annotate data/fft/FFTDataServer.cpp @ 213:e0e7f6c5fda9

* Make FFT data server more resilient when running out of memory

/* -*- 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 and 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 "FFTDataServer.h"

#include "FFTFileCache.h"
#include "FFTMemoryCache.h"

#include "model/DenseTimeValueModel.h"

#include "system/System.h"

#include "base/StorageAdviser.h"
#include "base/Exceptions.h"
#include "base/Profiler.h"

#include <QMessageBox>
#include <QApplication>


//#define DEBUG_FFT_SERVER 1
//#define DEBUG_FFT_SERVER_FILL 1

#ifdef DEBUG_FFT_SERVER_FILL
#ifndef DEBUG_FFT_SERVER
#define DEBUG_FFT_SERVER 1
#endif
#endif

FFTDataServer::ServerMap FFTDataServer::m_servers;
QMutex FFTDataServer::m_serverMapMutex;

FFTDataServer *
FFTDataServer::getInstance(const DenseTimeValueModel *model,
                           int channel,
                           WindowType windowType,
                           size_t windowSize,
                           size_t windowIncrement,
                           size_t fftSize,
                           bool polar,
                           size_t fillFromColumn)
{
    QString n = generateFileBasename(model,
                                     channel,
                                     windowType,
                                     windowSize,
                                     windowIncrement,
                                     fftSize,
                                     polar);

    FFTDataServer *server = 0;
    
    QMutexLocker locker(&m_serverMapMutex);

    if ((server = findServer(n))) {
        return server;
    }

    QString npn = generateFileBasename(model,
                                       channel,
                                       windowType,
                                       windowSize,
                                       windowIncrement,
                                       fftSize,
                                       !polar);

    if ((server = findServer(npn))) {
        return server;
    }

    try {
        server = new FFTDataServer(n,
                                   model,
                                   channel,
                                   windowType,
                                   windowSize,
                                   windowIncrement,
                                   fftSize,
                                   polar,
                                   fillFromColumn);
    } catch (InsufficientDiscSpace) {
        delete server;
        server = 0;
    }

    if (server) {
        m_servers[n] = ServerCountPair(server, 1);
    }

    return server;
}

FFTDataServer *
FFTDataServer::getFuzzyInstance(const DenseTimeValueModel *model,
                                int channel,
                                WindowType windowType,
                                size_t windowSize,
                                size_t windowIncrement,
                                size_t fftSize,
                                bool polar,
                                size_t fillFromColumn)
{
    // Fuzzy matching:
    // 
    // -- if we're asked for polar and have non-polar, use it (and
    // vice versa).  This one is vital, and we do it for non-fuzzy as
    // well (above).
    //
    // -- if we're asked for an instance with a given fft size and we
    // have one already with a multiple of that fft size but the same
    // window size and type (and model), we can draw the results from
    // it (e.g. the 1st, 2nd, 3rd etc bins of a 512-sample FFT are the
    // same as the the 1st, 5th, 9th etc of a 2048-sample FFT of the
    // same window plus zero padding).
    //
    // -- if we're asked for an instance with a given window type and
    // size and fft size and we have one already the same but with a
    // smaller increment, we can draw the results from it (provided
    // our increment is a multiple of its)
    //
    // The FFTModel knows how to interpret these things.  In
    // both cases we require that the larger one is a power-of-two
    // multiple of the smaller (e.g. even though in principle you can
    // draw the results at increment 256 from those at increment 768
    // or 1536, the model doesn't support this).

