19 Commits (9ad45c18b6c8d03ce18a26223eb0d15e900c7a2c)

Author	SHA1	Message	Date
Bruce Momjian	927d61eeff	Run pgindent on 9.2 source tree in preparation for first 9.3 ... commit-fest.	14 years ago
Tom Lane	e42a21b9e6	Assert that WaitLatchOrSocket callers cannot wait only for writability. ... Since we have chosen to report socket EOF and error conditions via the WL_SOCKET_READABLE flag bit, it's unsafe to wait only for WL_SOCKET_WRITEABLE; the caller would never be notified of the socket condition, and in some of these implementations WaitLatchOrSocket would busy-wait until something else happens. Add this restriction to the API specification, and add Asserts to check that callers don't try to do that. At some point we might want to consider adjusting the API to relax this restriction, but until we have an actual use case for waiting on a write-only socket, it seems premature to design a solution.	14 years ago
Tom Lane	31ad655364	Fix WaitLatchOrSocket to handle EOF on socket correctly. ... When using poll(), EOF on a socket is reported with the POLLHUP not POLLIN flag (at least on Linux). WaitLatchOrSocket failed to check this bit, causing it to go into a busy-wait loop if EOF occurs. We earlier fixed the same mistake in the test for the state of the postmaster_alive socket, but missed it for the caller-supplied socket. Fortunately, this error is new in 9.2, since 9.1 only had a select() based code path not a poll() based one.	14 years ago
Tom Lane	f40022f1ad	Make WaitLatch's WL_POSTMASTER_DEATH result trustworthy; simplify callers. ... Per a suggestion from Peter Geoghegan, make WaitLatch responsible for verifying that the WL_POSTMASTER_DEATH bit it returns is truthful (by testing PostmasterIsAlive). Then simplify its callers, who no longer need to do that for themselves. Remove weasel wording about falsely-set result bits from WaitLatch's API contract.	14 years ago
Heikki Linnakangas	b2b4af535e	Fix poll() implementation of WaitLatchOrSocket to notice postmaster death. ... When the remote end of the pipe is closed, select() reports the fd as readable, but poll() has a separate POLLHUP return code for that. Spotted by Peter Geoghegan.	14 years ago
Bruce Momjian	e126958c2e	Update copyright notices for year 2012.	14 years ago
Tom Lane	a180776f7a	Teach unix_latch.c to use poll() where available. ... poll() is preferred over select() on platforms where both are available, because it tends to be a bit faster and it doesn't have an arbitrary limit on the range of FD numbers that can be accessed. The FD range limit does not appear to be a risk factor for any 9.1 usages, so this doesn't need to be back-patched, but we need to have it in place if we keep on expanding the uses of WaitLatch.	15 years ago
Tom Lane	4dab3d5ae1	Change the autovacuum launcher to use WaitLatch instead of a poll loop. ... In pursuit of this (and with the expectation that WaitLatch will be needed in more places), convert the latch field that was already added to PGPROC for sync rep into a generic latch that is activated for all PGPROC-owning processes, and change many of the standard backend signal handlers to set that latch when a signal happens. This will allow WaitLatch callers to be wakened properly by these signals. In passing, fix a whole bunch of signal handlers that had been hacked to do things that might change errno, without adding the necessary save/restore logic for errno. Also make some minor fixes in unix_latch.c, and clean up bizarre and unsafe scheme for disowning the process's latch. Much of this has to be back-patched into 9.1. Peter Geoghegan, with additional work by Tom	15 years ago
Tom Lane	9f17ffd866	Measure WaitLatch's timeout parameter in milliseconds, not microseconds. ... The original definition had the problem that timeouts exceeding about 2100 seconds couldn't be specified on 32-bit machines. Milliseconds seem like sufficient resolution, and finer grain than that would be fantasy anyway on many platforms. Back-patch to 9.1 so that this aspect of the latch API won't change between 9.1 and later releases. Peter Geoghegan	15 years ago
