[ios, osx] Unified offline and ambient caches

There is now only one instance of mbgl::OfflineFileSource, created when the shared MGLOfflineStorage object is initialized. Also create and use the shared MGLOfflineStorage object when initializing an MGLMapView object. The unified cache file is located in a subdirectory of Application Support, where the SDK has control over the file’s lifetime. The subdirectory is already named after the host application’s bundle identifier, ensuring that each Mapbox-powered application has an independent tile limit. If there’s an ambient cache in a subdirectory of Caches, delete it. If there’s an offline cache in a subdirectory of Documents on iOS or Caches on OS X, move it to the unified cache location in a subdirectory of Application Support.

Fixes the iOS/OS X side of #4338.

4 files changed, 64 insertions, 82 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 618f4d2615..9cd8ae1e20 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,9 +57,10 @@ Known issues:
 - Black Screen On Ice Cream Sandwich and Jelly Bean devices ([#2802](https://github.com/mapbox/mapbox-gl-native/issues/2802))
   - Resolved in 2.2.0
 
-## iOS master
+## iOS 3.2.0
 
 - Offline packs can now be downloaded to allow users to view specific regions of the map offline. A new MGLOfflineStorage class provides APIs for managing MGLOfflinePacks. ([#4221](https://github.com/mapbox/mapbox-gl-native/pull/4221))
+- Tiles and other resources are cached in the same file that holds offline resources. The combined cache file is located in a subdirectory of the user’s Application Support directory, which means iOS will not delete the file when disk space runs low. ([#4377](https://github.com/mapbox/mapbox-gl-native/pull/4377))
 - The user dot no longer disappears after panning the map across the antimeridian at low zoom levels. ([#4275](https://github.com/mapbox/mapbox-gl-native/pull/4275))
 - The map no longer recoils when panning quickly at low zoom levels. ([#4214](https://github.com/mapbox/mapbox-gl-native/pull/4214))
 - An icon laid out along a line no longer appears if it would extend past the end of the line. Some one-way arrows no longer point the wrong way. ([#3839](https://github.com/mapbox/mapbox-gl-native/pull/3839))
diff --git a/platform/darwin/src/MGLOfflineStorage.mm b/platform/darwin/src/MGLOfflineStorage.mm
index 3eac28ca78..1f925b3ee2 100644
--- a/platform/darwin/src/MGLOfflineStorage.mm
+++ b/platform/darwin/src/MGLOfflineStorage.mm
@@ -22,18 +22,20 @@
     static dispatch_once_t onceToken;
     static MGLOfflineStorage *sharedOfflineStorage;
     dispatch_once(&onceToken, ^{
-        sharedOfflineStorage = [[self alloc] initWithFileName:@"offline.db"];
+        sharedOfflineStorage = [[self alloc] initWithFileName:@"cache.db"];
     });
     return sharedOfflineStorage;
 }
 
