Implement efficient DiskCache.clear()

Summary: public

Ability to efficiently remove all keys with a particular prefix

Reviewed By: tadeuzagallo

Differential Revision: D2658741

fb-gh-sync-id: 3770f061c83288efe645162ae84a9fd9194d2fd6

Libraries/Storage/AsyncStorage.js

@@ -137,6 +137,26 @@ var AsyncStorage = {
     });
   },
 
+  /**
+   * Erases all keys with a particular prefix. Useful if all your keys have a
+   * specific prefix.
+   */
+  clearPrefix: function(
+    prefix: string,
+    callback?: ?(error: ?Error) => void
+  ): Promise {
+    return new Promise((resolve, reject) => {
+      RCTAsyncStorage.clearPrefix(prefix, function(error) {
+        callback && callback(convertError(error));
+        if (error && convertError(error)){
+          reject(convertError(error));
+        } else {
+          resolve(null);
+        }
+      });
+    });
+  },
+
   /**
    * Gets *all* keys known to the app, for all callers, libraries, etc. Returns a `Promise` object.
    */
@@ -259,6 +279,11 @@ if (!RCTAsyncStorage.multiMerge) {
   delete AsyncStorage.multiMerge;
 }
 
+// clearPrefix() only supported by certain backends
+if (!RCTAsyncStorage.clearPrefix) {
+  delete AsyncStorage.clearPrefix;
+}
+
 function convertErrors(errs) {
   if (!errs) {
     return null;

React/Modules/RCTAsyncLocalStorage.m

@@ -435,6 +435,24 @@ RCT_EXPORT_METHOD(clear:(RCTResponseSenderBlock)callback)
   callback(@[RCTNullIfNil(error)]);
 }
 
+RCT_EXPORT_METHOD(clearPrefix:(NSString *)prefix callack:(RCTResponseSenderBlock)callback)
+{
+  NSDictionary *errorOut = [self _ensureSetup];
+  if (errorOut) {
+    callback(@[errorOut]);
+    return;
+  }
+
+  NSMutableArray<NSString *> *keys = [NSMutableArray array];
+  for (NSString *key in _manifest.allKeys) {
+    if ([key hasPrefix:prefix]) {
+      [keys addObject:key];
+    }
+  }
+
+  [self multiRemove:keys callback:callback];
+}
+
 RCT_EXPORT_METHOD(getAllKeys:(RCTResponseSenderBlock)callback)
 {
   NSDictionary *errorOut = [self _ensureSetup];