Until now __attribute__() was defined to be empty for all compilers but
gcc. That's problematic because it prevents using it in other compilers;
which is necessary e.g. for atomics portability. It's also just
generally dubious to do so in a header as widely included as c.h.
Instead add pg_attribute_format_arg, pg_attribute_printf,
pg_attribute_noreturn macros which are implemented in the compilers that
understand them. Also add pg_attribute_noreturn and pg_attribute_packed,
but don't provide fallbacks, since they can affect functionality.
This means that external code that, possibly unwittingly, relied on
__attribute__ defined to be empty on !gcc compilers may now run into
warnings or errors on those compilers. But there shouldn't be many
occurances of that and it's hard to work around...
Discussion: 54B58BA3.8040302@ohmu.fi
Author: Oskari Saarenmaa, with some minor changes by me.
Instead of having a single knob (checkpoint_segments) that both triggers
checkpoints, and determines how many checkpoints to recycle, they are now
separate concerns. There is still an internal variable called
CheckpointSegments, which triggers checkpoints. But it no longer determines
how many segments to recycle at a checkpoint. That is now auto-tuned by
keeping a moving average of the distance between checkpoints (in bytes),
and trying to keep that many segments in reserve. The advantage of this is
that you can set max_wal_size very high, but the system won't actually
consume that much space if there isn't any need for it. The min_wal_size
sets a floor for that; you can effectively disable the auto-tuning behavior
by setting min_wal_size equal to max_wal_size.
The max_wal_size setting is now the actual target size of WAL at which a
new checkpoint is triggered, instead of the distance between checkpoints.
Previously, you could calculate the actual WAL usage with the formula
"(2 + checkpoint_completion_target) * checkpoint_segments + 1". With this
patch, you set the desired WAL usage with max_wal_size, and the system
calculates the appropriate CheckpointSegments with the reverse of that
formula. That's a lot more intuitive for administrators to set.
Reviewed by Amit Kapila and Venkata Balaji N.
This works by keeping a per-subtransaction record of the ins/upd/del
counters before the truncate, and then resetting them; this record is
useful to return to the previous state in case the truncate is rolled
back, either in a subtransaction or whole transaction. The state is
propagated upwards as subtransactions commit.
When the per-table data is sent to the stats collector, a flag indicates
to reset the live/dead counters to zero as well.
Catalog version bumped due to the change in pgstat format.
Author: Alexander Shulgin
Discussion: 1007.1207238291@sss.pgh.pa.us
Discussion: 548F7D38.2000401@BlueTreble.com
Reviewed-by: Álvaro Herrera, Jim Nasby
Replace some bogus "x[1]" declarations with "x[FLEXIBLE_ARRAY_MEMBER]".
Aside from being more self-documenting, this should help prevent bogus
warnings from static code analyzers and perhaps compiler misoptimizations.
This patch is just a down payment on eliminating the whole problem, but
it gets rid of a lot of easy-to-fix cases.
Note that the main problem with doing this is that one must no longer rely
on computing sizeof(the containing struct), since the result would be
compiler-dependent. Instead use offsetof(struct, lastfield). Autoconf
also warns against spelling that offsetof(struct, lastfield[0]).
Michael Paquier, review and additional fixes by me.
Up to now large swathes of backend code ran inside signal handlers
while reading commands from the client, to allow for speedy reaction to
asynchronous events. Most prominently shared invalidation and NOTIFY
handling. That means that complex code like the starting/stopping of
transactions is run in signal handlers... The required code was
fragile and verbose, and is likely to contain bugs.
That approach also severely limited what could be done while
communicating with the client. As the read might be from within
openssl it wasn't safely possible to trigger an error, e.g. to cancel
a backend in idle-in-transaction state. We did that in some cases,
namely fatal errors, nonetheless.
Now that FE/BE communication in the backend employs non-blocking
sockets and latches to block, we can quite simply interrupt reads from
signal handlers by setting the latch. That allows us to signal an
interrupted read, which is supposed to be retried after returning from
within the ssl library.