Tom Lane	4e15a4db5e	Documentation improvement and minor code cleanups for the latch facility. ... Improve the documentation around weak-memory-ordering risks, and do a pass of general editorialization on the comments in the latch code. Make the Windows latch code more like the Unix latch code where feasible; in particular provide the same Assert checks in both implementations. Fix poorly-placed WaitLatch call in syncrep.c. This patch resolves, for the moment, concerns around weak-memory-ordering bugs in latch-related code: we have documented the restrictions and checked that existing calls meet them. In 9.2 I hope that we will install suitable memory barrier instructions in SetLatch/ResetLatch, so that their callers don't need to be quite so careful.	15 years ago
Heikki Linnakangas	89fd72cbf2	Introduce a pipe between postmaster and each backend, which can be used to ... detect postmaster death. Postmaster keeps the write-end of the pipe open, so when it dies, children get EOF in the read-end. That can conveniently be waited for in select(), which allows eliminating some of the polling loops that check for postmaster death. This patch doesn't yet change all the loops to use the new mechanism, expect a follow-on patch to do that. This changes the interface to WaitLatch, so that it takes as argument a bitmask of events that it waits for. Possible events are latch set, timeout, postmaster death, and socket becoming readable or writeable. The pipe method behaves slightly differently from the kill() method previously used in PostmasterIsAlive() in the case that postmaster has died, but its parent has not yet read its exit code with waitpid(). The pipe returns EOF as soon as the process dies, but kill() continues to return true until waitpid() has been called (IOW while the process is a zombie). Because of that, change PostmasterIsAlive() to use the pipe too, otherwise WaitLatch() would return immediately with WL_POSTMASTER_DEATH, while PostmasterIsAlive() would claim it's still alive. That could easily lead to busy-waiting while postmaster is in zombie state. Peter Geoghegan with further changes by me, reviewed by Fujii Masao and Florian Pflug.	15 years ago
Bruce Momjian	bf50caf105	pgindent run before PG 9.1 beta 1.	15 years ago
Heikki Linnakangas	754baa21f7	Automatically terminate replication connections that are idle for more ... than replication_timeout (a new GUC) milliseconds. The TCP timeout is often too long, you want the master to notice a dead connection much sooner. People complained about that in 9.0 too, but with synchronous replication it's even more important to notice dead connections promptly. Fujii Masao and Heikki Linnakangas	15 years ago
Bruce Momjian	5d950e3b0c	Stamp copyrights for year 2011.	15 years ago
Magnus Hagander	9f2e211386	Remove cvs keywords from all files.	15 years ago
Heikki Linnakangas	236b6bc29e	Simplify Windows implementation of latches. There's no need to keep a ... dynamic pool of event handles, we can permanently assign one for each shared latch. Thanks to that, we no longer need a separate shared memory block for latches, and we don't need to know in advance how many shared latches there is, so you no longer need to remember to update NumSharedLatches when you introduce a new latch to the system.	15 years ago
Heikki Linnakangas	c1ba7db6c1	Add a comment noting that the owner_pid test in OwnLatch is just a sanity ... check, per request by Jeff Davis.	15 years ago
Heikki Linnakangas	262c71ab63	Add missing #includes, needed on some platforms. This should make ... the unixware buildfarm animals happy again.	15 years ago
Heikki Linnakangas	2746e5f21d	Introduce latches. A latch is a boolean variable, with the capability to ... wait until it is set. Latches can be used to reliably wait until a signal arrives, which is hard otherwise because signals don't interrupt select() on some platforms, and even when they do, there's race conditions. On Unix, latches use the so called self-pipe trick under the covers to implement the sleep until the latch is set, without race conditions. On Windows, Windows events are used. Use the new latch abstraction to sleep in walsender, so that as soon as a transaction finishes, walsender is woken up to immediately send the WAL to the standby. This reduces the latency between master and standby, which is good. Preliminary work by Fujii Masao. The latch implementation is by me, with helpful comments from many people.	15 years ago