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diff --git a/Firestore/Source/Local/FSTRemoteDocumentChangeBuffer.h b/Firestore/Source/Local/FSTRemoteDocumentChangeBuffer.h
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+++ b/Firestore/Source/Local/FSTRemoteDocumentChangeBuffer.h
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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 <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol FSTRemoteDocumentCache;
+@class FSTMaybeDocument;
+@class FSTDocumentKey;
+@class FSTWriteGroup;
+
+/**
+ * An in-memory buffer of entries to be written to an FSTRemoteDocumentCache. It can be used to
+ * batch up a set of changes to be written to the cache, but additionally supports reading entries
+ * back with the `entryForKey:` method, falling back to the underlying FSTRemoteDocumentCache if
+ * no entry is buffered. In the absence of LevelDB transactions (that would allow reading back
+ * uncommitted writes), this greatly simplifies the implementation of complex operations that
+ * may want to freely read/write entries to the FSTRemoteDocumentCache while still ensuring that
+ * the final writing of the buffered entries is atomic.
+ *
+ * For doing blind writes that don't depend on the current state of the FSTRemoteDocumentCache
+ * or for plain reads, you can/should still just use the FSTRemoteDocumentCache directly.
+ */
+@interface FSTRemoteDocumentChangeBuffer : NSObject
+
++ (instancetype)changeBufferWithCache:(id<FSTRemoteDocumentCache>)cache;
+
+- (instancetype)init __attribute__((unavailable("Use a static constructor instead")));
+
+/** Buffers an `FSTRemoteDocumentCache addEntry:group:` call. */
+- (void)addEntry:(FSTMaybeDocument *)maybeDocument;
+
+// NOTE: removeEntryForKey: is not presently necessary and so is omitted.
+
+/**
+ * Looks up an entry in the cache. The buffered changes will first be checked, and if no
+ * buffered change applies, this will forward to `FSTRemoteDocumentCache entryForKey:`.
+ *
+ * @param documentKey The key of the entry to look up.
+ * @return The cached FSTDocument or FSTDeletedDocument entry, or nil if we have nothing cached.
+ */
+- (nullable FSTMaybeDocument *)entryForKey:(FSTDocumentKey *)documentKey;
+
+/**
+ * Applies buffered changes to the underlying FSTRemoteDocumentCache, using the provided
+ * FSTWriteGroup.
+ */
+- (void)applyToWriteGroup:(FSTWriteGroup *)group;
+
+@end
+
+NS_ASSUME_NONNULL_END