As signal handlers now only need to set the latch to guarantee timely
interrupt processing, remove a fair amount of complicated & fragile
code from async.c and sinval.c.
We could now actually start to process some kinds of interrupts, like
sinval ones, more often that before, but that seems better done
separately.
This work will hopefully allow to handle cases like being blocked by
sending data, interrupting idle transactions and similar to be
implemented without too much effort. In addition to allowing getting
rid of ImmediateInterruptOK, that is.
Author: Andres Freund
Reviewed-By: Heikki Linnakangas
Sometimes it's useful for a background worker to be able to initialize
its database connection by OID rather than by name, so provide a way
to do that.
If any error occurred while we were in the middle of reading a protocol
message from the client, we could lose sync, and incorrectly try to
interpret a part of another message as a new protocol message. That will
usually lead to an "invalid frontend message" error that terminates the
connection. However, this is a security issue because an attacker might
be able to deliberately cause an error, inject a Query message in what's
supposed to be just user data, and have the server execute it.
We were quite careful to not have CHECK_FOR_INTERRUPTS() calls or other
operations that could ereport(ERROR) in the middle of processing a message,
but a query cancel interrupt or statement timeout could nevertheless cause
it to happen. Also, the V2 fastpath and COPY handling were not so careful.
It's very difficult to recover in the V2 COPY protocol, so we will just
terminate the connection on error. In practice, that's what happened
previously anyway, as we lost protocol sync.
To fix, add a new variable in pqcomm.c, PqCommReadingMsg, that is set
whenever we're in the middle of reading a message. When it's set, we cannot
safely ERROR out and continue running, because we might've read only part
of a message. PqCommReadingMsg acts somewhat similarly to critical sections
in that if an error occurs while it's set, the error handler will force the
connection to be terminated, as if the error was FATAL. It's not
implemented by promoting ERROR to FATAL in elog.c, like ERROR is promoted
to PANIC in critical sections, because we want to be able to use
PG_TRY/CATCH to recover and regain protocol sync. pq_getmessage() takes
advantage of that to prevent an OOM error from terminating the connection.
To prevent unnecessary connection terminations, add a holdoff mechanism
similar to HOLD/RESUME_INTERRUPTS() that can be used hold off query cancel
interrupts, but still allow die interrupts. The rules on which interrupts
are processed when are now a bit more complicated, so refactor
ProcessInterrupts() and the calls to it in signal handlers so that the
signal handlers always call it if ImmediateInterruptOK is set, and
ProcessInterrupts() can decide to not do anything if the other conditions
are not met.
Reported by Emil Lenngren. Patch reviewed by Noah Misch and Andres Freund.
Backpatch to all supported versions.
Security: CVE-2015-0244
strncpy() has a well-deserved reputation for being unsafe, so make an
effort to get rid of nearly all occurrences in HEAD.
A large fraction of the remaining uses were passing length less than or
equal to the known strlen() of the source, in which case no null-padding
can occur and the behavior is equivalent to memcpy(), though doubtless
slower and certainly harder to reason about. So just use memcpy() in
these cases.
In other cases, use either StrNCpy() or strlcpy() as appropriate (depending
on whether padding to the full length of the destination buffer seems
useful).
I left a few strncpy() calls alone in the src/timezone/ code, to keep it
in sync with upstream (the IANA tzcode distribution). There are also a
few such calls in ecpg that could possibly do with more analysis.
AFAICT, none of these changes are more than cosmetic, except for the four
occurrences in fe-secure-openssl.c, which are in fact buggy: an overlength
source leads to a non-null-terminated destination buffer and ensuing
misbehavior. These don't seem like security issues, first because no stack
clobber is possible and second because if your values of sslcert etc are
coming from untrusted sources then you've got problems way worse than this.
Still, it's undesirable to have unpredictable behavior for overlength
inputs, so back-patch those four changes to all active branches.
Per discussion, change the log level of this message to be LOG not WARNING.
The main point of this change is to avoid causing buildfarm run failures
when the stats collector is exceptionally slow to respond, which it not
infrequently is on some of the smaller/slower buildfarm members.
