fixes #1157, #1255: cache parsed tiles in memory

9 files changed, 191 insertions, 7 deletions

diff --git a/include/mbgl/ios/MGLMapView.h b/include/mbgl/ios/MGLMapView.h
index f2aef61830..8717b5e8a1 100644
--- a/include/mbgl/ios/MGLMapView.h
+++ b/include/mbgl/ios/MGLMapView.h
@@ -279,6 +279,9 @@ IB_DESIGNABLE
 /** Toggle the current value of debugActive. */
 - (void)toggleDebug;
 
+/** Empties the in-memory tile cache. */
+- (void)emptyMemoryCache;
+
 /** Resets the map to the minimum zoom level, a center coordinate of (0, 0), and a northern heading. */
 - (void)resetPosition;
 
diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index 38a37a8057..8c7f5f3961 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -152,6 +152,11 @@ public:
     std::vector<uint32_t> getAnnotationsInBounds(const LatLngBounds&);
     LatLngBounds getBoundsForAnnotations(const std::vector<uint32_t>&);
 
+    // Memory
+    void setSourceTileCacheSize(size_t);
+    size_t getSourceTileCacheSize() const { return sourceCacheSize; }
+    void onLowMemory();
+
     // Debug
     void setDebug(bool value);
     void toggleDebug();
@@ -196,6 +201,8 @@ private:
 
     void updateAnnotationTiles(const std::vector<TileID>&);
 
+    size_t sourceCacheSize;
+
     enum class Mode : uint8_t {
         None, // we're not doing any processing
         Continuous, // continually updating map
diff --git a/ios/app/MBXViewController.mm b/ios/app/MBXViewController.mm
index 078d67d398..13235beb07 100644
--- a/ios/app/MBXViewController.mm
+++ b/ios/app/MBXViewController.mm
@@ -145,6 +145,7 @@ mbgl::Settings_NSUserDefaults *settings = nullptr;
                                               otherButtonTitles:@"Reset North",
                                                                 @"Reset Position",
                                                                 @"Toggle Debug",
+                                                                @"Empty Memory",
                                                                 @"Add 100 Points",
                                                                 @"Add 1,000 Points",
                                                                 @"Add 10,000 Points",
@@ -170,18 +171,22 @@ mbgl::Settings_NSUserDefaults *settings = nullptr;
     }
     else if (buttonIndex == actionSheet.firstOtherButtonIndex + 3)
     {
-        [self parseFeaturesAddingCount:100];
+        [self.mapView emptyMemoryCache];
     }
     else if (buttonIndex == actionSheet.firstOtherButtonIndex + 4)
     {
-        [self parseFeaturesAddingCount:1000];
+        [self parseFeaturesAddingCount:100];
     }
     else if (buttonIndex == actionSheet.firstOtherButtonIndex + 5)
     {
-        [self parseFeaturesAddingCount:10000];
+        [self parseFeaturesAddingCount:1000];
     }
     else if (buttonIndex == actionSheet.firstOtherButtonIndex + 6)
     {
+        [self parseFeaturesAddingCount:10000];
+    }
+    else if (buttonIndex == actionSheet.firstOtherButtonIndex + 7)
+    {
         [self.mapView removeAnnotations:self.mapView.annotations];
     }
 }
diff --git a/platform/ios/MGLMapView.mm b/platform/ios/MGLMapView.mm
index 0395114825..8721b2a4d6 100644
--- a/platform/ios/MGLMapView.mm
+++ b/platform/ios/MGLMapView.mm
@@ -367,6 +367,7 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     //
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appDidBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appWillForeground:) name:UIApplicationWillEnterForegroundNotification object:nil];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didReceiveMemoryWarning) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
 
     // set initial position
     //
@@ -574,6 +575,17 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     else
     {
         mbglView->resize(rect.size.width, rect.size.height, view.contentScaleFactor, view.drawableWidth, view.drawableHeight);
+
+        CGFloat zoomFactor   = mbglMap->getMaxZoom() - mbglMap->getMinZoom() + 1;
+        CGFloat cpuFactor    = (CGFloat)[[NSProcessInfo processInfo] processorCount];
+        CGFloat memoryFactor = (CGFloat)[[NSProcessInfo processInfo] physicalMemory] / 1000 / 1000 / 1000;
+        CGFloat sizeFactor   = ((CGFloat)mbglMap->getState().getWidth()  / mbgl::util::tileSize) *
+                               ((CGFloat)mbglMap->getState().getHeight() / mbgl::util::tileSize);
+
+        NSUInteger cacheSize = zoomFactor * cpuFactor * memoryFactor * sizeFactor * 0.5;
+
+        mbglMap->setSourceTileCacheSize(cacheSize);
+
         mbglMap->renderSync();
     }
 }
@@ -1166,6 +1178,11 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     mbglMap->toggleDebug();
 }
 
