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Overview
Comment: | Delay the decision to restart the log file until data is actually ready to be written to the log file (instead of at the start of a write transaction). |
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Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
b1abfaaf5309cc0d0dda4fb2c237862c |
User & Date: | dan 2010-06-01 15:44:57.000 |
Context
2010-06-01
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17:46 | Change the OOM and IO error test cases in walfault.test so that each test case runs both types of error simulation. (check-in: b627e15368 user: dan tags: trunk) | |
15:44 | Delay the decision to restart the log file until data is actually ready to be written to the log file (instead of at the start of a write transaction). (check-in: b1abfaaf53 user: dan tags: trunk) | |
15:24 | The incremental checkpoint feature is not perfect yet, but it is working well enough to merge it into the trunk. (check-in: 1d3e569e59 user: drh tags: trunk) | |
Changes
Changes to src/wal.c.
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1998 1999 2000 2001 2002 2003 2004 | ** thread to write as doing so would cause a fork. So this routine ** returns SQLITE_BUSY in that case and no write transaction is started. ** ** There can only be a single writer active at a time. */ int sqlite3WalBeginWriteTransaction(Wal *pWal){ int rc; | < | 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 | ** thread to write as doing so would cause a fork. So this routine ** returns SQLITE_BUSY in that case and no write transaction is started. ** ** There can only be a single writer active at a time. */ int sqlite3WalBeginWriteTransaction(Wal *pWal){ int rc; /* Cannot start a write transaction without first holding a read ** transaction. */ assert( pWal->readLock>=0 ); /* Only one writer allowed at a time. Get the write lock. Return ** SQLITE_BUSY if unable. |
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2026 2027 2028 2029 2030 2031 2032 | walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1); pWal->writeLock = 0; return rc; } if( memcmp(&pWal->hdr, (void*)pWal->pWiData, sizeof(WalIndexHdr))!=0 ){ walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1); pWal->writeLock = 0; | < | < < < < < < < < < < < < < < < < < < < < < < < < < < < < < | 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 | walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1); pWal->writeLock = 0; return rc; } if( memcmp(&pWal->hdr, (void*)pWal->pWiData, sizeof(WalIndexHdr))!=0 ){ walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1); pWal->writeLock = 0; rc = SQLITE_BUSY; } walIndexUnmap(pWal); return rc; } /* ** End a write transaction. The commit has already been done. This ** routine merely releases the lock. |
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2145 2146 2147 2148 2149 2150 2151 2152 | if( rc==SQLITE_OK ){ walCleanupHash(pWal); walIndexUnmap(pWal); } } return rc; } | | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | | 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 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 | if( rc==SQLITE_OK ){ walCleanupHash(pWal); walIndexUnmap(pWal); } } return rc; } /* ** This function is called just before writing a set of frames to the log ** file (see sqlite3WalFrames()). It checks to see if, instead of appending ** to the current log file, it is possible to overwrite the start of the ** existing log file with the new frames (i.e. "reset" the log). If so, ** it sets pWal->hdr.mxFrame to 0. Otherwise, pWal->hdr.mxFrame is left ** unchanged. ** ** SQLITE_OK is returned if no error is encountered (regardless of whether ** or not pWal->hdr.mxFrame is modified). An SQLite error code is returned ** if some error */ static int walRestartLog(Wal *pWal){ int rc = SQLITE_OK; if( pWal->readLock==0 && SQLITE_OK==(rc = walIndexMap(pWal, walMappingSize(pWal->hdr.mxFrame))) ){ volatile WalCkptInfo *pInfo = walCkptInfo(pWal); assert( pInfo->nBackfill==pWal->hdr.mxFrame ); if( pInfo->nBackfill>0 ){ rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1); if( rc==SQLITE_OK ){ /* If all readers are using WAL_READ_LOCK(0) (in other words if no ** readers are currently using the WAL), then the transactions ** frames will overwrite the start of the existing log. Update the ** wal-index header to reflect this. ** ** In theory it would be Ok to update the cache of the header only ** at this point. But updating the actual wal-index header is also ** safe and means there is no special case for sqlite3WalUndo() ** to handle if this transaction is rolled back. */ u32 *aSalt = pWal->hdr.aSalt; /* Big-endian salt values */ pWal->nCkpt++; pWal->hdr.mxFrame = 0; sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0])); sqlite3_randomness(4, &aSalt[1]); walIndexWriteHdr(pWal); memset((void*)pInfo, 0, sizeof(*pInfo)); walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1); } } walUnlockShared(pWal, WAL_READ_LOCK(0)); pWal->readLock = -1; do{ int notUsed; rc = walTryBeginRead(pWal, ¬Used, 1); }while( rc==WAL_RETRY ); /* Unmap the wal-index before returning. Otherwise the VFS layer may ** hold a mutex for the duration of the IO performed by WalFrames(). */ walIndexUnmap(pWal); } return rc; } /* ** Write a set of frames to the log. The caller must hold the write-lock ** on the log file (obtained using sqlite3WalBeginWriteTransaction()). */ int sqlite3WalFrames( Wal *pWal, /* Wal handle to write to */ int szPage, /* Database page-size in bytes */ PgHdr *pList, /* List of dirty pages to write */ Pgno nTruncate, /* Database size after this commit */ int isCommit, /* True if this is a commit */ |
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2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 | #if defined(SQLITE_TEST) && defined(SQLITE_DEBUG) { int cnt; for(cnt=0, p=pList; p; p=p->pDirty, cnt++){} WALTRACE(("WAL%p: frame write begin. %d frames. mxFrame=%d. %s\n", pWal, cnt, pWal->hdr.mxFrame, isCommit ? "Commit" : "Spill")); } #endif /* If this is the first frame written into the log, write the WAL ** header to the start of the WAL file. See comments at the top of ** this source file for a description of the WAL header format. */ iFrame = pWal->hdr.mxFrame; if( iFrame==0 ){ | > > > > > > > > > | 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 | #if defined(SQLITE_TEST) && defined(SQLITE_DEBUG) { int cnt; for(cnt=0, p=pList; p; p=p->pDirty, cnt++){} WALTRACE(("WAL%p: frame write begin. %d frames. mxFrame=%d. %s\n", pWal, cnt, pWal->hdr.mxFrame, isCommit ? "Commit" : "Spill")); } #endif /* See if it is possible to write these frames into the start of the ** log file, instead of appending to it at pWal->hdr.mxFrame. */ if( SQLITE_OK!=(rc = walRestartLog(pWal)) ){ assert( pWal->pWiData==0 ); return rc; } assert( pWal->pWiData==0 && pWal->readLock>0 ); /* If this is the first frame written into the log, write the WAL ** header to the start of the WAL file. See comments at the top of ** this source file for a description of the WAL header format. */ iFrame = pWal->hdr.mxFrame; if( iFrame==0 ){ |
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2199 2200 2201 2202 2203 2204 2205 | if( rc!=SQLITE_OK ){ return rc; } walChecksumBytes(1, aWalHdr, sizeof(aWalHdr), 0, pWal->hdr.aFrameCksum); } assert( pWal->szPage==szPage ); | | | 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 | if( rc!=SQLITE_OK ){ return rc; } walChecksumBytes(1, aWalHdr, sizeof(aWalHdr), 0, pWal->hdr.aFrameCksum); } assert( pWal->szPage==szPage ); /* Write the log file. */ for(p=pList; p; p=p->pDirty){ u32 nDbsize; /* Db-size field for frame header */ i64 iOffset; /* Write offset in log file */ iOffset = walFrameOffset(++iFrame, szPage); /* Populate and write the frame header */ |
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