annotate rdf/SimpleSPARQLQuery.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 2008 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 "SimpleSPARQLQuery.h"
#include "base/ProgressReporter.h"
#include "base/Profiler.h"

#include <QMutex>
#include <QMutexLocker>
#include <QRegExp>

#include <set>

#include <redland.h>

//#define DEBUG_SIMPLE_SPARQL_QUERY 1

#include <iostream>

using std::cerr;
using std::endl;

class WredlandWorldWrapper
{
public:
    WredlandWorldWrapper();
    ~WredlandWorldWrapper();

    bool isOK() const;

    bool loadUriIntoDefaultModel(QString uriString, QString &errorString);
        
    librdf_world *getWorld() { return m_world; }
    const librdf_world *getWorld() const { return m_world; }
        
    librdf_model *getDefaultModel() { return m_defaultModel; }
    const librdf_model *getDefaultModel() const { return m_defaultModel; }

    librdf_model *getModel(QString fromUri);
    void freeModel(QString forUri);

private:
    QMutex m_mutex;

    librdf_world *m_world;
    librdf_storage *m_defaultStorage;
    librdf_model *m_defaultModel;

    std::set<QString> m_defaultModelUris;

    std::map<QString, librdf_storage *> m_ownStorageUris;
    std::map<QString, librdf_model *> m_ownModelUris;

    bool loadUri(librdf_model *model, QString uri, QString &errorString);
};

WredlandWorldWrapper::WredlandWorldWrapper() :
    m_world(0), m_defaultStorage(0), m_defaultModel(0)
{
    m_world = librdf_new_world();
    if (!m_world) {
        cerr << "SimpleSPARQLQuery: ERROR: Failed to create LIBRDF world!" << endl;
        return;
    }
    librdf_world_open(m_world);

    m_defaultStorage = librdf_new_storage(m_world, "trees", NULL, NULL);
    if (!m_defaultStorage) {
        std::cerr << "SimpleSPARQLQuery: WARNING: Failed to initialise Redland trees datastore, falling back to memory store" << std::endl;
        m_defaultStorage = librdf_new_storage(m_world, NULL, NULL, NULL);
        if (!m_defaultStorage) {
            std::cerr << "SimpleSPARQLQuery: ERROR: Failed to initialise Redland memory datastore" << std::endl;
            return;
        }                
    }
    m_defaultModel = librdf_new_model(m_world, m_defaultStorage, NULL);
    if (!m_defaultModel) {
        std::cerr << "SimpleSPARQLQuery: ERROR: Failed to initialise Redland data model" << std::endl;
        return;
    }
}

WredlandWorldWrapper::~WredlandWorldWrapper()
{
/*!!! This is a static singleton; destroying it while there are
      queries outstanding can be problematic, it appears, and since
      the storage is non-persistent there shouldn't be any need to
      destroy it explicitly, except for the sake of tidiness.

    while (!m_ownModelUris.empty()) {
        librdf_free_model(m_ownModelUris.begin()->second);
        m_ownModelUris.erase(m_ownModelUris.begin());
    }
    while (!m_ownStorageUris.empty()) {
        librdf_free_storage(m_ownStorageUris.begin()->second);
        m_ownStorageUris.erase(m_ownStorageUris.begin());
    }
    if (m_defaultModel) librdf_free_model(m_defaultModel);
    if (m_defaultStorage) librdf_free_storage(m_defaultStorage);
    if (m_world) librdf_free_world(m_world);
*/
}

bool
WredlandWorldWrapper::isOK() const {
    return (m_defaultModel != 0); 
}

bool
WredlandWorldWrapper::loadUriIntoDefaultModel(QString uriString, QString &errorString)
{
    QMutexLocker locker(&m_mutex);
    
    if (m_defaultModelUris.find(uriString) != m_defaultModelUris.end()) {
        return true;
    }
    
    if (loadUri(m_defaultModel, uriString, errorString)) {
        m_defaultModelUris.insert(uriString);
        return true;
    } else {
        return false;
    }
}

librdf_model *
WredlandWorldWrapper::getModel(QString fromUri)
{
    QMutexLocker locker(&m_mutex);
    if (fromUri == "") {
        return getDefaultModel();
    }
    if (m_ownModelUris.find(fromUri) != m_ownModelUris.end()) {
        return m_ownModelUris[fromUri];
    }
    librdf_storage *storage = librdf_new_storage(m_world, "trees", NULL, NULL);
    if (!storage) { // don't warn here, we probably already did it in main ctor
        storage = librdf_new_storage(m_world, NULL, NULL, NULL);
    }
    librdf_model *model = librdf_new_model(m_world, storage, NULL);
    if (!model) {
        std::cerr << "SimpleSPARQLQuery: ERROR: Failed to create new model" << std::endl;
        librdf_free_storage(storage);
        return 0;
    }
    QString err;
    if (!loadUri(model, fromUri, err)) {
        std::cerr << "SimpleSPARQLQuery: ERROR: Failed to parse into new model: " << err.toStdString() << std::endl;
        librdf_free_model(model);
        librdf_free_storage(storage);
        m_ownModelUris[fromUri] = 0;
        return 0;
    }
    m_ownModelUris[fromUri] = model;
    m_ownStorageUris[fromUri] = storage;
    return model;
}