+// This method can’t be called -init, because that selector has been marked
+// unavailable in MGLOfflineStorage.h.
 - (instancetype)initWithFileName:(NSString *)fileName {
     if (self = [super init]) {
-#if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
-        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
-        NSString *cachePath = [paths.firstObject stringByAppendingPathComponent:fileName];
-#elif TARGET_OS_MAC
-        NSURL *cacheDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSCachesDirectory
+        // Place the cache in a location specific to the application, so that
+        // packs downloaded by other applications don’t count toward this
+        // application’s limits.
+        // ~/Library/Application Support/tld.app.bundle.id/cache.db
+        NSURL *cacheDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSApplicationSupportDirectory
                                                                           inDomain:NSUserDomainMask
                                                                  appropriateForURL:nil
                                                                             create:YES
@@ -46,7 +48,34 @@
                                                        error:nil];
         NSURL *cacheURL = [cacheDirectoryURL URLByAppendingPathComponent:fileName];
         NSString *cachePath = cacheURL ? cacheURL.path : @"";
+        
+        // Move the offline cache from v3.2.0-beta.1 to a location that can also
+        // be used for ambient caching.
+        NSString *legacyCacheFileName = @"offline.db";
+#if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
+        // ~/Documents/offline.db
+        NSArray *legacyPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
+        NSString *legacyCachePath = [legacyPaths.firstObject stringByAppendingPathComponent:legacyCacheFileName];
+#elif TARGET_OS_MAC
+        // ~/Library/Caches/tld.app.bundle.id/offline.db
+        NSURL *legacyCacheDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSCachesDirectory
+                                                                                inDomain:NSUserDomainMask
+                                                                       appropriateForURL:nil
+                                                                                  create:YES
+                                                                                   error:nil];
+        legacyCacheDirectoryURL = [legacyCacheDirectoryURL URLByAppendingPathComponent:
+                                   [NSBundle mainBundle].bundleIdentifier];
+        [[NSFileManager defaultManager] createDirectoryAtURL:legacyCacheDirectoryURL
+                                 withIntermediateDirectories:YES
+                                                  attributes:nil
+                                                       error:nil];
+        NSURL *legacyCacheURL = [legacyCacheDirectoryURL URLByAppendingPathComponent:legacyCacheFileName];
+        NSString *legacyCachePath = legacyCacheURL ? legacyCacheURL.path : @"";
 #endif
+        if (![[NSFileManager defaultManager] fileExistsAtPath:cachePath]) {
+            [[NSFileManager defaultManager] moveItemAtPath:legacyCachePath toPath:cachePath error:NULL];
+        }
+        
         _mbglFileSource = new mbgl::DefaultFileSource(cachePath.UTF8String, [NSBundle mainBundle].resourceURL.path.UTF8String);
         
         // Observe for changes to the global access token (and find out the current one).
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 21d15ed1dd..2def0c54f0 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -30,6 +30,7 @@
 #import "Mapbox.h"
 #import "../../darwin/src/MGLGeometry_Private.h"
 #import "../../darwin/src/MGLMultiPoint_Private.h"
+#import "../../darwin/src/MGLOfflineStorage_Private.h"
 
 #import "NSBundle+MGLAdditions.h"
 #import "NSString+MGLAdditions.h"
@@ -37,7 +38,6 @@
 #import "NSException+MGLAdditions.h"
 #import "MGLUserLocationAnnotationView.h"
 #import "MGLUserLocation_Private.h"
-#import "MGLAccountManager_Private.h"
 #import "MGLAnnotationImage_Private.h"
 #import "MGLMapboxEvents.h"
 #import "MGLCompactCalloutView.h"
@@ -187,7 +187,6 @@ public:
 {
     mbgl::Map *_mbglMap;
     MBGLView *_mbglView;
-    mbgl::DefaultFileSource *_mbglFileSource;
     
     BOOL _opaque;
 
@@ -303,18 +302,15 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
     // setup mbgl view
     const float scaleFactor = [UIScreen instancesRespondToSelector:@selector(nativeScale)] ? [[UIScreen mainScreen] nativeScale] : [[UIScreen mainScreen] scale];
     _mbglView = new MBGLView(self, scaleFactor);
-
-    // setup mbgl cache & file source
-    NSString *fileCachePath = @"";
+    
+    // Delete the pre-offline ambient cache at ~/Library/Caches/cache.db.
     NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
-    if ([paths count] != 0) {
-        NSString *libraryDirectory = [paths objectAtIndex:0];
-        fileCachePath = [libraryDirectory stringByAppendingPathComponent:@"cache.db"];
-    }
-    _mbglFileSource = new mbgl::DefaultFileSource([fileCachePath UTF8String], [[[[NSBundle mainBundle] resourceURL] path] UTF8String]);
+    NSString *fileCachePath = [paths.firstObject stringByAppendingPathComponent:@"cache.db"];
+    [[NSFileManager defaultManager] removeItemAtPath:fileCachePath error:NULL];
 
     // setup mbgl map
-    _mbglMap = new mbgl::Map(*_mbglView, *_mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None);
+    mbgl::DefaultFileSource *mbglFileSource = [MGLOfflineStorage sharedOfflineStorage].mbglFileSource;
+    _mbglMap = new mbgl::Map(*_mbglView, *mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None);
 
