Add LwwRegister CRDT

blimp/helium/syncable_primitive_serializer.cc

Index: blimp/helium/syncable_primitive_serializer.cc
diff --git a/blimp/helium/syncable_primitive_serializer.cc b/blimp/helium/syncable_primitive_serializer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e48b2da387bd9c695d0b134e109c84a7fb3a02f1
--- /dev/null
+++ b/blimp/helium/syncable_primitive_serializer.cc
@@ -0,0 +1,82 @@
+// 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.
+
+#include "blimp/helium/syncable_primitive_serializer.h"
+
+#include <stdint.h>
+
+#include <string>
+
+#include "base/logging.h"
+#include "blimp/helium/version_vector.h"
+#include "third_party/protobuf/src/google/protobuf/io/coded_stream.h"
+
+namespace blimp {
+namespace helium {
+namespace {
+constexpr uint32_t kMaxStringLength = (10 << 20);  // 10MB
+}
+
+// -----------------------------
+// int32_t serialization methods
+
+void SyncablePrimitiveSerializer::Serialize(
+    const int32_t& value,
+    google::protobuf::io::CodedOutputStream* output_stream) {
+  output_stream->WriteVarint32(static_cast<uint32_t>(value));
+}
+
+bool SyncablePrimitiveSerializer::Deserialize(
+    google::protobuf::io::CodedInputStream* input_stream,
+    int32_t* value) {
+  return input_stream->ReadVarint32(reinterpret_cast<uint32_t*>(value));
+}
+
+// ---------------------------------
+// std::string serialization methods
+
+void SyncablePrimitiveSerializer::Serialize(
+    const std::string& value,
+    google::protobuf::io::CodedOutputStream* output_stream) {
+  DCHECK(value.length() < kMaxStringLength);

[Kevin M, 2016/10/20 00:38:24]

DCHECK_LT

[steimel, 2016/10/20 00:57:38]

Done.

+  output_stream->WriteVarint32(value.length());
+  output_stream->WriteString(value);
+}
+
+bool SyncablePrimitiveSerializer::Deserialize(
+    google::protobuf::io::CodedInputStream* input_stream,
+    std::string* value) {
+  uint32_t length;
+  if (input_stream->ReadVarint32(&length) && length < kMaxStringLength) {
+    return input_stream->ReadString(value, length);
+  }
+  return false;
+}
+
+// ------

[Kevin M, 2016/10/20 00:38:24]

Moar dashes?

[steimel, 2016/10/20 00:57:38]

Done.

+// VersionVector serialization methods
+
+void SyncablePrimitiveSerializer::Serialize(
+    const VersionVector& value,
+    google::protobuf::io::CodedOutputStream* output_stream) {
+  output_stream->WriteVarint64(value.local_revision());
+  output_stream->WriteVarint64(value.remote_revision());
+}
+
+bool SyncablePrimitiveSerializer::Deserialize(
+    google::protobuf::io::CodedInputStream* input_stream,
+    VersionVector* value) {
+  Revision local_revision;
+  Revision remote_revision;
+  if (input_stream->ReadVarint64(&local_revision) &&
+      input_stream->ReadVarint64(&remote_revision)) {
+    value->set_local_revision(local_revision);
+    value->set_remote_revision(remote_revision);
+    return true;

[Kevin M, 2016/10/20 00:38:24]

Can you flip the conditional so that "return true" is executed at the bottom?
It's more readable to have error handling/returns happen inside the
conditionals, and letting the the main execution flow belong to the happy path.

[steimel, 2016/10/20 00:57:38]

Done.

+  }
+  return false;
+}
+
+}  // namespace helium
+}  // namespace blimp