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Overview
Comment:Fix spacing typo in comment. No changes to code.
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SHA1: 3a18526fc2253658dad84c5e600481c8a62efe40
User & Date: mistachkin 2015-12-10 03:16:47.044
Context
2015-12-10
15:45
Have sqlite3_snapshot_open() avoid a race condition by taking a shared CHECKPOINTER lock while checking pInfo->nBackfillAttempted. (check-in: 8084eae0bc user: dan tags: snapshot-get)
03:16
Fix spacing typo in comment. No changes to code. (check-in: 3a18526fc2 user: mistachkin tags: snapshot-get)
02:15
Add the nBackfillAttempted field in formerly unused space in WalCkptInfo and use that field to close the race condition on opening a snapshot. (check-in: cb68e9d073 user: drh tags: snapshot-get)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/wal.c.
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** holding the WAL_CKPT_LOCK lock (which includes a recovery thread).
** However, a WAL_WRITE_LOCK thread can move the value of nBackfill from
** mxFrame back to zero when the WAL is reset.
**
** nBackfillAttempted is the largest value of nBackfill that a checkpoint
** has attempted to achieve.  Normally nBackfill==nBackfillAtempted, however
** the nBackfillAttempted is set before any backfilling is done and the
** nBackfill is only set afte rall backfilling completes.  So if a checkpoint
** crashes, nBackfillAttempted might be larger than nBackfill.  The
** WalIndexHdr.mxFrame must never be less than nBackfillAttempted.
**
** The aLock[] field is a set of bytes used for locking.  These bytes should
** never be read or written.
**
** There is one entry in aReadMark[] for each reader lock.  If a reader








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328
329
330
331
332
333
334
335
336
337
338
339
340
341
342

** holding the WAL_CKPT_LOCK lock (which includes a recovery thread).
** However, a WAL_WRITE_LOCK thread can move the value of nBackfill from
** mxFrame back to zero when the WAL is reset.
**
** nBackfillAttempted is the largest value of nBackfill that a checkpoint
** has attempted to achieve.  Normally nBackfill==nBackfillAtempted, however
** the nBackfillAttempted is set before any backfilling is done and the
** nBackfill is only set after all backfilling completes.  So if a checkpoint
** crashes, nBackfillAttempted might be larger than nBackfill.  The
** WalIndexHdr.mxFrame must never be less than nBackfillAttempted.
**
** The aLock[] field is a set of bytes used for locking.  These bytes should
** never be read or written.
**
** There is one entry in aReadMark[] for each reader lock.  If a reader
︙︙