Implement Invalidator::Acknowledge

sync/internal_api/public/base/invalidation_state.cc

Index: sync/internal_api/public/base/invalidation_state.cc
diff --git a/sync/internal_api/public/base/invalidation_state.cc b/sync/internal_api/public/base/invalidation_state.cc
index 6f71351ecda9da6a3c7a6e10e2901acfc7d2a985..f368641c6e561c4d706f2a4425759c7953ee3e46 100644
--- a/sync/internal_api/public/base/invalidation_state.cc
+++ b/sync/internal_api/public/base/invalidation_state.cc
@@ -4,20 +4,48 @@
 
 #include "sync/internal_api/public/base/invalidation_state.h"
 
+#include "base/rand_util.h"
 #include "base/values.h"
 
 namespace syncer {
 
+namespace {
+// Hopefully enough bytes for uniqueness.
+const size_t kBytesInHandle = 16;
+// This is not a valid handle name, since all valid handles are 16 bytes long.
+const char kInvalidHandleName[] = "INVALIDHANDLENAME";
+COMPILE_ASSERT(kBytesInHandle != arraysize(kInvalidHandleName),
+               invalid_handle_name_must_differ_in_length_from_valid_handles);
+}  // namespace
+
+AckHandle AckHandle::CreateUnique() {
+  // We don't have a UUID generator, or else it'd be nice to use that instead.
+  // TODO(dcheng): Do we want to base64 encode this?
+  return AckHandle(base::RandBytesAsString(kBytesInHandle));

[Pete Williamson, 2012/09/14 18:28:22]

Why not just something that increments by one?  Does this have to be thread
safe?
Also, I found when debugging that strings with non-typeable characters are a
royal pain.  So, while we don't necessarily need Base64, some kind of typeable
encoding might be a good idea.

[dcheng, 2012/09/14 19:08:49]

I thought about doing that, but I think it's easier to reason this way, since
there's no dependency between ack handles.
Debugging could be an issue, but the main issue I was concerned about is that
PrefService would sanely handle binary strings (I think it does, since we
actually already store some other binary data in there).

+}
+
+AckHandle AckHandle::InvalidAckHandle() {
+  return AckHandle(kInvalidHandleName);
+}
+
 bool AckHandle::Equals(const AckHandle& other) const {
-  return true;
+  return state_ == other.state_;
 }
 
 scoped_ptr<base::Value> AckHandle::ToValue() const {
-  return scoped_ptr<base::Value>(new DictionaryValue());
+  return scoped_ptr<base::Value>(new StringValue(state_));
 }
 
 bool AckHandle::ResetFromValue(const base::Value& value) {
-  return true;
+  // TODO(dcheng): Add debug mode sanity checking?
+  return value.GetAsString(&state_);
+}
+
+AckHandle::AckHandle(const std::string& state) : state_(state) {
+}
+
+InvalidationState::InvalidationState()
+    : ack_handle(AckHandle::InvalidAckHandle()) {
 }
 
 bool InvalidationState::Equals(const InvalidationState& other) const {