On 14.01.2011 14:01, Simon Riggs wrote:
On Fri, 2011-01-14 at 13:47 +0200, Heikki Linnakangas wrote:
On 14.01.2011 13:15, Simon Riggs wrote:
/*
+ * Recheck shared recoveryPause by polling.
+ *
+ * XXX It might seem we should do this via a shared Latch, but
+ * currently we only support one shared latch per process and
+ * that is already taken for Startup process. Polling is used
+ * in other places in xlog.c already, so not a concern.
+ */
There is no such limitation with latches.
SIGUSR1 handler can only handle one shared latch
You can only *wait* for one latch at a time, but you can own more than
that. AFAICS you would never need to wait for the recovery-pause-latch
at the same time as the other latch.
(That you can't wait for more than one latch at a time isn't a
limitation of the SIGUSR1 handler either. The signal handler and the
self-pipe mechanism wouldn't need any changes to support multi-latch
waits. We're just missing a WaitMultipleLatches() function that would
check the is_set flag on multiple latches.)
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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