icondatabase.cpp

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                pool.cycle();
            }
        }
        
        // Stop the import at any time of the thread has been asked to shutdown
        if (shouldStopThreadActivity()) {
            LOG(IconDatabase, "IconDatabase asked to terminate during performURLImport()");
            return;
        }
        
        result = query.step();
    }
    
    if (result != SQLResultDone)
        LOG(IconDatabase, "Error reading page->icon url mappings from database");

    // Clear the m_pageURLsPendingImport set - either the page URLs ended up with an iconURL (that we'll notify about) or not, 
    // but after m_iconURLImportComplete is set to true, we don't care about this set anymore
    Vector<String> urls;
    {
        MutexLocker locker(m_pendingReadingLock);

        urls.appendRange(m_pageURLsPendingImport.begin(), m_pageURLsPendingImport.end());
        m_pageURLsPendingImport.clear();        
        m_iconURLImportComplete = true;
    }
    
    Vector<String> urlsToNotify;
    
    // Loop through the urls pending import
    // Remove unretained ones if database cleanup is allowed
    // Keep a set of ones that are retained and pending notification
    
    {
        MutexLocker locker(m_urlAndIconLock);
        
        for (unsigned i = 0; i < urls.size(); ++i) {
            if (!m_retainedPageURLs.contains(urls[i])) {
                PageURLRecord* record = m_pageURLToRecordMap.get(urls[i]);
                if (record && !databaseCleanupCounter) {
                    m_pageURLToRecordMap.remove(urls[i]);
                    IconRecord* iconRecord = record->iconRecord();
                    
                    // If this page is the only remaining retainer of its icon, mark that icon for deletion and don't bother
                    // reading anything related to it 
                    if (iconRecord && iconRecord->hasOneRef()) {
                        m_iconURLToRecordMap.remove(iconRecord->iconURL());
                        
                        {
                            MutexLocker locker(m_pendingReadingLock);
                            m_pageURLsInterestedInIcons.remove(urls[i]);
                            m_iconsPendingReading.remove(iconRecord);
                        }
                        {
                            MutexLocker locker(m_pendingSyncLock);
                            m_iconsPendingSync.set(iconRecord->iconURL(), iconRecord->snapshot(true));                    
                        }
                    }
                    
                    delete record;
                }
            } else {
                urlsToNotify.append(urls[i]);
            }
        }
    }

    LOG(IconDatabase, "Notifying %zu interested page URLs that their icon URL is known due to the import", urlsToNotify.size());
    // Now that we don't hold any locks, perform the actual notifications
    for (unsigned i = 0; i < urlsToNotify.size(); ++i) {
        LOG(IconDatabase, "Notifying icon info known for pageURL %s", urlsToNotify[i].ascii().data());
        m_client->dispatchDidAddIconForPageURL(urlsToNotify[i]);
        if (shouldStopThreadActivity())
            return;

        pool.cycle();
    }
    
    // Notify all DocumentLoaders that were waiting for an icon load decision on the main thread
    callOnMainThread(notifyPendingLoadDecisionsOnMainThread, this);
}

void* IconDatabase::syncThreadMainLoop()
{
    ASSERT_ICON_SYNC_THREAD();
    static bool prunedUnretainedIcons = false;

    m_syncLock.lock();

    // It's possible thread termination is requested before the main loop even starts - in that case, just skip straight to cleanup
    while (!m_threadTerminationRequested) {
        m_syncLock.unlock();

#ifndef NDEBUG
        double timeStamp = currentTime();
#endif
        LOG(IconDatabase, "(THREAD) Main work loop starting");

        // If we should remove all icons, do it now.  This is an uninteruptible procedure that we will always do before quitting if it is requested
        if (m_removeIconsRequested) {
            removeAllIconsOnThread();
            m_removeIconsRequested = false;
        }
        
