39 lines
1.0 KiB
Groff
39 lines
1.0 KiB
Groff
.Dd December 19, 2018
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.Dt SQLITE_SHM_UNLOCK 3
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.Os
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.Sh NAME
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.Nm SQLITE_SHM_UNLOCK ,
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.Nm SQLITE_SHM_LOCK ,
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.Nm SQLITE_SHM_SHARED ,
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.Nm SQLITE_SHM_EXCLUSIVE
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.Nd Flags for the xShmLock VFS method
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.Sh SYNOPSIS
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.Fd #define SQLITE_SHM_UNLOCK
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.Fd #define SQLITE_SHM_LOCK
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.Fd #define SQLITE_SHM_SHARED
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.Fd #define SQLITE_SHM_EXCLUSIVE
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.Sh DESCRIPTION
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These integer constants define the various locking operations allowed
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by the xShmLock method of sqlite3_io_methods.
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The following are the only legal combinations of flags to the xShmLock
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method:
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.Bl -bullet
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.It
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SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
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.It
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SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
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.It
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SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
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.It
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SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
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.El
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.Pp
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When unlocking, the same SHARED or EXCLUSIVE flag must be supplied
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as was given on the corresponding lock.
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.Pp
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The xShmLock method can transition between unlocked and SHARED or between
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unlocked and EXCLUSIVE.
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It cannot transition between SHARED and EXCLUSIVE.
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.Sh SEE ALSO
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.Xr sqlite3_io_methods 3
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