WritableFileWriter: default buffer size equal min(64k,options.writabl?
WritableFileWriter: default buffer size equal min(64k,options.writabl?

Summary:
?e_file_max_buffer_size)

If we overwrite WritableFile and has a buffer which has the same
function of buf_. We hope remove the cache function of
WritableFileWriter. So using options.writable_file_max_buffer_size = 0
to disable cache function.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
Closes https://github.com/facebook/rocksdb/pull/1628

Differential Revision: D4307219

Pulled By: yiwu-arbug

fbshipit-source-id: 77a6e26

SunguckLee/RocksDB,vmx/rocksdb,Andymic/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,vmx/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,bbiao/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,vmx/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,bbiao/rocksdb,Andymic/rocksdb,bbiao/rocksdb,bbiao/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb