view data/fileio/FileReadThread.cpp @ 490:c3fb8258e34d

* Make it possible to import an entire session from an RDF document.
  However, at the moment the timings of events appear to be constrained
  by how far the audio decoder has got through its audio file at the
  time the event is queried -- need to investigate.

/* -*- 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 2006 Chris Cannam.
    
    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 "FileReadThread.h"

#include "base/Profiler.h"
#include "base/Thread.h"

#include <iostream>
#include <unistd.h>

//#define DEBUG_FILE_READ_THREAD 1

FileReadThread::FileReadThread() :
    m_nextToken(0),
    m_exiting(false)
{
}

void
FileReadThread::run()
{
    MutexLocker locker(&m_mutex, "FileReadThread::run::m_mutex");

    while (!m_exiting) {
        if (m_queue.empty()) {
            m_condition.wait(&m_mutex, 1000);
        } else {
            process();
        }
        notifyCancelled();
    }

    notifyCancelled();

#ifdef DEBUG_FILE_READ_THREAD
    std::cerr << "FileReadThread::run() exiting" << std::endl;
#endif
}

void
FileReadThread::finish()
{
#ifdef DEBUG_FILE_READ_THREAD
    std::cerr << "FileReadThread::finish()" << std::endl;
#endif

    {
        MutexLocker locker(&m_mutex, "FileReadThread::finish::m_mutex");

        while (!m_queue.empty()) {
            m_cancelledRequests[m_queue.begin()->first] = m_queue.begin()->second;
            m_newlyCancelled.insert(m_queue.begin()->first);
            m_queue.erase(m_queue.begin());
        }
        
        m_exiting = true;
    }

    m_condition.wakeAll();

#ifdef DEBUG_FILE_READ_THREAD
    std::cerr << "FileReadThread::finish() exiting" << std::endl;
#endif
}

int
FileReadThread::request(const Request &request)
{
    int token;

    {
        MutexLocker locker(&m_mutex, "FileReadThread::request::m_mutex");
    
        token = m_nextToken++;
        m_queue[token] = request;
    }

    m_condition.wakeAll();

    return token;
}

void
FileReadThread::cancel(int token)
{
    {
        MutexLocker locker(&m_mutex, "FileReadThread::cancel::m_mutex");

        if (m_queue.find(token) != m_queue.end()) {
            m_cancelledRequests[token] = m_queue[token];
            m_queue.erase(token);
            m_newlyCancelled.insert(token);
        } else if (m_readyRequests.find(token) != m_readyRequests.end()) {
            m_cancelledRequests[token] = m_readyRequests[token];
            m_readyRequests.erase(token);
        } else {
            std::cerr << "WARNING: FileReadThread::cancel: token " << token << " not found" << std::endl;
        }
    }

#ifdef DEBUG_FILE_READ_THREAD
    std::cerr << "FileReadThread::cancel(" << token << ") waking condition" << std::endl;
#endif

    m_condition.wakeAll();
}

bool
FileReadThread::isReady(int token)
{
    MutexLocker locker(&m_mutex, "FileReadThread::isReady::m_mutex");

    bool ready = m_readyRequests.find(token) != m_readyRequests.end();

    return ready;
}

bool
FileReadThread::isCancelled(int token)
{
    MutexLocker locker(&m_mutex, "FileReadThread::isCancelled::m_mutex");

    bool cancelled = 
        m_cancelledRequests.find(token) != m_cancelledRequests.end() &&
        m_newlyCancelled.find(token) == m_newlyCancelled.end();

    return cancelled;
}

bool
FileReadThread::haveRequest(int token)
{
    MutexLocker locker(&m_mutex, "FileReadThread::haveRequest::m_mutex");

    bool found = false;

    if (m_queue.find(token) != m_queue.end()) {
        found = true;
    } else if (m_cancelledRequests.find(token) != m_cancelledRequests.end()) {
        found = true;
    } else if (m_readyRequests.find(token) != m_readyRequests.end()) {
        found = true;
    }

    return found;
}

bool
FileReadThread::getRequest(int token, Request &request)
{
    MutexLocker locker(&m_mutex, "FileReadThread::getRequest::m_mutex");

    bool found = false;

