This file is indexed.

/usr/include/mongo/db/repl/bgsync.h is in mongodb-dev 1:2.4.9-1ubuntu2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
/**
 *    Copyright (C) 2012 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include <boost/thread/mutex.hpp>

#include "mongo/util/queue.h"
#include "mongo/db/oplogreader.h"
#include "mongo/db/repl/rs.h"
#include "mongo/db/jsobj.h"

namespace mongo {
namespace replset {

    // This interface exists to facilitate easier testing;
    // the test infrastructure implements these functions with stubs.
    class BackgroundSyncInterface {
    public:
        virtual ~BackgroundSyncInterface();

        // Gets the head of the buffer, but does not remove it. 
        // Returns true if an element was present at the head;
        // false if the queue was empty.
        virtual bool peek(BSONObj* op) = 0;

        // Deletes objects in the queue;
        // called by sync thread after it has applied an op
        virtual void consume() = 0;

        // Returns the member we're currently syncing from (or NULL)
        virtual const Member* getSyncTarget() = 0;

        // wait up to 1 second for more ops to appear
        virtual void waitForMore() = 0;
    };


    /**
     * notifierThread() uses lastOpTimeWritten to inform the sync target where this member is
     * currently synced to.
     *
     * Lock order:
     * 1. rslock
     * 2. rwlock
     * 3. BackgroundSync::_mutex
     */
    class BackgroundSync : public BackgroundSyncInterface {
        static BackgroundSync *s_instance;
        // protects creation of s_instance
        static boost::mutex s_mutex;

        // _mutex protects all of the class variables
        boost::mutex _mutex;

        // Production thread
        BlockingQueue<BSONObj> _buffer;

        OpTime _lastOpTimeFetched;
        long long _lastH;
        // if produce thread should be running
        bool _pause;
        bool _appliedBuffer;
        bool _assumingPrimary;
        boost::condition _condvar;

        const Member* _currentSyncTarget;

        // Notifier thread

        // used to wait until another op has been replicated
        boost::condition_variable _lastOpCond;
        boost::mutex _lastOpMutex;

        const Member* _oplogMarkerTarget;
        OplogReader _oplogMarker; // not locked, only used by notifier thread
        OpTime _consumedOpTime; // not locked, only used by notifier thread

        BackgroundSync();
        BackgroundSync(const BackgroundSync& s);
        BackgroundSync operator=(const BackgroundSync& s);

        // Production thread
        void _producerThread();
        // Adds elements to the list, up to maxSize.
        void produce();
        // Check if rollback is necessary
        bool isRollbackRequired(OplogReader& r);
        void getOplogReader(OplogReader& r);
        // Evaluate if the current sync target is still good
        bool shouldChangeSyncTarget();
        // check lastOpTimeWritten against the remote's earliest op, filling in remoteOldestOp.
        bool isStale(OplogReader& r, BSONObj& remoteOldestOp);
        // stop syncing when this becomes a primary
        void stop();
        // restart syncing
        void start();

        // Tracker thread
        // tells the sync target where this member is synced to
        void markOplog();
        bool hasCursor();

        bool isAssumingPrimary();

    public:
        static BackgroundSync* get();
        static void shutdown();
        static void notify();

        virtual ~BackgroundSync() {}

        // starts the producer thread
        void producerThread();
        // starts the sync target notifying thread
        void notifierThread();

        // Interface implementation

        virtual bool peek(BSONObj* op);
        virtual void consume();
        virtual const Member* getSyncTarget();
        virtual void waitForMore();

        // For monitoring
        BSONObj getCounters();

        // Wait for replication to finish and buffer to be applied so that the member can become
        // primary.
        void stopReplicationAndFlushBuffer();
    };


} // namespace replset
} // namespace mongo