    {
        QMutexLocker locker(&m_serverMapMutex);

        ServerMap::iterator best = m_servers.end();
        int bestdist = -1;
    
        for (ServerMap::iterator i = m_servers.begin(); i != m_servers.end(); ++i) {

            FFTDataServer *server = i->second.first;

            if (server->getModel() == model &&
                (server->getChannel() == channel || model->getChannelCount() == 1) &&
                server->getWindowType() == windowType &&
                server->getWindowSize() == windowSize &&
                server->getWindowIncrement() <= windowIncrement &&
                server->getFFTSize() >= fftSize) {
                
                if ((windowIncrement % server->getWindowIncrement()) != 0) continue;
                int ratio = windowIncrement / server->getWindowIncrement();
                bool poweroftwo = true;
                while (ratio > 1) {
                    if (ratio & 0x1) {
                        poweroftwo = false;
                        break;
                    }
                    ratio >>= 1;
                }
                if (!poweroftwo) continue;

                if ((server->getFFTSize() % fftSize) != 0) continue;
                ratio = server->getFFTSize() / fftSize;
                while (ratio > 1) {
                    if (ratio & 0x1) {
                        poweroftwo = false;
                        break;
                    }
                    ratio >>= 1;
                }
                if (!poweroftwo) continue;
                
                int distance = 0;
                
                if (server->getPolar() != polar) distance += 1;
                
                distance += ((windowIncrement / server->getWindowIncrement()) - 1) * 15;
                distance += ((server->getFFTSize() / fftSize) - 1) * 10;
                
                if (server->getFillCompletion() < 50) distance += 100;

#ifdef DEBUG_FFT_SERVER
                std::cerr << "Distance " << distance << ", best is " << bestdist << std::endl;
#endif
                
                if (bestdist == -1 || distance < bestdist) {
                    bestdist = distance;
                    best = i;
                }
            }
        }

        if (bestdist >= 0) {
            ++best->second.second;
            return best->second.first;
        }
    }

    // Nothing found, make a new one

    return getInstance(model,
                       channel,
                       windowType,
                       windowSize,
                       windowIncrement,
                       fftSize,
                       polar,
                       fillFromColumn);
}

FFTDataServer *
FFTDataServer::findServer(QString n)
{    
    if (m_servers.find(n) != m_servers.end()) {
        ++m_servers[n].second;
        return m_servers[n].first;
    }

    return 0;
}

void
FFTDataServer::claimInstance(FFTDataServer *server)
{
    
    QMutexLocker locker(&m_serverMapMutex);

    for (ServerMap::iterator i = m_servers.begin(); i != m_servers.end(); ++i) {
        if (i->second.first == server) {
            ++i->second.second;
            return;
        }
    }
    
    std::cerr << "ERROR: FFTDataServer::claimInstance: instance "
              << server << " unknown!" << std::endl;
}

void
FFTDataServer::releaseInstance(FFTDataServer *server)
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer::releaseInstance(" << server << ")" << std::endl;
#endif

    QMutexLocker locker(&m_serverMapMutex);

    //!!! not a good strategy.  Want something like:

    // -- if ref count > 0, decrement and return
    // -- if the instance hasn't been used at all, delete it immediately 
    // -- if fewer than N instances (N = e.g. 3) remain with zero refcounts,
    //    leave them hanging around
    // -- if N instances with zero refcounts remain, delete the one that
    //    was last released first
    // -- if we run out of disk space when allocating an instance, go back
    //    and delete the spare N instances before trying again
    // -- have an additional method to indicate that a model has been
    //    destroyed, so that we can delete all of its fft server instances

    // also:
    //

    for (ServerMap::iterator i = m_servers.begin(); i != m_servers.end(); ++i) {
        if (i->second.first == server) {
            if (i->second.second == 0) {
                std::cerr << "ERROR: FFTDataServer::releaseInstance("
                          << server << "): instance not allocated" << std::endl;
            } else if (--i->second.second == 0) {
                if (server->m_lastUsedCache == -1) { // never used
                    delete server;
                    m_servers.erase(i);
                } else {
                    server->suspend();
                    purgeLimbo();
                }
            }
            return;
        }
    }

    std::cerr << "ERROR: FFTDataServer::releaseInstance(" << server << "): "
              << "instance not found" << std::endl;
}

void
FFTDataServer::purgeLimbo(int maxSize)
{
    ServerMap::iterator i = m_servers.end();

    int count = 0;

    while (i != m_servers.begin()) {
        --i;
        if (i->second.second == 0) {
            if (++count > maxSize) {
                delete i->second.first;
                m_servers.erase(i);
                return;
            }
        }
    }
}

