98 lines
1.9 KiB
C++
98 lines
1.9 KiB
C++
/*
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* Copyright (C) 2003-2013 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/** \file
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*
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* Support for locking data structures from the database, for safe
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* multi-threading.
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*/
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#ifndef MPD_DB_LOCK_HXX
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#define MPD_DB_LOCK_HXX
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#include "check.h"
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#include "thread/Mutex.hxx"
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#include "gcc.h"
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#include <assert.h>
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extern Mutex db_mutex;
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#ifndef NDEBUG
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#include "thread/Id.hxx"
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extern ThreadId db_mutex_holder;
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/**
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* Does the current thread hold the database lock?
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*/
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gcc_pure
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static inline bool
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holding_db_lock(void)
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{
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return db_mutex_holder.IsInside();
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}
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#endif
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/**
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* Obtain the global database lock. This is needed before
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* dereferencing a #song or #directory. It is not recursive.
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*/
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static inline void
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db_lock(void)
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{
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assert(!holding_db_lock());
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db_mutex.lock();
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assert(db_mutex_holder.IsNull());
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#ifndef NDEBUG
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db_mutex_holder = ThreadId::GetCurrent();
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#endif
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}
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/**
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* Release the global database lock.
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*/
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static inline void
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db_unlock(void)
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{
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assert(holding_db_lock());
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#ifndef NDEBUG
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db_mutex_holder = ThreadId::Null();
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#endif
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db_mutex.unlock();
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}
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class ScopeDatabaseLock {
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public:
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ScopeDatabaseLock() {
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db_lock();
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}
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~ScopeDatabaseLock() {
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db_unlock();
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}
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};
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#endif
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