sync: Implement NonBlockingTypeProcessorCore

sync/engine/non_blocking_type_commit_contribution.h

Index: sync/engine/non_blocking_type_commit_contribution.h
diff --git a/sync/engine/non_blocking_type_commit_contribution.h b/sync/engine/non_blocking_type_commit_contribution.h
new file mode 100644
index 0000000000000000000000000000000000000000..e2b19cd7bad71eb440cede002248f808dce6b9a4
--- /dev/null
+++ b/sync/engine/non_blocking_type_commit_contribution.h
@@ -0,0 +1,62 @@
+#ifndef SYNC_ENGINE_NON_BLOCKING_TYPE_COMMIT_CONTRIBUTION_H_
+#define SYNC_ENGINE_NON_BLOCKING_TYPE_COMMIT_CONTRIBUTION_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "sync/engine/commit_contribution.h"
+#include "sync/protocol/sync.pb.h"
+
+namespace syncer {
+
+class NonBlockingTypeProcessorCore;
+
+// A non-blocking sync type's contribution to an outgoing commit message.
+//
+// Helps build a commit message and process its response.  It collaborates
+// closely with the NonBlockingTypeProcessorCore.
+class NonBlockingTypeCommitContribution : public CommitContribution {
+ public:
+  NonBlockingTypeCommitContribution(
+      NonBlockingTypeProcessorCore* parent,

[Nicolas Zea, 2014/05/28 23:56:15]

Parent is a pretty overloaded/ambiguous term. How about type_core or something?

[rlarocque, 2014/05/29 20:54:52]

I went with processor_core_ to match the class name.

+      const sync_pb::DataTypeContext& context,
+      const google::protobuf::RepeatedPtrField<sync_pb::SyncEntity>& entities,

[Nicolas Zea, 2014/05/28 23:56:15]

I wonder if it's worth passing this as vector of some wrapper struct that
encapsulates an entity and a sequence number. It might be useful to have a
tighter coupling of the two.

[rlarocque, 2014/05/29 20:54:52]

I'm on the fence about this.  We have to balance the advantages of more explicit
coupling with the disadvantages of adding yet another struct or class
definition.  I think this makes sense for now, but we should definitely
reconsider if there were three or four parallel vectors.

+      const std::vector<int64> sequence_numbers);
+  virtual ~NonBlockingTypeCommitContribution();
+
+  // Implementation of CommitContribution
+  virtual void AddToCommitMessage(sync_pb::ClientToServerMessage* msg) OVERRIDE;
+  virtual SyncerError ProcessCommitResponse(
+      const sync_pb::ClientToServerResponse& response,
+      sessions::StatusController* status) OVERRIDE;
+  virtual void CleanUp() OVERRIDE;
+  virtual size_t GetNumEntries() const OVERRIDE;
+
+ private:
+  // A non-owned pointer back to the object that created this contribution.
+  NonBlockingTypeProcessorCore* parent_;

[Nicolas Zea, 2014/05/28 23:56:15]

make a const pointer?

[rlarocque, 2014/05/29 20:54:52]

Done.

It could even be a reference, since it's guaranteed to be non-NULL.  I kept it
as a pointer because I don't recall seeing many non-const references or
references that are members of a class in this code base, so I inferred that
there may be some convention that discourages it.

+
+  // The type-global context inforamtion.

[Nicolas Zea, 2014/05/28 23:56:15]

nit: information

[rlarocque, 2014/05/29 20:54:52]

Done.

+  sync_pb::DataTypeContext context_;

[Nicolas Zea, 2014/05/28 23:56:15]

make const?

[rlarocque, 2014/05/29 20:54:52]

Done.

+
+  // The set of entities to be committed, serialized as SyncEntities.
+  const google::protobuf::RepeatedPtrField<sync_pb::SyncEntity> entities_;
+
+  // The sequence numbers associated with the pending commits.  These match up
+  // with the entities_ vector.
+  const std::vector<int64> sequence_numbers_;
+
+  // The index in the commit message where this contribution's entities are
+  // added.  Used to correlate per-item requests with per-item responses.
+  size_t entries_start_index_;
+
+  // A flag used to ensure this object's contract is respected.  Helps to check
+  // that CleanUp() is called before the object is destructed.
+  bool cleaned_up_;
+
+  DISALLOW_COPY_AND_ASSIGN(NonBlockingTypeCommitContribution);
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_ENGINE_NON_BLOCKING_TYPE_COMMIT_CONTRIBUTION_H_