1 files changed, 58 insertions, 0 deletions
diff --git a/Firebase/Database/FClock.m b/Firebase/Database/FClock.m
new file mode 100644
index 0000000..2464056
--- /dev/null
+++ b/Firebase/Database/FClock.m
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2017 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import "FClock.h"
+
+@implementation FSystemClock
+
+- (NSTimeInterval)currentTime {
+    return [[NSDate date] timeIntervalSince1970];
+}
+
++ (FSystemClock *)clock {
+    static dispatch_once_t onceToken;
+    static FSystemClock *clock;
+    dispatch_once(&onceToken, ^{
+        clock = [[FSystemClock alloc] init];
+    });
+    return clock;
+}
+
+@end
+
+@interface FOffsetClock ()
+
+@property (nonatomic, strong) id<FClock> clock;
+@property (nonatomic) NSTimeInterval offset;
+
+@end
+
+@implementation FOffsetClock
+
+- (NSTimeInterval)currentTime {
+    return [self.clock currentTime] + self.offset;
+}
+
+- (id)initWithClock:(id<FClock>)clock offset:(NSTimeInterval)offset {
+    self = [super init];
+    if (self != nil) {
+        self->_clock = clock;
+        self->_offset = offset;
+    }
+    return self;
+}
+
+@end