tree 695abad99252bbfe5fcf0d04f6d85b5759fc4927
parent 70b7ec1b3b394d7b79291edf4928d1094b6a760d
author gabor@google.com <gabor@google.com@62dab493-f737-651d-591e-8d6aee1b9529> 1309307450 +0000
committer gabor@google.com <gabor@google.com@62dab493-f737-651d-591e-8d6aee1b9529> 1309307450 +0000

Platform detection during build, plus compatibility patches for machines without <cstdatomic>.

This revision adds two major changes:
1. build_detect_platform which generates build_config.mk
   with platform-dependent flags for the build process
2. /port/atomic_pointer.h with anAtomicPointerimplementation
   for platforms without <cstdatomic>

Some of this code is loosely based on patches submitted to the 
LevelDB mailing list at https://groups.google.com/forum/#!forum/leveldb
Tip of the hat to Dave Smith and Edouard A, who both sent patches.

The presence of Snappy (http://code.google.com/p/snappy/) and
cstdatomic are now both detected in the build_detect_platform
script (1.) which gets executing during make.

For (2.), instead of broadly importing atomicops_* from Chromium or
the Google performance tools, we chose to just implement AtomicPointer 
and the limited atomic load and store operations it needs. 
This resulted in much less code and fewer files - everything is 
contained in atomic_pointer.h.


git-svn-id: http://leveldb.googlecode.com/svn/trunk@34 62dab493-f737-651d-591e-8d6aee1b9529