Fix a chunk recycling bug that could cause the allocator to lose track
of whether a chunk was zeroed.  On FreeBSD, NetBSD, and OS X, it could
cause corruption if allocating via sbrk(2) (unlikely unless running with
the "dss:primary" option specified).  This was completely harmless on
Linux unless using mlockall(2) (and unlikely even then, unless the
--disable-munmap configure option or the "dss:primary" option was
specified).  This regression was introduced in 3.1.0 by the
mlockall(2)/madvise(2) interaction fix.

Internal reallocation of the quarantined object array leaked the old array.

Reallocation failure for internal reallocation of the quarantined object
array (very unlikely) resulted in memory corruption.

Avoid writing to uninitialized TLS as a side effect of deallocation.
Initializing TLS during deallocation is unsafe because it is possible
that a thread never did any allocation, and that TLS has already been
deallocated by the threads library, resulting in write-after-free
corruption.  These fixes affect prof_tdata and quarantine; all other
uses of TLS are already safe, whether intentionally (as for tcache) or
unintentionally (as for arenas).

Specify both inline and __attribute__((always_inline)), in order to
avoid warnings when using newer versions of gcc.

Revert refactoring of opt_abort and opt_junk declarations.  clang
accepts the config_*-based declarations (and generates correct code),
but gcc complains with:

  error: initializer element is not constant

Submitted by Frederik Deweerdt.

Convert a couple of stragglers from JEMALLOC_* to use config_*.

Update hash from MurmurHash2 to MurmurHash3, primarily because the
latter generates 128 bits in a single call for no extra cost, which
simplifies integration with cuckoo hashing.

Fix AC_PATH_PROG() calls to specify 'false' as the default, so that if
the configure script fails to find a program, the false program is
instead called, and an error occurs.  Prior to this fix, if xsltproc
could not be found, make would not report an error due to the leading -o
in the xsltproc invocation.

Reported by David Reiss.

Add JEMALLOC_ALWAYS_INLINE and use it to guarantee that the entire fast
paths of the primary allocation/deallocation functions are inlined.

Tighten valgrind integration such that immediately after memory is
validated or zeroed, valgrind is told to forget the memory's 'defined'
state.  The only place newly allocated memory should be left marked as
'defined' is in the public functions (e.g. calloc() and realloc()).

Move validation of supposedly zeroed pages from chunk_alloc() to
chunk_recycle().  There is little point to validating newly mapped
memory returned by chunk_alloc_mmap(), and memory that comes from sbrk()
is explicitly zeroed, so there is little risk to assuming that
chunk_alloc_dss() actually does the zeroing properly.

This relaxation of validation can make a big difference to application
startup time and overall system usage on platforms that use jemalloc as
the system allocator (namely FreeBSD).

Submitted by Ian Lepore <ian@FreeBSD.org>.

Linux uses alloca.h; many other operating systems define alloca(3) in
stdlib.h.

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>

In particular:
- ffsl always returns int, not long, on FreeBSD, Linux, and OSX.
- Mute compiler warnings about rv being unused (and the potential for
   compilers optimizing out the call completely) by dumping the value
   with printf(3).

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>

This ensures POLA on FreeBSD (at least) as free(3) is generally assumed
to not fiddle around with errno.

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>

Modify processing of the lg_chunk option so that it clips an
out-of-range input to the edge of the valid range.  This makes it
possible to request the minimum possible chunk size without intimate
knowledge of allocator internals.

Submitted by Ian Lepore (see FreeBSD PR bin/174641).

Fix chunk_recycyle() to unconditionally inform Valgrind that returned
memory is undefined.  This fixes Valgrind warnings that would result
from a huge allocation being freed, then recycled for use as an arena
chunk.  The arena code would write metadata to the chunk header, and
Valgrind would consider these invalid writes.

Reported by Mike Hommey.

When statically linking jemalloc, it may be beneficial not to export its
symbols if it makes sense, which allows the compiler and the linker to do
some further optimizations.

Refactor arena_prof_accum() and its callers to avoid arena locking when
prof_interval is 0 (as when profiling is disabled).

Reported by Ben Maurer.

Tweak chunk purge order to purge unfragmented chunks from high to low
memory.  This facilitates dirty run reuse.

Based on http://www.canonware.com/pipermail/jemalloc-discuss/2012-March/000164.html

Purge unused dirty pages in an order that first performs clean/dirty run
defragmentation, in order to mitigate available run fragmentation.

Remove the limitation that prevented purging unless at least one chunk
worth of dirty pages had accumulated in an arena.  This limitation was
intended to avoid excessive purging for small applications, but the
threshold was arbitrary, and the effect of questionable utility.

Relax opt_lg_dirty_mult from 5 to 3.  This compensates for increased
likelihood of allocating clean runs, given the same ratio of clean:dirty
runs, and reduces the potential for repeated purging in pathological
large malloc/free loops that push the active:dirty page ratio just over
the purge threshold.

Fix deadlock in the arenas.purge mallctl due to recursive mutex
acquisition.

Fix dss/mmap allocation precedence code to use recyclable mmap memory
only after primary dss allocation fails.

Add ctl_mutex proection to arena_i_dss_ctl(), since ctl_stats.narenas is
accessed.

Add the "arenas.extend" mallctl, so that it is possible to create new
arenas that are outside the set that jemalloc automatically multiplexes
threads onto.

Add the ALLOCM_ARENA() flag for {,r,d}allocm(), so that it is possible
to explicitly allocate from a particular arena.

Add the "opt.dss" mallctl, which controls the default precedence of dss
allocation relative to mmap allocation.

Add the "arena.<i>.dss" mallctl, which makes it possible to set the
default dss precedence on a per arena or global basis.

Add the "arena.<i>.purge" mallctl, which obsoletes "arenas.purge".

Add the "stats.arenas.<i>.dss" mallctl.

Mozilla build hides everything by default using visibility pragma and
unhides only explicitly listed headers. But this doesn't work on FreeBSD
because _pthread_mutex_init_calloc_cb is neither documented nor exposed
via any header.

Use JEMALLOC_USABLE_SIZE_CONST for the malloc_usable_size()
implementation as well as the prototype, for consistency's sake.

Drop const from malloc_usable_size() argument on Linux, in order to
match the prototype in Linux's malloc.h.