Helium: Initial proto and Syncable interface definition

blimp/net/helium/syncable_unittest.cc

Index: blimp/net/helium/syncable_unittest.cc
diff --git a/blimp/net/helium/syncable_unittest.cc b/blimp/net/helium/syncable_unittest.cc
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index 0000000000000000000000000000000000000000..297f908db273fbc44402ec30634ec31558d34a08
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+++ b/blimp/net/helium/syncable_unittest.cc
@@ -0,0 +1,202 @@
+// 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/net/helium/syncable.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blimp {
+namespace {
+
+// This is a sample implementation that demostrates the implementation
+// of the SyncableMember and SyncableObject
+
+// For simplicity of this example, the ChangeSet will be an integer.
+class IntValueSyncable : public SyncableMember<int> {
+ public:
+  explicit IntValueSyncable(SyncableObject* parent)
+      : SyncableMember(parent), value_(0) {
+    // We initialize the last time we modified with the parent clock

[Kevin M, 2016/09/30 18:34:37]

This is already made pretty clear by the code - recommend removing the comment.

[scf, 2016/09/30 22:13:24]

Done.

+    last_modified_ = parent_->get_clock();
+  }
+
+  bool ModifiedSince(const VectorClock& from) override {
+    // If something was modified from the last time we synchronized with
+    // my current clock.

[Kevin M, 2016/09/30 18:34:37]

"my"?

Also, the sentence doesn't parse.

[scf, 2016/09/30 22:13:24]

Done.

+    return from.local_revision() < last_modified_.local_revision();
+  }
+
+  void CreateChangesetToCurrent(
+      const VectorClock& from,
+      const CreateChangesetCallback& callback) override {
+    std::unique_ptr<int> changeset = base::MakeUnique<int>();
+    *changeset = value_;
+    callback.Run(std::move(changeset));
+  }
+
+  void ApplyChangeset(const VectorClock& from,
+                      const VectorClock& to,
+                      const int& changeset,
+                      const base::Closure& done) override {
+    // Restore the value
+    value_ = changeset;
+    // Update our clock to the latest clock

[Kevin M, 2016/09/30 18:34:37]

add newline above

[scf, 2016/09/30 22:13:24]

Done.

+    last_modified_ = to;
+
+    done.Run();
+  }
+
+  void ReleaseCheckpointsBefore(const VectorClock& checkpoint) override {
+    last_modified_ = checkpoint;
+  }
+
+  void SetValue(int value) {
+    value_ = value;
+    // Increment the parent clock and update our last_modified_ value

[Kevin M, 2016/09/30 18:34:37]

add newline above

[scf, 2016/09/30 22:13:24]

Done.

+    last_modified_ = IncrementParentClock();
+  }
+
+  int get_value() { return value_; }

[Kevin M, 2016/09/30 18:34:37]

value()

[scf, 2016/09/30 22:13:24]

Done.

+
+ private:
+  // The last time this object was changed
+  VectorClock last_modified_;
+  int32_t value_;
+};
+
+class ParentObjectSyncable : public SyncableObject {
+ public:
+  explicit ParentObjectSyncable(VectorClock clock)
+      : SyncableObject(clock), child1_(this), child2_(this) {}
+
+  void CreateChangesetToCurrent(
+      const VectorClock& from,
+      const CreateChangesetCallback& response_callback) override {
+    std::unique_ptr<helium::Changeset> changeset =
+        base::MakeUnique<helium::Changeset>();
+
+    int value1 = 0;

[Kevin M, 2016/09/30 18:34:37]

In practice, we will only be setting values in the proto if those values are
worth sending. I recommend moving the set_value1, set_value2 calls into the
conditional blocks and removing these value1, value2 locals.

[scf, 2016/09/30 22:13:24]

Done.