void
WredlandWorldWrapper::freeModel(QString forUri)
{
#ifdef DEBUG_SIMPLE_SPARQL_QUERY
    std::cerr << "SimpleSPARQLQuery::freeModel: Model uri = \"" << forUri.toStdString() << "\"" << std::endl;
#endif

    QMutexLocker locker(&m_mutex);
    if (forUri == "") {
        std::cerr << "SimpleSPARQLQuery::freeModel: ERROR: Can't free default model" << std::endl;
        return;
    }
    if (m_ownModelUris.find(forUri) == m_ownModelUris.end()) {
#ifdef DEBUG_SIMPLE_SPARQL_QUERY
        std::cerr << "SimpleSPARQLQuery::freeModel: NOTE: Unknown or already-freed model (uri = \"" << forUri.toStdString() << "\")" << std::endl;
#endif
        return;
    }

    librdf_model *model = m_ownModelUris[forUri];
    if (model) librdf_free_model(model);
    m_ownModelUris.erase(forUri);

    if (m_ownStorageUris.find(forUri) != m_ownStorageUris.end()) {
        librdf_storage *storage = m_ownStorageUris[forUri];
        if (storage) librdf_free_storage(storage);
        m_ownStorageUris.erase(forUri);
    }        
}

bool
WredlandWorldWrapper::loadUri(librdf_model *model, QString uri, QString &errorString)
{
    librdf_uri *luri = librdf_new_uri
        (m_world, (const unsigned char *)uri.toUtf8().data());
    if (!luri) {
        errorString = "Failed to construct librdf_uri!";
        return false;
    }
    
    librdf_parser *parser = librdf_new_parser(m_world, "guess", NULL, NULL);
    if (!parser) {
        errorString = "Failed to initialise Redland parser";
        return false;
    }

#ifdef DEBUG_SIMPLE_SPARQL_QUERY    
    std::cerr << "About to parse \"" << uri.toStdString() << "\"" << std::endl;
#endif
    
    Profiler p("SimpleSPARQLQuery: Parse URI into LIBRDF model");
    
    if (librdf_parser_parse_into_model(parser, luri, NULL, model)) {
        
        errorString = QString("Failed to parse RDF from URI \"%1\"")
            .arg(uri);
        librdf_free_parser(parser);
        return false;
        
    } else {
        
        librdf_free_parser(parser);
        return true;
    }
}        


class SimpleSPARQLQuery::Impl
{
public:
    Impl(SimpleSPARQLQuery::QueryType, QString query);
    ~Impl();

    static bool addSourceToModel(QString sourceUri);
    static void closeSingleSource(QString sourceUri);

    void setProgressReporter(ProgressReporter *reporter) { m_reporter = reporter; }
    bool wasCancelled() const { return m_cancelled; }

    ResultList execute();

    bool isOK() const;
    QString getErrorString() const;

protected:
    static QMutex m_mutex;

    static WredlandWorldWrapper *m_redland;

    ResultList executeDirectParser();
    ResultList executeDatastore();
    ResultList executeFor(QString modelUri);

    QueryType m_type;
    QString m_query;
    QString m_errorString;
    ProgressReporter *m_reporter;
    bool m_cancelled;
};

WredlandWorldWrapper *SimpleSPARQLQuery::Impl::m_redland = 0;

QMutex SimpleSPARQLQuery::Impl::m_mutex;

SimpleSPARQLQuery::SimpleSPARQLQuery(QueryType type, QString query) :
    m_impl(new Impl(type, query))
{
}

SimpleSPARQLQuery::~SimpleSPARQLQuery() 
{
    delete m_impl;
}

void
SimpleSPARQLQuery::setProgressReporter(ProgressReporter *reporter)
{
    m_impl->setProgressReporter(reporter);
}

bool
SimpleSPARQLQuery::wasCancelled() const
{
    return m_impl->wasCancelled();
}