FFTDataServer::FFTDataServer(QString fileBaseName,
                             const DenseTimeValueModel *model,
                             int channel,
			     WindowType windowType,
			     size_t windowSize,
			     size_t windowIncrement,
			     size_t fftSize,
                             bool polar,
                             size_t fillFromColumn) :
    m_fileBaseName(fileBaseName),
    m_model(model),
    m_channel(channel),
    m_windower(windowType, windowSize),
    m_windowSize(windowSize),
    m_windowIncrement(windowIncrement),
    m_fftSize(fftSize),
    m_polar(polar),
    m_width(0),
    m_height(0),
    m_cacheWidth(0),
    m_memoryCache(false),
    m_compactCache(false),
    m_lastUsedCache(-1),
    m_fftInput(0),
    m_exiting(false),
    m_suspended(true), //!!! or false?
    m_fillThread(0)
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "])::FFTDataServer" << std::endl;
#endif

    size_t start = m_model->getStartFrame();
    size_t end = m_model->getEndFrame();

    m_width = (end - start) / m_windowIncrement + 1;
    m_height = m_fftSize / 2 + 1; // DC == 0, Nyquist == fftsize/2

    size_t maxCacheSize = 20 * 1024 * 1024;
    size_t columnSize = m_height * sizeof(fftsample) * 2 + sizeof(fftsample);
    if (m_width * columnSize < maxCacheSize * 2) m_cacheWidth = m_width;
    else m_cacheWidth = maxCacheSize / columnSize;
    
    int bits = 0;
    while (m_cacheWidth) { m_cacheWidth >>= 1; ++bits; }
    m_cacheWidth = 2;
    while (bits) { m_cacheWidth <<= 1; --bits; }

    //!!! Need to pass in what this server is intended for
    // (e.g. playback processing, spectrogram, feature extraction),
    // or pass in something akin to the storage adviser criteria.
    // That probably goes alongside the polar argument.
    // For now we'll assume "spectrogram" criteria for polar ffts,
    // and "feature extraction" criteria for rectangular ones.

    StorageAdviser::Criteria criteria;
    if (m_polar) {
        criteria = StorageAdviser::Criteria
            (StorageAdviser::SpeedCritical | StorageAdviser::LongRetentionLikely);
    } else {
        criteria = StorageAdviser::Criteria(StorageAdviser::PrecisionCritical);
    }

    int cells = m_width * m_height;
    int minimumSize = (cells / 1024) * sizeof(uint16_t); // kb
    int maximumSize = (cells / 1024) * sizeof(float); // kb

    // This can throw InsufficientDiscSpace.  We don't catch it here -- we
    // haven't allocated anything yet and can safely let the exception out.
    // Caller needs to check for it.
    
    StorageAdviser::Recommendation recommendation = 
        StorageAdviser::recommend(criteria, minimumSize, maximumSize);

    std::cerr << "Recommendation was: " << recommendation << std::endl;

    m_memoryCache = ((recommendation & StorageAdviser::UseMemory) ||
                     (recommendation & StorageAdviser::PreferMemory));

    m_compactCache = (recommendation & StorageAdviser::ConserveSpace);
    
#ifdef DEBUG_FFT_SERVER
    std::cerr << "Width " << m_width << ", cache width " << m_cacheWidth << " (size " << m_cacheWidth * columnSize << ")" << std::endl;
#endif

    StorageAdviser::notifyPlannedAllocation
        (m_memoryCache ? StorageAdviser::MemoryAllocation :
                         StorageAdviser::DiscAllocation,
         m_compactCache ? minimumSize : maximumSize);

    for (size_t i = 0; i <= m_width / m_cacheWidth; ++i) {
        m_caches.push_back(0);
    }

    m_fftInput = (fftsample *)
        fftwf_malloc(fftSize * sizeof(fftsample));

    m_fftOutput = (fftwf_complex *)
        fftwf_malloc((fftSize/2 + 1) * sizeof(fftwf_complex));

    m_workbuffer = (float *)
        fftwf_malloc((fftSize+2) * sizeof(float));

