Summary:
This patch adds direct IO capability to RocksDB Env.
The direct IO capability is required for persistent cache since NVM is best
accessed as 4K direct IO. SSDs can leverage direct IO for reading.
Direct IO requires the offset and size be sector size aligned, and memory to
be kernel page aligned. Since neither RocksDB/Persistent read cache data
layout is aligned to sector size, the code can accommodate reading unaligned IO size
(or unaligned memory) at the cost of an alloc/copy.
The write code path expects the size and memory to be aligned.
Test Plan: Run RocksDB unit tests
Reviewers: sdong
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D57393
Summary:
Persistent read cache relies on the accuracy of the GetUniqueIdFromFile
to generate a unique key for a given block of data. Currently we don't have an
implementation for Mac.
This patch adds an implementation.
Test Plan: Run unit tests
Reviewers: sdong
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D58413
in 64-bit.
Currently, a signed off_t type is being used for the following
interfaces for both offset and the length in bytes:
* `Allocate`
* `RangeSync`
On Linux `off_t` is automatically either 32 or 64-bit depending on
the platform. On Windows it is always a 32-bit signed long which
limits file access and in particular space pre-allocation
to effectively 2 Gb.
Proposal is to replace off_t with uint64_t as a portable type
always access files with 64-bit interfaces.
May need to modify posix code but lack resources to test it.
Summary: include/posix/io_posix.h is not a public API. Although include/posix/ is not a public header directory, it is confusing to put non-public headers to under include/. Move it to util/ to be clearer.
Test Plan: Run all tests
Reviewers: rven, IslamAbdelRahman, anthony, kradhakrishnan, yhchiang, igor
Reviewed By: igor
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D49611
