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Comment cleanup in btree.c.

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FossilOrigin-Name: 32966ba4796e70d0afcff6abdda9bdcba08b098a
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drh
2009-10-16 15:05:18 +00:00
parent fa401def25
commit 0ee3dbef79
3 changed files with 80 additions and 47 deletions
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24
manifest
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@@ -1,5 +1,8 @@
C Experimental\sfix\sfor\s[f777251dc7].\sThis\smay\sbe\schanged\syet. -----BEGIN PGP SIGNED MESSAGE-----
D 2009-10-16T14:55:03 Hash: SHA1
C Comment\scleanup\sin\sbtree.c.
D 2009-10-16T15:05:19
F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
F Makefile.in 4ca3f1dd6efa2075bcb27f4dc43eef749877740d F Makefile.in 4ca3f1dd6efa2075bcb27f4dc43eef749877740d
F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -106,7 +109,7 @@ F src/auth.c a5471a6951a18f79d783da34be22cd94dfbe603a
F src/backup.c 6f1c2d9862c8a3feb7739dfcca02c1f5352e37f3 F src/backup.c 6f1c2d9862c8a3feb7739dfcca02c1f5352e37f3
F src/bitvec.c ed215b95734045e58358c3b3e16448f8fe6a235a F src/bitvec.c ed215b95734045e58358c3b3e16448f8fe6a235a
F src/btmutex.c 0f43a75bb5b8147b386e8e1c3e71ba734e3863b7 F src/btmutex.c 0f43a75bb5b8147b386e8e1c3e71ba734e3863b7
F src/btree.c 953ad6635e39df97bcd5ff6983128622c634e9f6 F src/btree.c b2d060e41b4318fb5e52d80b75e19bcef1b1f2db
F src/btree.h 577448a890c2ab9b21e6ab74f073526184bceebe F src/btree.h 577448a890c2ab9b21e6ab74f073526184bceebe
F src/btreeInt.h cce1c3360cd5549ffa79f981951dfae93118ad79 F src/btreeInt.h cce1c3360cd5549ffa79f981951dfae93118ad79
F src/build.c 3c5762687d0554ebe8844dfaddb828fcc15fe16d F src/build.c 3c5762687d0554ebe8844dfaddb828fcc15fe16d
@@ -758,7 +761,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
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R 778bb64a8b1c35d3d0457babdafdb276 R 86490e3083ac0bc0fd081f22ec541c2a
U dan U drh
Z b88fc6ff2b43f8e3419b27ff47f04190 Z b17767b2b8f9c8009e027786b6c3af45
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2
manifest.uuid
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@@ -1 +1 @@
174477bca05d019e663fd2b7cd031189ab2e010a 32966ba4796e70d0afcff6abdda9bdcba08b098a

101
src/btree.c
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@@ -90,22 +90,24 @@ int sqlite3_enable_shared_cache(int enable){
#ifdef SQLITE_DEBUG #ifdef SQLITE_DEBUG
/* /*
** This function is only used as part of an assert() statement. It checks **** This function is only used as part of an assert() statement. ***
** that connection p holds the required locks to read or write to the **
** b-tree with root page iRoot. If so, true is returned. Otherwise, false. ** Check to see if pBtree holds the required locks to read or write to the
** For example, when writing to a table b-tree with root-page iRoot via ** table with root page iRoot. Return 1 if it does and 0 if not.
**
** For example, when writing to a table with root-page iRoot via
** Btree connection pBtree: ** Btree connection pBtree:
** **
** assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) ); ** assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) );
** **
** When writing to an index b-tree that resides in a sharable database, the ** When writing to an index that resides in a sharable database, the
** caller should have first obtained a lock specifying the root page of ** caller should have first obtained a lock specifying the root page of
** the corresponding table b-tree. This makes things a bit more complicated, ** the corresponding table. This makes things a bit more complicated,
** as this module treats each b-tree as a separate structure. To determine ** as this module treats each table as a separate structure. To determine
** the table b-tree corresponding to the index b-tree being written, this ** the table corresponding to the index being written, this
** function has to search through the database schema. ** function has to search through the database schema.
** **
** Instead of a lock on the b-tree rooted at page iRoot, the caller may ** Instead of a lock on the table/index rooted at page iRoot, the caller may
** hold a write-lock on the schema table (root page 1). This is also ** hold a write-lock on the schema table (root page 1). This is also
** acceptable. ** acceptable.
*/ */
@@ -119,20 +121,25 @@ static int hasSharedCacheTableLock(
Pgno iTab = 0; Pgno iTab = 0;
BtLock *pLock; BtLock *pLock;
/* If this b-tree database is not shareable, or if the client is reading /* If this database is not shareable, or if the client is reading
** and has the read-uncommitted flag set, then no lock is required. ** and has the read-uncommitted flag set, then no lock is required.