    m_fftPlan = fftwf_plan_dft_r2c_1d(m_fftSize,
                                      m_fftInput,
                                      m_fftOutput,
                                      FFTW_ESTIMATE);

    if (!m_fftPlan) {
        std::cerr << "ERROR: fftwf_plan_dft_r2c_1d(" << m_windowSize << ") failed!" << std::endl;
        throw(0);
    }

    m_fillThread = new FillThread(*this, fillFromColumn);
}

FFTDataServer::~FFTDataServer()
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "])::~FFTDataServer()" << std::endl;
#endif

    m_suspended = false;
    m_exiting = true;
    m_condition.wakeAll();
    if (m_fillThread) {
        m_fillThread->wait();
        delete m_fillThread;
    }

    QMutexLocker locker(&m_writeMutex);

    for (CacheVector::iterator i = m_caches.begin(); i != m_caches.end(); ++i) {
        if (*i) {
            delete *i;
        } else {
            StorageAdviser::notifyDoneAllocation
                (m_memoryCache ? StorageAdviser::MemoryAllocation :
                                 StorageAdviser::DiscAllocation,
                 m_cacheWidth * m_height *
                 (m_compactCache ? sizeof(uint16_t) : sizeof(float)) / 1024 + 1);
        }
    }

    deleteProcessingData();
}

void
FFTDataServer::deleteProcessingData()
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): deleteProcessingData" << std::endl;
#endif
    if (m_fftInput) {
        fftwf_destroy_plan(m_fftPlan);
        fftwf_free(m_fftInput);
        fftwf_free(m_fftOutput);
        fftwf_free(m_workbuffer);
    }
    m_fftInput = 0;
}

void
FFTDataServer::suspend()
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): suspend" << std::endl;
#endif
    Profiler profiler("FFTDataServer::suspend", false);

    QMutexLocker locker(&m_writeMutex);
    m_suspended = true;
    for (CacheVector::iterator i = m_caches.begin(); i != m_caches.end(); ++i) {
        if (*i) (*i)->suspend();
    }
}

void
FFTDataServer::suspendWrites()
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): suspendWrites" << std::endl;
#endif
    Profiler profiler("FFTDataServer::suspendWrites", false);

    m_suspended = true;
}

void
FFTDataServer::resume()
{
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): resume" << std::endl;
#endif
    Profiler profiler("FFTDataServer::resume", false);

    m_suspended = false;
    if (m_fillThread) {
        if (m_fillThread->isFinished()) {
            delete m_fillThread;
            m_fillThread = 0;
            deleteProcessingData();
        } else {
            m_condition.wakeAll();
        }
    }
}

FFTCache *
FFTDataServer::getCacheAux(size_t c)
{
    Profiler profiler("FFTDataServer::getCacheAux", false);
#ifdef DEBUG_FFT_SERVER
    std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "])::getCacheAux" << std::endl;
#endif

    QMutexLocker locker(&m_writeMutex);

    if (m_lastUsedCache == -1) {
        m_fillThread->start();
    }

    if (int(c) != m_lastUsedCache) {

//        std::cerr << "switch from " << m_lastUsedCache << " to " << c << std::endl;

        for (IntQueue::iterator i = m_dormantCaches.begin();
             i != m_dormantCaches.end(); ++i) {
            if (*i == c) {
                m_dormantCaches.erase(i);
                break;
            }
        }

        if (m_lastUsedCache >= 0) {
            bool inDormant = false;
            for (size_t i = 0; i < m_dormantCaches.size(); ++i) {
                if (m_dormantCaches[i] == m_lastUsedCache) {
                    inDormant = true;
                    break;
                }
            }
            if (!inDormant) {
                m_dormantCaches.push_back(m_lastUsedCache);
            }
            while (m_dormantCaches.size() > 4) {
                int dc = m_dormantCaches.front();
                m_dormantCaches.pop_front();
                m_caches[dc]->suspend();
            }
        }
    }

    if (m_caches[c]) {
        m_lastUsedCache = c;
        return m_caches[c];
    }

    QString name = QString("%1-%2").arg(m_fileBaseName).arg(c);

