LevelDB-Time-To-Live

作者：韩晨旭 10225101440 李畅 10225102463

Vēsture

costan 05709fb43e Remove InitOnce from the port API. This is not an API-breaking change, because it reduces the API that the leveldb embedder must implement. The project will build just fine against ports that still implement InitOnce. C++11 guarantees thread-safe initialization of static variables inside functions. This is a more restricted form of std::call_once or pthread_once_t (e.g., single call site), so the compiler might be able to generate better code [1]. Equally important, having less code in port_example.h makes it easier to port to other platforms. Due to the change above, this CL introduces a new approach for storing the singleton BytewiseComparatorImpl instance returned by BytewiseComparator(). The new approach avoids a dynamic memory allocation, which eliminates the false positive from LeakSanitizer reported in https://github.com/google/leveldb/issues/200 [1] https://stackoverflow.com/a/27206650/ ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=212348004			pirms 6 gadiem
..
win	reverting disastrous MOE commit, returning to r21	删除	pirms 13 gadiem
README	Replace port_posix with port_stdcxx.		pirms 6 gadiem
atomic_pointer.h	Take <atomic> for granted in port/atomic_pointer.h.		pirms 6 gadiem
port.h	Replace port_posix with port_stdcxx.		pirms 6 gadiem
port_config.h.in	Take <atomic> for granted in port/atomic_pointer.h.		pirms 6 gadiem
port_example.h	Remove InitOnce from the port API.		pirms 6 gadiem
port_stdcxx.h	Remove InitOnce from the port API.		pirms 6 gadiem
thread_annotations.h	Enable thread safety annotations in open source version.		pirms 6 gadiem

README

This directory contains interfaces and implementations that isolate the
rest of the package from platform details.

Code in the rest of the package includes "port.h" from this directory.
"port.h" in turn includes a platform specific "port_<platform>.h" file
that provides the platform specific implementation.

See port_stdcxx.h for an example of what must be provided in a platform
specific header file.