This change does lose notice to an interactive user when his stats query
is looking at out-of-date stats, but the majority opinion (not necessarily
that of yours truly) is that WARNING messages would probably not get
noticed anyway on heavily loaded production systems. A LOG message at
least ensures that the problem is recorded somewhere where bulk auditing
for the issue is possible.
Also, instead of an untranslated "pgstat wait timeout" message, provide
a translatable and hopefully more understandable message "using stale
statistics instead of current ones because stats collector is not
responding". The original text was written hastily under the assumption
that it would never really happen in practice, which we now know to be
unduly optimistic.
Back-patch to all active branches, since we've seen the buildfarm issue
in all branches.
To do so, move InitializeLatchSupport() into the new common process
initialization functions, and add a new global variable MyLatch.
MyLatch is usable as soon InitPostmasterChild() has been called
(i.e. very early during startup). Initially it points to a process
local latch that exists in all processes. InitProcess/InitAuxiliaryProcess
then replaces that local latch with PGPROC->procLatch. During shutdown
the reverse happens.
This is primarily advantageous for two reasons: For one it simplifies
dealing with the shared process latch, especially in signal handlers,
because instead of having to check for MyProc, MyLatch can be used
unconditionally. For another, a later patch that makes FEs/BE
communication use latches, now can rely on the existence of a latch,
even before having gone through InitProcess.
Discussion: 20140927191243.GD5423@alap3.anarazel.de
Move common code, that was duplicated in every postmaster child/every
standalone process, into two functions in miscinit.c. Not only does
that already result in a fair amount of net code reduction but it also
makes it much easier to remove more duplication in the future. The
prime motivation wasn't code deduplication though, but easier addition
of new common code.
Commit b94ce6e80 reordered postmaster's startup sequence so that the
tempfile directory is only cleaned up after all the necessary state
for pg_ctl is collected. Unfortunately the chosen location is after
the syslogger has been started; which normally is fine, except for
!WIN32 EXEC_BACKEND builds, which pass information to children via
files in the temp directory.
Move the call to RemovePgTempFiles() to just before the syslogger has
started. That's the first child we fork.
Luckily EXEC_BACKEND is pretty much only used by endusers on windows,
which has a separate method to pass information to children. That
means the real world impact of this bug is very small.
Discussion: 20150113182344.GF12272@alap3.anarazel.de
Backpatch to 9.1, just as the previous commit was.
The previous commit introduced its report at LOG level to avoid
surprises at minor release upgrade time. Compel users deploying the
next major release to also deploy the reported workaround.
Darwin --enable-nls builds use a substitute setlocale() that may start a
thread. Buildfarm member orangutan experienced BackendList corruption
on account of different postmaster threads executing signal handlers
simultaneously. Furthermore, a multithreaded postmaster risks undefined
behavior from sigprocmask() and fork(). Emit LOG messages about the
problem and its workaround. Back-patch to 9.0 (all supported versions).
StrategyGetBuffer() has proven to be a bottleneck in a number of
buffer acquisition heavy workloads. To some degree this has already
been alleviated by 5d7962c6, but it still can be quite a heavy
bottleneck. The problem is that in unfortunate usage patterns a
single StrategyGetBuffer() call will have to look at a large number of
buffers - in turn making it likely that the process will be put to
sleep while still holding the spinlock.
Replace most of the usage of the buffer_strategy_lock spinlock for the
clock sweep by a atomic nextVictimBuffer variable. That variable,
modulo NBuffers, is the current hand of the clock sweep. The buffer
clock-sweep then only needs to acquire the spinlock after a
wraparound. And even then only in the process that did the wrapping
around. That alleviates nearly all the contention on the relevant
spinlock, although significant contention on the cacheline can still
exist.
Reviewed-By: Robert Haas and Amit Kapila
Discussion: 20141010160020.GG6670@alap3.anarazel.de,
20141027133218.GA2639@awork2.anarazel.de
Previously, if you wanted anything besides C-string hash keys, you had to
specify a custom hashing function to hash_create(). Nearly all such
callers were specifying tag_hash or oid_hash; which is tedious, and rather
error-prone, since a caller could easily miss the opportunity to optimize
by using hash_uint32 when appropriate. Replace this with a design whereby
callers using simple binary-data keys just specify HASH_BLOBS and don't
need to mess with specific support functions. hash_create() itself will
take care of optimizing when the key size is four bytes.
This nets out saving a few hundred bytes of code space, and offers
a measurable performance improvement in tidbitmap.c (which was not
exploiting the opportunity to use hash_uint32 for its 4-byte keys).
There might be some wins elsewhere too, I didn't analyze closely.
In future we could look into offering a similar optimized hashing function
for 8-byte keys. Under this design that could be done in a centralized
and machine-independent fashion, whereas getting it right for keys of
platform-dependent sizes would've been notationally painful before.
For the moment, the old way still works fine, so as not to break source
code compatibility for loadable modules. Eventually we might want to
remove tag_hash and friends from the exported API altogether, since there's
no real need for them to be explicitly referenced from outside dynahash.c.
Teodor Sigaev and Tom Lane
st_changecount protocol needs the memory barriers to ensure that
the apparent order of execution is as it desires. Otherwise,
for example, the CPU might rearrange the code so that st_changecount
is incremented twice before the modification on a machine with
weak memory ordering. This surprising result can lead to bugs.
This commit introduces the macros to load and store st_changecount
with the memory barriers. These are called before and after
PgBackendStatus entries are modified or copied into private memory,
in order to prevent CPU from reordering PgBackendStatus access.
Per discussion on pgsql-hackers, we decided not to back-patch this
to 9.4 or before until we get an actual bug report about this.
Patch by me. Review by Robert Haas.
In passing, also make some debugging elog's in pgstat.c a bit more
consistently worded.
Back-patch as far as applicable (9.3 or 9.4; none of these mistakes are
really old).
Mark Dilger identified and patched the type violations; the message
rewordings are mine.
Teach sigusr1_handler() to use the same test for whether a worker
might need to be started as ServerLoop(). Aside from being perhaps
a bit simpler, this prevents a potentially-unbounded delay when
starting a background worker. On some platforms, select() doesn't
return when interrupted by a signal, but is instead restarted,
including a reset of the timeout to the originally-requested value.
If signals arrive often enough, but no connection requests arrive,
sigusr1_handler() will be executed repeatedly, but the body of
ServerLoop() won't be reached. This change ensures that, even in
that case, background workers will eventually get launched.
This is far from a perfect fix; really, we need select() to return
control to ServerLoop() after an interrupt, either via the self-pipe
trick or some other mechanism. But that's going to require more
work and discussion, so let's do this for now to at least mitigate
the damage.
Per investigation of test_shm_mq failures on buildfarm member anole.
When there are cost-delay-related storage options set for a table,
trying to make that table participate in the autovacuum cost-limit
balancing algorithm produces undesirable results: instead of using the
configured values, the global values are always used,
as illustrated by Mark Kirkwood in
http://www.postgresql.org/message-id/52FACF15.8020507@catalyst.net.nz
Since the mechanism is already complicated, just disable it for those
cases rather than trying to make it cope. There are undesirable
side-effects from this too, namely that the total I/O impact on the
system will be higher whenever such tables are vacuumed. However, this
is seen as less harmful than slowing down vacuum, because that would
cause bloat to accumulate. Anyway, in the new system it is possible to
tweak options to get the precise behavior one wants, whereas with the
previous system one was simply hosed.
This has been broken forever, so backpatch to all supported branches.
This might affect systems where cost_limit and cost_delay have been set
for individual tables.
DetermineSleepTime() was previously called without blocked
signals. That's not good, because it allows signal handlers to
interrupt its workings.
DetermineSleepTime() was added in 9.3 with the addition of background
workers (da07a1e856), where it only read from
BackgroundWorkerList.
Since 9.4, where dynamic background workers were added (7f7485a0cd),
the list is also manipulated in DetermineSleepTime(). That's bad
because the list now can be persistently corrupted if modified by both
a signal handler and DetermineSleepTime().