    FFTCache *cache = 0;

    size_t width = m_cacheWidth;
    if (c * m_cacheWidth + width > m_width) {
        width = m_width - c * m_cacheWidth;
    }

    try {
        
        if (m_memoryCache) {

            cache = new FFTMemoryCache();

        } else if (m_compactCache) {

            cache = new FFTFileCache(name, MatrixFile::ReadWrite,
                                     FFTFileCache::Compact);

        } else {

            cache = new FFTFileCache(name, MatrixFile::ReadWrite,
                                     m_polar ? FFTFileCache::Polar :
                                               FFTFileCache::Rectangular);
        }

        cache->resize(width, m_height);
        cache->reset();

    } catch (std::bad_alloc) {

        delete cache;
        cache = 0;

        if (m_memoryCache) {
            
            std::cerr << "WARNING: Memory allocation failed when resizing"
                      << " FFT memory cache no. " << c << " to " << width 
                      << "x" << m_height << " (of total width " << m_width
                      << "): falling back to disc cache" << std::endl;

            try {

                cache = new FFTFileCache(name, MatrixFile::ReadWrite,
                                         FFTFileCache::Compact);

                cache->resize(width, m_height);
                cache->reset();

            } catch (std::bad_alloc) {

                delete cache;
                cache = 0;
            }
        }

        if (cache) {
            std::cerr << "ERROR: Memory allocation failed when resizing"
                      << " FFT file cache no. " << c << " to " << width
                      << "x" << m_height << " (of total width " << m_width
                      << "): abandoning this cache" << std::endl;
        }

        //!!! Shouldn't be using QtGui here.  Need a better way to report this.
        QMessageBox::critical
            (0, QApplication::tr("FFT cache resize failed"),
             QApplication::tr
             ("Failed to create or resize an FFT model slice.\n"
              "There may be insufficient memory or disc space to continue."));
    }

    StorageAdviser::notifyDoneAllocation
        (m_memoryCache ? StorageAdviser::MemoryAllocation :
         StorageAdviser::DiscAllocation,
         width * m_height *
         (m_compactCache ? sizeof(uint16_t) : sizeof(float)) / 1024 + 1);

    m_caches[c] = cache;
    m_lastUsedCache = c;
    return cache;
}

float
FFTDataServer::getMagnitudeAt(size_t x, size_t y)
{
    Profiler profiler("FFTDataServer::getMagnitudeAt", false);

    size_t col;
    FFTCache *cache = getCache(x, col);
    if (!cache) return 0;

    if (!cache->haveSetColumnAt(col)) {
        std::cerr << "FFTDataServer::getMagnitudeAt: calling fillColumn(" 
                  << x << ")" << std::endl;
        fillColumn(x);
    }
    return cache->getMagnitudeAt(col, y);
}

float
FFTDataServer::getNormalizedMagnitudeAt(size_t x, size_t y)
{
    Profiler profiler("FFTDataServer::getNormalizedMagnitudeAt", false);

    size_t col;
    FFTCache *cache = getCache(x, col);
    if (!cache) return 0;

    if (!cache->haveSetColumnAt(col)) {
        fillColumn(x);
    }
    return cache->getNormalizedMagnitudeAt(col, y);
}

float
FFTDataServer::getMaximumMagnitudeAt(size_t x)
{
    Profiler profiler("FFTDataServer::getMaximumMagnitudeAt", false);

    size_t col;
    FFTCache *cache = getCache(x, col);
    if (!cache) return 0;

    if (!cache->haveSetColumnAt(col)) {
        fillColumn(x);
    }
    return cache->getMaximumMagnitudeAt(col);
}

float
FFTDataServer::getPhaseAt(size_t x, size_t y)
{
    Profiler profiler("FFTDataServer::getPhaseAt", false);

    size_t col;
    FFTCache *cache = getCache(x, col);
    if (!cache) return 0;

    if (!cache->haveSetColumnAt(col)) {
        fillColumn(x);
    }
    return cache->getPhaseAt(col, y);
}

void
FFTDataServer::getValuesAt(size_t x, size_t y, float &real, float &imaginary)
{
    Profiler profiler("FFTDataServer::getValuesAt", false);

