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Revision 91ddd587cc658b2899a4fe2b2b734e71e41c29a6 authored by Igor Canadi on 03 June 2014, 00:23:55 UTC, committed by Igor Canadi on 03 June 2014, 00:23:55 UTC 
Only signal cond variable if need to
 
Summary:
At the end of BackgroundCallCompaction(), we call SignalAll(), even though we don't need to. If compaction hasn't done anything and there's another compaction running, there is no need to signal on the condition variable. Doing so creates a tight feedback loop which results in log files like:

   wait for memtable flush
   compaction nothing to do
   wait for memtable flush
   compaction nothing to do

This change eliminates that

Test Plan:
make check
Also:

    icanadi@dev1440 ~ $ grep "nothing to do" /fast-rocksdb-tmp/rocksdb_test/column_family_test/LOG | wc -l
    7435
    icanadi@dev1440 ~ $ grep "nothing to do" /fast-rocksdb-tmp/rocksdb_test/column_family_test/LOG | wc -l
    372

First version is before the change, second version is after the change.

Reviewers: dhruba, ljin, haobo, yhchiang, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18855
1 parent 8cb7ad8
Raw File
INSTALL.md 
## Compilation

RocksDB's library should be able to compile without any dependency installed,
although we recommend installing some compression libraries (see below).
We do depend on newer gcc with C++11 support.

There are few options when compiling RocksDB:

* [recommended] `make static_lib` will compile librocksdb.a, RocksDB static library.

* `make shared_lib` will compile librocksdb.so, RocksDB shared library.

* `make check` will compile and run all the unit tests

* `make all` will compile our static library, and all our tools and unit tests. Our tools
depend on gflags. You will need to have gflags installed to run `make all`.

## Dependencies

* You can link RocksDB with following compression libraries:
  - [zlib](http://www.zlib.net/) - a library for data compression.
  - [bzip2](http://www.bzip.org/) - a library for data compression.
  - [snappy](https://code.google.com/p/snappy/) - a library for fast
      data compression.

* All our tools depend on:
  - [gflags](https://code.google.com/p/gflags/) - a library that handles
      command line flags processing. You can compile rocksdb library even
      if you don't have gflags installed.

## Supported platforms

* **Linux - Ubuntu**
    * Upgrade your gcc to version at least 4.7 to get C++11 support.
    * Install gflags. First, try: `sudo apt-get install libgflags-dev`
      If this doesn't work and you're using Ubuntu, here's a nice tutorial:
      (http://askubuntu.com/questions/312173/installing-gflags-12-04)
    * Install snappy. This is usually as easy as:
      `sudo apt-get install libsnappy-dev`.
    * Install zlib. Try: `sudo apt-get install zlib1g-dev`.
    * Install bzip2: `sudo apt-get install libbz2-dev`.
* **Linux - CentOS**
    * Upgrade your gcc to version at least 4.7 to get C++11 support:
      `yum install gcc47-c++`
    * Install gflags:

              wget https://gflags.googlecode.com/files/gflags-2.0-no-svn-files.tar.gz
              tar -xzvf gflags-2.0-no-svn-files.tar.gz
              cd gflags-2.0
              ./configure && make && sudo make install

    * Install snappy:

              wget https://snappy.googlecode.com/files/snappy-1.1.1.tar.gz
              tar -xzvf snappy-1.1.1.tar.gz
              cd snappy-1.1.1
              ./configure && make && sudo make install

    * Install zlib:

              sudo yum install zlib
              sudo yum install zlib-devel

    * Install bzip2:

              sudo yum install bzip2
              sudo yum install bzip2-devel

* **OS X**:
    * Install latest C++ compiler that supports C++ 11:
        * Update XCode:  run `xcode-select --install` (or install it from XCode App's settting).
        * Install via [homebrew](http://brew.sh/).
            * If you're first time developer in MacOS, you still need to run: `xcode-select --install` in your command line.
            * run `brew tap homebrew/dupes; brew install gcc47 --use-llvm` to install gcc 4.7 (or higher).
    * Install zlib, bzip2 and snappy libraries for compression.
    * Install gflags. We have included a script
    `build_tools/mac-install-gflags.sh`, which should automatically install it.
    If you installed gflags by other means (for example, `brew install gflags`),
    please set `LIBRARY_PATH` and `CPATH` accordingly.
    * Please note that some of the optimizations/features are disabled in OSX.
    We did not run any production workloads on it.

* **iOS**:
  * Run: `TARGET_OS=IOS make static_lib`
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