This was discovered during the investigation of hangs on buildfarm
member anole. It's unclear whether this bug is the source of these
hangs or not, but it's worth fixing either way. I have confirmed that
it can cause crashes.
It luckily looks like this only can cause problems when bgworkers are
actively used.
Discussion: 20140929193733.GB14400@awork2.anarazel.de
Backpatch to 9.3 where background workers were introduced.
This is useful to allow to set GUCs to values that include spaces;
something that wasn't previously possible. The primary case motivating
this is the desire to set default_transaction_isolation to 'repeatable
read' on a per connection basis, but other usecases like seach_path do
also exist.
This introduces a slight backward incompatibility: Previously a \ in
an option value would have been passed on literally, now it'll be
taken as an escape.
The relevant mailing list discussion starts with
20140204125823.GJ12016@awork2.anarazel.de.
This refactoring is in preparation for adding support for other SSL
implementations, with no user-visible effects. There are now two #defines,
USE_OPENSSL which is defined when building with OpenSSL, and USE_SSL which
is defined when building with any SSL implementation. Currently, OpenSSL is
the only implementation so the two #defines go together, but USE_SSL is
supposed to be used for implementation-independent code.
The libpq SSL code is changed to use a custom BIO, which does all the raw
I/O, like we've been doing in the backend for a long time. That makes it
possible to use MSG_NOSIGNAL to block SIGPIPE when using SSL, which avoids
a couple of syscall for each send(). Probably doesn't make much performance
difference in practice - the SSL encryption is expensive enough to mask the
effect - but it was a natural result of this refactoring.
Based on a patch by Martijn van Oosterhout from 2006. Briefly reviewed by
Alvaro Herrera, Andreas Karlsson, Jeff Janes.
When autovacuum is nominally off, we will still launch autovac workers
to vacuum tables that are at risk of XID wraparound. But after we'd done
that, an autovac worker would proceed to autovacuum every table in the
targeted database, if they meet the usual thresholds for autovacuuming.
This is at best pretty unexpected; at worst it delays response to the
wraparound threat. Fix it so that if autovacuum is nominally off, we
*only* do forced vacuums and not any other work.
Per gripe from Andrey Zhidenkov. This has been like this all along,
so back-patch to all supported branches.
InitProcess() relies on IsBackgroundWorker to decide whether the PGPROC
for a new backend should be taken from ProcGlobal's freeProcs or from
bgworkerFreeProcs. In EXEC_BACKEND builds, InitProcess() is called
sooner than in non-EXEC_BACKEND builds, and IsBackgroundWorker wasn't
getting initialized soon enough.
Report by Noah Misch. Diagnosis and fix by me.
If a connection committed or rolled back any transactions within a
PGSTAT_STAT_INTERVAL pacing interval without accessing any tables,
the reporting of those statistics would be held up until the
connection closed or until it ended a PGSTAT_STAT_INTERVAL interval
in which it had accessed a table. This could result in under-
reporting of transactions for an extended period, followed by a
spike in reported transactions.
While this is arguably a bug, the impact is minimal, primarily
affecting, and being affected by, monitoring software. It might
cause more confusion than benefit to change the existing behavior
in released stable branches, so apply only to master and the 9.4
beta.
Gurjeet Singh, with review and editing by Kevin Grittner,
incorporating suggested changes from Abhijit Menon-Sen and Tom
Lane.
The assertion failed if WAL_DEBUG or LWLOCK_STATS was enabled; fix that by
using separate memory contexts for the allocations made within those code
blocks.
This patch introduces a mechanism for marking any memory context as allowed
in a critical section. Previously ErrorContext was exempt as a special case.
Instead of a blanket exception of the checkpointer process, only exempt the
memory context used for the pending ops hash table.
The existance of the assert_enabled variable (backing the
debug_assertions GUC) reduced the amount of knowledge some static code
checkers (like coverity and various compilers) could infer from the
existance of the assertion. That could have been solved by optionally
removing the assertion_enabled variable from the Assert() et al macros
at compile time when some special macro is defined, but the resulting
complication doesn't seem to be worth the gain from having
debug_assertions. Recompiling is fast enough.
