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Comment edits and cleanup in wal.c. No functional code changes.

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FossilOrigin-Name: e8e666ab8273f5db5265f0773b39820f75b6df1a
This commit is contained in:
drh
2010-06-01 01:08:08 +00:00
parent ad24581e65
commit 181e091ff3
3 changed files with 25 additions and 22 deletions
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33
src/wal.c
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@@ -595,7 +595,8 @@ static int walDecodeFrame(
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
/*
** Names of locks.
** Names of locks. This routine is used to provide debugging output and is not
** a part of an ordinary build.
*/
static const char *walLockName(int lockIdx){
if( lockIdx==WAL_WRITE_LOCK ){
@@ -615,7 +616,9 @@ static const char *walLockName(int lockIdx){
/*
** Set or release locks.
** Set or release locks on the WAL. Locks are either shared or exclusive.
** A lock cannot be moved directly between shared and exclusive - it must go
** through the unlocked state first.
**
** In locking_mode=EXCLUSIVE, all of these routines become no-ops.
*/
@@ -674,10 +677,10 @@ static int walIndexEntry(u32 iFrame){
}
/*
** Return the minimum mapping size in bytes that can be used to read the
** wal-index up to and including frame iFrame. If iFrame is the last frame
** in a block of 256 frames, the returned byte-count includes the space
** required by the 256-byte index block.
** Return the minimum size of the shared-memory, in bytes, that is needed
** to support a wal-index containing frame iFrame. The value returned
** includes the wal-index header and the complete "block" containing iFrame,
** including the hash table segment that follows the block.
*/
static int walMappingSize(u32 iFrame){
const int nByte = (sizeof(u32)*HASHTABLE_NPAGE + HASHTABLE_NBYTE) ;
@@ -743,7 +746,8 @@ static int walIndexRemap(Wal *pWal, int enlargeTo){
/*
** Compute a hash on a page number. The resulting hash value must land
** between 0 and (HASHTABLE_NSLOT-1).
** between 0 and (HASHTABLE_NSLOT-1). The walHashNext() function advances
** the hash to the next value in the event of a collision.
*/
static int walHash(u32 iPage){
assert( iPage>0 );
@@ -806,9 +810,10 @@ static void walHashFind(
** This function is called whenever pWal->hdr.mxFrame is decreased due
** to a rollback or savepoint.
**
** At most only the very last hash table needs to be updated. Any
** later hash tables will be automatically cleared when pWal->hdr.mxFrame
** advances to the point where those hash tables are actually needed.
** At most only the hash table containing pWal->hdr.mxFrame needs to be
** updated. Any later hash tables will be automatically cleared when
** pWal->hdr.mxFrame advances to the point where those hash tables are
** actually needed.
*/
static void walCleanupHash(Wal *pWal){
volatile HASHTABLE_DATATYPE *aHash; /* Pointer to hash table to clear */
@@ -1089,14 +1094,12 @@ static void walIndexClose(Wal *pWal, int isDelete){
}
/*
** Open a connection to the log file associated with database zDb. The
** database file does not actually have to exist. zDb is used only to
** figure out the name of the log file to open. If the log file does not
** exist it is created by this call.
** Open a connection to the WAL file associated with database zDbName.
** The database file must already be opened on connection pDbFd.
**
** A SHARED lock should be held on the database file when this function
** is called. The purpose of this SHARED lock is to prevent any other
** client from unlinking the log or wal-index file. If another process
** client from unlinking the WAL or wal-index file. If another process
** were to do this just after this client opened one of these files, the
** system would be badly broken.
**