port TargetIdGenerator to iOS (#709)

* port TargetIdGenerator to iOS

* fix style

* move pointer property to instance variable

* TriggerTravis

3 files changed, 9 insertions, 167 deletions

diff --git a/Firestore/Source/Core/FSTSyncEngine.m b/Firestore/Source/Core/FSTSyncEngine.mm
index f90c5dd..d82cc99 100644
--- a/Firestore/Source/Core/FSTSyncEngine.m
+++ b/Firestore/Source/Core/FSTSyncEngine.mm
@@ -22,7 +22,6 @@
 #import "Firestore/Source/Auth/FSTUser.h"
 #import "Firestore/Source/Core/FSTQuery.h"
 #import "Firestore/Source/Core/FSTSnapshotVersion.h"
-#import "Firestore/Source/Core/FSTTargetIDGenerator.h"
 #import "Firestore/Source/Core/FSTTransaction.h"
 #import "Firestore/Source/Core/FSTView.h"
 #import "Firestore/Source/Core/FSTViewSnapshot.h"
@@ -41,6 +40,8 @@
 #import "Firestore/Source/Util/FSTDispatchQueue.h"
 #import "Firestore/Source/Util/FSTLogger.h"
 
+#include "Firestore/core/src/firebase/firestore/core/target_id_generator.h"
+
 NS_ASSUME_NONNULL_BEGIN
 
 // Limbo documents don't use persistence, and are eagerly GC'd. So, listens for them don't need
@@ -141,14 +142,14 @@ static const FSTListenSequenceNumber kIrrelevantSequenceNumber = -1;
     NSMutableDictionary<FSTUser *, NSMutableDictionary<NSNumber *, FSTVoidErrorBlock> *>
         *mutationCompletionBlocks;
 
-/** Used for creating the FSTTargetIDs for the listens used to resolve limbo documents. */
-@property(nonatomic, strong, readonly) FSTTargetIDGenerator *targetIdGenerator;
-
 @property(nonatomic, strong) FSTUser *currentUser;
 
 @end
 
-@implementation FSTSyncEngine
+@implementation FSTSyncEngine {
+  /** Used for creating the FSTTargetIDs for the listens used to resolve limbo documents. */
+  firebase::firestore::core::TargetIdGenerator _targetIdGenerator;
+}
 
 - (instancetype)initWithLocalStore:(FSTLocalStore *)localStore
                        remoteStore:(FSTRemoteStore *)remoteStore
@@ -167,7 +168,8 @@ static const FSTListenSequenceNumber kIrrelevantSequenceNumber = -1;
     [_limboCollector addGarbageSource:_limboDocumentRefs];
 
     _mutationCompletionBlocks = [NSMutableDictionary dictionary];
-    _targetIdGenerator = [FSTTargetIDGenerator generatorForSyncEngineStartingAfterID:0];
+    _targetIdGenerator =
+        firebase::firestore::core::TargetIdGenerator::SyncEngineTargetIdGenerator(0);
     _currentUser = initialUser;
   }
   return self;
@@ -490,7 +492,7 @@ static const FSTListenSequenceNumber kIrrelevantSequenceNumber = -1;
 
