mojo leveldb: Add an iteration interface.

components/leveldb/leveldb_database_impl.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_LEVELDB_LEVELDB_DATABASE_IMPL_H_
 #define COMPONENTS_LEVELDB_LEVELDB_DATABASE_IMPL_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "components/leveldb/public/interfaces/leveldb.mojom.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
@@ skipping 19 matching lines @@
   void Delete(mojo::Array<uint8_t> key,
               const DeleteCallback& callback) override;
   void Write(mojo::Array<BatchedOperationPtr> operations,
              const WriteCallback& callback) override;
   void Get(mojo::Array<uint8_t> key, const GetCallback& callback) override;
   void GetSnapshot(const GetSnapshotCallback& callback) override;
   void ReleaseSnapshot(uint64_t snapshot_id) override;
   void GetFromSnapshot(uint64_t snapshot_id,
                        mojo::Array<uint8_t> key,
                        const GetCallback& callback) override;
+  void NewIterator(const NewIteratorCallback& callback) override;
+  void NewIteratorFromSnapshot(uint64_t snapshot_id,
+                               const NewIteratorCallback& callback) override;
+  void ReleaseIterator(uint64_t iterator_id) override;
+  void IteratorSeekToFirst(
+      uint64_t iterator_id,
+      const IteratorSeekToFirstCallback& callback) override;
+  void IteratorSeekToLast(uint64_t iterator_id,
+                          const IteratorSeekToLastCallback& callback) override;
+  void IteratorSeek(uint64_t iterator_id,
+                    mojo::Array<uint8_t> target,
+                    const IteratorSeekToLastCallback& callback) override;
+  void IteratorNext(uint64_t iterator_id,
+                    const IteratorNextCallback& callback) override;
+  void IteratorPrev(uint64_t iterator_id,
+                    const IteratorPrevCallback& callback) override;
 
  private:
+  // Returns the state of |it| to a caller. Note: This assumes that all the
+  // iterator movement methods have the same callback signature. We don't
+  // directly reference the underlying type in case of bindings change.
+  void ReplyToIteratorMessage(leveldb::Iterator* it,
+                              const IteratorSeekToFirstCallback& callback);
+
   mojo::StrongBinding<LevelDBDatabase> binding_;
   scoped_ptr<leveldb::Env> environment_;
   scoped_ptr<leveldb::DB> db_;
 
   std::map<uint64_t, const Snapshot*> snapshot_map_;
 
   // TODO(erg): If we have an existing iterator which depends on a snapshot,
   // and delete the snapshot from the client side, that shouldn't delete the
   // snapshot maybe? At worse it's a DDoS if there's multiple users of the
   // system, but this maybe should be fixed...
 
   std::map<uint64_t, Iterator*> iterator_map_;
 
   DISALLOW_COPY_AND_ASSIGN(LevelDBDatabaseImpl);
 };
 
 }  // namespace leveldb
 
 #endif  // COMPONENTS_LEVELDB_LEVELDB_DATABASE_IMPL_H_