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Overview
Comment: | In lsm (not SQLite), avoid opening the *-shm file before the database file is locked. Otherwise, there is a race condition whereby a connection in another process process may unlink() it while it is still in use. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
c8b8b9b573665c2b4d278bb679a48ac4 |
User & Date: | dan 2017-10-23 11:48:00.248 |
Context
2017-10-23
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17:36 | Cleanup a test database file prior to using it. (check-in: e1bf5e1d06 user: mistachkin tags: trunk) | |
11:48 | In lsm (not SQLite), avoid opening the *-shm file before the database file is locked. Otherwise, there is a race condition whereby a connection in another process process may unlink() it while it is still in use. (check-in: c8b8b9b573 user: dan tags: trunk) | |
07:52 | Fix minor test script problems revealed by releasetest.tcl. (check-in: 15e87d9bc8 user: dan tags: trunk) | |
Changes
Changes to ext/lsm1/lsm_shared.c.
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336 337 338 339 340 341 342 | const int nUsMax = 100000; /* Max value for nUs */ int nUs = 1000; /* us to wait between DMS1 attempts */ int rc; /* Obtain a pointer to the shared-memory header */ assert( pDb->pShmhdr==0 ); assert( pDb->bReadonly==0 ); | < < < | | < > > | 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 | const int nUsMax = 100000; /* Max value for nUs */ int nUs = 1000; /* us to wait between DMS1 attempts */ int rc; /* Obtain a pointer to the shared-memory header */ assert( pDb->pShmhdr==0 ); assert( pDb->bReadonly==0 ); /* Block for an exclusive lock on DMS1. This lock serializes all calls ** to doDbConnect() and doDbDisconnect() across all processes. */ while( 1 ){ rc = lsmShmLock(pDb, LSM_LOCK_DMS1, LSM_LOCK_EXCL, 1); if( rc!=LSM_BUSY ) break; lsmEnvSleep(pDb->pEnv, nUs); nUs = nUs * 2; if( nUs>nUsMax ) nUs = nUsMax; } if( rc==LSM_OK ){ rc = lsmShmCacheChunks(pDb, 1); } if( rc!=LSM_OK ) return rc; pDb->pShmhdr = (ShmHeader *)pDb->apShm[0]; /* Try an exclusive lock on DMS2/DMS3. If successful, this is the first ** and only connection to the database. In this case initialize the ** shared-memory and run log file recovery. */ assert( LSM_LOCK_DMS3==1+LSM_LOCK_DMS2 ); rc = lsmShmTestLock(pDb, LSM_LOCK_DMS2, 2, LSM_LOCK_EXCL); if( rc==LSM_OK ){ |
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