/usr/include/mongo/util/concurrency/mapsf.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 | #pragma once
/**
* 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/>.
*/
#include "mongo/platform/unordered_map.h"
namespace mongo {
/** Thread safe map.
Be careful not to use this too much or it could make things slow;
if not a hot code path no problem.
Examples:
mapsf< map<int,int>, int, int > mp;
int x = mp.get();
map< map<int,int>, int, int > two;
mp.swap(two);
{
mapsf< map<int,int>, int, int >::ref r(mp);
r[9] = 1;
map<int,int>::iterator i = r.r.begin();
}
*/
template< class M >
struct mapsf : boost::noncopyable {
SimpleMutex m;
M val;
friend struct ref;
public:
typedef typename M::const_iterator const_iterator;
typedef typename M::key_type key_type;
typedef typename M::mapped_type mapped_type;
mapsf() : m("mapsf") { }
void swap(M& rhs) {
SimpleMutex::scoped_lock lk(m);
val.swap(rhs);
}
bool empty() {
SimpleMutex::scoped_lock lk(m);
return val.empty();
}
// safe as we pass by value:
mapped_type get(key_type k) {
SimpleMutex::scoped_lock lk(m);
const_iterator i = val.find(k);
if( i == val.end() )
return mapped_type();
return i->second;
}
// think about deadlocks when using ref. the other methods
// above will always be safe as they are "leaf" operations.
struct ref {
SimpleMutex::scoped_lock lk;
public:
M &r;
ref(mapsf &m) : lk(m.m), r(m.val) { }
mapped_type& operator[](const key_type& k) { return r[k]; }
};
};
}
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