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// lockstate.h
/**
* Copyright (C) 2008 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/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/d_concurrency.h"
namespace mongo {
class Acquiring;
// per thread
class LockState {
public:
LockState();
void dump();
static void Dump();
BSONObj reportState();
void reportState(BSONObjBuilder& b);
unsigned recursiveCount() const { return _recursive; }
/**
* @return 0 rwRW
*/
char threadState() const { return _threadState; }
bool isRW() const; // RW
bool isW() const; // W
bool hasAnyReadLock() const; // explicitly rR
bool hasAnyWriteLock() const; // wWX
bool isLocked( const StringData& ns ); // rwRW
/** pending means we are currently trying to get a lock */
bool hasLockPending() const { return _lockPending || _lockPendingParallelWriter; }
// ----
void lockedStart( char newState ); // RWrw
void unlocked(); // _threadState = 0
/**
* you have to be locked already to call this
* this is mostly for W_to_R or R_to_W
*/
void changeLockState( char newstate );
Lock::Nestable whichNestable() const { return _whichNestable; }
int nestableCount() const { return _nestableCount; }
int otherCount() const { return _otherCount; }
const std::string& otherName() const { return _otherName; }
WrapperForRWLock* otherLock() const { return _otherLock; }
void enterScopedLock( Lock::ScopedLock* lock );
Lock::ScopedLock* leaveScopedLock();
void lockedNestable( Lock::Nestable what , int type );
void unlockedNestable();
void lockedOther( const StringData& db , int type , WrapperForRWLock* lock );
void lockedOther( int type ); // "same lock as last time" case
void unlockedOther();
bool _batchWriter;
LockStat* getRelevantLockStat();
void recordLockTime() { _scopedLk->recordTime(); }
void resetLockTime() { _scopedLk->resetTime(); }
private:
unsigned _recursive; // we allow recursively asking for a lock; we track that here
// global lock related
char _threadState; // 0, 'r', 'w', 'R', 'W'
// db level locking related
Lock::Nestable _whichNestable;
int _nestableCount; // recursive lock count on local or admin db XXX - change name
int _otherCount; // >0 means write lock, <0 read lock - XXX change name
std::string _otherName; // which database are we locking and working with (besides local/admin)
WrapperForRWLock* _otherLock; // so we don't have to check the map too often (the map has a mutex)
// for temprelease
// for the nonrecursive case. otherwise there would be many
// the first lock goes here, which is ok since we can't yield recursive locks
Lock::ScopedLock* _scopedLk;
bool _lockPending;
bool _lockPendingParallelWriter;
friend class Acquiring;
friend class AcquiringParallelWriter;
};
class WrapperForRWLock : boost::noncopyable {
SimpleRWLock rw;
SimpleMutex m;
bool sharedLatching;
LockStat stats;
public:
std::string name() const { return rw.name; }
LockStat& getStats() { return stats; }
WrapperForRWLock(const StringData& name)
: rw(name), m(name) {
// For the local datbase, all operations are short,
// either writing one entry, or doing a tail.
// In tests, use a SimpleMutex is much faster for the local db.
sharedLatching = name != "local";
}
void lock() { if ( sharedLatching ) { rw.lock(); } else { m.lock(); } }
void lock_shared() { if ( sharedLatching ) { rw.lock_shared(); } else { m.lock(); } }
void unlock() { if ( sharedLatching ) { rw.unlock(); } else { m.unlock(); } }
void unlock_shared() { if ( sharedLatching ) { rw.unlock_shared(); } else { m.unlock(); } }
};
class ScopedLock;
class Acquiring {
public:
Acquiring( Lock::ScopedLock* lock, LockState& ls );
~Acquiring();
private:
Lock::ScopedLock* _lock;
LockState& _ls;
};
class AcquiringParallelWriter {
public:
AcquiringParallelWriter( LockState& ls );
~AcquiringParallelWriter();
private:
LockState& _ls;
};
}
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