    size_t col;
    FFTCache *cache = getCache(x, col);
    if (!cache) { real = 0; imaginary = 0; return; }

    if (!cache->haveSetColumnAt(col)) {
#ifdef DEBUG_FFT_SERVER
        std::cerr << "FFTDataServer::getValuesAt(" << x << ", " << y << "): filling" << std::endl;
#endif
        fillColumn(x);
    }        
    float magnitude = cache->getMagnitudeAt(col, y);
    float phase = cache->getPhaseAt(col, y);
    real = magnitude * cosf(phase);
    imaginary = magnitude * sinf(phase);
}

bool
FFTDataServer::isColumnReady(size_t x)
{
    Profiler profiler("FFTDataServer::isColumnReady", false);

    if (!haveCache(x)) {
        if (m_lastUsedCache == -1) {
            if (m_suspended) {
                std::cerr << "FFTDataServer::isColumnReady(" << x << "): no cache, calling resume" << std::endl;
                resume();
            }
            m_fillThread->start();
        }
        return false;
    }

    size_t col;
    FFTCache *cache = getCache(x, col);
    if (!cache) return true;

    return cache->haveSetColumnAt(col);
}    

void
FFTDataServer::fillColumn(size_t x)
{
    Profiler profiler("FFTDataServer::fillColumn", false);

    size_t col;
#ifdef DEBUG_FFT_SERVER_FILL
    std::cout << "FFTDataServer::fillColumn(" << x << ")" << std::endl;
#endif
    FFTCache *cache = getCache(x, col);
    if (!cache) return;

    QMutexLocker locker(&m_writeMutex);

    if (cache->haveSetColumnAt(col)) return;

    int startFrame = m_windowIncrement * x;
    int endFrame = startFrame + m_windowSize;

    startFrame -= int(m_windowSize - m_windowIncrement) / 2;
    endFrame   -= int(m_windowSize - m_windowIncrement) / 2;
    size_t pfx = 0;

    size_t off = (m_fftSize - m_windowSize) / 2;

    for (size_t i = 0; i < off; ++i) {
        m_fftInput[i] = 0.0;
        m_fftInput[m_fftSize - i - 1] = 0.0;
    }

    if (startFrame < 0) {
	pfx = size_t(-startFrame);
	for (size_t i = 0; i < pfx; ++i) {
	    m_fftInput[off + i] = 0.0;
	}
    }

#ifdef DEBUG_FFT_SERVER_FILL
    std::cerr << "FFTDataServer::fillColumn: requesting frames "
              << startFrame + pfx << " -> " << endFrame << " ( = "
              << endFrame - (startFrame + pfx) << ") at index "
              << off + pfx << " in buffer of size " << m_fftSize
              << " with window size " << m_windowSize 
              << " from channel " << m_channel << std::endl;
#endif

    size_t got = m_model->getValues(m_channel, startFrame + pfx,
				    endFrame, m_fftInput + off + pfx);

    while (got + pfx < m_windowSize) {
	m_fftInput[off + got + pfx] = 0.0;
	++got;
    }

    if (m_channel == -1) {
	int channels = m_model->getChannelCount();
	if (channels > 1) {
	    for (size_t i = 0; i < m_windowSize; ++i) {
		m_fftInput[off + i] /= channels;
	    }
	}
    }

    m_windower.cut(m_fftInput + off);

    for (size_t i = 0; i < m_fftSize/2; ++i) {
	fftsample temp = m_fftInput[i];
	m_fftInput[i] = m_fftInput[i + m_fftSize/2];
	m_fftInput[i + m_fftSize/2] = temp;
    }

    fftwf_execute(m_fftPlan);

    fftsample factor = 0.0;

    for (size_t i = 0; i <= m_fftSize/2; ++i) {

	fftsample mag = sqrtf(m_fftOutput[i][0] * m_fftOutput[i][0] +
                              m_fftOutput[i][1] * m_fftOutput[i][1]);
	mag /= m_windowSize / 2;

	if (mag > factor) factor = mag;

	fftsample phase = atan2f(m_fftOutput[i][1], m_fftOutput[i][0]);
	phase = princargf(phase);

