If the compiler/arch combination does not provide compiler barriers,
provide a fallback. That fallback simply consists out of a function
call into a externally defined function. That should guarantee
compiler barrierer semantics except for compilers that do inter
translation unit/global optimization - those better provide an actual
compiler barrier.
Hopefully this fixes Tom's report of linker failures due to
pg_compiler_barrier_impl not being provided.
I'm not backpatching this commit as it builds on the new atomics
infrastructure. If we decide an equivalent fix needs to be
backpatched, I'll do so in a separate commit.
Discussion: 27746.1420930690@sss.pgh.pa.us
Per report from Tom Lane.
I failed to recognize that pg_atomic_uint64 wasn't guaranteed to be 8
byte aligned on some 32bit platforms - which it has to be on some
platforms to guarantee the desired atomicity and which we assert.
As this is all compiler specific code anyway we can just rely on
compiler specific tricks to enforce alignment.
I've been unable to find concrete documentation about the version that
introduce the sunpro alignment support, so that might need additional
guards.
I've verified that this works with gcc x86 32bit, but I don't have
access to any other 32bit environment.
Discussion: op.xpsjdkil0sbe7t@vld-kuci
Per report from Vladimir Koković.
* Don't play tricks for a more efficient pg_atomic_clear_flag() in the
generic gcc implementation. The old version was broken on gcc < 4.7
on !x86 platforms. Per buildfarm member chipmunk.
* Make usage of __atomic() fences depend on HAVE_GCC__ATOMIC_INT32_CAS
instead of HAVE_GCC__ATOMIC_INT64_CAS - there's platforms with 32bit
support that don't support 64bit atomics.
* Blindly fix two superflous #endif in generic-xlc.h
* Check for --disable-atomics in platforms but x86.
Some x86 32bit versions of gcc apparently generate references to the
nonexistant %sil register when using when using the r input
constraint, but not with the =q constraint. The latter restricts
allocations to a/b/c/d which should all work.
Several upcoming performance/scalability improvements require atomic
operations. This new API avoids the need to splatter compiler and
architecture dependent code over all the locations employing atomic
ops.
For several of the potential usages it'd be problematic to maintain
both, a atomics using implementation and one using spinlocks or
similar. In all likelihood one of the implementations would not get
tested regularly under concurrency. To avoid that scenario the new API
provides a automatic fallback of atomic operations to spinlocks. All
properties of atomic operations are maintained. This fallback -
obviously - isn't as fast as just using atomic ops, but it's not bad
either. For one of the future users the atomics ontop spinlocks
implementation was actually slightly faster than the old purely
spinlock using implementation. That's important because it reduces the
fear of regressing older platforms when improving the scalability for
new ones.
The API, loosely modeled after the C11 atomics support, currently
provides 'atomic flags' and 32 bit unsigned integers. If the platform
efficiently supports atomic 64 bit unsigned integers those are also
provided.
To implement atomics support for a platform/architecture/compiler for
a type of atomics 32bit compare and exchange needs to be
implemented. If available and more efficient native support for flags,
32 bit atomic addition, and corresponding 64 bit operations may also
be provided. Additional useful atomic operations are implemented
generically ontop of these.
The implementation for various versions of gcc, msvc and sun studio have
been tested. Additional existing stub implementations for
* Intel icc
* HUPX acc
* IBM xlc
are included but have never been tested. These will likely require
fixes based on buildfarm and user feedback.
As atomic operations also require barriers for some operations the
existing barrier support has been moved into the atomics code.
Author: Andres Freund with contributions from Oskari Saarenmaa
Reviewed-By: Amit Kapila, Robert Haas, Heikki Linnakangas and Álvaro Herrera
Discussion: CA+TgmoYBW+ux5-8Ja=Mcyuy8=VXAnVRHp3Kess6Pn3DMXAPAEA@mail.gmail.com,
20131015123303.GH5300@awork2.anarazel.de,
20131028205522.GI20248@awork2.anarazel.de
Support for running postgres on Alpha hasn't been tested for a long
while. Due to Alpha's uniquely lax cache coherency model it's a hard
to develop for platform (especially blindly!) and thought to be
unlikely to currently work correctly.
As Alpha is the only supported architecture for Tru64 drop support for
it as well. Tru64's support has ended 2012 and it has been in
maintenance-only mode for much longer.
