The intention is to initialize tls-key variable with this invalid
value. This will help us avoid separate "tls ready" flag and possible
memory ordering issues around distinct tls key and tls-ready
variables.
On windows we use TLS_OUT_OF_INDEXES values which is properly
"impossible" tls index value. On POSIX systems we add theoretically
unportable, but practically portable assumption that tls keys are
integers. And we make value of -1 be that invalid key.
We use __builtin_trap (which compiles to explicitly undefined
instruction or "int 3" on x64-en), when available, to make those
crashing Log invokations a little nicer to debug.
This will not only make things right w.r.t. possible order of test
runs, but it also unbreaks test failures on windows (where gtest ends
up doing some malloc after test completion, hits the limit and dies).
Sadly, certain/many implementations of std::this_thread::id invoke
malloc. So we need something more robust. On Unix systems we use
address of errno as thread identifier. Sadly, this doesn't cover
windows where MS's C runtime facility will occasionally malloc when
errno location is grabbed (with some special trickery for when malloc
itself needs to set errno to ENOMEM!). So on windows, we do
GetCurrentThreadId which appears to be roughly as efficient as
"normal" system's __errno_location implementation.
We use mmap when we initialize it, which could via heap checker
recurse back into backtracing and check-address. So before we do mmap
and rest of initialization, we now set check-address implementation
to conservative two-syscalls version.
We had duplicate definition of flags_tmp variable.
Signed-off-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
[alkondratenko@gmail.com] updated commit message
Apparently some recent FreeBSDs occasionally lack brk. So our code
which previously hard-coded that this OS has brk (which we use to
implement hooked sbrk) fails to compile.
Our configure scripts already detects sbrk, so we simply need to pay
attention. Fixes github issue #1499
Our implementation of emergency malloc slow-path actually depends on
good TLS implementation. So on systems without good TLS (i.e. OSX), we
lied to ourselves that emergency malloc is available, but then failed
tests.
We don't expose DefaultArena anymore. Simply passing nullptr implies
default arena.
We also streamline default arena initialization (we
previously relied on combination of lazy initialazation in ArenaInit
and constexpr construction).
There is also no need to have elaborate ArenaLock thingy. We use plain
SpinLockHolder instead.
This is off by default for now. And autotools-only. But after
significant preparatory work, we're now able to do it cleanly. Stuff
that was previously exported just for tests (like page heap stuff or
flags) is now unexported.
Just like on windows all symbols explicitly exported by
PERFTOOLS_DLL_DECL are visible and exported and rest are hidden. Those
include all the malloc/new APIs of course, and all the other symbols
we advertise in our headers (e.g. MallocExtension, MallocHook).
Updates issue #600
While it still needs more work to be up to highest standards of
cleanness and clarity, we made it better.
One big part of this change is we're now liberated from
tcmalloc_unittest.sh. We now arrange testing of various environment
variable tweaks in C++ by self-execing with updated environment at the
end of tests.
Biggest part of it is removal of SetTestResourceLimit. The reasoning
behind it is, we don't do it on windows. Tests pass just fine. So,
there is no reason to bother.
I just dealt with somewhat curious failure in page heap test and the
change was due to breakage of HaveSystemRelease on OSX. And since OSX
can truly release memory and Windows too, lets assert this.