     // start paused if in IB
     if (_isTargetingInterfaceBuilder || background) {
@@ -322,13 +318,6 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
         _mbglMap->pause();
     }
 
-    // Observe for changes to the global access token (and find out the current one).
-    [[MGLAccountManager sharedManager] addObserver:self
-                                        forKeyPath:@"accessToken"
-                                           options:(NSKeyValueObservingOptionInitial |
-                                                    NSKeyValueObservingOptionNew)
-                                           context:NULL];
-
     // Notify map object when network reachability status changes.
     [[NSNotificationCenter defaultCenter] addObserver:self
                                              selector:@selector(reachabilityChanged:)
@@ -506,7 +495,6 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
 - (void)dealloc
 {
     [[NSNotificationCenter defaultCenter] removeObserver:self];
-    [[MGLAccountManager sharedManager] removeObserver:self forKeyPath:@"accessToken"];
     [_attributionButton removeObserver:self forKeyPath:@"hidden"];
     
     [self validateDisplayLink];
@@ -517,12 +505,6 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
         _mbglMap = nullptr;
     }
 
-    if (_mbglFileSource)
-    {
-        delete _mbglFileSource;
-        _mbglFileSource = nullptr;
-    }
-
     if (_mbglView)
     {
         delete _mbglView;
@@ -1606,15 +1588,7 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
 
 - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(__unused void *)context
 {
-    // Synchronize mbgl::Map’s access token with the global one in MGLAccountManager.
-    if ([keyPath isEqualToString:@"accessToken"] && object == [MGLAccountManager sharedManager])
-    {
-        NSString *accessToken = change[NSKeyValueChangeNewKey];
-        if (![accessToken isKindOfClass:[NSNull class]]) {
-            _mbglFileSource->setAccessToken((std::string)[accessToken UTF8String]);
-        }
-    }
-    else if ([keyPath isEqualToString:@"hidden"] && object == _attributionButton)
+    if ([keyPath isEqualToString:@"hidden"] && object == _attributionButton)
     {
         NSNumber *hiddenNumber = change[NSKeyValueChangeNewKey];
         BOOL attributionButtonWasHidden = [hiddenNumber boolValue];
diff --git a/platform/osx/src/MGLMapView.mm b/platform/osx/src/MGLMapView.mm
index 07c080663f..e09a6c2672 100644
--- a/platform/osx/src/MGLMapView.mm
+++ b/platform/osx/src/MGLMapView.mm
@@ -4,10 +4,11 @@
 #import "MGLOpenGLLayer.h"
 #import "MGLStyle.h"
 
-#import "../../darwin/src/MGLAccountManager_Private.h"
 #import "../../darwin/src/MGLGeometry_Private.h"
 #import "../../darwin/src/MGLMultiPoint_Private.h"
+#import "../../darwin/src/MGLOfflineStorage_Private.h"
 
+#import "MGLAccountManager.h"
 #import "MGLMapCamera.h"
 #import "MGLPolygon.h"
 #import "MGLPolyline.h"
@@ -151,7 +152,6 @@ public:
     /// Cross-platform map view controller.
     mbgl::Map *_mbglMap;
     MGLMapViewImpl *_mbglView;
-    mbgl::DefaultFileSource *_mbglFileSource;
     
     NSPanGestureRecognizer *_panGestureRecognizer;
     NSMagnificationGestureRecognizer *_magnificationGestureRecognizer;
@@ -232,36 +232,25 @@ public:
     // Set up cross-platform controllers and resources.
     _mbglView = new MGLMapViewImpl(self, [NSScreen mainScreen].backingScaleFactor);
     