+    if (child1_.ModifiedSince(from)) {
+      IntValueSyncable::CreateChangesetCallback callback =
+          base::Bind(&ParentObjectSyncable::OnChildChangesetCreated,
+                     base::Unretained(this), &value1);
+      child1_.CreateChangesetToCurrent(from, callback);
+    }
+
+    int value2 = 0;
+    if (child2_.ModifiedSince(from)) {
+      IntValueSyncable::CreateChangesetCallback callback =
+          base::Bind(&ParentObjectSyncable::OnChildChangesetCreated,
+                     base::Unretained(this), &value2);
+      child2_.CreateChangesetToCurrent(from, callback);
+    }
+
+    // HACK2: Since we know about the internals of IntValueSyncable we can
+    // safely access value1 and value2 since the calls are blocking
+    helium::TestChangeset* bm = changeset->mutable_test();
+    bm->set_value1(value1);
+    bm->set_value2(value2);
+
+    response_callback.Run(std::move(changeset));
+  }
+
+  void OnChildChangesetCreated(int* out, std::unique_ptr<int> value) {
+    *out = *value;
+  }
+
+  void ApplyChangeset(const VectorClock& from,
+                      const VectorClock& to,
+                      const helium::Changeset& content,
+                      const base::Closure& done) override {
+    helium::TestChangeset bm = content.test();
+
+    base::Closure dummy =
+        base::Bind(&ParentObjectSyncable::OnDummy, base::Unretained(this));

[Kevin M, 2016/09/30 18:34:37]

base::DoNothing

[scf, 2016/09/30 22:13:24]

Done.

+
+    int child1_value = bm.value1();
+    if (child1_value != 0) {
+      child1_.ApplyChangeset(from, to, child1_value, dummy);
+    }
+
+    int child2_value = bm.value2();
+    if (child2_value != 0) {
+      child2_.ApplyChangeset(from, to, child2_value, dummy);
+    }
+
+    done.Run();
+  }
+
+  void OnDummy() {}
+
+  void ReleaseCheckpointsBefore(const VectorClock& checkpoint) override {
+    child1_.ReleaseCheckpointsBefore(checkpoint);
+    child2_.ReleaseCheckpointsBefore(checkpoint);
+  }
+
+  IntValueSyncable& get_child1() { return child1_; }
+  IntValueSyncable& get_child2() { return child2_; }
+
+ private:
+  IntValueSyncable child1_;
+  IntValueSyncable child2_;

[Kevin M, 2016/09/30 18:34:37]

DISALLOW yada yada

[scf, 2016/09/30 22:13:24]

Done.

+};
+
+class SyncableTest : public testing::Test {
+ public:
+  SyncableTest()
+      : last_sync_local_(),
+        last_sync_remote_(),
+        parent_local_(last_sync_local_),
+        parent_remote_(last_sync_remote_) {}

[Kevin M, 2016/09/30 18:34:37]

add newline below this

[scf, 2016/09/30 22:13:24]

Done.

+  ~SyncableTest() override {}
+
+  void OnLocalChangesetCreated(std::unique_ptr<helium::Changeset> changeset) {
+    VectorClock local_clock = parent_local_.get_clock();
+    VectorClock remote_clock = local_clock.Invert();
+    base::Closure done = base::Bind(&SyncableTest::OnRemoteChangesetApplied,
+                                    base::Unretained(this));
+    parent_remote_.ApplyChangeset(last_sync_remote_, remote_clock,
+                                  *(changeset.get()), done);
+    last_sync_local_ = local_clock;
+    parent_local_.ReleaseCheckpointsBefore(local_clock);
+    EXPECT_FALSE(parent_local_.get_child1().ModifiedSince(last_sync_local_));
+    EXPECT_FALSE(parent_local_.get_child2().ModifiedSince(last_sync_local_));
+  }
+
+  void OnRemoteChangesetApplied() {
+    EXPECT_EQ(123, parent_remote_.get_child1().get_value());
+    EXPECT_EQ(0, parent_remote_.get_child2().get_value());
+  }
+
+ protected:
+  VectorClock last_sync_local_;
+  VectorClock last_sync_remote_;
+  ParentObjectSyncable parent_local_;
+  ParentObjectSyncable parent_remote_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SyncableTest);
+};
+
+TEST_F(SyncableTest, DemoAPITest) {
+  // Lets modify a children object
+  parent_local_.get_child1().SetValue(123);
+
+  // At this point |child1| and |parentObject| should have its clock incremented
+  // whereas |child2| should still be the same.
+  EXPECT_TRUE(parent_local_.get_child1().ModifiedSince(last_sync_local_));
+  EXPECT_FALSE(parent_local_.get_child2().ModifiedSince(last_sync_local_));
+
+  ParentObjectSyncable::CreateChangesetCallback callback = base::Bind(
+      &SyncableTest::OnLocalChangesetCreated, base::Unretained(this));
+  parent_local_.CreateChangesetToCurrent(last_sync_local_, callback);
+}
+
+}  // namespace
+}  // namespace blimp