SimpleSPARQLQuery::ResultList
SimpleSPARQLQuery::execute()
{
    return m_impl->execute();
}

bool
SimpleSPARQLQuery::isOK() const
{
    return m_impl->isOK();
}

QString
SimpleSPARQLQuery::getErrorString() const
{
    return m_impl->getErrorString();
}

bool
SimpleSPARQLQuery::addSourceToModel(QString sourceUri)
{
    return SimpleSPARQLQuery::Impl::addSourceToModel(sourceUri);
}

void
SimpleSPARQLQuery::closeSingleSource(QString sourceUri)
{
    SimpleSPARQLQuery::Impl::closeSingleSource(sourceUri);
}

SimpleSPARQLQuery::Impl::Impl(QueryType type, QString query) :
    m_type(type),
    m_query(query),
    m_reporter(0),
    m_cancelled(false)
{
}

SimpleSPARQLQuery::Impl::~Impl()
{
}

bool
SimpleSPARQLQuery::Impl::isOK() const
{
    return (m_errorString == "");
}

QString
SimpleSPARQLQuery::Impl::getErrorString() const
{
    return m_errorString;
}

SimpleSPARQLQuery::ResultList
SimpleSPARQLQuery::Impl::execute()
{
    ResultList list;

    QMutexLocker locker(&m_mutex);

    if (!m_redland) {
        m_redland = new WredlandWorldWrapper();
    }

    if (!m_redland->isOK()) {
        cerr << "ERROR: SimpleSPARQLQuery::execute: Failed to initialise Redland datastore" << endl;
        return list;
    }

    if (m_type == QueryFromSingleSource) {
        return executeDirectParser();
    } else {
        return executeDatastore();
    }

#ifdef DEBUG_SIMPLE_SPARQL_QUERY
    if (m_errorString != "") {
        std::cerr << "SimpleSPARQLQuery::execute: error returned: \""
                  << m_errorString.toStdString() << "\"" << std::endl;
    }
#endif
}

SimpleSPARQLQuery::ResultList
SimpleSPARQLQuery::Impl::executeDirectParser()
{
#ifdef DEBUG_SIMPLE_SPARQL_QUERY
    std::cerr << "SimpleSPARQLQuery::executeDirectParser: Query is: \"" << m_query.toStdString() << "\"" << std::endl;
#endif

    ResultList list;

    Profiler profiler("SimpleSPARQLQuery::executeDirectParser");

    static QRegExp fromRE("from\\s+<([^>]+)>", Qt::CaseInsensitive);
    QString fromUri;

    if (fromRE.indexIn(m_query) < 0) {
        std::cerr << "SimpleSPARQLQuery::executeDirectParser: Query contains no FROM clause, nothing to parse from" << std::endl;
        return list;
    } else {
        fromUri = fromRE.cap(1);
#ifdef DEBUG_SIMPLE_SPARQL_QUERY
        std::cerr << "SimpleSPARQLQuery::executeDirectParser: FROM URI is <"
                  << fromUri.toStdString() << ">" << std::endl;
#endif
    }

    return executeFor(fromUri);
}

SimpleSPARQLQuery::ResultList
SimpleSPARQLQuery::Impl::executeDatastore()
{
#ifdef DEBUG_SIMPLE_SPARQL_QUERY
    std::cerr << "SimpleSPARQLQuery::executeDatastore: Query is: \"" << m_query.toStdString() << "\"" << std::endl;
#endif

    ResultList list;

    Profiler profiler("SimpleSPARQLQuery::executeDatastore");

    return executeFor("");
}

SimpleSPARQLQuery::ResultList
SimpleSPARQLQuery::Impl::executeFor(QString modelUri)
{
    ResultList list;
    librdf_query *query;

#ifdef DEBUG_SIMPLE_SPARQL_QUERY
    static std::map<QString, int> counter;
    if (counter.find(m_query) == counter.end()) counter[m_query] = 1;
    else ++counter[m_query];
    std::cerr << "Counter for this query: " << counter[m_query] << std::endl;
    std::cerr << "Base URI is: \"" << modelUri.toStdString() << "\"" << std::endl;
#endif

    {
        Profiler p("SimpleSPARQLQuery: Prepare LIBRDF query");
        query = librdf_new_query
            (m_redland->getWorld(), "sparql", NULL,
             (const unsigned char *)m_query.toUtf8().data(), NULL);
    }
    
    if (!query) {
        m_errorString = "Failed to construct query";
        return list;
    }

    librdf_query_results *results;
    {
        Profiler p("SimpleSPARQLQuery: Execute LIBRDF query");
        results = librdf_query_execute(query, m_redland->getModel(modelUri));
    }

    if (!results) {
        m_errorString = "RDF query failed";
        librdf_free_query(query);
        return list;
    }

    if (!librdf_query_results_is_bindings(results)) {
        m_errorString = "RDF query returned non-bindings results";
        librdf_free_query_results(results);
        librdf_free_query(query);
        return list;
    }
    
    int resultCount = 0;
    int resultTotal = librdf_query_results_get_count(results); // probably wrong
    m_cancelled = false;

    while (!librdf_query_results_finished(results)) {

        int count = librdf_query_results_get_bindings_count(results);

