135 lines
4.8 KiB
HTML
135 lines
4.8 KiB
HTML
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<!-- keywords: sqlite3_mutex_held sqlite3_mutex_notheld -->
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<a href="intro.html"><h2>SQLite C Interface</h2></a>
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<h2>Mutex Verification Routines</h2>
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</div>
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<blockquote><pre>
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#ifndef NDEBUG
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int sqlite3_mutex_held(sqlite3_mutex*);
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int sqlite3_mutex_notheld(sqlite3_mutex*);
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#endif
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</pre></blockquote>
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<p>
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The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
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are intended for use inside assert() statements. The SQLite core
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never uses these routines except inside an assert() and applications
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are advised to follow the lead of the core. The SQLite core only
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provides implementations for these routines when it is compiled
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with the SQLITE_DEBUG flag. External mutex implementations
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are only required to provide these routines if SQLITE_DEBUG is
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defined and if NDEBUG is not defined.</p>
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<p>These routines should return true if the mutex in their argument
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is held or not held, respectively, by the calling thread.</p>
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<p>The implementation is not required to provide versions of these
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routines that actually work. If the implementation does not provide working
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versions of these routines, it should at least provide stubs that always
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return true so that one does not get spurious assertion failures.</p>
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<p>If the argument to sqlite3_mutex_held() is a NULL pointer then
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the routine should return 1. This seems counter-intuitive since
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clearly the mutex cannot be held if it does not exist. But
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the reason the mutex does not exist is because the build is not
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using mutexes. And we do not want the assert() containing the
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call to sqlite3_mutex_held() to fail, so a non-zero return is
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the appropriate thing to do. The sqlite3_mutex_notheld()
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interface should also return 1 when given a NULL pointer.
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</p><p>See also lists of
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<a href="objlist.html">Objects</a>,
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<a href="constlist.html">Constants</a>, and
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<a href="funclist.html">Functions</a>.</p>
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