A library that provides an embeddable, persistent key-value store for fast storage.
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Dhruba Borthakur 38671c4d54 Fix a race condition while processing tasks by background threads.
Summary:
Suppose you submit 100 background tasks one after another. The first
enqueu task finds that the queue is empty and wakes up one worker thread.
Now suppose that all remaining 99 work items are enqueued, they do not
wake up any worker threads because the queue is already non-empty.
This causes a situation when there are 99 tasks in the task queue but
only one worker thread is processing a task while the remaining
worker threads are waiting.
The fix is to always wakeup one worker thread while enqueuing a task.

I also added a check to count the number of elements in the queue
to help in debugging.

Test Plan: make clean check.

Reviewers: chip

Reviewed By: chip

CC: leveldb

Differential Revision: https://reviews.facebook.net/D7203
2012-12-09 17:15:27 -08:00
db GetUpdatesSince API to enable replication. 2012-12-07 11:42:13 -08:00
doc merge 1.5 2012-08-28 11:43:33 -07:00
hdfs Move WAL files to archive directory, instead of deleting. 2012-11-28 17:28:08 -08:00
helpers/memenv Move WAL files to archive directory, instead of deleting. 2012-11-28 17:28:08 -08:00
include/leveldb GetUpdatesSince API to enable replication. 2012-12-07 11:42:13 -08:00
java Add LevelDb's JNI wrapper 2012-10-05 13:13:49 -07:00
linters/src Moved FBCode Linter's to LevelDB. 2012-11-28 09:49:01 -08:00
port Make compression options configurable. These include window-bits, level and strategy for ZlibCompression 2012-11-02 11:26:39 -07:00
scribe fix db_test error with scribe logger turned on 2012-08-28 11:22:58 -07:00
snappy Build with gcc-4.7.1-glibc-2.14.1. 2012-09-17 10:56:26 -07:00
table Metrics: record compaction drop's and bloom filter effectiveness 2012-11-09 11:38:45 -08:00
thrift Implement RowLocks for assoc schema 2012-10-03 23:19:01 -07:00
tools Enhance manifest_dump to print each individual edit. 2012-11-19 12:04:35 -08:00
util Fix a race condition while processing tasks by background threads. 2012-12-09 17:15:27 -08:00
.arcconfig Moved FBCode Linter's to LevelDB. 2012-11-28 09:49:01 -08:00
.gitignore Fix ldb segfault and use static libsnappy for all builds 2012-11-21 11:07:19 -08:00
AUTHORS reverting disastrous MOE commit, returning to r21 2011-04-19 23:11:15 +00:00
build_detect_platform Fix ldb segfault and use static libsnappy for all builds 2012-11-21 11:07:19 -08:00
build_detect_version Record the version of the source repository that was used to build the leveldb library. 2012-08-24 15:18:43 -07:00
fbcode.gcc471.sh Fix ldb segfault and use static libsnappy for all builds 2012-11-21 11:07:19 -08:00
LICENSE reverting disastrous MOE commit, returning to r21 2011-04-19 23:11:15 +00:00
Makefile Fix all warnings generated by -Wall option to the compiler. 2012-11-06 14:07:31 -08:00
NEWS sync with upstream @ 21409451 2011-05-21 02:17:43 +00:00
README rocksdb README file. 2012-11-29 22:39:08 -08:00
README.fb Release 1.5.6.fb 2012-11-28 16:09:41 -08:00
TODO A number of smaller fixes and performance improvements: 2011-06-22 02:36:45 +00:00

rocksdb: A persistent key-value store for flash storage
Authors: The Facebook Database Engineering Team

This code is a library that forms the core building block for a fast 
key value server, especially suited for storing data on flash drives.
It has an Log-Stuctured-Merge-Database (LSM) design with flexible tradeoffs
between Write-Amplification-Factor(WAF), Read-Amplification-Factor (RAF)
and Space-Amplification-Factor(SAF). It has multi-threaded compactions,
making it specially suitable for storing multiple terabytes of data in a
single database.

The core of this code has been derived from open-source leveldb.

leveldb: A key-value store
Authors: Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)

The code under this directory implements a system for maintaining a
persistent key/value store.

See doc/index.html for more explanation.
See doc/impl.html for a brief overview of the implementation.

The public interface is in include/*.h.  Callers should not include or
rely on the details of any other header files in this package.  Those
internal APIs may be changed without warning.

Guide to header files:

include/db.h
    Main interface to the DB: Start here

include/options.h
    Control over the behavior of an entire database, and also
    control over the behavior of individual reads and writes.

include/comparator.h
    Abstraction for user-specified comparison function.  If you want
    just bytewise comparison of keys, you can use the default comparator,
    but clients can write their own comparator implementations if they
    want custom ordering (e.g. to handle different character
    encodings, etc.)

include/iterator.h
    Interface for iterating over data. You can get an iterator
    from a DB object.

include/write_batch.h
    Interface for atomically applying multiple updates to a database.

include/slice.h
    A simple module for maintaining a pointer and a length into some
    other byte array.

include/status.h
    Status is returned from many of the public interfaces and is used
    to report success and various kinds of errors.

include/env.h
    Abstraction of the OS environment.  A posix implementation of
    this interface is in util/env_posix.cc

include/table.h
include/table_builder.h
    Lower-level modules that most clients probably won't use directly