loolwsd: canceltiles re-designed using tilecache instead of queue

Change-Id: I4b9ba91ee08bc9dd8d27df275e303f5517d9740c
Reviewed-on: https://gerrit.libreoffice.org/28526
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Tested-by: Ashod Nakashian <ashnakash@gmail.com>

loolwsd/ChildSession.cpp

@@ -119,12 +119,6 @@ bool ChildSession::_handleInput(const char *buffer, int length)
         // Just to update the activity of a view-only client.
         return true;
     }
-    else if (tokens[0] == "canceltiles")
-    {
-        // This command makes sense only on the command queue level.
-        // Shouldn't get this here.
-        return true;
-    }
     else if (tokens[0] == "commandvalues")
     {
         return getCommandValues(buffer, length, tokens);

loolwsd/ClientSession.cpp

@@ -147,10 +147,7 @@ bool ClientSession::_handleInput(const char *buffer, int length)
     }
     else if (tokens[0] == "canceltiles")
     {
-        if (!_peer.expired())
-        {
-            return forwardToPeer(_peer, buffer, length, false);
-        }
+        _docBroker->cancelTileRequests(shared_from_this());
     }
     else if (tokens[0] == "commandvalues")
     {

loolwsd/DocumentBroker.cpp

@@ -613,6 +613,13 @@ void DocumentBroker::handleTileCombinedRequest(TileCombined& tileCombined,
     }
 }
 
+void DocumentBroker::cancelTileRequests(const std::shared_ptr<ClientSession>& session)
+{
+    std::unique_lock<std::mutex> lock(_mutex);
+
+    tileCache().cancelTiles(session);
+}
+
 void DocumentBroker::handleTileResponse(const std::vector<char>& payload)
 {
     const std::string firstLine = getFirstLine(payload);

loolwsd/DocumentBroker.hpp

@@ -214,6 +214,8 @@ public:
     void handleTileCombinedRequest(TileCombined& tileCombined,
                                    const std::shared_ptr<ClientSession>& session);
 
+    void cancelTileRequests(const std::shared_ptr<ClientSession>& session);
+
     void handleTileResponse(const std::vector<char>& payload);
     void handleTileCombinedResponse(const std::vector<char>& payload);
 

loolwsd/TileCache.cpp

@@ -461,4 +461,26 @@ int TileCache::subscribeToTileRendering(const TileDesc& tile, const std::shared_
     }
 }
 
+void TileCache::cancelTiles(const std::shared_ptr<ClientSession> &subscriber)
+{
+    std::unique_lock<std::mutex> lock(_tilesBeingRenderedMutex);
+
+    const auto sub = subscriber.get();
+
+    Log::trace("Cancelling tiles for " + subscriber->getName());
+
+    for (auto it = _tilesBeingRendered.begin(); it != _tilesBeingRendered.end(); )
+    {
+        auto& subscribers = it->second->_subscribers;
+        Log::trace("Tile " + it->first + " has " + std::to_string(subscribers.size()) + " subscribers.");
+        subscribers.erase(std::remove_if(subscribers.begin(), subscribers.end(),
+                                         [sub](std::weak_ptr<ClientSession>& ptr){ return ptr.lock().get() == sub; }),
+                          subscribers.end());
+        Log::trace(" Tile " + it->first + " has " + std::to_string(subscribers.size()) + " subscribers.");
+
+        // Remove if there are no more subscribers on this tile.
+        it = (subscribers.empty() ? _tilesBeingRendered.erase(it) : ++it);
+    }
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

loolwsd/TileCache.hpp

@@ -42,6 +42,9 @@ public:
     /// Otherwise returns 0 to signify a subscription exists.
     int subscribeToTileRendering(const TileDesc& tile, const std::shared_ptr<ClientSession> &subscriber);
 
+    /// Cancels all tile requests by the given subscriber.
+    void cancelTiles(const std::shared_ptr<ClientSession> &subscriber);
+
     std::unique_ptr<std::fstream> lookupTile(const TileDesc& tile);
 
     void saveTileAndNotify(const TileDesc& tile, const char *data, const size_t size, const bool priority);

loolwsd/test/TileCacheTests.cpp

@@ -33,6 +33,7 @@ class TileCacheTests : public CPPUNIT_NS::TestFixture
     CPPUNIT_TEST(testSimple);
     CPPUNIT_TEST(testSimpleCombine);
     CPPUNIT_TEST(testPerformance);
+    CPPUNIT_TEST(testCancelTiles);
     CPPUNIT_TEST(testUnresponsiveClient);
     CPPUNIT_TEST(testClientPartImpress);
     CPPUNIT_TEST(testClientPartCalc);
@@ -48,6 +49,7 @@ class TileCacheTests : public CPPUNIT_NS::TestFixture
     void testSimple();
     void testSimpleCombine();
     void testPerformance();
+    void testCancelTiles();
     void testUnresponsiveClient();
     void testClientPartImpress();
     void testClientPartCalc();
@@ -208,6 +210,18 @@ void TileCacheTests::testPerformance()
     socket.shutdown();
 }
 
+void TileCacheTests::testCancelTiles()
+{
+    const auto testName = "cancelTiles ";
+    auto socket = *loadDocAndGetSocket("load12.ods", _uri, testName);
+
+    // Request a huge tile, and cancel immediately.
+    sendTextFrame(socket, "tilecombine part=0 width=2560 height=2560 tileposx=0 tileposy=0 tilewidth=38400 tileheight=38400");
+    sendTextFrame(socket, "canceltiles");
+
+    assertNotInResponse(socket, "tile:", testName);
+}
+
 void TileCacheTests::testUnresponsiveClient()
 {
     const std::string docFilename = "hello.odt";

loolwsd/test/helpers.hpp

@@ -330,6 +330,15 @@ std::string assertResponseLine(T& ws, const std::string& prefix, const std::stri
     return res;
 }
 
+/// Assert that we don't get a response with the given prefix.
+template <typename T>
+std::string assertNotInResponse(T& ws, const std::string& prefix, const std::string name = "")
+{
+    const auto res = getResponseLine(ws, prefix, name);
+    CPPUNIT_ASSERT_MESSAGE("Did not expect getting message [" + res + "].", res.empty());
+    return res;
+}
+
 inline
 void getResponseMessage(const std::shared_ptr<Poco::Net::WebSocket>& ws, const std::string& prefix, std::string& response, const bool isLine)
 {