        m_workbuffer[i] = mag;
        m_workbuffer[i + m_fftSize/2+1] = phase;
    }

    cache->setColumnAt(col,
                       m_workbuffer,
                       m_workbuffer + m_fftSize/2+1,
                       factor);

    if (m_suspended) {
//        std::cerr << "FFTDataServer::fillColumn(" << x << "): calling resume" << std::endl;
//        resume();
    }
}    

size_t
FFTDataServer::getFillCompletion() const 
{
    if (m_fillThread) return m_fillThread->getCompletion();
    else return 100;
}

size_t
FFTDataServer::getFillExtent() const
{
    if (m_fillThread) return m_fillThread->getExtent();
    else return m_model->getEndFrame();
}

QString
FFTDataServer::generateFileBasename() const
{
    return generateFileBasename(m_model, m_channel, m_windower.getType(),
                                m_windowSize, m_windowIncrement, m_fftSize,
                                m_polar);
}

QString
FFTDataServer::generateFileBasename(const DenseTimeValueModel *model,
                                    int channel,
                                    WindowType windowType,
                                    size_t windowSize,
                                    size_t windowIncrement,
                                    size_t fftSize,
                                    bool polar)
{
    char buffer[200];

    sprintf(buffer, "%u-%u-%u-%u-%u-%u%s",
            (unsigned int)XmlExportable::getObjectExportId(model),
            (unsigned int)(channel + 1),
            (unsigned int)windowType,
            (unsigned int)windowSize,
            (unsigned int)windowIncrement,
            (unsigned int)fftSize,
            polar ? "-p" : "-r");

    return buffer;
}

void
FFTDataServer::FillThread::run()
{
    m_extent = 0;
    m_completion = 0;
    
    size_t start = m_server.m_model->getStartFrame();
    size_t end = m_server.m_model->getEndFrame();
    size_t remainingEnd = end;

    int counter = 0;
    int updateAt = (end / m_server.m_windowIncrement) / 20;
    if (updateAt < 100) updateAt = 100;

    if (m_fillFrom > start) {

        for (size_t f = m_fillFrom; f < end; f += m_server.m_windowIncrement) {
	    
            m_server.fillColumn(int((f - start) / m_server.m_windowIncrement));

            if (m_server.m_exiting) return;

            while (m_server.m_suspended) {
#ifdef DEBUG_FFT_SERVER
                std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): suspended, waiting..." << std::endl;
#endif
                m_server.m_writeMutex.lock();
                m_server.m_condition.wait(&m_server.m_writeMutex, 10000);
                m_server.m_writeMutex.unlock();
#ifdef DEBUG_FFT_SERVER
                std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): waited" << std::endl;
#endif
                if (m_server.m_exiting) return;
            }

            if (++counter == updateAt) {
                m_extent = f;
                m_completion = size_t(100 * fabsf(float(f - m_fillFrom) /
                                                  float(end - start)));
                counter = 0;
            }
        }

        remainingEnd = m_fillFrom;
        if (remainingEnd > start) --remainingEnd;
        else remainingEnd = start;
    }

    size_t baseCompletion = m_completion;

    for (size_t f = start; f < remainingEnd; f += m_server.m_windowIncrement) {

        m_server.fillColumn(int((f - start) / m_server.m_windowIncrement));

        if (m_server.m_exiting) return;

        while (m_server.m_suspended) {
#ifdef DEBUG_FFT_SERVER
            std::cerr << "FFTDataServer(" << this << " [" << (void *)QThread::currentThreadId() << "]): suspended, waiting..." << std::endl;
#endif
            m_server.m_writeMutex.lock();
            m_server.m_condition.wait(&m_server.m_writeMutex, 10000);
            m_server.m_writeMutex.unlock();
            if (m_server.m_exiting) return;
        }
		    
        if (++counter == updateAt) {
            m_extent = f;
            m_completion = baseCompletion +
                size_t(100 * fabsf(float(f - start) /
                                   float(end - start)));
            counter = 0;
        }
    }

    m_completion = 100;
    m_extent = end;
}