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/*
Copyright (c) 2006 Gábor Lehel <illissius@gmail.com>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include <config.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <tqdeepcopy.h>
#include <tqstring.h>
#include <pthread.h>
#include "atomicstring.h"
class AtomicString::Data: public TQString
{
public:
uint refcount;
Data(): refcount( 0 ) { }
Data( const TQString &s ): TQString( s ), refcount( 0 ) { }
};
AtomicString::AtomicString(): m_string( 0 ) { }
AtomicString::AtomicString( const AtomicString &other )
{
s_storeMutex.lock();
m_string = other.m_string;
ref( m_string );
s_storeMutex.unlock();
}
AtomicString::AtomicString( const TQString &string ): m_string( 0 )
{
if( string.isEmpty() )
return;
Data *s = new Data( string ); // note: s is a shallow copy
s_storeMutex.lock();
m_string = static_cast<Data*>( *( s_store.insert( s ).first ) );
ref( m_string );
uint rc = s->refcount;
if( rc && !isMainThread()) {
// Inserted, and we are not in the main thread -- we need to make s a deep copy,
// as this copy may be refcounted by the main thread outside our locks
(TQString &) (*s) = TQDeepCopy<TQString>( string );
}
s_storeMutex.unlock();
if ( !rc ) delete( s ); // already present
}
AtomicString::~AtomicString()
{
s_storeMutex.lock();
deref( m_string );
s_storeMutex.unlock();
}
TQString AtomicString::string() const
{
if ( !m_string ) return TQString();
// References to the stored string are only allowed to circulate in the main thread
if ( isMainThread() ) return *m_string;
else return deepCopy();
}
TQString AtomicString::deepCopy() const
{
if (m_string)
return TQString( m_string->unicode(), m_string->length() );
return TQString();
}
bool AtomicString::isEmpty() const
{
return !m_string;
}
const TQString *AtomicString::ptr() const
{
if( m_string )
return m_string;
return &null_tqstring;
}
uint AtomicString::refcount() const
{
if ( m_string ) {
s_storeMutex.lock();
uint rc = m_string->refcount;
s_storeMutex.unlock();
return rc;
}
return 0;
}
AtomicString &AtomicString::operator=( const AtomicString &other )
{
if( m_string == other.m_string )
return *this;
s_storeMutex.lock();
deref( m_string );
m_string = other.m_string;
ref( m_string );
s_storeMutex.unlock();
return *this;
}
// needs to be called holding the lock
inline void AtomicString::deref( Data *s )
{
checkLazyDeletes(); // a good time to do this
if( !s )
return;
if( !( --s->refcount ) )
{
s_store.erase( s );
// only the main thread is allowed to delete stored strings
if ( isMainThread() )
delete s;
else
s_lazyDeletes.append(s);
}
}
// needs to be called holding the lock
inline void AtomicString::ref( Data *s )
{
checkLazyDeletes(); // a good time to do this
if( s )
s->refcount++;
}
// It is not necessary to hold the store mutex here.
bool AtomicString::isMainThread()
{
// For isMainThread(), we could use TQThread::currentThread(), except the
// docs say it's unreliable. And in general TQThreads don't like to be called from
// app destructors. Good old pthreads will serve us well. As for Windows, these
// two calls surely have equivalents; better yet we'll have QT4 and thread safe
// TQStrings by then.
// Note that the the static local init is thread safe.
static pthread_t main_thread = pthread_self();
return pthread_equal(pthread_self(), main_thread);
}
// call holding the store mutex
inline void AtomicString::checkLazyDeletes()
{
// only the main thread is allowed to delete
if ( isMainThread() )
{
s_lazyDeletes.setAutoDelete(true);
s_lazyDeletes.clear();
}
}
AtomicString::set_type AtomicString::s_store;
TQPtrList<TQString> AtomicString::s_lazyDeletes;
TQMutex AtomicString::s_storeMutex;
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