Also remove stray references to __ksr__ and ultrix defines.
asprintf(), aside from not being particularly portable, has a fundamentally
badly-designed API; the psprintf() function that was added in passing in
the previous patch has a much better API choice. Moreover, the NetBSD
implementation that was borrowed for the previous patch doesn't work with
non-C99-compliant vsnprintf, which is something we still have to cope with
on some platforms; and it depends on va_copy which isn't all that portable
either. Get rid of that code in favor of an implementation similar to what
we've used for many years in stringinfo.c. Also, move it into libpgcommon
since it's not really libpgport material.
I think this patch will be enough to turn the buildfarm green again, but
there's still cosmetic work left to do, namely get rid of pg_asprintf()
in favor of using psprintf(). That will come in a followon patch.
Development of IRIX has been discontinued, and support is scheduled
to end in December of 2013. Therefore, there will be no supported
versions of this operating system by the time PostgreSQL 9.4 is
released. Furthermore, we have no maintainer for this platform.
This change will only apply to mingw compilers, and has been found
necessary by late versions of the mingw-w64 compiler. It's the same as
what is done elsewhere for the Microsoft compilers.
If this doesn't upset older compilers in the buildfarm, it will be
backpatched to 9.1.
Problem reported by Michael Cronenworth, although not his patch.
Remove the following ports:
- dgux
- nextstep
- sunos4
- svr4
- ultrix4
- univel
These are obsolete and not worth rescuing. In most cases, there is
circumstantial evidence that they wouldn't work anymore anyway.
Original patch by Lars Kanis, reviewed by Nishiyama Tomoaki and tweaked some by me.
This compiler, or at least the latest version of it, is currently broken, and
only passes the regression tests if built with -O0.
These functions should take a pg_locale_t, not a collation OID, and should
call mbstowcs_l/wcstombs_l where available. Where those functions are not
available, temporarily select the correct locale with uselocale().
This change removes the bogus assumption that all locales selectable in
a given database have the same wide-character conversion method; in
particular, the collate.linux.utf8 regression test now passes with
LC_CTYPE=C, so long as the database encoding is UTF8.
I decided to move the char2wchar/wchar2char functions out of mbutils.c and
into pg_locale.c, because they work on wchar_t not pg_wchar_t and thus
don't really belong with the mbutils.c functions. Keeping them where they
were would have required importing pg_locale_t into pg_wchar.h somehow,
which did not seem like a good plan.
This can be used to build 64 bit Windows binaries, not only on 64 bit
Windows but on supported cross-compiling hosts including 32 bit Windows,
Cygwin, Darwin and Linux.
Add support for collecting "minidump" style crash dumps on
Windows, by setting up an exception handling filter. Crash
dumps will be generated in PGDATA/crashdumps if the directory
is created (the existance of the directory is used as on/off
switch for the generation of the dumps).
Craig Ringer and Magnus Hagander
Recent versions of the Linux system header files cause xlogdefs.h to
believe that open_datasync should be the default sync method, whereas
formerly fdatasync was the default on Linux. open_datasync is a bad
choice, first because it doesn't actually outperform fdatasync (in fact
the reverse), and second because we try to use O_DIRECT with it, causing
failures on certain filesystems (e.g., ext4 with data=journal option).
This part of the patch is largely per a proposal from Marti Raudsepp.
More extensive changes are likely to follow in HEAD, but this is as much
change as we want to back-patch.
Also clean up confusing code and incorrect documentation surrounding the
fsync_writethrough option. Those changes shouldn't result in any actual
behavioral change, but I chose to back-patch them anyway to keep the
branches looking similar in this area.
In 9.0 and HEAD, also do some copy-editing on the WAL Reliability
documentation section.
Back-patch to all supported branches, since any of them might get used
on modern Linux versions.
and use this in pq_getbyte_if_available.
It's only a limited implementation which swithes the whole emulation layer
no non-blocking mode, but that's enough as long as non-blocking is only
used during a short period of time, and only one socket is accessed during
this time.
compilers, by applying a configure check to see if the compiler will accept
an unreferenced "static inline foo ..." function without warnings. It is
believed that such warnings are the only reason not to declare inlined
functions in headers, if the compiler understands "inline" at all.
Kurt Harriman
Robert Haas
Heikki Linnakangas
Andres Freund
Bruce Momjian
Peter Eisentraut
Andrew Dunstan
Tom Lane
Magnus Hagander
Itagaki Takahiro