FirebaseInstallations: API requests backoff (#6232)

* FirebaseInstallations: API requests backoff (#6207)

* FIRInstallationsBackoffController introduced

* FIRCurrentDateProvider introduced

* FIRInstallationsBackoffControllerTests

* style

* FIRInstallationsBackoffController implementation

* WIP: tests

* Response to backoff event mapping

* FIRInstallationsIDController: integration with FIRInstallationsBackoffController

* Remove not existing error code.

* FIRInstallationsIDController: integration with FIRInstallationsBackoffController

* FIRInstallationsIDController: depend on FIRInstallationsBackoffControllerProtocol

* FIRInstallationsIDControllerTests: supplement tests with backoff validation

* TODOs

* TODO

* API docs

* Header import fixed

* FIS backoff adjustments and tests (#6230)

* Maximum backoff interval 30 min

* Errors adjusted

* Tests updated

* Exclude 401 and 404 from backoff as autorecoverable

* comments

* FIS 1.6.0 changelog (#6234)

* Change log version fixed

Author: maksymmalyhin

FirebaseInstallations/CHANGELOG.md

@@ -1,5 +1,6 @@
-# v1.5.1 -- Unreleased
+# v1.7.0 -- Unreleased
 - [changed] Use ephemeral `NSURLSession` to prevent caching of request/response. (#6226)
+- [changed] Backoff added for some error to prevent unnecessary API requests. (#6232)
 
 # v1.5.0 -- M75
 - [changed] Functionally neutral source reorganization. (#5832)

FirebaseInstallations/Source/Library/Errors/FIRInstallationsErrorUtil.h

@@ -19,6 +19,7 @@
 #import "FirebaseInstallations/Source/Library/Public/FirebaseInstallations/FIRInstallationsErrors.h"
 
 @class FIRInstallationsHTTPError;
+@class FBLPromise<ResultType>;
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -45,12 +46,16 @@ void FIRInstallationsItemSetErrorToPointer(NSError *error, NSError **pointer);
                                                    data:(nullable NSData *)data;
 + (BOOL)isAPIError:(NSError *)error withHTTPCode:(NSInteger)HTTPCode;
 
++ (NSError *)backoffIntervalWaitError;
+
 /**
  * Returns the passed error if it is already in the public domain or a new error with the passed
  * error at `NSUnderlyingErrorKey`.
  */
 + (NSError *)publicDomainErrorWithError:(NSError *)error;
 
++ (FBLPromise *)rejectedPromiseWithError:(NSError *)error;
+
 @end
 
 NS_ASSUME_NONNULL_END

FirebaseInstallations/Source/Library/Errors/FIRInstallationsErrorUtil.m

@@ -18,6 +18,12 @@
 
 #import "FirebaseInstallations/Source/Library/Errors/FIRInstallationsHTTPError.h"
 
+#if __has_include(<FBLPromises/FBLPromises.h>)
+#import <FBLPromises/FBLPromises.h>
+#else
+#import "FBLPromises.h"
+#endif
+
 NSString *const kFirebaseInstallationsErrorDomain = @"com.firebase.installations";
 
 void FIRInstallationsItemSetErrorToPointer(NSError *error, NSError **pointer) {
@@ -101,6 +107,12 @@ + (NSError *)networkErrorWithError:(NSError *)error {
                           underlyingError:error];
 }
 
++ (NSError *)backoffIntervalWaitError {
+  return [self installationsErrorWithCode:FIRInstallationsErrorCodeServerUnreachable
+                            failureReason:@"Too many server requests."
+                          underlyingError:nil];
+}
+
 + (NSError *)publicDomainErrorWithError:(NSError *)error {
   if ([error.domain isEqualToString:kFirebaseInstallationsErrorDomain]) {
     return error;
@@ -121,4 +133,10 @@ + (NSError *)installationsErrorWithCode:(FIRInstallationsErrorCode)code
   return [NSError errorWithDomain:kFirebaseInstallationsErrorDomain code:code userInfo:userInfo];
 }
 
++ (FBLPromise *)rejectedPromiseWithError:(NSError *)error {
+  FBLPromise *rejectedPromise = [FBLPromise pendingPromise];
+  [rejectedPromise reject:error];
+  return rejectedPromise;
+}
+
 @end

