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A few more comment changes. No code alterations. (CVS 1689)

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FossilOrigin-Name: b68b4a4262c2ab60f9a7cc0c206b9db207f86933
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danielk1977
2004-06-25 08:32:25 +00:00
parent f42f25c2c5
commit 90ba3bd065
5 changed files with 48 additions and 25 deletions
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src/os_unix.c
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@@ -711,23 +711,23 @@ int sqlite3OsLock(OsFile *id, int locktype){
** byte'. If this is successful, a random byte from the 'shared byte
** range' is read-locked and the lock on the 'pending byte' released.
**
** A process may only obtain a RESERVED lock after it has a SHARED lock
** (the sqlite3OsLock() routine will try to obtain this lock
** automatically if it is not already held). A RESERVED lock is
** implemented by grabbing a write-lock on the 'reserved byte'.
** A process may only obtain a RESERVED lock after it has a SHARED lock.
** A RESERVED lock is implemented by grabbing a write-lock on the
** 'reserved byte'.
**
** A process may only obtain a PENDING lock after it has obtained a
** SHARED lock (done automatically by sqlite3OsLock()). A PENDING lock is
** implemented by obtaining a write-lock on the 'pending byte'. This
** ensures that no new SHARED locks can be obtained, but existing SHARED
** locks are allowed to persist. A process does not have to obtain a
** RESERVED lock on the way to a PENDING lock. This property is used by
** the algorithm for rolling back a journal file after a crash.
** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
** on the 'pending byte'. This ensures that no new SHARED locks can be
** obtained, but existing SHARED locks are allowed to persist. A process
** does not have to obtain a RESERVED lock on the way to a PENDING lock.
** This property is used by the algorithm for rolling back a journal file
** after a crash.
**
** An EXCLUSIVE lock is implemented by obtaining a write-lock on the
** entire 'shared byte range'. Since all other locks require a read-lock
** on one of the bytes within this range, this ensures that no other
** locks are held on the database.
** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
** implemented by obtaining a write-lock on the entire 'shared byte
** range'. Since all other locks require a read-lock on one of the bytes
** within this range, this ensures that no other locks are held on the
** database.
**
** The reason a single byte cannot be used instead of the 'shared byte
** range' is that some versions of windows do not support read-locks. By