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Overview
| Comment: | Avoid running recovery while there is another read/write client. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | server-edition |
| Files: | files | file ages | folders |
| SHA3-256: |
a38858a24c6edaa05966b7e158e603bc |
| User & Date: | dan 2017-05-13 19:07:10 |
Context
|
2017-05-15
| ||
| 19:32 | Avoid writer starvation by adding a RESERVED state to page locks. (check-in: 9b7f8024 user: dan tags: server-edition) | |
|
2017-05-13
| ||
| 19:07 | Avoid running recovery while there is another read/write client. (check-in: a38858a2 user: dan tags: server-edition) | |
|
2017-05-12
| ||
| 18:52 | Require exclusive access to the db to wrap the wal file. Have "PRAGMA wal_checkpoint = restart" block for this. (check-in: cbf44ed9 user: dan tags: server-edition) | |
Changes
Changes to src/server.c.
508 509 510 511 512 513 514 515 516 |
v = *pSlot;
}
}
server_lock_out:
return rc;
}
#endif /* ifdef SQLITE_SERVER_EDITION */
|
> > > > > > > > |
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v = *pSlot;
}
}
server_lock_out:
return rc;
}
int sqlite3ServerHasLock(Server *p, Pgno pgno, int bWrite){
u32 v = *serverPageLockSlot(p, pgno);
if( bWrite ){
return (v>>HMA_CLIENT_SLOTS)==(p->iClient+1);
}
return (v & (1 << p->iClient))!=0;
}
#endif /* ifdef SQLITE_SERVER_EDITION */
|
Changes to src/server.h.
24 25 26 27 28 29 30 31 32 33 34 |
void sqlite3ServerDisconnect(Server *p, sqlite3_file *dbfd); int sqlite3ServerBegin(Server *p); int sqlite3ServerEnd(Server *p); int sqlite3ServerReleaseWriteLocks(Server *p); int sqlite3ServerLock(Server *p, Pgno pgno, int bWrite, int bBlock); #endif /* SQLITE_SERVER_H */ #endif /* SQLITE_SERVER_EDITION */ |
> > |
24 25 26 27 28 29 30 31 32 33 34 35 36 |
void sqlite3ServerDisconnect(Server *p, sqlite3_file *dbfd);
int sqlite3ServerBegin(Server *p);
int sqlite3ServerEnd(Server *p);
int sqlite3ServerReleaseWriteLocks(Server *p);
int sqlite3ServerLock(Server *p, Pgno pgno, int bWrite, int bBlock);
int sqlite3ServerHasLock(Server *p, Pgno pgno, int bWrite);
#endif /* SQLITE_SERVER_H */
#endif /* SQLITE_SERVER_EDITION */
|
Changes to src/wal.c.
2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 .... 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 .... 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 .... 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 |
testcase( pWal->szPage<=32768 );
testcase( pWal->szPage>=65536 );
}
/* The header was successfully read. Return zero. */
return 0;
}
/*
** Read the wal-index header from the wal-index and into pWal->hdr.
** If the wal-header appears to be corrupt, try to reconstruct the
** wal-index from the WAL before returning.
**
** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
................................................................................
/* If the first attempt failed, it might have been due to a race
** with a writer. So get a WRITE lock and try again.
*/
assert( badHdr==0 || pWal->writeLock==0 );
if( badHdr ){
if( pWal->readOnly & WAL_SHM_RDONLY ){
if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
walUnlockShared(pWal, WAL_WRITE_LOCK);
rc = SQLITE_READONLY_RECOVERY;
}
}else if( SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
pWal->writeLock = 1;
if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
badHdr = walIndexTryHdr(pWal, pChanged);
if( badHdr ){
/* If the wal-index header is still malformed even while holding
** a WRITE lock, it can only mean that the header is corrupted and
** needs to be reconstructed. So run recovery to do exactly that.
*/
rc = walIndexRecover(pWal);
*pChanged = 1;
}
}
pWal->writeLock = 0;
walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
}
}
/* If the header is read successfully, check the version number to make
** sure the wal-index was not constructed with some future format that
** this version of SQLite cannot understand.
*/
................................................................................
