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diff --git a/Firestore/Source/Remote/FSTExponentialBackoff.m b/Firestore/Source/Remote/FSTExponentialBackoff.m
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+++ b/Firestore/Source/Remote/FSTExponentialBackoff.m
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+/*
+ * 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 "FSTExponentialBackoff.h"
+
+#import "FSTDispatchQueue.h"
+#import "FSTLogger.h"
+#import "FSTUtil.h"
+
+@interface FSTExponentialBackoff ()
+- (instancetype)initWithDispatchQueue:(FSTDispatchQueue *)dispatchQueue
+                         initialDelay:(NSTimeInterval)initialDelay
+                        backoffFactor:(double)backoffFactor
+                             maxDelay:(NSTimeInterval)maxDelay NS_DESIGNATED_INITIALIZER;
+
+@property(nonatomic, strong) FSTDispatchQueue *dispatchQueue;
+@property(nonatomic) double backoffFactor;
+@property(nonatomic) NSTimeInterval initialDelay;
+@property(nonatomic) NSTimeInterval maxDelay;
+@property(nonatomic) NSTimeInterval currentBase;
+@end
+
+@implementation FSTExponentialBackoff
+
+- (instancetype)initWithDispatchQueue:(FSTDispatchQueue *)dispatchQueue
+                         initialDelay:(NSTimeInterval)initialDelay
+                        backoffFactor:(double)backoffFactor
+                             maxDelay:(NSTimeInterval)maxDelay {
+  if (self = [super init]) {
+    _dispatchQueue = dispatchQueue;
+    _initialDelay = initialDelay;
+    _backoffFactor = backoffFactor;
+    _maxDelay = maxDelay;
+
+    [self reset];
+  }
+  return self;
+}
+
++ (instancetype)exponentialBackoffWithDispatchQueue:(FSTDispatchQueue *)dispatchQueue
+                                       initialDelay:(NSTimeInterval)initialDelay
+                                      backoffFactor:(double)backoffFactor
+                                           maxDelay:(NSTimeInterval)maxDelay {
+  return [[FSTExponentialBackoff alloc] initWithDispatchQueue:dispatchQueue
+                                                 initialDelay:initialDelay
+                                                backoffFactor:backoffFactor
+                                                     maxDelay:maxDelay];
+}
+
+- (void)reset {
+  _currentBase = 0;
+}
+
+- (void)resetToMax {
+  _currentBase = _maxDelay;
+}
+
+- (void)backoffAndRunBlock:(void (^)())block {
+  // First schedule the block using the current base (which may be 0 and should be honored as such).
+  NSTimeInterval delayWithJitter = _currentBase + [self jitterDelay];
+  if (_currentBase > 0) {
+    FSTLog(@"Backing off for %.2f seconds (base delay: %.2f seconds)", delayWithJitter,
+           _currentBase);
+  }
+  dispatch_time_t delay =
+      dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayWithJitter * NSEC_PER_SEC));
+  dispatch_after(delay, self.dispatchQueue.queue, block);
+
+  // Apply backoff factor to determine next delay and ensure it is within bounds.
+  _currentBase *= _backoffFactor;
+  if (_currentBase < _initialDelay) {
+    _currentBase = _initialDelay;
+  }
+  if (_currentBase > _maxDelay) {
+    _currentBase = _maxDelay;
+  }
+}
+
+/** Returns a random value in the range [-currentBase/2, currentBase/2] */
+- (NSTimeInterval)jitterDelay {
+  return ([FSTUtil randomDouble] - 0.5) * _currentBase;
+}
+
+@end