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Overview
Comment: | Performance enhancements in the b-tree mutex logic. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
8914530644f938a7a98e25ea1fb0bca1 |
User & Date: | drh 2014-08-22 21:58:10.354 |
Context
2014-08-22
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22:26 | Factor the saveAllCursors() routine of btree.c into two separate routines, for a noticable performance improvement. (check-in: 3eb0843903 user: drh tags: trunk) | |
21:58 | Performance enhancements in the b-tree mutex logic. (check-in: 8914530644 user: drh tags: trunk) | |
20:35 | Combine the pcacheAddToDirtyList() and pcacheRemoveFromDirtyList() routines into a single pcacheManageDirtyList() routine. The resulting binary code is slightly faster and a few bytes smaller. (check-in: 6bcf1af6a4 user: drh tags: trunk) | |
Changes
Changes to src/btmutex.c.
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34 35 36 37 38 39 40 | p->locked = 1; } /* ** Release the BtShared mutex associated with B-Tree handle p and ** clear the p->locked boolean. */ | | > > > < < | 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 | p->locked = 1; } /* ** Release the BtShared mutex associated with B-Tree handle p and ** clear the p->locked boolean. */ static void SQLITE_NOINLINE unlockBtreeMutex(Btree *p){ BtShared *pBt = p->pBt; assert( p->locked==1 ); assert( sqlite3_mutex_held(pBt->mutex) ); assert( sqlite3_mutex_held(p->db->mutex) ); assert( p->db==pBt->db ); sqlite3_mutex_leave(pBt->mutex); p->locked = 0; } /* Forward reference */ static void SQLITE_NOINLINE btreeLockCarefully(Btree *p); /* ** Enter a mutex on the given BTree object. ** ** If the object is not sharable, then no mutex is ever required ** and this routine is a no-op. The underlying mutex is non-recursive. ** But we keep a reference count in Btree.wantToLock so the behavior ** of this interface is recursive. ** ** To avoid deadlocks, multiple Btrees are locked in the same order ** by all database connections. The p->pNext is a list of other ** Btrees belonging to the same database connection as the p Btree ** which need to be locked after p. If we cannot get a lock on ** p, then first unlock all of the others on p->pNext, then wait ** for the lock to become available on p, then relock all of the ** subsequent Btrees that desire a lock. */ void sqlite3BtreeEnter(Btree *p){ /* Some basic sanity checking on the Btree. The list of Btrees ** connected by pNext and pPrev should be in sorted order by ** Btree.pBt value. All elements of the list should belong to ** the same connection. Only shared Btrees are on the list. */ assert( p->pNext==0 || p->pNext->pBt>p->pBt ); assert( p->pPrev==0 || p->pPrev->pBt<p->pBt ); assert( p->pNext==0 || p->pNext->db==p->db ); |
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88 89 90 91 92 93 94 95 96 97 98 99 100 101 | /* Unless the database is sharable and unlocked, then BtShared.db ** should already be set correctly. */ assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db ); if( !p->sharable ) return; p->wantToLock++; if( p->locked ) return; /* In most cases, we should be able to acquire the lock we ** want without having to go throught the ascending lock ** procedure that follows. Just be sure not to block. */ if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){ p->pBt->db = p->db; | > > > > > > > > > > > | 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 | /* Unless the database is sharable and unlocked, then BtShared.db ** should already be set correctly. */ assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db ); if( !p->sharable ) return; p->wantToLock++; if( p->locked ) return; btreeLockCarefully(p); } /* This is a helper function for sqlite3BtreeLock(). By moving ** complex, but seldom used logic, out of sqlite3BtreeLock() and ** into this routine, we avoid unnecessary stack pointer changes ** and thus help the sqlite3BtreeLock() routine to run much faster ** in the common case. */ static void SQLITE_NOINLINE btreeLockCarefully(Btree *p){ Btree *pLater; /* In most cases, we should be able to acquire the lock we ** want without having to go throught the ascending lock ** procedure that follows. Just be sure not to block. */ if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){ p->pBt->db = p->db; |
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119 120 121 122 123 124 125 126 127 128 129 130 131 132 | lockBtreeMutex(p); for(pLater=p->pNext; pLater; pLater=pLater->pNext){ if( pLater->wantToLock ){ lockBtreeMutex(pLater); } } } /* ** Exit the recursive mutex on a Btree. */ void sqlite3BtreeLeave(Btree *p){ if( p->sharable ){ assert( p->wantToLock>0 ); | > | 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 | lockBtreeMutex(p); for(pLater=p->pNext; pLater; pLater=pLater->pNext){ if( pLater->wantToLock ){ lockBtreeMutex(pLater); } } } /* ** Exit the recursive mutex on a Btree. */ void sqlite3BtreeLeave(Btree *p){ if( p->sharable ){ assert( p->wantToLock>0 ); |
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