The debug_assertions GUC is still available, but readonly, as it's
useful when diagnosing problems. The commandline/client startup option
-A, which previously also allowed to enable/disable assertions, has
been removed as it doesn't serve a purpose anymore.
While at it, reduce code duplication in bufmgr.c and localbuf.c
assertions checking for spurious buffer pins. That code had to be
reindented anyway to cope with the assert_enabled removal.
Arrange for postmaster child processes to respond to two environment
variables, PG_OOM_ADJUST_FILE and PG_OOM_ADJUST_VALUE, to determine whether
they reset their OOM score adjustments and if so to what. This is superior
to the previous design involving #ifdef's in several ways. The behavior is
now available in a default build, and both ends of the adjustment --- the
original adjustment of the postmaster's level and the subsequent
readjustment by child processes --- can now be controlled in one place,
namely the postmaster launch script. So it's no longer necessary for the
launch script to act on faith that the server was compiled with the
appropriate options. In addition, if someone wants to use an OOM score
other than zero for the child processes, that doesn't take a recompile
anymore; and we no longer have to cater separately to the two different
historical kernel APIs for this adjustment.
Gurjeet Singh, somewhat revised by me
187492b6c2 changed pgstat.c so that
the stats files were saved into $PGDATA/pg_stat directory when the server
was shutdowned. But it accidentally forgot to change the location of
pg_stat_statements permanent stats file. This commit fixes pg_stat_statements
so that its stats file is also saved into $PGDATA/pg_stat at shutdown.
Since this fix changes the file layout, we don't back-patch it to 9.3
where this oversight was introduced.
In yesterday's commit 2dc4f011fd, I tried
to force buffering of stdout/stderr in initdb to be what it is by
default when the program is run interactively on Unix (since that's how
most manual testing is done). This tripped over the fact that Windows
doesn't support _IOLBF mode. We dealt with that a long time ago in
syslogger.c by falling back to unbuffered mode on Windows. Export that
solution in port.h and use it in initdb.
Back-patch to 8.4, like the previous commit.
Just as we would start bgworkers immediately after an initial startup
of the server, we should restart them immediately when reinitializing.
Petr Jelinek and Robert Haas
Since the postmaster won't perform a crash-and-restart sequence
for background workers which don't request shared memory access,
we'd better make sure that they can't corrupt shared memory.
Patch by me, review by Tom Lane.
The motivation for a crash and restart cycle when a backend dies is
that it might have corrupted shared memory on the way down; and we
can't recover reliably except by reinitializing everything. But that
doesn't apply to processes that don't touch shared memory. Currently,
there's nothing to prevent a background worker that doesn't request
shared memory access from touching shared memory anyway, but that's a
separate bug.
Previous to this commit, the coding in postmaster.c was inconsistent:
an exit status other than 0 or 1 didn't provoke a crash-and-restart,
but failure to release the postmaster child slot did. This change
makes those cases consistent.
According to the Single Unix Spec and assorted man pages, you're supposed
to use the constants named AF_xxx when setting ai_family for a getaddrinfo
call. In a few places we were using PF_xxx instead. Use of PF_xxx
appears to be an ancient BSD convention that was not adopted by later
standardization. On BSD and most later Unixen, it doesn't matter much
because those constants have equivalent values anyway; but nonetheless
this code is not per spec.
In the same vein, replace PF_INET by AF_INET in one socket() call, which
wasn't even consistent with the other socket() call in the same function
let alone the remainder of our code.
Per investigation of a Cygwin trouble report from Marco Atzeri. It's
probably a long shot that this will fix his issue, but it's wrong in
any case.
Previously, in some places, socket creation errors were checked for
negative values, which is not true for Windows because sockets are
unsigned. This masked socket creation errors on Windows.
Backpatch through 9.0. 8.4 doesn't have the infrastructure to fix this.
