Simon Riggs wrote:
On Sat, 2008-11-01 at 15:18 +0200, Heikki Linnakangas wrote:
Simon Riggs wrote:
On Fri, 2008-10-31 at 15:05 +, Heikki Linnakangas wrote:
Log Message:
---
Unite ReadBufferWithFork, ReadBufferWithStrategy, and ZeroOrReadBuffer
functions into one ReadBufferExtended function, that takes the strategy
and mode as argument. There's three modes, RBM_NORMAL which is the default
used by plain ReadBuffer(), RBM_ZERO, which replaces ZeroOrReadBuffer, and
a new mode RBM_ZERO_ON_ERROR, which allows callers to read corrupt pages
without throwing an error. The FSM needs the new mode to recover from
corrupt pages, which could happend if we crash after extending an FSM file,
and the new page is torn.
I thought you were adding the read buffer only if in cache option
also?
No, but if it's needed, it should now fit well into the infrastructure,
as a new ReadBuffer mode.
Not sure how this helps me; maybe it wasn't supposed to?
Well, no, not directly. it was to plug the hole in the FSM
implementation with torn pages, and to make the ReadBuffer interface nicer.
I need to
implement XLogReadBufferExtended to take a cleanup lock. It seems wrong
to make that a ReadBufferMode, since the option refers to what happens
after we do ReadBuffer and especially because we need to do RBM_ZERO and
Cleanup mode at same time.
It would be much better to have ReadBufferExtended take a lockmode
argument also.
No, I don't think we should mix ReadBuffer with the locking. On the
contrary, my suggestion is to modify XLogReadBufferExtended so that it
doesn't lock the page either, and leave the locking to the callers.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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