FirebaseInstallations/Source/Library/Errors/FIRInstallationsHTTPError.h

@@ -41,7 +41,6 @@ typedef NS_ENUM(NSInteger, FIRInstallationsHTTPCodes) {
 typedef NS_ENUM(NSInteger, FIRInstallationsRegistrationHTTPCode) {
   FIRInstallationsRegistrationHTTPCodeSuccess = 201,
   FIRInstallationsRegistrationHTTPCodeInvalidArgument = 400,
-  FIRInstallationsRegistrationHTTPCodeInvalidAPIKey = 401,
   FIRInstallationsRegistrationHTTPCodeAPIKeyToProjectIDMismatch = 403,
   FIRInstallationsRegistrationHTTPCodeProjectNotFound = 404,
   FIRInstallationsRegistrationHTTPCodeTooManyRequests = 429,

FirebaseInstallations/Source/Library/InstallationsAPI/FIRInstallationsAPIService.m

@@ -26,6 +26,7 @@
 
 #import "FirebaseCore/Sources/Private/FirebaseCoreInternal.h"
 #import "FirebaseInstallations/Source/Library/Errors/FIRInstallationsErrorUtil.h"
+#import "FirebaseInstallations/Source/Library/Errors/FIRInstallationsHTTPError.h"
 #import "FirebaseInstallations/Source/Library/FIRInstallationsLogger.h"
 #import "FirebaseInstallations/Source/Library/InstallationsAPI/FIRInstallationsItem+RegisterInstallationAPI.h"
 
@@ -333,7 +334,8 @@ - (instancetype)initWithURLSession:(NSURLSession *)URLSession
   return [FBLPromise attempts:1
       delay:1
       condition:^BOOL(NSInteger remainingAttempts, NSError *_Nonnull error) {
-        return [FIRInstallationsErrorUtil isAPIError:error withHTTPCode:500];
+        return [FIRInstallationsErrorUtil isAPIError:error
+                                        withHTTPCode:FIRInstallationsHTTPCodesServerInternalError];
       }
       retry:^id _Nullable {
         return [self URLRequestPromise:request];

FirebaseInstallations/Source/Library/InstallationsIDController/FIRCurrentDateProvider.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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 <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/** A block returning current date. */
+typedef NSDate *_Nonnull (^FIRCurrentDateProvider)(void);
+
+/** The function returns a `FIRCurrentDateProvider` block that returns a real current date. */
+FIRCurrentDateProvider FIRRealCurrentDateProvider(void);
+
+NS_ASSUME_NONNULL_END

FirebaseInstallations/Source/Library/InstallationsIDController/FIRCurrentDateProvider.m

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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 "FirebaseInstallations/Source/Library/InstallationsIDController/FIRCurrentDateProvider.h"
+
+FIRCurrentDateProvider FIRRealCurrentDateProvider(void) {
+  return ^NSDate *(void) {
+    return [NSDate date];
+  };
+}

FirebaseInstallations/Source/Library/InstallationsIDController/FIRInstallationsBackoffController.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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 <Foundation/Foundation.h>
+
+#import "FirebaseInstallations/Source/Library/InstallationsIDController/FIRCurrentDateProvider.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+typedef NS_ENUM(NSInteger, FIRInstallationsBackoffEvent) {
+  FIRInstallationsBackoffEventSuccess,
+  FIRInstallationsBackoffEventRecoverableFailure,
+  FIRInstallationsBackoffEventUnrecoverableFailure
+};
+
+/** The protocol defines API for a class that encapsulates backoff logic that prevents the SDK from
+ * sending unnecessary server requests. See API docs for the methods for more details. */
+
+@protocol FIRInstallationsBackoffControllerProtocol <NSObject>
+
+/** The client must call the method each time a protected server request succeeds of fails. It will
+ * affect the `isNextRequestAllowed` method result for the current time, e.g. when 3 recoverable
+ * errors were logged in a row, then `isNextRequestAllowed` will return `YES` only in `pow(2, 3)`
+ * seconds. */
+- (void)registerEvent:(FIRInstallationsBackoffEvent)event;
+
+/** Returns if sending a next protected is recommended based on the time and the sequence of logged
+ * events and the current time. See also `registerEvent:`. */
+- (BOOL)isNextRequestAllowed;
+
+@end
+
+/** An implementation of `FIRInstallationsBackoffControllerProtocol` with exponential backoff for
+ * recoverable errors and constant backoff for recoverable errors. */
+@interface FIRInstallationsBackoffController : NSObject <FIRInstallationsBackoffControllerProtocol>
+
+- (instancetype)initWithCurrentDateProvider:(FIRCurrentDateProvider)currentDateProvider;
+
+@end
+
+NS_ASSUME_NONNULL_END

