Improved AsyncLocalStorage performance

Reviewed By: javache

Differential Revision: D2540626

fb-gh-sync-id: f94def7463075d40c2dcfea1cb4c01502aefa117

React/Modules/RCTAsyncLocalStorage.m

@@ -19,7 +19,7 @@
 
 static NSString *const RCTStorageDirectory = @"RCTAsyncLocalStorage_V1";
 static NSString *const RCTManifestFileName = @"manifest.json";
-static const NSUInteger RCTInlineValueThreshold = 100;
+static const NSUInteger RCTInlineValueThreshold = 1024;
 
 #pragma mark - Static helper functions
 
@@ -83,31 +83,32 @@ static NSString *RCTGetManifestFilePath()
 }
 
 // Only merges objects - all other types are just clobbered (including arrays)
-static void RCTMergeRecursive(NSMutableDictionary *destination, NSDictionary *source)
+// returns YES if destination was modified, or NO if no changes were needed.
+static BOOL RCTMergeRecursive(NSMutableDictionary *destination, NSDictionary *source)
 {
+  BOOL modified = NO;
   for (NSString *key in source) {
     id sourceValue = source[key];
-    if ([sourceValue isKindOfClass:[NSDictionary class]]) {
     id destinationValue = destination[key];
-      NSMutableDictionary *nestedDestination;
+    if ([sourceValue isKindOfClass:[NSDictionary class]]) {
-      if ([destinationValue classForCoder] == [NSMutableDictionary class]) {
-        nestedDestination = destinationValue;
-      } else {
       if ([destinationValue isKindOfClass:[NSDictionary class]]) {
-          // Ideally we wouldn't eagerly copy here...
+        if ([destinationValue classForCoder] != [NSMutableDictionary class]) {
-          nestedDestination = [destinationValue mutableCopy];
+          destinationValue = [destinationValue mutableCopy];
+        }
+        if (RCTMergeRecursive(destinationValue, sourceValue)) {
+          destination[key] = destinationValue;
+          modified = YES;
+        }
       } else {
         destination[key] = [sourceValue copy];
+        modified = YES;
+      }
+    } else if (![source isEqual:destinationValue]) {
+      destination[key] = [sourceValue copy];
+      modified = YES;
     }
   }
-      if (nestedDestination) {
+  return modified;
-        RCTMergeRecursive(nestedDestination, sourceValue);
-        destination[key] = nestedDestination;
-      }
-    } else {
-      destination[key] = sourceValue;
-    }
-  }
 }
 
 static dispatch_queue_t RCTGetMethodQueue()
@@ -121,6 +122,23 @@ static dispatch_queue_t RCTGetMethodQueue()
   return queue;
 }
 
+static NSCache *RCTGetCache()
+{
+  // We want all instances to share the same cache since they will be reading/writing the same files.
+  static NSCache *cache;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    cache = [NSCache new];
+    cache.totalCostLimit = 2 * 1024 * 1024; // 2MB
+
+    // Clear cache in the event of a memory warning
+    [[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationDidReceiveMemoryWarningNotification object:nil queue:nil usingBlock:^(__unused NSNotification *note) {
+      [cache removeAllObjects];
+    }];
+  });
+  return cache;
+}
+
 static BOOL RCTHasCreatedStorageDirectory = NO;
 static NSError *RCTDeleteStorageDirectory()
 {
@@ -150,6 +168,7 @@ RCT_EXPORT_MODULE()
 
 + (void)clearAllData
 {
+  [RCTGetCache() removeAllObjects];
   dispatch_async(RCTGetMethodQueue(), ^{
     RCTDeleteStorageDirectory();
   });
@@ -158,6 +177,7 @@ RCT_EXPORT_MODULE()
 - (void)invalidate
 {
   if (_clearOnInvalidate) {
+    [RCTGetCache() removeAllObjects];
     RCTDeleteStorageDirectory();
   }
   _clearOnInvalidate = NO;
@@ -199,7 +219,7 @@ RCT_EXPORT_MODULE()
   if (!_haveSetup) {
     NSDictionary *errorOut;
     NSString *serialized = RCTReadFile(RCTGetManifestFilePath(), nil, &errorOut);
-    _manifest = serialized ? [RCTJSONParse(serialized, &error) mutableCopy] : [NSMutableDictionary new];
+    _manifest = serialized ? RCTJSONParseMutable(serialized, &error) : [NSMutableDictionary new];
     if (error) {
       RCTLogWarn(@"Failed to parse manifest - creating new one.\n\n%@", error);
       _manifest = [NSMutableDictionary new];
@@ -222,23 +242,16 @@ RCT_EXPORT_MODULE()
   return errorOut;
 }
 
