view base/ById.cpp @ 1879:652c5360e682

Ensure transforms are populated before instantiateDefaultPluginFor runs - otherwise if we have prior knowledge of a transform id, we can find ourselves trying to instantiate it before the plugin factory has heard of it and e.g. knows which server to use
author Chris Cannam
date Thu, 25 Jun 2020 12:20:06 +0100
parents 871a2050236b
children
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/* -*- 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 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 "ById.h"

#include <unordered_map>
#include <typeinfo>

//#define DEBUG_BY_ID 1

int IdAlloc::getNextId()
{
    static int nextId = 0;
    static QMutex mutex;
    QMutexLocker locker(&mutex);
    int i = nextId;
    if (nextId == INT_MAX) {
        nextId = INT_MIN;
    } else {
        ++nextId;
        if (nextId == 0 || nextId == NO_ID) {
            throw std::runtime_error("Internal ID limit exceeded!");
        }
    }
    return i;
}

// "warning: expression with side effects will be evaluated despite
// being used as an operand to 'typeid'"
#ifdef __clang__
#pragma clang diagnostic ignored "-Wpotentially-evaluated-expression"
#endif

class AnyById::Impl
{
public:    
    ~Impl() {
        QMutexLocker locker(&m_mutex);
        bool empty = true;
        for (const auto &p: m_items) {
            if (p.second && p.second.use_count() > 0) {
                empty = false;
                break;
            }
        }
        if (!empty) {
            SVCERR << "WARNING: ById map is not empty at close; some items have not been released" << endl;
            SVCERR << "         Unreleased items are:" << endl;
            for (const auto &p: m_items) {
                auto ptr = p.second;
                if (ptr && ptr.use_count() > 0) {
                    QString message = QString("id #%1: type %2")
                        .arg(p.first).arg(typeid(*ptr.get()).name());
                    if (auto qobj = std::dynamic_pointer_cast<QObject>(ptr)) {
                        message += QString(", object name \"%1\"")
                            .arg(qobj->objectName());
                    }
                    message += QString(", use count %1").arg(ptr.use_count());
                    SVCERR << "         - " << message << endl; 
                }
            }
        }
    }
        
    int add(std::shared_ptr<WithId> item) {
        int id = item->getUntypedId();
        if (id == IdAlloc::NO_ID) {
            throw std::logic_error("item id should never be NO_ID");
        }
#ifdef DEBUG_BY_ID
        SVCERR << "ById::add(#" << id << ") of type "
               << typeid(*item.get()).name() << endl;
#endif
        QMutexLocker locker(&m_mutex);
        if (m_items.find(id) != m_items.end()) {
            SVCERR << "ById::add: item with id " << id
                   << " is already recorded (existing item type is "
                   << typeid(*m_items.find(id)->second.get()).name()
                   << ", proposed is "
                   << typeid(*item.get()).name() << ")" << endl;
            throw std::logic_error("item id is already recorded in add");
        }
        m_items[id] = item;
        return id;
    }

    void release(int id) {
        if (id == IdAlloc::NO_ID) {
            return;
        }
#ifdef DEBUG_BY_ID
        SVCERR << "ById::release(#" << id << ")" << endl;
#endif
        QMutexLocker locker(&m_mutex);
        if (m_items.find(id) == m_items.end()) {
            SVCERR << "ById::release: unknown item id " << id << endl;
            throw std::logic_error("unknown item id in release");
        }
        m_items.erase(id);
    }
    
    std::shared_ptr<WithId> get(int id) const {
        if (id == IdAlloc::NO_ID) {
            return {}; // this id cannot be added: avoid locking
        }
        QMutexLocker locker(&m_mutex);
        const auto &itr = m_items.find(id);
        if (itr != m_items.end()) {
            return itr->second;
        } else {
            return {};
        }
    }

private:
    mutable QMutex m_mutex;
    std::unordered_map<int, std::shared_ptr<WithId>> m_items;
};

int
AnyById::add(std::shared_ptr<WithId> item)
{
    return impl().add(item);
}

void
AnyById::release(int id)
{
    impl().release(id);
}

std::shared_ptr<WithId>
AnyById::get(int id)
{
    return impl().get(id);
}

AnyById::Impl &
AnyById::impl()
{
    static Impl impl;
    return impl;
}