+- (void)emptyMemoryCache
+{
+    mbglMap->onLowMemory();
+}
+
 #pragma mark - Geography -
 
 + (NSSet *)keyPathsForValuesAffectingCenterCoordinate
@@ -2450,7 +2467,8 @@ class MBGLView : public mbgl::View
         [EAGLContext setCurrentContext:nil];
     }
 
-    void resize(uint16_t width, uint16_t height, float ratio, uint16_t fbWidth, uint16_t fbHeight) {
+    void resize(uint16_t width, uint16_t height, float ratio, uint16_t fbWidth, uint16_t fbHeight)
+    {
         View::resize(width, height, ratio, fbWidth, fbHeight);
     }
 
@@ -2566,4 +2584,9 @@ class MBGLView : public mbgl::View
     self.rotateEnabled = allowsRotating;
 }
 
+- (void)didReceiveMemoryWarning
+{
+    mbglMap->onLowMemory();
+}
+
 @end
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index f76845e3a7..adaf22d60f 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -818,3 +818,26 @@ void Map::render() {
         triggerUpdate();
     }
 }
+
+void Map::setSourceTileCacheSize(size_t size) {
+    if (size != getSourceTileCacheSize()) {
+        invokeTask([=] {
+            sourceCacheSize = size;
+            if (!style) return;
+            for (const auto &source : style->sources) {
+                source->setCacheSize(sourceCacheSize);
+            }
+            env->performCleanup();
+        });
+    }
+}
+
+void Map::onLowMemory() {
+    invokeTask([=] {
+        if (!style) return;
+        for (const auto &source : style->sources) {
+            source->onLowMemory();
+        }
+        env->performCleanup();
+    });
+};
diff --git a/src/mbgl/map/source.cpp b/src/mbgl/map/source.cpp
index 29f84171d1..3245bab2e3 100644
--- a/src/mbgl/map/source.cpp
+++ b/src/mbgl/map/source.cpp
@@ -245,6 +245,10 @@ TileData::State Source::addTile(Map &map, Worker &worker,
     }
 
     if (!new_tile.data) {
+        new_tile.data = cache.get(id.to_uint64());
+    }
+
+    if (!new_tile.data) {
         // If we don't find working tile data, we're just going to load it.
         if (info.type == SourceType::Vector) {
             new_tile.data =
@@ -394,20 +398,33 @@ void Source::update(Map &map,
         }
     }
 
+    if (info.type != SourceType::Raster && cache.getSize() == 0) {
+        size_t conservativeCacheSize = ((float)map.getState().getWidth()  / util::tileSize) *
+                                       ((float)map.getState().getHeight() / util::tileSize) *
+                                       (map.getMaxZoom() - map.getMinZoom() + 1) *
+                                       0.5;
+        cache.setSize(conservativeCacheSize);
+    }
+
+    auto& tileCache = cache;
+    auto& type = info.type;
+
     // Remove tiles that we definitely don't need, i.e. tiles that are not on
     // the required list.
     std::set<TileID> retain_data;
-    util::erase_if(tiles, [&retain, &retain_data](std::pair<const TileID, std::unique_ptr<Tile>> &pair) {
+    util::erase_if(tiles, [&retain, &retain_data, &tileCache, &type](std::pair<const TileID, std::unique_ptr<Tile>> &pair) {
         Tile &tile = *pair.second;
         bool obsolete = std::find(retain.begin(), retain.end(), tile.id) == retain.end();
         if (!obsolete) {
             retain_data.insert(tile.data->id);
+        } else if (type != SourceType::Raster && tile.data->ready()) {
+            tileCache.add(tile.id.to_uint64(), tile.data);
         }
         return obsolete;
     });
 
     // Remove all the expired pointers from the set.
-    util::erase_if(tile_data, [&retain_data](std::pair<const TileID, std::weak_ptr<TileData>> &pair) {
+    util::erase_if(tile_data, [&retain_data, &tileCache](std::pair<const TileID, std::weak_ptr<TileData>> &pair) {
         const util::ptr<TileData> tile = pair.second.lock();
         if (!tile) {
             return true;
@@ -415,7 +432,9 @@ void Source::update(Map &map,
 
         bool obsolete = retain_data.find(tile->id) == retain_data.end();
         if (obsolete) {
-            tile->cancel();
+            if (!tileCache.has(tile->id.to_uint64())) {
+                tile->cancel();
+            }
             return true;
         } else {
             return false;
@@ -426,10 +445,19 @@ void Source::update(Map &map,
 }
 
 void Source::invalidateTiles(const std::vector<TileID>& ids) {
+    cache.clear();
     for (auto& id : ids) {
         tiles.erase(id);
         tile_data.erase(id);
     }
 }
 
