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Is SQLITE.DLL compiled with HAVE_USLEEP=1 ?

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Is SQLITE.DLL compiled with HAVE_USLEEP=1 ?

This options allows for better multi-user capability because of shorter lockouts.  All systems today have usleep capability, so that option should be enabled with the compile flags.  Without that compile option, sqlite will sleep in 1 second intervals instead of millisecond intervals.



Edited by ferbfletcher
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Only low-end embedded systems don't offer usleep or an equivalent, so this is enabled for major desktop-class platform. In particular, SQLITE_OS_WIN overrides HAVE_USLEEP.

This is what is used in main.c

** This routine implements a busy callback that sleeps and tries
** again until a timeout value is reached.  The timeout value is
** an integer number of milliseconds passed in as the first
** argument.
static int sqliteDefaultBusyCallback(
 void *ptr,               /* Database connection */
 int count                /* Number of times table has been busy */
  static const u8 delays[] =
     { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
  static const u8 totals[] =
     { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
# define NDELAY ArraySize(delays)
  sqlite3 *db = (sqlite3 *)ptr;
  int timeout = db->busyTimeout;
  int delay, prior;

BTW you seem to care about "multi-users". I hope you meant multi-process (i.e. several processes and/or threads) on a local DB only. Remote use would bite you severely and usleep would be the latest of your issues.

Edited by jchd
Clarify about multi-users or not.

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Yes, multi processes on the same system.  From the sqlite's point of view, it would be multi users, but yes that is what I meant on the same system.  

Thank you for the information regarding "SQLITE_OS_WIN" to show that sqlite will sleep in millisecond intervals!

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