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Overview
| Comment: | Add the new PGHDR_CLEAN bit to PgHdr.flags in pcache.c. This bit is always the opposite of PGHDR_DIRTY. Use the extra bit to avoid a comparison for a small performance boost. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 8619fc346d9a5a66a3c4566b4cc032b6 |
| User & Date: | drh 2015-06-29 04:21:15 |
Context
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2015-06-29
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| 14:11 | Simplifications and performance improvement in pager_write(). check-in: ab7aeeea user: drh tags: trunk | |
| 04:21 | Add the new PGHDR_CLEAN bit to PgHdr.flags in pcache.c. This bit is always the opposite of PGHDR_DIRTY. Use the extra bit to avoid a comparison for a small performance boost. check-in: 8619fc34 user: drh tags: trunk | |
| 03:28 | Very small size reduction and performance increase in sqlite3BitvecTest(). check-in: 9b3a7281 user: drh tags: trunk | |
Changes
Changes to src/pcache.c.
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memset(pPgHdr, 0, sizeof(PgHdr)); pPgHdr->pPage = pPage; pPgHdr->pData = pPage->pBuf; pPgHdr->pExtra = (void *)&pPgHdr[1]; memset(pPgHdr->pExtra, 0, pCache->szExtra); pPgHdr->pCache = pCache; pPgHdr->pgno = pgno; return sqlite3PcacheFetchFinish(pCache,pgno,pPage); } /* ** This routine converts the sqlite3_pcache_page object returned by ** sqlite3PcacheFetch() into an initialized PgHdr object. This routine ** must be called after sqlite3PcacheFetch() in order to get a usable ................................................................................ ** reference count drops to 0, then it is made eligible for recycling. */ void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){ assert( p->nRef>0 ); p->nRef--; if( p->nRef==0 ){ p->pCache->nRef--; if( (p->flags&PGHDR_DIRTY)==0 ){ pcacheUnpin(p); }else if( p->pDirtyPrev!=0 ){ /* Move the page to the head of the dirty list. */ pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT); } } } ................................................................................ } /* ** Make sure the page is marked as dirty. If it isn't dirty already, ** make it so. */ void sqlite3PcacheMakeDirty(PgHdr *p){ p->flags &= ~PGHDR_DONT_WRITE; assert( p->nRef>0 ); if( 0==(p->flags & PGHDR_DIRTY) ){ p->flags |= PGHDR_DIRTY; pcacheManageDirtyList(p, PCACHE_DIRTYLIST_ADD); } } /* ** Make sure the page is marked as clean. If it isn't clean already, ** make it so. */ void sqlite3PcacheMakeClean(PgHdr *p){ if( (p->flags & PGHDR_DIRTY) ){ pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE); p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC); if( p->nRef==0 ){ pcacheUnpin(p); } } } /* |
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memset(pPgHdr, 0, sizeof(PgHdr)); pPgHdr->pPage = pPage; pPgHdr->pData = pPage->pBuf; pPgHdr->pExtra = (void *)&pPgHdr[1]; memset(pPgHdr->pExtra, 0, pCache->szExtra); pPgHdr->pCache = pCache; pPgHdr->pgno = pgno; pPgHdr->flags = PGHDR_CLEAN; return sqlite3PcacheFetchFinish(pCache,pgno,pPage); } /* ** This routine converts the sqlite3_pcache_page object returned by ** sqlite3PcacheFetch() into an initialized PgHdr object. This routine ** must be called after sqlite3PcacheFetch() in order to get a usable ................................................................................ ** reference count drops to 0, then it is made eligible for recycling. */ void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){ assert( p->nRef>0 ); p->nRef--; if( p->nRef==0 ){ p->pCache->nRef--; if( p->flags&PGHDR_CLEAN ){ pcacheUnpin(p); }else if( p->pDirtyPrev!=0 ){ /* Move the page to the head of the dirty list. */ pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT); } } } ................................................................................ } /* ** Make sure the page is marked as dirty. If it isn't dirty already, ** make it so. */ void sqlite3PcacheMakeDirty(PgHdr *p){ assert( p->nRef>0 ); if( p->flags & (PGHDR_CLEAN|PGHDR_DONT_WRITE) ){ p->flags &= ~PGHDR_DONT_WRITE; if( p->flags & PGHDR_CLEAN ){ p->flags ^= (PGHDR_DIRTY|PGHDR_CLEAN); assert( (p->flags & (PGHDR_DIRTY|PGHDR_CLEAN))==PGHDR_DIRTY ); pcacheManageDirtyList(p, PCACHE_DIRTYLIST_ADD); } } } /* ** Make sure the page is marked as clean. If it isn't clean already, ** make it so. */ void sqlite3PcacheMakeClean(PgHdr *p){ if( (p->flags & PGHDR_DIRTY) ){ assert( (p->flags & PGHDR_CLEAN)==0 ); pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE); p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC); p->flags |= PGHDR_CLEAN; if( p->nRef==0 ){ pcacheUnpin(p); } } } /* |
Changes to src/pcache.h.
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PCache *pCache; /* Cache that owns this page */
PgHdr *pDirtyNext; /* Next element in list of dirty pages */
PgHdr *pDirtyPrev; /* Previous element in list of dirty pages */
};
/* Bit values for PgHdr.flags */
#define PGHDR_DIRTY 0x002 /* Page has changed */
#define PGHDR_NEED_SYNC 0x004 /* Fsync the rollback journal before
** writing this page to the database */
#define PGHDR_NEED_READ 0x008 /* Content is unread */
#define PGHDR_REUSE_UNLIKELY 0x010 /* A hint that reuse is unlikely */
#define PGHDR_DONT_WRITE 0x020 /* Do not write content to disk */
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PCache *pCache; /* Cache that owns this page */
PgHdr *pDirtyNext; /* Next element in list of dirty pages */
PgHdr *pDirtyPrev; /* Previous element in list of dirty pages */
};
/* Bit values for PgHdr.flags */
#define PGHDR_CLEAN 0x001 /* Page is unchanged */
#define PGHDR_DIRTY 0x002 /* Page has changed */
#define PGHDR_NEED_SYNC 0x004 /* Fsync the rollback journal before
** writing this page to the database */
#define PGHDR_NEED_READ 0x008 /* Content is unread */
#define PGHDR_REUSE_UNLIKELY 0x010 /* A hint that reuse is unlikely */
#define PGHDR_DONT_WRITE 0x020 /* Do not write content to disk */
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