+void Source::setCacheSize(size_t size) {
+    cache.setSize(size);
+}
+
+void Source::onLowMemory() {
+    cache.clear();
+}
+
 }
diff --git a/src/mbgl/map/source.hpp b/src/mbgl/map/source.hpp
index 625647ac5e..035e862284 100644
--- a/src/mbgl/map/source.hpp
+++ b/src/mbgl/map/source.hpp
@@ -3,6 +3,7 @@
 
 #include <mbgl/map/tile_id.hpp>
 #include <mbgl/map/tile_data.hpp>
+#include <mbgl/map/tile_cache.hpp>
 #include <mbgl/style/types.hpp>
 
 #include <mbgl/util/noncopyable.hpp>
@@ -72,6 +73,9 @@ public:
 
     std::forward_list<Tile *> getLoadedTiles() const;
 
+    void setCacheSize(size_t);
+    void onLowMemory();
+
     SourceInfo info;
     bool enabled;
 
@@ -96,6 +100,7 @@ private:
 
     std::map<TileID, std::unique_ptr<Tile>> tiles;
     std::map<TileID, std::weak_ptr<TileData>> tile_data;
+    TileCache cache;
 };
 
 }
diff --git a/src/mbgl/map/tile_cache.cpp b/src/mbgl/map/tile_cache.cpp
new file mode 100644
index 0000000000..71eb500be6
--- /dev/null
+++ b/src/mbgl/map/tile_cache.cpp
@@ -0,0 +1,60 @@
+#include <mbgl/map/tile_cache.hpp>
+
+#include <cassert>
+
+namespace mbgl {
+
+void TileCache::setSize(size_t size_) {
+    size = size_;
+
+    while (orderedKeys.size() > size) {
+        auto key = orderedKeys.front();
+        orderedKeys.pop_front();
+        tiles.erase(key);
+    }
+
+    assert(orderedKeys.size() <= size);
+
+    tiles.reserve(size);
+    orderedKeys.resize(size);
+}
+
+void TileCache::add(uint64_t key, std::shared_ptr<TileData> data) {
+
+    assert(tiles.find(key) == tiles.end());
+
+    tiles.emplace(key, data);
+    orderedKeys.push_back(key);
+
+    if (orderedKeys.size() > size) {
+        get(orderedKeys.front());
+    }
+
+    assert(orderedKeys.size() <= size);
+};
+
+std::shared_ptr<TileData> TileCache::get(uint64_t key) {
+
+    std::shared_ptr<TileData> data;
+
+    auto it = tiles.find(key);
+    if (it != tiles.end()) {
+        data = it->second;
+        tiles.erase(it);
+        orderedKeys.remove(key);
+        assert(data->ready());
+    }
+
+    return data;
+};
+
+bool TileCache::has(uint64_t key) {
+    return tiles.find(key) != tiles.end();
+}
+
+void TileCache::clear() {
+    orderedKeys.clear();
+    tiles.clear();
+}
+
+};
diff --git a/src/mbgl/map/tile_cache.hpp b/src/mbgl/map/tile_cache.hpp
new file mode 100644
index 0000000000..26d830c123
--- /dev/null
+++ b/src/mbgl/map/tile_cache.hpp
@@ -0,0 +1,30 @@
+#ifndef MBGL_MAP_TILE_CACHE
+#define MBGL_MAP_TILE_CACHE
+
+#include <mbgl/map/tile_data.hpp>
+
+#include <list>
+#include <unordered_map>
+
+namespace mbgl {
+
+class TileCache {
+public:
+    TileCache(size_t size_ = 0) : size(size_) {}
+
+    void setSize(size_t);
+    size_t getSize() const { return size; };
+    void add(uint64_t key, std::shared_ptr<TileData> data);
+    std::shared_ptr<TileData> get(uint64_t key);
+    bool has(uint64_t key);
+    void clear();
+private:
+    std::unordered_map<uint64_t, std::shared_ptr<TileData>> tiles;
+    std::list<uint64_t> orderedKeys;
+
+    size_t size;
+};
+
+};
+
+#endif