        // Then, if the thread should be quitting, quit now!
        if (m_threadTerminationRequested)
            break;
        
        bool didAnyWork = true;
        while (didAnyWork) {
            bool didWrite = writeToDatabase();
            if (shouldStopThreadActivity())
                break;
                
            didAnyWork = readFromDatabase();
            if (shouldStopThreadActivity())
                break;
                
            // Prune unretained icons after the first time we sync anything out to the database
            // This way, pruning won't be the only operation we perform to the database by itself
            // We also don't want to bother doing this if the thread should be terminating (the user is quitting)
            // or if private browsing is enabled
            // We also don't want to prune if the m_databaseCleanupCounter count is non-zero - that means someone
            // has asked to delay pruning
            if (didWrite && !m_privateBrowsingEnabled && !prunedUnretainedIcons && !databaseCleanupCounter) {
#ifndef NDEBUG
                double time = currentTime();
#endif
                LOG(IconDatabase, "(THREAD) Starting pruneUnretainedIcons()");
                
                pruneUnretainedIcons();
                
                LOG(IconDatabase, "(THREAD) pruneUnretainedIcons() took %.4f seconds", currentTime() - time);
                
                // If pruneUnretainedIcons() returned early due to requested thread termination, its still okay
                // to mark prunedUnretainedIcons true because we're about to terminate anyway
                prunedUnretainedIcons = true;
            }
            
            didAnyWork = didAnyWork || didWrite;
            if (shouldStopThreadActivity())
                break;
        }
        
#ifndef NDEBUG
        double newstamp = currentTime();
        LOG(IconDatabase, "(THREAD) Main work loop ran for %.4f seconds, %s requested to terminate", newstamp - timeStamp, shouldStopThreadActivity() ? "was" : "was not");
#endif
                    
        m_syncLock.lock();
        
        // There is some condition that is asking us to stop what we're doing now and handle a special case
        // This is either removing all icons, or shutting down the thread to quit the app
        // We handle those at the top of this main loop so continue to jump back up there
        if (shouldStopThreadActivity())
            continue;
            
        m_syncCondition.wait(m_syncLock); 
    }
    m_syncLock.unlock();
    
    // Thread is terminating at this point
    return cleanupSyncThread();
}

bool IconDatabase::readFromDatabase()
{
    ASSERT_ICON_SYNC_THREAD();
    
#ifndef NDEBUG
    double timeStamp = currentTime();
#endif

    bool didAnyWork = false;

    // We'll make a copy of the sets of things that need to be read.  Then we'll verify at the time of updating the record that it still wants to be updated
    // This way we won't hold the lock for a long period of time
    Vector<IconRecord*> icons;
    {
        MutexLocker locker(m_pendingReadingLock);
        icons.appendRange(m_iconsPendingReading.begin(), m_iconsPendingReading.end());
    }
    
    // Keep track of icons we actually read to notify them of the new icon    
    HashSet<String> urlsToNotify;
    
    for (unsigned i = 0; i < icons.size(); ++i) {
        didAnyWork = true;
        RefPtr<SharedBuffer> imageData = getImageDataForIconURLFromSQLDatabase(icons[i]->iconURL());

        // Verify this icon still wants to be read from disk
        {
            MutexLocker urlLocker(m_urlAndIconLock);
            {
                MutexLocker readLocker(m_pendingReadingLock);
                
                if (m_iconsPendingReading.contains(icons[i])) {
                    // Set the new data
                    icons[i]->setImageData(imageData.get());
                    
                    // Remove this icon from the set that needs to be read
                    m_iconsPendingReading.remove(icons[i]);
                    
                    // We have a set of all Page URLs that retain this icon as well as all PageURLs waiting for an icon
                    // We want to find the intersection of these two sets to notify them
                    // Check the sizes of these two sets to minimize the number of iterations
                    const HashSet<String>* outerHash;
                    const HashSet<String>* innerHash;
                    
                    if (icons[i]->retainingPageURLs().size() > m_pageURLsInterestedInIcons.size()) {
                        outerHash = &m_pageURLsInterestedInIcons;
                        innerHash = &(icons[i]->retainingPageURLs());
                    } else {
                        innerHash = &m_pageURLsInterestedInIcons;
                        outerHash = &(icons[i]->retainingPageURLs());
                    }
                    
