cf25d4a82f385d093cd64b7e93e5285f66f
+F src/pager.c 198e037aa1f945e19cc4b4e89a80a40c31fc6beafacfe068fb3ca88cb602b523
+F src/pager.h f82e9844166e1585f5786837ddc7709966138ced17f568c16af7ccf946c2baa3
 F src/parse.y 0f02b27cdaa334441463153fff3ceb780fea006ab53ffd6ef566d4468f93e924
 F src/pcache.c 084e638432c610f95aea72b8509f0845d2791293f39d1b82f0c0a7e089c3bb6b
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
@@ -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 40fa792d359f84c3b9e9d6623743e1a59826274e221df1bde8f47086968a1bab
-R 8e774d76a97f244938c2cd31e6e650dd
+P 710de6a2137c872812effa43ea888aa77d339362ca0b6c8990d4426c8fb20689
+R 31db230ec1e00447c3c5dedc2a12edf4
 U drh
-Z 87215546f30ba5e5b58306e47d0efae5
+Z d8442a86814fe9e42893b593cc0d0a34
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index 30ca50acbdf7377e18d65521ed608f819dde8efe..0daec02da3dcad68883074f2b72fe124b615298a 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-710de6a2137c872812effa43ea888aa77d339362ca0b6c8990d4426c8fb20689
\ No newline at end of file
+5aa9c3eb45514d5eb7b32696d25a9aeb7dad485e1ea5adb833fac6d1f2105f1a
\ No newline at end of file

diff --git a/src/btreeInt.h b/src/btreeInt.h
index 1076fd8f2ca394eff503ecd98d888333eb194956..e038f313e2fbb929b214d15e5ca12239d3f61cf2 100644 (file)
--- a/src/btreeInt.h
+++ b/src/btreeInt.h
@@ -598,7 +598,7 @@ struct BtCursor {
 /* 
 ** The database page the PENDING_BYTE occupies. This page is never used.
 */
-# define PENDING_BYTE_PAGE(pBt) PAGER_MJ_PGNO(pBt)
+#define PENDING_BYTE_PAGE(pBt)  ((Pgno)((PENDING_BYTE/((pBt)->pageSize))+1))
 
 /*
 ** These macros define the location of the pointer-map entry for a 

diff --git a/src/pager.c b/src/pager.c
index 15bd9a22fe57c1c7a42d0ff0c52e7241989f677a..5d0aa73775ee8e7b10ea50826403d43a9430331d 100644 (file)
--- a/src/pager.c
+++ b/src/pager.c
@@ -681,6 +681,7 @@ struct Pager {
   u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */
   u32 sectorSize;             /* Assumed sector size during rollback */
   Pgno mxPgno;                /* Maximum allowed size of the database */
+  Pgno lckPgno;               /* Page number for the locking page */
   i64 pageSize;               /* Number of bytes in a page */
   i64 journalSizeLimit;       /* Size limit for persistent journal files */
   char *zFilename;            /* Name of the database file */
@@ -1667,7 +1668,7 @@ static int readJournalHdr(
 ** journal file descriptor is advanced to the next sector boundary before
 ** anything is written. The format is:
 **
-**   + 4 bytes: PAGER_MJ_PGNO.
+**   + 4 bytes: PAGER_SJ_PGNO.
 **   + N bytes: super-journal filename in utf-8.
 **   + 4 bytes: N (length of super-journal name in bytes, no nul-terminator).
 **   + 4 bytes: super-journal name checksum.
@@ -1715,7 +1716,7 @@ static int writeSuperJournal(Pager *pPager, const char *zSuper){
   /* Write the super-journal data to the end of the journal file. If
   ** an error occurs, return the error code to the caller.
   */
-  if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
+  if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_SJ_PGNO(pPager))))
    || (0 != (rc = sqlite3OsWrite(pPager->jfd, zSuper, nSuper, iHdrOff+4)))
    || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nSuper, nSuper)))
    || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nSuper+4, cksum)))
@@ -2225,7 +2226,7 @@ static u32 pager_cksum(Pager *pPager, const u8 *aData){
 ** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
 ** two circumstances:
 ** 
-**   * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
+**   * If the record page-number is illegal (0 or PAGER_SJ_PGNO), or
 **   * If the record is being rolled back from the main journal file
 **     and the checksum field does not match the record content.
 **
@@ -2285,7 +2286,7 @@ static int pager_playback_one_page(
   ** it could cause invalid data to be written into the journal.  We need to
   ** detect this invalid data (with high probability) and ignore it.
   */
-  if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
+  if( pgno==0 || pgno==PAGER_SJ_PGNO(pPager) ){
     assert( !isSavepnt );
     return SQLITE_DONE;
   }
@@ -3740,6 +3741,7 @@ int sqlite3PagerSetPagesize(Pager *pPager, u32 *pPageSize, int nReserve){
       pPager->pTmpSpace = pNew;
       pPager->dbSize = (Pgno)((nByte+pageSize-1)/pageSize);
       pPager->pageSize = pageSize;
+      pPager->lckPgno = (Pgno)(PENDING_BYTE/pageSize) + 1;
     }else{
       sqlite3PageFree(pNew);
     }
@@ -5509,7 +5511,7 @@ static int getPageNormal(
   if( pPg->pPager && !noContent ){
     /* In this case the pcache already contains an initialized copy of
     ** the page. Return without further ado.  */
-    assert( pgno!=PAGER_MJ_PGNO(pPager) );
+    assert( pgno!=PAGER_SJ_PGNO(pPager) );
     pPager->aStat[PAGER_STAT_HIT]++;
     return SQLITE_OK;
 