-    // Place the cache in a location that can be shared among all the
-    // applications that embed the Mapbox OS X SDK.
-    NSURL *cacheDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSCachesDirectory
-                                                                      inDomain:NSUserDomainMask
-                                                             appropriateForURL:nil
-                                                                        create:YES
-                                                                         error:nil];
-    cacheDirectoryURL = [cacheDirectoryURL URLByAppendingPathComponent:
-                         [[NSBundle mgl_frameworkBundle] bundleIdentifier]];
-    [[NSFileManager defaultManager] createDirectoryAtURL:cacheDirectoryURL
-                             withIntermediateDirectories:YES
-                                              attributes:nil
-                                                   error:nil];
-    NSURL *cacheURL = [cacheDirectoryURL URLByAppendingPathComponent:@"cache.db"];
-    NSString *cachePath = cacheURL ? cacheURL.path : @"";
-    _mbglFileSource = new mbgl::DefaultFileSource(cachePath.UTF8String, [[[[NSBundle mainBundle] resourceURL] path] UTF8String]);
-    
-    _mbglMap = new mbgl::Map(*_mbglView, *_mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None);
+    // Delete the pre-offline ambient cache at
+    // ~/Library/Caches/com.mapbox.sdk.ios/cache.db.
+    NSURL *cachesDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSCachesDirectory
+                                                                       inDomain:NSUserDomainMask
+                                                              appropriateForURL:nil
+                                                                         create:NO
+                                                                          error:nil];
+    cachesDirectoryURL = [cachesDirectoryURL URLByAppendingPathComponent:
+                          [NSBundle mgl_frameworkBundle].bundleIdentifier];
+    NSURL *legacyCacheURL = [cachesDirectoryURL URLByAppendingPathComponent:@"cache.db"];
+    [[NSFileManager defaultManager] removeItemAtURL:legacyCacheURL error:NULL];
+    
+    mbgl::DefaultFileSource *mbglFileSource = [MGLOfflineStorage sharedOfflineStorage].mbglFileSource;
+    _mbglMap = new mbgl::Map(*_mbglView, *mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None);
     
     // Install the OpenGL layer. Interface Builder’s synchronous drawing means
     // we can’t display a map, so don’t even bother to have a map layer.
     self.layer = _isTargetingInterfaceBuilder ? [CALayer layer] : [MGLOpenGLLayer layer];
     
-    // Observe for changes to the global access token (and find out the current one).
-    [[MGLAccountManager sharedManager] addObserver:self
-                                        forKeyPath:@"accessToken"
-                                           options:(NSKeyValueObservingOptionInitial |
-                                                    NSKeyValueObservingOptionNew)
-                                           context:NULL];
-    
     // Notify map object when network reachability status changes.
     MGLReachability *reachability = [MGLReachability reachabilityForInternetConnection];
     reachability.reachableBlock = ^(MGLReachability *) {
@@ -443,7 +432,6 @@ public:
 }
 
 - (void)dealloc {
-    [[MGLAccountManager sharedManager] removeObserver:self forKeyPath:@"accessToken"];
     [self.window removeObserver:self forKeyPath:@"contentLayoutRect"];
     [self.window removeObserver:self forKeyPath:@"titlebarAppearsTransparent"];
     
@@ -455,25 +443,15 @@ public:
         delete _mbglMap;
         _mbglMap = nullptr;
     }
-    if (_mbglFileSource) {
-        delete _mbglFileSource;
-        _mbglFileSource = nullptr;
-    }
     if (_mbglView) {
         delete _mbglView;
         _mbglView = nullptr;
     }
 }
 
-- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(__unused void *)context {
-    // Synchronize mbgl::Map’s access token with the global one in MGLAccountManager.
-    if ([keyPath isEqualToString:@"accessToken"] && object == [MGLAccountManager sharedManager]) {
-        NSString *accessToken = change[NSKeyValueChangeNewKey];
-        if (![accessToken isKindOfClass:[NSNull class]]) {
-            _mbglFileSource->setAccessToken((std::string)accessToken.UTF8String);
-        }
-    } else if ([keyPath isEqualToString:@"contentLayoutRect"] ||
-               [keyPath isEqualToString:@"titlebarAppearsTransparent"]) {
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(__unused id)object change:(__unused NSDictionary *)change context:(__unused void *)context {
+    if ([keyPath isEqualToString:@"contentLayoutRect"] ||
+        [keyPath isEqualToString:@"titlebarAppearsTransparent"]) {
         [self adjustContentInsets];
     }
 }