                    HashSet<String>::const_iterator iter = outerHash->begin();
                    HashSet<String>::const_iterator end = outerHash->end();
                    for (; iter != end; ++iter) {
                        if (innerHash->contains(*iter)) {
                            LOG(IconDatabase, "%s is interesting in the icon we just read.  Adding it to the list and removing it from the interested set", urlForLogging(*iter).ascii().data());
                            urlsToNotify.add(*iter);
                        }
                        
                        // If we ever get to the point were we've seen every url interested in this icon, break early
                        if (urlsToNotify.size() == m_pageURLsInterestedInIcons.size())
                            break;
                    }
                    
                    // We don't need to notify a PageURL twice, so all the ones we're about to notify can be removed from the interested set
                    if (urlsToNotify.size() == m_pageURLsInterestedInIcons.size())
                        m_pageURLsInterestedInIcons.clear();
                    else {
                        iter = urlsToNotify.begin();
                        end = urlsToNotify.end();
                        for (; iter != end; ++iter)
                            m_pageURLsInterestedInIcons.remove(*iter);
                    }
                }
            }
        }
    
        if (shouldStopThreadActivity())
            return didAnyWork;
        
        // Informal testing shows that draining the autorelease pool every 25 iterations is about as low as we can go
        // before performance starts to drop off, but we don't want to increase this number because then accumulated memory usage will go up
        AutodrainedPool pool(25);

        // Now that we don't hold any locks, perform the actual notifications
        HashSet<String>::iterator iter = urlsToNotify.begin();
        HashSet<String>::iterator end = urlsToNotify.end();
        for (unsigned iteration = 0; iter != end; ++iter, ++iteration) {
            LOG(IconDatabase, "Notifying icon received for pageURL %s", urlForLogging(*iter).ascii().data());
            m_client->dispatchDidAddIconForPageURL(*iter);
            if (shouldStopThreadActivity())
                return didAnyWork;
            
            pool.cycle();
        }

        LOG(IconDatabase, "Done notifying %i pageURLs who just received their icons", urlsToNotify.size());
        urlsToNotify.clear();
        
        if (shouldStopThreadActivity())
            return didAnyWork;
    }

    LOG(IconDatabase, "Reading from database took %.4f seconds", currentTime() - timeStamp);

    return didAnyWork;
}

bool IconDatabase::writeToDatabase()
{
    ASSERT_ICON_SYNC_THREAD();

#ifndef NDEBUG
    double timeStamp = currentTime();
#endif

    bool didAnyWork = false;
    
    // We can copy the current work queue then clear it out - If any new work comes in while we're writing out,
    // we'll pick it up on the next pass.  This greatly simplifies the locking strategy for this method and remains cohesive with changes
    // asked for by the database on the main thread
    Vector<IconSnapshot> iconSnapshots;
    Vector<PageURLSnapshot> pageSnapshots;
    {
        MutexLocker locker(m_pendingSyncLock);
        
        iconSnapshots.appendRange(m_iconsPendingSync.begin().values(), m_iconsPendingSync.end().values());
        m_iconsPendingSync.clear();
        
        pageSnapshots.appendRange(m_pageURLsPendingSync.begin().values(), m_pageURLsPendingSync.end().values());
        m_pageURLsPendingSync.clear();
    }
    
    if (iconSnapshots.size() || pageSnapshots.size())
        didAnyWork = true;
        
    SQLiteTransaction syncTransaction(m_syncDB);
    syncTransaction.begin();
    
    for (unsigned i = 0; i < iconSnapshots.size(); ++i) {
        writeIconSnapshotToSQLDatabase(iconSnapshots[i]);
        LOG(IconDatabase, "Wrote IconRecord for IconURL %s with timeStamp of %i to the DB", urlForLogging(iconSnapshots[i].iconURL).ascii().data(), iconSnapshots[i].