Revision 3df07d1703297cf8bf98327c1dc65f48d18957f5 authored by sdong on 19 May 2014, 17:40:18 UTC, committed by sdong on 19 May 2014, 18:52:12 UTC
Summary:
Add a feature to decrease the number of threads in thread pool.
Also instantly schedule more threads if number of threads is increased.

Here is the way it is implemented: each background thread needs its thread ID. After decreasing number of threads, all threads are woken up. The thread with the largest thread ID will terminate. If there are more threads to terminate, the thread will wake up all threads again.

Another change is made so that when number of threads is increased, more threads are created and all previous excessive threads are woken up to do the work.

Test Plan: Add a unit test.

Reviewers: haobo, dhruba

Reviewed By: haobo

CC: yhchiang, igor, nkg-, leveldb

Differential Revision: https://reviews.facebook.net/D18675
1 parent 1e56045
Raw File
filename.h
//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
//  This source code is licensed under the BSD-style license found in the
//  LICENSE file in the root directory of this source tree. An additional grant
//  of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// File names used by DB code

#pragma once
#include <stdint.h>
#include <string>
#include "rocksdb/slice.h"
#include "rocksdb/status.h"
#include "rocksdb/transaction_log.h"
#include "port/port.h"

namespace rocksdb {

class Env;
class Directory;

enum FileType {
  kLogFile,
  kDBLockFile,
  kTableFile,
  kDescriptorFile,
  kCurrentFile,
  kTempFile,
  kInfoLogFile,  // Either the current one, or an old one
  kMetaDatabase,
  kIdentityFile
};

// Return the name of the log file with the specified number
// in the db named by "dbname".  The result will be prefixed with
// "dbname".
extern std::string LogFileName(const std::string& dbname, uint64_t number);

static const std::string ARCHIVAL_DIR = "archive";

extern std::string ArchivalDirectory(const std::string& dbname);

//  Return the name of the archived log file with the specified number
//  in the db named by "dbname". The result will be prefixed with "dbname".
extern std::string ArchivedLogFileName(const std::string& dbname,
                                       uint64_t num);

// Return the name of the sstable with the specified number
// in the db named by "dbname".  The result will be prefixed with
// "dbname".
extern std::string TableFileName(const std::string& dbname, uint64_t number);

// Return the name of the descriptor file for the db named by
// "dbname" and the specified incarnation number.  The result will be
// prefixed with "dbname".
extern std::string DescriptorFileName(const std::string& dbname,
                                      uint64_t number);

// Return the name of the current file.  This file contains the name
// of the current manifest file.  The result will be prefixed with
// "dbname".
extern std::string CurrentFileName(const std::string& dbname);

// Return the name of the lock file for the db named by
// "dbname".  The result will be prefixed with "dbname".
extern std::string LockFileName(const std::string& dbname);

// Return the name of a temporary file owned by the db named "dbname".
// The result will be prefixed with "dbname".
extern std::string TempFileName(const std::string& dbname, uint64_t number);

// Return the name of the info log file for "dbname".
extern std::string InfoLogFileName(const std::string& dbname,
    const std::string& db_path="", const std::string& log_dir="");

// Return the name of the old info log file for "dbname".
extern std::string OldInfoLogFileName(const std::string& dbname, uint64_t ts,
    const std::string& db_path="", const std::string& log_dir="");

// Return the name to use for a metadatabase. The result will be prefixed with
// "dbname".
extern std::string MetaDatabaseName(const std::string& dbname,
                                    uint64_t number);

// Return the name of the Identity file which stores a unique number for the db
// that will get regenerated if the db loses all its data and is recreated fresh
// either from a backup-image or empty
extern std::string IdentityFileName(const std::string& dbname);

// If filename is a rocksdb file, store the type of the file in *type.
// The number encoded in the filename is stored in *number.  If the
// filename was successfully parsed, returns true.  Else return false.
extern bool ParseFileName(const std::string& filename,
                          uint64_t* number,
                          FileType* type,
                          WalFileType* log_type = nullptr);

// Make the CURRENT file point to the descriptor file with the
// specified number.
extern Status SetCurrentFile(Env* env, const std::string& dbname,
                             uint64_t descriptor_number,
                             Directory* directory_to_fsync);

// Make the IDENTITY file for the db
extern Status SetIdentityFile(Env* env, const std::string& dbname);

}  // namespace rocksdb
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