** In these cases return true immediately. If the client is reading ** Return true immediately.
** or writing an index b-tree, but the schema is not loaded, then return */
** true also. In this case the lock is required, but it is too difficult
** to check if the client actually holds it. This doesn't happen very
** often. */
if( (pBtree->sharable==0) if( (pBtree->sharable==0)
|| (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommitted)) || (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommitted))
|| (isIndex && (!pSchema || (pSchema->flags&DB_SchemaLoaded)==0 ))
){ ){
return 1; return 1;
} }
/* If the client is reading or writing an index and the schema is
** not loaded, then it is too difficult to actually check to see if
** the correct locks are held. So do not bother - just return true.
** This case does not come up very often anyhow.
*/
if( isIndex && (!pSchema || (pSchema->flags&DB_SchemaLoaded)==0) ){
return 1;
}
/* Figure out the root-page that the lock should be held on. For table /* Figure out the root-page that the lock should be held on. For table
** b-trees, this is just the root page of the b-tree being read or ** b-trees, this is just the root page of the b-tree being read or
** written. For index b-trees, it is the root page of the associated ** written. For index b-trees, it is the root page of the associated
@@ -164,14 +171,24 @@ static int hasSharedCacheTableLock(
/* Failed to find the required lock. */ /* Failed to find the required lock. */
return 0; return 0;
} }
#endif /* SQLITE_DEBUG */
#ifdef SQLITE_DEBUG
/* /*
** This function is also used as part of assert() statements only. It **** This function may be used as part of assert() statements only. ****
** returns true if there exist one or more cursors open on the table
** with root page iRoot that do not belong to either connection pBtree
** or some other connection that has the read-uncommitted flag set.
** **
** For example, before writing to page iRoot: ** Return true if it would be illegal for pBtree to write into the
** table or index rooted at iRoot because other shared connections are
** simultaneously reading that same table or index.
**
** It is illegal for pBtree to write if some other Btree object that
** shares the same BtShared object is currently reading or writing
** the iRoot table. Except, if the other Btree object has the
** read-uncommitted flag set, then it is OK for the other object to
** have a read cursor.
**
** For example, before writing to any part of the table or index
** rooted at page iRoot, one should call:
** **
** assert( !hasReadConflicts(pBtree, iRoot) ); ** assert( !hasReadConflicts(pBtree, iRoot) );
*/ */
@@ -190,7 +207,7 @@ static int hasReadConflicts(Btree *pBtree, Pgno iRoot){
#endif /* #ifdef SQLITE_DEBUG */ #endif /* #ifdef SQLITE_DEBUG */
/* /*
** Query to see if btree handle p may obtain a lock of type eLock ** Query to see if Btree handle p may obtain a lock of type eLock
** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return ** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
** SQLITE_OK if the lock may be obtained (by calling ** SQLITE_OK if the lock may be obtained (by calling
** setSharedCacheTableLock()), or SQLITE_LOCKED if not. ** setSharedCacheTableLock()), or SQLITE_LOCKED if not.
@@ -211,7 +228,7 @@ static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){
assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) ); assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) );
assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE ); assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE );
/* This is a no-op if the shared-cache is not enabled */ /* This routine is a no-op if the shared-cache is not enabled */
if( !p->sharable ){ if( !p->sharable ){
return SQLITE_OK; return SQLITE_OK;
} }
@@ -257,10 +274,10 @@ static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){
** **
** This function assumes the following: ** This function assumes the following:
** **
** (a) The specified b-tree connection handle is connected to a sharable ** (a) The specified Btree object p is connected to a sharable
** b-tree database (one with the BtShared.sharable) flag set, and ** database (one with the BtShared.sharable flag set), and
** **
** (b) No other b-tree connection handle holds a lock that conflicts ** (b) No other Btree objects hold a lock that conflicts
** with the requested lock (i.e. querySharedCacheTableLock() has ** with the requested lock (i.e. querySharedCacheTableLock() has
** already been called and returned SQLITE_OK). ** already been called and returned SQLITE_OK).
** **
@@ -325,9 +342,9 @@ static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
#ifndef SQLITE_OMIT_SHARED_CACHE #ifndef SQLITE_OMIT_SHARED_CACHE
/* /*
** Release all the table locks (locks obtained via calls to ** Release all the table locks (locks obtained via calls to
** the setSharedCacheTableLock() procedure) held by Btree handle p. ** the setSharedCacheTableLock() procedure) held by Btree object p.
** **
** This function assumes that handle p has an open read or write ** This function assumes that Btree p has an open read or write
** transaction. If it does not, then the BtShared.isPending variable ** transaction. If it does not, then the BtShared.isPending variable
** may be incorrectly cleared. ** may be incorrectly cleared.
*/ */
@@ -360,7 +377,7 @@ static void clearAllSharedCacheTableLocks(Btree *p){
pBt->isExclusive = 0; pBt->isExclusive = 0;
pBt->isPending = 0; pBt->isPending = 0;
}else if( pBt->nTransaction==2 ){ }else if( pBt->nTransaction==2 ){
/* This function is called when connection p is concluding its /* This function is called when Btree p is concluding its
** transaction. If there currently exists a writer, and p is not ** transaction. If there currently exists a writer, and p is not
** that writer, then the number of locks held by connections other ** that writer, then the number of locks held by connections other
** than the writer must be about to drop to zero. In this case ** than the writer must be about to drop to zero. In this case
@@ -374,7 +391,7 @@ static void clearAllSharedCacheTableLocks(Btree *p){
} }
/* /*
** This function changes all write-locks held by connection p to read-locks. ** This function changes all write-locks held by Btree p into read-locks.
