From 34ddddae1b8449c90911fb74288c72f728c5a392 Mon Sep 17 00:00:00 2001
From: Andrzej Kapolka <drzej.k@gmail.com>
Date: Mon, 10 Mar 2014 12:06:07 -0700
Subject: [PATCH] Basic LRU cache.  Closes #2234.

---
 interface/src/renderer/GeometryCache.h  |  2 +-
 interface/src/renderer/TextureCache.cpp |  2 +-
 libraries/shared/src/ResourceCache.cpp  | 25 +++++++++++++++++--------
 libraries/shared/src/ResourceCache.h    | 10 +++++++++-
 4 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/interface/src/renderer/GeometryCache.h b/interface/src/renderer/GeometryCache.h
index 6e9604e79e..da1955039d 100644
--- a/interface/src/renderer/GeometryCache.h
+++ b/interface/src/renderer/GeometryCache.h
@@ -89,7 +89,7 @@ public:
 protected:
 
     virtual void downloadFinished(QNetworkReply* reply);
-    virtual void reinsert() const;
+    virtual void reinsert();
     
     Q_INVOKABLE void setGeometry(const FBXGeometry& geometry);
     
diff --git a/interface/src/renderer/TextureCache.cpp b/interface/src/renderer/TextureCache.cpp
index e3f750e676..80eef66ff5 100644
--- a/interface/src/renderer/TextureCache.cpp
+++ b/interface/src/renderer/TextureCache.cpp
@@ -133,7 +133,7 @@ QSharedPointer<NetworkTexture> TextureCache::getTexture(const QUrl& url, bool no
         texture->setCache(this);
         _dilatableNetworkTextures.insert(url, texture);
     } else {
-        _unusedResources.removeOne(texture);
+        _unusedResources.remove(texture->getLRUKey());
     }
     return texture;
 }
diff --git a/libraries/shared/src/ResourceCache.cpp b/libraries/shared/src/ResourceCache.cpp
index 6434376cd8..65c68b23ef 100644
--- a/libraries/shared/src/ResourceCache.cpp
+++ b/libraries/shared/src/ResourceCache.cpp
@@ -15,7 +15,8 @@
 #include "ResourceCache.h"
 
 ResourceCache::ResourceCache(QObject* parent) :
-    QObject(parent) {
+    QObject(parent),
+    _lastLRUKey(0) {
 }
 
 ResourceCache::~ResourceCache() {
@@ -38,19 +39,21 @@ QSharedPointer<Resource> ResourceCache::getResource(const QUrl& url, const QUrl&
         _resources.insert(url, resource);
         
     } else {
-        _unusedResources.removeOne(resource);
+        _unusedResources.remove(resource->getLRUKey());
     }
     return resource;
 }
 
 void ResourceCache::addUnusedResource(const QSharedPointer<Resource>& resource) {
-    const int RETAINED_RESOURCE_COUNT = 1;
+    const int RETAINED_RESOURCE_COUNT = 50;
     if (_unusedResources.size() > RETAINED_RESOURCE_COUNT) {
         // unload the oldest resource
-        QSharedPointer<Resource> oldResource = _unusedResources.takeFirst();
-        oldResource->setCache(NULL);
+        QMap<int, QSharedPointer<Resource> >::iterator it = _unusedResources.begin();
+        it.value()->setCache(NULL);
+        _unusedResources.erase(it);
     }
-    _unusedResources.append(resource);
+    resource->setLRUKey(++_lastLRUKey);
+    _unusedResources.insert(resource->getLRUKey(), resource);
 }
 
 void ResourceCache::attemptRequest(Resource* resource) {
@@ -100,6 +103,7 @@ Resource::Resource(const QUrl& url, bool delayLoad) :
     _startedLoading(false),
     _failedToLoad(false),
     _loaded(false),
+    _lruKey(0),
     _reply(NULL),
     _attempts(0) {
     
@@ -171,10 +175,9 @@ void Resource::allReferencesCleared() {
         reinsert();
         
         // add to the unused list
-        _cache->_unusedResources.append(self);
+        _cache->addUnusedResource(self);
         
     } else {
-        qDebug() << "deleting" << _url;
         delete this;
     }
 }
@@ -231,6 +234,7 @@ void Resource::makeRequest() {
     
     connect(_reply, SIGNAL(downloadProgress(qint64,qint64)), SLOT(handleDownloadProgress(qint64,qint64)));
     connect(_reply, SIGNAL(error(QNetworkReply::NetworkError)), SLOT(handleReplyError()));
+    connect(_reply, SIGNAL(finished()), SLOT(handleReplyFinished()));
     
     _replyTimer = new QTimer(this);
     connect(_replyTimer, SIGNAL(timeout()), SLOT(handleReplyTimeout()));
@@ -275,6 +279,11 @@ void Resource::handleReplyError(QNetworkReply::NetworkError error, QDebug debug)
     }
 }
 
+void Resource::handleReplyFinished() {
+    qDebug() << "Got finished without download progress/error?" << _url;
+    handleDownloadProgress(0, 0);
+}
+
 uint qHash(const QPointer<QObject>& value, uint seed) {
     return qHash(value.data(), seed);
 }
diff --git a/libraries/shared/src/ResourceCache.h b/libraries/shared/src/ResourceCache.h
index 2826902598..a544f43731 100644
--- a/libraries/shared/src/ResourceCache.h
+++ b/libraries/shared/src/ResourceCache.h
@@ -42,7 +42,7 @@ public:
 
 protected:
 
-    QList<QSharedPointer<Resource> > _unusedResources;
+    QMap<int, QSharedPointer<Resource> > _unusedResources;
 
     /// Loads a resource from the specified URL.
     /// \param fallback a fallback URL to load if the desired one is unavailable
@@ -65,6 +65,7 @@ private:
     friend class Resource;
 
     QHash<QUrl, QWeakPointer<Resource> > _resources;
+    int _lastLRUKey;
     
     static QNetworkAccessManager* _networkAccessManager;
     static int _requestLimit;
@@ -80,6 +81,9 @@ public:
     Resource(const QUrl& url, bool delayLoad = false);
     ~Resource();
     
+    /// Returns the key last used to identify this resource in the unused map.
+    int getLRUKey() const { return _lruKey; }
+
     /// Makes sure that the resource has started loading.
     void ensureLoading();
 
@@ -132,16 +136,20 @@ private slots:
     
     void handleDownloadProgress(qint64 bytesReceived, qint64 bytesTotal);
     void handleReplyError();
+    void handleReplyFinished();
     void handleReplyTimeout();
 
 private:
     
+    void setLRUKey(int lruKey) { _lruKey = lruKey; }
+    
     void makeRequest();
     
     void handleReplyError(QNetworkReply::NetworkError error, QDebug debug);
     
     friend class ResourceCache;
     
+    int _lruKey;
     QNetworkReply* _reply;
     QTimer* _replyTimer;
     qint64 _bytesReceived;