    if (m_queue.find(token) != m_queue.end()) {
        request = m_queue[token];
        found = true;
    } else if (m_cancelledRequests.find(token) != m_cancelledRequests.end()) {
        request = m_cancelledRequests[token];
        found = true;
    } else if (m_readyRequests.find(token) != m_readyRequests.end()) {
        request = m_readyRequests[token];
        found = true;
    }

    return found;
}

void
FileReadThread::done(int token)
{
    MutexLocker locker(&m_mutex, "FileReadThread::done::m_mutex");

    bool found = false;

    if (m_cancelledRequests.find(token) != m_cancelledRequests.end()) {
        m_cancelledRequests.erase(token);
        m_newlyCancelled.erase(token);
        found = true;
    } else if (m_readyRequests.find(token) != m_readyRequests.end()) {
        m_readyRequests.erase(token);
        found = true;
    } else if (m_queue.find(token) != m_queue.end()) {
        std::cerr << "WARNING: FileReadThread::done(" << token << "): request is still in queue (wait or cancel it)" << std::endl;
    }

    if (!found) {
        std::cerr << "WARNING: FileReadThread::done(" << token << "): request not found" << std::endl;
    }
}

void
FileReadThread::process()
{
    // entered with m_mutex locked and m_queue non-empty

    Profiler profiler("FileReadThread::process", true);

    int token = m_queue.begin()->first;
    Request request = m_queue.begin()->second;

    m_mutex.unlock();

#ifdef DEBUG_FILE_READ_THREAD
    std::cerr << "FileReadThread::process: reading " << request.start << ", " << request.size << " on " << request.fd << std::endl;
#endif

    bool successful = false;
    bool seekFailed = false;
    ssize_t r = 0;

    { 
        MutexLocker rlocker(request.mutex, "FileReadThread::process::request.mutex");

        if (::lseek(request.fd, request.start, SEEK_SET) == (off_t)-1) {
            seekFailed = true;
        } else {
        
            // if request.size is large, we want to avoid making a single
            // system call to read it all as it may block too much
            
            static const size_t blockSize = 256 * 1024;
            
            size_t size = request.size;
            char *destination = request.data;
            
            while (size > 0) {
                size_t readSize = size;
                if (readSize > blockSize) readSize = blockSize;
                ssize_t br = ::read(request.fd, destination, readSize);
                if (br < 0) { 
                    r = br;
                    break;
                } else {
                    r += br;
                    if (br < ssize_t(readSize)) break;
                }
                destination += readSize;
                size -= readSize;
            }
        }
    }

    if (seekFailed) {
        ::perror("Seek failed");
        std::cerr << "ERROR: FileReadThread::process: seek to "
                  << request.start << " failed" << std::endl;
        request.size = 0;
    } else {
        if (r < 0) {
            ::perror("ERROR: FileReadThread::process: Read failed");
            std::cerr << "ERROR: FileReadThread::process: read of "
                      << request.size << " at "
                      << request.start << " failed" << std::endl;
            request.size = 0;
        } else if (r < ssize_t(request.size)) {
            std::cerr << "WARNING: FileReadThread::process: read "
                      << request.size << " returned only " << r << " bytes"
                      << std::endl;
            request.size = r;
            usleep(100000);
        } else {
            successful = true;
        }
    }
        
    // Check that the token hasn't been cancelled and the thread
    // hasn't been asked to finish
    
    m_mutex.lock();

    request.successful = successful;
        
    if (m_queue.find(token) != m_queue.end() && !m_exiting) {
        m_queue.erase(token);
        m_readyRequests[token] = request;
#ifdef DEBUG_FILE_READ_THREAD
        std::cerr << "FileReadThread::process: done, marking as ready (success = " << m_readyRequests[token].successful << ")" << std::endl;
#endif
    } else {
#ifdef DEBUG_FILE_READ_THREAD
        if (m_exiting) {
            std::cerr << "FileReadThread::process: exiting" << std::endl;
        } else {
            std::cerr << "FileReadThread::process: request disappeared" << std::endl;
        }
#endif
    }
}

void
FileReadThread::notifyCancelled()
{
    // entered with m_mutex locked

    while (!m_newlyCancelled.empty()) {

        int token = *m_newlyCancelled.begin();

#ifdef DEBUG_FILE_READ_THREAD
        std::cerr << "FileReadThread::notifyCancelled: token " << token << std::endl;
#endif

        m_newlyCancelled.erase(token);
    }
}