*/ */
static void downgradeAllSharedCacheTableLocks(Btree *p){ static void downgradeAllSharedCacheTableLocks(Btree *p){
BtShared *pBt = p->pBt; BtShared *pBt = p->pBt;
@@ -395,9 +412,11 @@ static void downgradeAllSharedCacheTableLocks(Btree *p){
static void releasePage(MemPage *pPage); /* Forward reference */ static void releasePage(MemPage *pPage); /* Forward reference */
/* /*
** Verify that the cursor holds a mutex on the BtShared ***** This routine is used inside of assert() only ****
**
** Verify that the cursor holds the mutex on its BtShared
*/ */
#ifndef NDEBUG #ifdef SQLITE_DEBUG
static int cursorHoldsMutex(BtCursor *p){ static int cursorHoldsMutex(BtCursor *p){
return sqlite3_mutex_held(p->pBt->mutex); return sqlite3_mutex_held(p->pBt->mutex);
} }
@@ -428,7 +447,7 @@ static void invalidateAllOverflowCache(BtShared *pBt){
/* /*
** This function is called before modifying the contents of a table ** This function is called before modifying the contents of a table
** b-tree to invalidate any incrblob cursors that are open on the ** to invalidate any incrblob cursors that are open on the
** row or one of the rows being modified. ** row or one of the rows being modified.
** **
** If argument isClearTable is true, then the entire contents of the ** If argument isClearTable is true, then the entire contents of the
@@ -437,7 +456,7 @@ static void invalidateAllOverflowCache(BtShared *pBt){
** **
** Otherwise, if argument isClearTable is false, then the row with ** Otherwise, if argument isClearTable is false, then the row with
** rowid iRow is being replaced or deleted. In this case invalidate ** rowid iRow is being replaced or deleted. In this case invalidate
** only those incrblob cursors open on this specific row. ** only those incrblob cursors open on that specific row.
*/ */
static void invalidateIncrblobCursors( static void invalidateIncrblobCursors(
Btree *pBtree, /* The database file to check */ Btree *pBtree, /* The database file to check */
@@ -455,10 +474,11 @@ static void invalidateIncrblobCursors(
} }
#else #else
/* Stub functions when INCRBLOB is omitted */
#define invalidateOverflowCache(x) #define invalidateOverflowCache(x)
#define invalidateAllOverflowCache(x) #define invalidateAllOverflowCache(x)
#define invalidateIncrblobCursors(x,y,z) #define invalidateIncrblobCursors(x,y,z)
#endif #endif /* SQLITE_OMIT_INCRBLOB */
/* /*
** Set bit pgno of the BtShared.pHasContent bitvec. This is called ** Set bit pgno of the BtShared.pHasContent bitvec. This is called
@@ -491,7 +511,7 @@ static void invalidateIncrblobCursors(
** The solution is the BtShared.pHasContent bitvec. Whenever a page is ** The solution is the BtShared.pHasContent bitvec. Whenever a page is
** moved to become a free-list leaf page, the corresponding bit is ** moved to become a free-list leaf page, the corresponding bit is
** set in the bitvec. Whenever a leaf page is extracted from the free-list, ** set in the bitvec. Whenever a leaf page is extracted from the free-list,
** optimization 2 above is ommitted if the corresponding bit is already ** optimization 2 above is omitted if the corresponding bit is already
** set in BtShared.pHasContent. The contents of the bitvec are cleared ** set in BtShared.pHasContent. The contents of the bitvec are cleared
** at the end of every transaction. ** at the end of every transaction.
*/ */
@@ -587,8 +607,8 @@ static int saveCursorPosition(BtCursor *pCur){
} }
/* /*
** Save the positions of all cursors except pExcept open on the table ** Save the positions of all cursors (except pExcept) that are open on
** with root-page iRoot. Usually, this is called just before cursor ** the table with root-page iRoot. Usually, this is called just before cursor
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()). ** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/ */
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){ static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
@@ -993,7 +1013,10 @@ static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
assert( nSize==debuginfo.nSize ); assert( nSize==debuginfo.nSize );
return (u16)nSize; return (u16)nSize;
} }
#ifndef NDEBUG
#ifdef SQLITE_DEBUG
/* This variation on cellSizePtr() is used inside of assert() statements
** only. */
static u16 cellSize(MemPage *pPage, int iCell){ static u16 cellSize(MemPage *pPage, int iCell){
return cellSizePtr(pPage, findCell(pPage, iCell)); return cellSizePtr(pPage, findCell(pPage, iCell));
} }