-- (id)_appendItemForKey:(NSString *)key toArray:(NSMutableArray *)result
-{
-  id errorOut = RCTErrorForKey(key);
-  if (errorOut) {
-    return errorOut;
-  }
-  id value = [self _getValueForKey:key errorOut:&errorOut];
-  [result addObject:@[key, RCTNullIfNil(value)]]; // Insert null if missing or failure.
-  return errorOut;
-}
-
 - (NSString *)_getValueForKey:(NSString *)key errorOut:(NSDictionary **)errorOut
 {
-  id value = _manifest[key]; // nil means missing, null means there is a data file, anything else is an inline value.
+  NSString *value = _manifest[key]; // nil means missing, null means there is a data file, anything else is an inline value.
   if (value == (id)kCFNull) {
+    value = [RCTGetCache() objectForKey:key];
+    if (!value) {
       NSString *filePath = [self _filePathForKey:key];
       value = RCTReadFile(filePath, key, errorOut);
+      [RCTGetCache() setObject:value forKey:key cost:value.length];
+    }
   }
   return value;
 }
@@ -263,11 +276,13 @@ RCT_EXPORT_MODULE()
     if (_manifest[key] && _manifest[key] != (id)kCFNull) {
       // If the value already existed but wasn't inlined, remove the old file.
       [[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
+      [RCTGetCache() removeObjectForKey:key];
     }
     _manifest[key] = value;
     return nil;
   }
   [value writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
+  [RCTGetCache() setObject:value forKey:key cost:value.length];
   if (error) {
     errorOut = RCTMakeError(@"Failed to write value.", error, @{@"key": key});
   } else {
@@ -294,7 +309,9 @@ RCT_EXPORT_METHOD(multiGet:(NSArray *)keys
   NSMutableArray *errors;
   NSMutableArray *result = [[NSMutableArray alloc] initWithCapacity:keys.count];
   for (NSString *key in keys) {
-    id keyError = [self _appendItemForKey:key toArray:result];
+    id keyError;
+    id value = [self _getValueForKey:key errorOut:&keyError];
+    [result addObject:@[key, RCTNullIfNil(value)]];
     RCTAppendError(keyError, &errors);
   }
   callback(@[RCTNullIfNil(errors), result]);
@@ -331,20 +348,19 @@ RCT_EXPORT_METHOD(multiMerge:(NSArray *)kvPairs
   for (__strong NSArray *entry in kvPairs) {
     id keyError;
     NSString *value = [self _getValueForKey:entry[0] errorOut:&keyError];
-    if (keyError) {
-      RCTAppendError(keyError, &errors);
-    } else {
-      if (value) {
-        NSMutableDictionary *mergedVal = [RCTJSONParseMutable(value, &keyError) mutableCopy];
-        RCTMergeRecursive(mergedVal, RCTJSONParse(entry[1], &keyError));
-        entry = @[entry[0], RCTJSONStringify(mergedVal, &keyError)];
-      }
     if (!keyError) {
+      if (value) {
+        NSMutableDictionary *mergedVal = RCTJSONParseMutable(value, &keyError);
+        if (RCTMergeRecursive(mergedVal, RCTJSONParse(entry[1], &keyError))) {
+          entry = @[entry[0], RCTJSONStringify(mergedVal, &keyError)];
           keyError = [self _writeEntry:entry];
         }
-      RCTAppendError(keyError, &errors);
+      } else {
+        keyError = [self _writeEntry:entry];
       }
     }
+    RCTAppendError(keyError, &errors);
+  }
   [self _writeManifest:&errors];
   if (callback) {
     callback(@[RCTNullIfNil(errors)]);
@@ -363,8 +379,10 @@ RCT_EXPORT_METHOD(multiRemove:(NSArray *)keys
   for (NSString *key in keys) {
     id keyError = RCTErrorForKey(key);
     if (!keyError) {
+      if ( _manifest[key] == (id)kCFNull) {
         NSString *filePath = [self _filePathForKey:key];
         [[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
+      }
       [_manifest removeObjectForKey:key];
     }
     RCTAppendError(keyError, &errors);
@@ -377,7 +395,8 @@ RCT_EXPORT_METHOD(multiRemove:(NSArray *)keys
 
 RCT_EXPORT_METHOD(clear:(RCTResponseSenderBlock)callback)
 {
-  _manifest = [NSMutableDictionary new];
+  [_manifest removeAllObjects];
+  [RCTGetCache() removeAllObjects];
   NSError *error = RCTDeleteStorageDirectory();
   if (callback) {
     callback(@[RCTNullIfNil(error)]);