annotate base/Serialiser.cpp @ 537:3cc4b7cd2aa5

* Merge from one-fftdataserver-per-fftmodel branch.  This bit of
reworking (which is not described very accurately by the title of
the branch) turns the MatrixFile object into something that either
reads or writes, but not both, and separates the FFT file cache
reader and writer implementations separately.  This allows the
FFT data server to have a single thread owning writers and one reader
per "customer" thread, and for all locking to be vastly simplified
and concentrated in the data server alone (because none of the
classes it makes use of is used in more than one thread at a time).
The result is faster and more trustworthy code.

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2007 QMUL.
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#include "Serialiser.h"

#include <iostream>

QMutex
Serialiser::m_mapMutex;

std::map<QString, QMutex *>
Serialiser::m_mutexMap;

Serialiser::Serialiser(QString id) :
    m_id(id)
{
    m_mapMutex.lock();
    
    if (m_mutexMap.find(m_id) == m_mutexMap.end()) {
        m_mutexMap[m_id] = new QMutex;
    }

    // The id mutexes are never deleted, so once we have a reference
    // to the one we need, we can hold on to it while we release the
    // map mutex.  We need to release the map mutex, otherwise if the
    // id mutex is currently held, it will never be released (because
    // the destructor needs to hold the map mutex to release the id
    // mutex).

    QMutex *idMutex = m_mutexMap[m_id];

    m_mapMutex.unlock();

    idMutex->lock();
}

Serialiser::~Serialiser()
{
    m_mapMutex.lock();
    
    m_mutexMap[m_id]->unlock();

    m_mapMutex.unlock();
}