Update to leveldb 1.6
Highlights
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Mmap at most 1000 files on Posix to improve performance for large databases.
Support for more architectures (thanks to Alexander K.)
Building and porting
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HP/UX support (issue 126)
AtomicPointer for ia64 (issue 123)
Sparc v9 support (issue 124)
Atomic ops for powerpc
Use -fno-builtin-memcmp only when using g++
Simplify IOS build rules (issue 114)
Use CXXFLAGS instead of CFLAGS when invoking C++ compiler (issue 118)
Fix snappy shared library problem (issue 94)
Fix shared library installation path regression
Endian-ness detection tweak for FreeBSD
Bug fixes
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Stop ignoring FLAGS_open_files in db_bench
Make bloom test behavior agnostic to endian-ness
Performance
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Limit number of mmapped files to 1000 to improve perf for large dbs
Do not delay for 1 second on shutdown path (issue 125)
Misc
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Make InMemoryEnv return a no-op logger
C binding now has a wrapper for free (issue 117)
Add thread-safety annotations
Added an in-process lock table (issue 120)
Make RandomAccessFile and SequentialFile non-copyable
25 files changed
