From ce307c6531053fc7edb966ba9bc2149f73cd18c2 Mon Sep 17 00:00:00 2001
From: Tobias Markmann <tm@ayena.de>
Date: Fri, 17 Feb 2017 19:21:32 +0100
Subject: Cache some recently used entity capability lookups in memory

Previously any entity capability lookup was only cached
on the disk. This meant that even for a cache hit, you would
read from disk and parse the disco info XML in the cache,
to return the result.
This commit adds an addition LRUCache based in-memory cache.

This extends the EntityCapsProvider API with a non-const
method, i.e. getCapsCached, which allows active caching
of results from the disk cache.

Test-Information:

All unit tests pass on macOS 10.12.3.

This noticeably speeds up the duration of a join of a large
MUC room, i.e. about 160 occupants, to about half of the
previous duration.

Change-Id: I0fc254cda962860416713822ddcad15ae13085f1

diff --git a/Swift/Controllers/Chat/MUCController.cpp b/Swift/Controllers/Chat/MUCController.cpp
index add7848..8f43b08 100644
--- a/Swift/Controllers/Chat/MUCController.cpp
+++ b/Swift/Controllers/Chat/MUCController.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -239,7 +239,7 @@ void MUCController::handleBareJIDCapsChanged(const JID& /*jid*/) {
     Tristate support = Yes;
     bool any = false;
     for (const auto& nick : currentOccupants_) {
-        DiscoInfo::ref disco = entityCapsProvider_->getCaps(toJID_.toBare().toString() + "/" + nick);
+        DiscoInfo::ref disco = entityCapsProvider_->getCapsCached(toJID_.toBare().toString() + "/" + nick);
         if (disco && disco->hasFeature(DiscoInfo::MessageCorrectionFeature)) {
             any = true;
         } else {
diff --git a/Swiften/Disco/DummyEntityCapsProvider.cpp b/Swiften/Disco/DummyEntityCapsProvider.cpp
index fce38fe..eba58ac 100644
--- a/Swiften/Disco/DummyEntityCapsProvider.cpp
+++ b/Swiften/Disco/DummyEntityCapsProvider.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -16,4 +16,8 @@ DiscoInfo::ref DummyEntityCapsProvider::getCaps(const JID& jid) const {
     return DiscoInfo::ref();
 }
 
+DiscoInfo::ref DummyEntityCapsProvider::getCapsCached(const JID& jid) {
+    return getCaps(jid);
+}
+
 }
diff --git a/Swiften/Disco/DummyEntityCapsProvider.h b/Swiften/Disco/DummyEntityCapsProvider.h
index 5171c91..971e183 100644
--- a/Swiften/Disco/DummyEntityCapsProvider.h
+++ b/Swiften/Disco/DummyEntityCapsProvider.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010 Isode Limited.
+ * Copyright (c) 2010-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -19,6 +19,8 @@ namespace Swift {
 
             DiscoInfo::ref getCaps(const JID& jid) const;
 
+            DiscoInfo::ref getCapsCached(const JID& jid);
+
             std::map<JID, DiscoInfo::ref> caps;
     };
 }
diff --git a/Swiften/Disco/EntityCapsManager.cpp b/Swiften/Disco/EntityCapsManager.cpp
index 64d90be..28c525f 100644
--- a/Swiften/Disco/EntityCapsManager.cpp
+++ b/Swiften/Disco/EntityCapsManager.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -76,4 +76,20 @@ DiscoInfo::ref EntityCapsManager::getCaps(const JID& jid) const {
     return DiscoInfo::ref();
 }
 
+DiscoInfo::ref EntityCapsManager::getCapsCached(const JID& jid) {
+    DiscoInfo::ref result;
+    auto capsHit = caps.find(jid);
+    if (capsHit != caps.end()) {
+        result = lruDiscoCache.get(capsHit->second, [&](const std::string& capsHash) {
+            boost::optional<DiscoInfo::ref> fileCacheResult;
+            auto fileCacheDiscoInfo = capsProvider->getCaps(capsHash);
+            if (fileCacheDiscoInfo) {
+                fileCacheResult = fileCacheDiscoInfo;
+            }
+            return fileCacheResult;
+        }).get_value_or(DiscoInfo::ref());
+    }
+    return result;
+}
+
 }
diff --git a/Swiften/Disco/EntityCapsManager.h b/Swiften/Disco/EntityCapsManager.h
index 4236326..3934fc7 100644
--- a/Swiften/Disco/EntityCapsManager.h
+++ b/Swiften/Disco/EntityCapsManager.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -11,6 +11,7 @@
 #include <boost/signals2.hpp>
 
 #include <Swiften/Base/API.h>
+#include <Swiften/Base/LRUCache.h>
 #include <Swiften/Disco/EntityCapsProvider.h>
 #include <Swiften/Elements/DiscoInfo.h>
 #include <Swiften/Elements/ErrorPayload.h>
@@ -35,6 +36,8 @@ namespace Swift {
              */
             DiscoInfo::ref getCaps(const JID&) const;
 
+            DiscoInfo::ref getCapsCached(const JID&);
+
         private:
             void handlePresenceReceived(std::shared_ptr<Presence>);
             void handleStanzaChannelAvailableChanged(bool);
@@ -43,5 +46,6 @@ namespace Swift {
         private:
             CapsProvider* capsProvider;
             std::map<JID, std::string> caps;
+            LRUCache<std::string, DiscoInfo::ref, 64> lruDiscoCache;
     };
 }
diff --git a/Swiften/Disco/EntityCapsProvider.h b/Swiften/Disco/EntityCapsProvider.h
index 5f4af18..e50a745 100644
--- a/Swiften/Disco/EntityCapsProvider.h
+++ b/Swiften/Disco/EntityCapsProvider.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -27,6 +27,8 @@ namespace Swift {
              */
             virtual DiscoInfo::ref getCaps(const JID&) const = 0;
 
+            virtual DiscoInfo::ref getCapsCached(const JID&) = 0;
+
             /**
              * Emitted when the capabilities of a JID changes.
              */
diff --git a/Swiften/Disco/FeatureOracle.cpp b/Swiften/Disco/FeatureOracle.cpp
index 2baf87c..63f7a4e 100644
--- a/Swiften/Disco/FeatureOracle.cpp
+++ b/Swiften/Disco/FeatureOracle.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016 Isode Limited.
+ * Copyright (c) 2015-2017 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -154,7 +154,7 @@ std::unordered_map<std::string, Tristate> FeatureOracle::getFeaturesForJID(const
         // Collect relevant disco info results and the set of features.
         for (auto&& presence : presenceOracle_->getAllPresence(jid)) {
             if (presence->getType() == Presence::Available) {
-                DiscoInfo::ref presenceDiscoInfo = capsProvider_->getCaps(presence->getFrom());
+                DiscoInfo::ref presenceDiscoInfo = capsProvider_->getCapsCached(presence->getFrom());
                 if (presenceDiscoInfo) {
                     onlineDiscoInfos.push_back(presenceDiscoInfo);
                     features.insert(presenceDiscoInfo->getFeatures().begin(), presenceDiscoInfo->getFeatures().end());
@@ -176,7 +176,7 @@ std::unordered_map<std::string, Tristate> FeatureOracle::getFeaturesForJID(const
     }
     else {
         // Return the disco result of the full JID.
-        auto discoInfo = capsProvider_->getCaps(jid);
+        auto discoInfo = capsProvider_->getCapsCached(jid);
         if (discoInfo) {
             for (auto&& feature : discoInfo->getFeatures()) {
                 supportedFeatures[feature] = Yes;
-- 
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