        KeyValueMap resultmap;

        for (int i = 0; i < count; ++i) {

            const char *name =
                librdf_query_results_get_binding_name(results, i);

            if (!name) {
                std::cerr << "WARNING: Result " << i << " of query has no name" << std::endl;
                continue;
            }

            librdf_node *node =
                librdf_query_results_get_binding_value(results, i);

            QString key = (const char *)name;

            if (!node) {
#ifdef DEBUG_SIMPLE_SPARQL_QUERY
                std::cerr << i << ". " << key.toStdString() << " -> (nil)" << std::endl;
#endif
                resultmap[key] = Value();
                continue;
            }

            ValueType type = LiteralValue;
            QString text;

            if (librdf_node_is_resource(node)) {

                type = URIValue;
                librdf_uri *uri = librdf_node_get_uri(node);
                const char *us = (const char *)librdf_uri_as_string(uri);

                if (!us) {
                    std::cerr << "WARNING: Result " << i << " of query claims URI type, but has null URI" << std::endl;
                } else {
                    text = us;
                }

            } else if (librdf_node_is_literal(node)) {

                type = LiteralValue;

                const char *lit = (const char *)librdf_node_get_literal_value(node);
                if (!lit) {
                    std::cerr << "WARNING: Result " << i << " of query claims literal type, but has no literal" << std::endl;
                } else {
                    text = lit;
                }

            } else if (librdf_node_is_blank(node)) {

                type = BlankValue;

                const char *lit = (const char *)librdf_node_get_literal_value(node);
                if (lit) text = lit;

            } else {

                cerr << "SimpleSPARQLQuery: LIBRDF query returned unknown node type (not resource, literal, or blank)" << endl;
            }

#ifdef DEBUG_SIMPLE_SPARQL_QUERY
            cerr << i << ". " << key.toStdString() << " -> " << text.toStdString() << " (type " << type << ")" << endl;
#endif

            resultmap[key] = Value(type, text);

//            librdf_free_node(node);
        }

        list.push_back(resultmap);

        librdf_query_results_next(results);

        resultCount++;

        if (m_reporter) {
            if (resultCount >= resultTotal) {
                if (m_reporter->isDefinite()) m_reporter->setDefinite(false);
                m_reporter->setProgress(resultCount);
            } else {
                m_reporter->setProgress((resultCount * 100) / resultTotal);
            }

            if (m_reporter->wasCancelled()) {
                m_cancelled = true;
                break;
            }
        }
    }

    librdf_free_query_results(results);
    librdf_free_query(query);

#ifdef DEBUG_SIMPLE_SPARQL_QUERY
    cerr << "SimpleSPARQLQuery::executeDatastore: All results retrieved (" << resultCount << " of them)" << endl;
#endif

    return list;
}

bool
SimpleSPARQLQuery::Impl::addSourceToModel(QString sourceUri)
{
    QString err;

    QMutexLocker locker(&m_mutex);

    if (!m_redland) {
        m_redland = new WredlandWorldWrapper();
    }

    if (!m_redland->isOK()) {
        std::cerr << "SimpleSPARQLQuery::addSourceToModel: Failed to initialise Redland datastore" << std::endl;
        return false;
    }

    if (!m_redland->loadUriIntoDefaultModel(sourceUri, err)) {
        std::cerr << "SimpleSPARQLQuery::addSourceToModel: Failed to add source URI \"" << sourceUri.toStdString() << ": " << err.toStdString() << std::endl;
        return false;
    }
    return true;
}

void
SimpleSPARQLQuery::Impl::closeSingleSource(QString sourceUri)
{
    QMutexLocker locker(&m_mutex);

    m_redland->freeModel(sourceUri);
}

SimpleSPARQLQuery::Value
SimpleSPARQLQuery::singleResultQuery(QueryType type,
                                     QString query, QString binding)
{
    SimpleSPARQLQuery q(type, query);
    ResultList results = q.execute();
    if (!q.isOK()) {
        cerr << "SimpleSPARQLQuery::singleResultQuery: ERROR: "
             << q.getErrorString().toStdString() << endl;
        return Value();
    }
    if (results.empty()) {
        return Value();
    }
    for (int i = 0; i < results.size(); ++i) {
        if (results[i].find(binding) != results[i].end() &&
            results[i][binding].type != NoValue) {
            return results[i][binding];
        }
    }
    return Value();
}