Formerly, we set up the postmaster's signal handling only when we were
about to start launching subprocesses. This is a bad idea though, as
it means that for example a SIGINT arriving before that will kill the
postmaster instantly, perhaps leaving lockfiles, socket files, shared
memory, etc laying about. We'd rather that such a signal caused orderly
postmaster termination including releasing of those resources. A simple
fix is to move the PostmasterMain stanza that initializes signal handling
to an earlier point, before we've created any such resources. Then, an
early-arriving signal will be blocked until we're ready to deal with it
in the usual way. (The only part that really needs to be moved up is
blocking of signals, but it seems best to keep the signal handler
installation calls together with that; for one thing this ensures the
kernel won't drop any signals we wished to get. The handlers won't get
invoked in any case until we unblock signals in ServerLoop.)
Per a report from MauMau. He proposed changing the way "pg_ctl stop"
works to deal with this, but that'd just be masking one symptom not
fixing the core issue.
It's been like this since forever, so back-patch to all supported branches.
The code for matching clients to pg_hba.conf lines that specify host names
(instead of IP address ranges) failed to complain if reverse DNS lookup
failed; instead it silently didn't match, so that you might end up getting
a surprising "no pg_hba.conf entry for ..." error, as seen in bug #9518
from Mike Blackwell. Since we don't want to make this a fatal error in
situations where pg_hba.conf contains a mixture of host names and IP
addresses (clients matching one of the numeric entries should not have to
have rDNS data), remember the lookup failure and mention it as DETAIL if
we get to "no pg_hba.conf entry". Apply the same approach to forward-DNS
lookup failures, too, rather than treating them as immediate hard errors.
Along the way, fix a couple of bugs that prevented us from detecting an
rDNS lookup error reliably, and make sure that we make only one rDNS lookup
attempt; formerly, if the lookup attempt failed, the code would try again
for each host name entry in pg_hba.conf. Since more or less the whole
point of this design is to ensure there's only one lookup attempt not one
per entry, the latter point represents a performance bug that seems
sufficient justification for back-patching.
Also, adjust src/port/getaddrinfo.c so that it plays as well as it can
with this code. Which is not all that well, since it does not have actual
support for rDNS lookup, but at least it should return the expected (and
required by spec) error codes so that the main code correctly perceives the
lack of functionality as a lookup failure. It's unlikely that PG is still
being used in production on any machines that require our getaddrinfo.c,
so I'm not excited about working harder than this.
To keep the code in the various branches similar, this includes
back-patching commits c424d0d105 and
1997f34db4 into 9.2 and earlier.
Back-patch to 9.1 where the facility for hostnames in pg_hba.conf was
introduced.
Initialization of this field was not being done according to the
st_changecount protocol (it has to be done within the changecount increment
range, not outside). And the test to see if the value should be reported
as null was wrong. Noted while perusing uses of Port.remote_hostname.
This was wrong from the introduction of this code (commit 4a25bc145),
so back-patch to 9.1.
The new function dsm_detach_all() can be used either by postmaster
children that don't wish to take any risk of accidentally corrupting
shared memory; or by forked children of regular backends with
the same need. This patch also updates the postmaster children that
already do PGSharedMemoryDetach() to do dsm_detach_all() as well.
Per discussion with Tom Lane.
In order for this to work, walsenders need the optional ability to
connect to a database, so the "replication" keyword now allows true
or false, for backward-compatibility, and the new value "database"
(which causes the "dbname" parameter to be respected).
walsender needs to loop not only when idle but also when sending
decoded data to the user and when waiting for more xlog data to decode.
This means that there are now three separate loops inside walsender.c;
although some refactoring has been done here, this is still a bit ugly.
Andres Freund, with contributions from Álvaro Herrera, and further
review by me.
We were unlinking the permanent file, not the non-permanent one. But
since the stat collector already unlinks all permanent files on startup,
there was nothing for it to unlink. The non-permanent file remained in
place, and was copied to the permanent directory on shutdown, so in
effect no file was ever dropped.
Backpatch to 9.3, where the issue was introduced by commit 187492b6c2.
Before that, there were no per-database files and thus no file to drop
on DROP DATABASE.
Per report from Thom Brown.
Author: Tomáš Vondra
