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// @file concurrency.h
/*
* Copyright (C) 2010 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/>.
*/
/*mongod concurrency rules & notes will be placed here.
Mutex heirarchy (1 = "leaf")
name level
Logstream::mutex 1
ClientCursor::ccmutex 2
dblock 3
End func name with _inlock to indicate "caller must lock before calling".
*/
#pragma once
#include "../util/concurrency/rwlock.h"
#include "../util/mmap.h"
#include "../util/time_support.h"
namespace mongo {
string sayClientState();
bool haveClient();
class Client;
Client* curopWaitingForLock( int type );
void curopGotLock(Client*);
/* mutex time stats */
class MutexInfo {
unsigned long long enter, timeLocked; // microseconds
int locked;
unsigned long long start; // last as we touch this least often
public:
MutexInfo() : timeLocked(0) , locked(0) {
start = curTimeMicros64();
}
void entered() {
if ( locked == 0 )
enter = curTimeMicros64();
locked++;
assert( locked >= 1 );
}
void leaving() {
locked--;
assert( locked >= 0 );
if ( locked == 0 )
timeLocked += curTimeMicros64() - enter;
}
int isLocked() const { return locked; }
void getTimingInfo(unsigned long long &s, unsigned long long &tl) const {
s = start;
tl = timeLocked;
}
unsigned long long getTimeLocked() const { return timeLocked; }
};
}
#include "mongomutex.h"
namespace mongo {
struct writelock {
writelock() { dbMutex.lock(); }
writelock(const string& ns) { dbMutex.lock(); }
~writelock() {
DESTRUCTOR_GUARD(
dbMutex.unlock();
);
}
};
struct readlock {
readlock(const string& ns) {
dbMutex.lock_shared();
}
readlock() { dbMutex.lock_shared(); }
~readlock() {
DESTRUCTOR_GUARD(
dbMutex.unlock_shared();
);
}
};
struct readlocktry {
readlocktry( const string&ns , int tryms ) {
_got = dbMutex.lock_shared_try( tryms );
}
~readlocktry() {
if ( _got ) {
dbMutex.unlock_shared();
}
}
bool got() const { return _got; }
private:
bool _got;
};
struct writelocktry {
writelocktry( const string&ns , int tryms ) {
_got = dbMutex.lock_try( tryms );
}
~writelocktry() {
if ( _got ) {
dbMutex.unlock();
}
}
bool got() const { return _got; }
private:
bool _got;
};
struct readlocktryassert : public readlocktry {
readlocktryassert(const string& ns, int tryms) :
readlocktry(ns,tryms) {
uassert(13142, "timeout getting readlock", got());
}
};
/** assure we have at least a read lock - they key with this being
if you have a write lock, that's ok too.
*/
struct atleastreadlock {
atleastreadlock( const string& ns ) {
_prev = dbMutex.getState();
if ( _prev == 0 )
dbMutex.lock_shared();
}
~atleastreadlock() {
if ( _prev == 0 )
dbMutex.unlock_shared();
}
private:
int _prev;
};
/* parameterized choice of read or write locking
use readlock and writelock instead of this when statically known which you want
*/
class mongolock {
bool _writelock;
public:
mongolock(bool write) : _writelock(write) {
if( _writelock ) {
dbMutex.lock();
}
else
dbMutex.lock_shared();
}
~mongolock() {
DESTRUCTOR_GUARD(
if( _writelock ) {
dbMutex.unlock();
}
else {
dbMutex.unlock_shared();
}
);
}
/* this unlocks, does NOT upgrade. that works for our current usage */
void releaseAndWriteLock();
};
/* deprecated - use writelock and readlock instead */
struct dblock : public writelock {
dblock() : writelock("") { }
};
// eliminate this - we should just type "dbMutex.assertWriteLocked();" instead
inline void assertInWriteLock() { dbMutex.assertWriteLocked(); }
}
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