FirebaseInstallations/Source/Library/InstallationsIDController/FIRInstallationsBackoffController.m

@@ -0,0 +1,132 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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 "FirebaseInstallations/Source/Library/InstallationsIDController/FIRInstallationsBackoffController.h"
+
+static const NSTimeInterval k24Hours = 24 * 60 * 60;
+static const NSTimeInterval k30Minutes = 30 * 60;
+
+/** The class represents `FIRInstallationsBackoffController` sate required to calculate next allowed
+ request time. The properties of the class are intentionally immutable because changing them
+ separately leads to an inconsistent state. */
+@interface FIRInstallationsBackoffEventData : NSObject
+
+@property(nonatomic, readonly) FIRInstallationsBackoffEvent eventType;
+@property(nonatomic, readonly) NSDate *lastEventDate;
+@property(nonatomic, readonly) NSInteger eventCount;
+
+@property(nonatomic, readonly) NSTimeInterval backoffTimeInterval;
+
+@end
+
+@implementation FIRInstallationsBackoffEventData
+
+- (instancetype)initWithEvent:(FIRInstallationsBackoffEvent)eventType
+                lastEventDate:(NSDate *)lastEventDate
+                   eventCount:(NSInteger)eventCount {
+  self = [super init];
+  if (self) {
+    _eventType = eventType;
+    _lastEventDate = lastEventDate;
+    _eventCount = eventCount;
+
+    _backoffTimeInterval = [[self class] backoffTimeIntervalWithEvent:eventType
+                                                           eventCount:eventCount];
+  }
+  return self;
+}
+
++ (NSTimeInterval)backoffTimeIntervalWithEvent:(FIRInstallationsBackoffEvent)eventType
+                                    eventCount:(NSInteger)eventCount {
+  switch (eventType) {
+    case FIRInstallationsBackoffEventSuccess:
+      return 0;
+      break;
+
+    case FIRInstallationsBackoffEventRecoverableFailure:
+      return [self recoverableErrorBackoffTimeForAttemptNumber:eventCount];
+      break;
+
+    case FIRInstallationsBackoffEventUnrecoverableFailure:
+      return k24Hours;
+      break;
+  }
+}
+
++ (NSTimeInterval)recoverableErrorBackoffTimeForAttemptNumber:(NSInteger)attemptNumber {
+  NSTimeInterval exponentialInterval = pow(2, attemptNumber) + [self randomMilliseconds];
+  return MIN(exponentialInterval, k30Minutes);
+}
+
++ (NSTimeInterval)randomMilliseconds {
+  int32_t random_millis = ABS(arc4random() % 1000);
+  return (double)random_millis * 0.001;
+}
+
+@end
+
+@interface FIRInstallationsBackoffController ()
+
+@property(nonatomic, readonly) FIRCurrentDateProvider currentDateProvider;
+
+@property(nonatomic, nullable) FIRInstallationsBackoffEventData *lastEventData;
+
+@end
+
+@implementation FIRInstallationsBackoffController
+
+- (instancetype)init {
+  return [self initWithCurrentDateProvider:FIRRealCurrentDateProvider()];
+}
+
+- (instancetype)initWithCurrentDateProvider:(FIRCurrentDateProvider)currentDateProvider {
+  self = [super init];
+  if (self) {
+    _currentDateProvider = [currentDateProvider copy];
+  }
+  return self;
+}
+
+- (BOOL)isNextRequestAllowed {
+  @synchronized(self) {
+    if (self.lastEventData == nil) {
+      return YES;
+    }
+
+    NSTimeInterval timeSinceLastEvent =
+        [self.currentDateProvider() timeIntervalSinceDate:self.lastEventData.lastEventDate];
+    return timeSinceLastEvent >= self.lastEventData.backoffTimeInterval;
+  }
+}
+
+- (void)registerEvent:(FIRInstallationsBackoffEvent)event {
+  @synchronized(self) {
+    // Event of the same type as was registered before.
+    if (self.lastEventData && self.lastEventData.eventType == event) {
+      self.lastEventData = [[FIRInstallationsBackoffEventData alloc]
+          initWithEvent:event
+          lastEventDate:self.currentDateProvider()
+             eventCount:self.lastEventData.eventCount + 1];
+    } else {  // A different event.
+      self.lastEventData =
+          [[FIRInstallationsBackoffEventData alloc] initWithEvent:event
+                                                    lastEventDate:self.currentDateProvider()
+                                                       eventCount:1];
+    }
+  }
+}
+
+@end