   if (!self.limboTargetsByKey[key]) {
     FSTLog(@"New document in limbo: %@", key);
-    FSTTargetID limboTargetID = [self.targetIdGenerator nextID];
+    FSTTargetID limboTargetID = _targetIdGenerator.NextId();
     FSTQuery *query = [FSTQuery queryWithPath:key.path];
     FSTQueryData *queryData = [[FSTQueryData alloc] initWithQuery:query
                                                          targetID:limboTargetID
diff --git a/Firestore/Source/Core/FSTTargetIDGenerator.h b/Firestore/Source/Core/FSTTargetIDGenerator.h
deleted file mode 100644
index 0b230ae..0000000
--- a/Firestore/Source/Core/FSTTargetIDGenerator.h
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
- * 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 <Foundation/Foundation.h>
-
-#import "Firestore/Source/Core/FSTTypes.h"
-
-NS_ASSUME_NONNULL_BEGIN
-
-/**
- * FSTTargetIDGenerator generates monotonically increasing integer IDs. There are separate
- * generators for different scopes. While these generators will operate independently of each
- * other, they are scoped, such that no two generators will ever produce the same ID. This is
- * useful, because sometimes the backend may group IDs from separate parts of the client into the
- * same ID space.
- */
-@interface FSTTargetIDGenerator : NSObject
-
-/**
- * Creates and returns the FSTTargetIDGenerator for the local store.
- *
- * @param after An ID to start at. Every call to nextID will return an ID > @a after.
- * @return A shared instance of FSTTargetIDGenerator.
- */
-+ (instancetype)generatorForLocalStoreStartingAfterID:(FSTTargetID)after;
-
-/**
- * Creates and returns the FSTTargetIDGenerator for the sync engine.
- *
- * @param after An ID to start at. Every call to nextID will return an ID > @a after.
- * @return A shared instance of FSTTargetIDGenerator.
- */
-+ (instancetype)generatorForSyncEngineStartingAfterID:(FSTTargetID)after;
-
-- (id)init __attribute__((unavailable("Use a static constructor method.")));
-
-/** Returns the next ID in the sequence. */
-- (FSTTargetID)nextID;
-
-@end
-
-NS_ASSUME_NONNULL_END
diff --git a/Firestore/Source/Core/FSTTargetIDGenerator.m b/Firestore/Source/Core/FSTTargetIDGenerator.m
deleted file mode 100644
index 58092ec..0000000
--- a/Firestore/Source/Core/FSTTargetIDGenerator.m
+++ /dev/null
@@ -1,105 +0,0 @@
-/*
- * 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 "Firestore/Source/Core/FSTTargetIDGenerator.h"
-
-#import <libkern/OSAtomic.h>
-
-NS_ASSUME_NONNULL_BEGIN
-
-#pragma mark - FSTTargetIDGenerator
-
-static const int kReservedBits = 1;
-
-/** FSTTargetIDGeneratorID is the set of all valid generators. */
-typedef NS_ENUM(NSInteger, FSTTargetIDGeneratorID) {
-  FSTTargetIDGeneratorIDLocalStore = 0,
-  FSTTargetIDGeneratorIDSyncEngine = 1
-};
-
-@interface FSTTargetIDGenerator () {
-  // This is volatile so it can be used with OSAtomicAdd32.
-  volatile FSTTargetID _previousID;
-}
-
-/**
- * Initializes the generator.
- *
- * @param generatorID A unique ID indicating which generator this is.
- * @param after Every call to nextID will return a number > @a after.
- */
-- (instancetype)initWithGeneratorID:(FSTTargetIDGeneratorID)generatorID
-                    startingAfterID:(FSTTargetID)after NS_DESIGNATED_INITIALIZER;
-
-// This is typed as FSTTargetID because we need to do bitwise operations with them together.
-@property(nonatomic, assign) FSTTargetID generatorID;
-@end
-
-@implementation FSTTargetIDGenerator
-
-#pragma mark - Constructors
-
-- (instancetype)initWithGeneratorID:(FSTTargetIDGeneratorID)generatorID
-                    startingAfterID:(FSTTargetID)after {
-  self = [super init];
-  if (self) {
-    _generatorID = generatorID;
-
-    // Replace the generator part of |after| with this generator's ID.
-    FSTTargetID afterWithoutGenerator = (after >> kReservedBits) << kReservedBits;
-    FSTTargetID afterGenerator = after - afterWithoutGenerator;
-    if (afterGenerator >= _generatorID) {
-      // For example, if:
-      //   self.generatorID = 0b0000
-      //   after = 0b1011
-      //   afterGenerator = 0b0001
-      // Then:
-      //   previous = 0b1010
-      //   next = 0b1100
-      _previousID = afterWithoutGenerator | self.generatorID;
-    } else {
-      // For example, if:
-      //   self.generatorID = 0b0001
-      //   after = 0b1010
-      //   afterGenerator = 0b0000
-      // Then:
-      //   previous = 0b1001
-      //   next = 0b1011
-      _previousID = (afterWithoutGenerator | self.generatorID) - (1 << kReservedBits);
-    }
-  }
-  return self;
-}
-
-+ (instancetype)generatorForLocalStoreStartingAfterID:(FSTTargetID)after {
-  return [[FSTTargetIDGenerator alloc] initWithGeneratorID:FSTTargetIDGeneratorIDLocalStore
-                                           startingAfterID:after];
-}
-
-+ (instancetype)generatorForSyncEngineStartingAfterID:(FSTTargetID)after {
-  return [[FSTTargetIDGenerator alloc] initWithGeneratorID:FSTTargetIDGeneratorIDSyncEngine
-                                           startingAfterID:after];
-}
-
-#pragma mark - Public methods
-
-- (FSTTargetID)nextID {
-  return OSAtomicAdd32(1 << kReservedBits, &_previousID);
-}
-
-@end
-
-NS_ASSUME_NONNULL_END