u32 iLast = pWal->hdr.mxFrame; /* Last page in WAL for this reader */
int iHash; /* Used to loop through N hash tables */
int iMinHash;
/* This routine is only be called from within a read transaction. */
assert( walIsServer(pWal) || pWal->readLock>=0 || pWal->lockError );
if( walIsServer(pWal) && pWal->writeLock==0 ){
/* A server mode connection must read from the most recent snapshot. */
iLast = walIndexHdr(pWal)->mxFrame;
}
/* If the "last page" field of the wal-index header snapshot is 0, then
** no data will be read from the wal under any circumstances. Return early
................................................................................
pWal->writeLock = 1;
rc = walIndexTryHdr(pWal, &bDummy);
}
if( rc!=SQLITE_OK ){
return rc;
}
}
/* If this frame set completes a transaction, then nTruncate>0. If
** nTruncate==0 then this frame set does not complete the transaction. */
assert( (isCommit!=0)==(nTruncate!=0) );
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
{ int cnt; for(cnt=0, p=pList; p; p=p->pDirty, cnt++){}
|
> > > > > > > > > | > | > > > > > |
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testcase( pWal->szPage<=32768 );
testcase( pWal->szPage>=65536 );
}
/* The header was successfully read. Return zero. */
return 0;
}
static int walIndexWriteLock(Wal *pWal){
if( walIsServer(pWal) ){
return sqlite3ServerLock(pWal->pServer, 0, 1, 0);
}else{
return walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
}
}
/*
** Read the wal-index header from the wal-index and into pWal->hdr.
** If the wal-header appears to be corrupt, try to reconstruct the
** wal-index from the WAL before returning.
**
** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
................................................................................
/* If the first attempt failed, it might have been due to a race
** with a writer. So get a WRITE lock and try again.
*/
assert( badHdr==0 || pWal->writeLock==0 );
if( badHdr ){
if( pWal->readOnly & WAL_SHM_RDONLY ){
assert( walIsServer(pWal)==0 );
if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
walUnlockShared(pWal, WAL_WRITE_LOCK);
rc = SQLITE_READONLY_RECOVERY;
}
}else if( SQLITE_OK==(rc = walIndexWriteLock(pWal)) ){
pWal->writeLock = 1;
if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
badHdr = walIndexTryHdr(pWal, pChanged);
if( badHdr ){
/* If the wal-index header is still malformed even while holding
** a WRITE lock, it can only mean that the header is corrupted and
** needs to be reconstructed. So run recovery to do exactly that.
*/
rc = walIndexRecover(pWal);
*pChanged = 1;
}
}
pWal->writeLock = 0;
if( walIsServer(pWal)==0 ){
walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
}
}
}
/* If the header is read successfully, check the version number to make
** sure the wal-index was not constructed with some future format that
** this version of SQLite cannot understand.
*/
................................................................................
u32 iLast = pWal->hdr.mxFrame; /* Last page in WAL for this reader */
int iHash; /* Used to loop through N hash tables */
int iMinHash;
/* This routine is only be called from within a read transaction. */
assert( walIsServer(pWal) || pWal->readLock>=0 || pWal->lockError );
assert( walIsServer(pWal)==0 || pWal->writeLock==0
|| sqlite3ServerHasLock(pWal->pServer, 0, 1)
);
if( walIsServer(pWal) && pWal->writeLock==0 ){
/* A server mode connection must read from the most recent snapshot. */
iLast = walIndexHdr(pWal)->mxFrame;
}
/* If the "last page" field of the wal-index header snapshot is 0, then
** no data will be read from the wal under any circumstances. Return early
................................................................................
pWal->writeLock = 1;
rc = walIndexTryHdr(pWal, &bDummy);
}
if( rc!=SQLITE_OK ){
return rc;
}
}
assert( walIsServer(pWal)==0 || sqlite3ServerHasLock(pWal->pServer, 0, 1) );
/* If this frame set completes a transaction, then nTruncate>0. If
** nTruncate==0 then this frame set does not complete the transaction. */
assert( (isCommit!=0)==(nTruncate!=0) );
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
{ int cnt; for(cnt=0, p=pList; p; p=p->pDirty, cnt++){}
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