@@ -5520,7 +5522,7 @@ static int getPageNormal(
     ** (*) obsolete.  Was: maximum page number is 2^31
     ** (2) Never try to fetch the locking page
     */
-    if( pgno==PAGER_MJ_PGNO(pPager) ){
+    if( pgno==PAGER_SJ_PGNO(pPager) ){
       rc = SQLITE_CORRUPT_BKPT;
       goto pager_acquire_err;
     }
@@ -5919,7 +5921,7 @@ static SQLITE_NOINLINE int pagerAddPageToRollbackJournal(PgHdr *pPg){
   /* We should never write to the journal file the page that
   ** contains the database locks.  The following assert verifies
   ** that we do not. */
-  assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
+  assert( pPg->pgno!=PAGER_SJ_PGNO(pPager) );
 
   assert( pPager->journalHdr<=pPager->journalOff );
   pData2 = pPg->pData;
@@ -6098,7 +6100,7 @@ static SQLITE_NOINLINE int pagerWriteLargeSector(PgHdr *pPg){
     Pgno pg = pg1+ii;
     PgHdr *pPage;
     if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
-      if( pg!=PAGER_MJ_PGNO(pPager) ){
+      if( pg!=PAGER_SJ_PGNO(pPager) ){
         rc = sqlite3PagerGet(pPager, pg, &pPage, 0);
         if( rc==SQLITE_OK ){
           rc = pager_write(pPage);
@@ -6576,7 +6578,7 @@ int sqlite3PagerCommitPhaseOne(
       ** last page is never written out to disk, leaving the database file
       ** undersized. Fix this now if it is the case.  */
       if( pPager->dbSize>pPager->dbFileSize ){
-        Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
+        Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_SJ_PGNO(pPager));
         assert( pPager->eState==PAGER_WRITER_DBMOD );
         rc = pager_truncate(pPager, nNew);
         if( rc!=SQLITE_OK ) goto commit_phase_one_exit;

diff --git a/src/pager.h b/src/pager.h
index 8d899bd1a6e0089649896048e23fab571cf67566..eb1306096c928049173f076d0e1a1d77abd7ad3e 100644 (file)
--- a/src/pager.h
+++ b/src/pager.h
@@ -43,14 +43,15 @@ typedef struct Pager Pager;
 typedef struct PgHdr DbPage;
 
 /*
-** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
+** Page number PAGER_SJ_PGNO is never used in an SQLite database (it is
 ** reserved for working around a windows/posix incompatibility). It is
 ** used in the journal to signify that the remainder of the journal file 
 ** is devoted to storing a super-journal name - there are no more pages to
 ** roll back. See comments for function writeSuperJournal() in pager.c 
 ** for details.
 */
-#define PAGER_MJ_PGNO(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))
+#define PAGER_SJ_PGNO_COMPUTED(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))
+#define PAGER_SJ_PGNO(x)          ((x)->lckPgno)
 
 /*
 ** Allowed values for the flags parameter to sqlite3PagerOpen().