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// Copyright 2014 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 "sync/engine/entity_tracker.h"
#include "base/logging.h"
#include "sync/engine/non_blocking_sync_common.h"
#include "sync/internal_api/public/base/model_type.h"
#include "sync/syncable/syncable_util.h"
#include "sync/util/time.h"
namespace syncer {
EntityTracker* EntityTracker::FromServerUpdate(
const std::string& id_string,
const std::string& client_tag_hash,
int64 received_version) {
return new EntityTracker(id_string, client_tag_hash, 0, received_version);
}
EntityTracker* EntityTracker::FromCommitRequest(
const std::string& id_string,
const std::string& client_tag_hash,
int64 sequence_number,
int64 base_version,
base::Time ctime,
base::Time mtime,
const std::string& non_unique_name,
bool deleted,
const sync_pb::EntitySpecifics& specifics) {
return new EntityTracker(id_string,
client_tag_hash,
0,
0,
true,
sequence_number,
base_version,
ctime,
mtime,
non_unique_name,
deleted,
specifics);
}
// Constructor that does not set any pending commit fields.
EntityTracker::EntityTracker(const std::string& id,
const std::string& client_tag_hash,
int64 highest_commit_response_version,
int64 highest_gu_response_version)
: id_(id),
client_tag_hash_(client_tag_hash),
highest_commit_response_version_(highest_commit_response_version),
highest_gu_response_version_(highest_gu_response_version),
is_commit_pending_(false),
sequence_number_(0),
base_version_(0),
deleted_(false) {
}
EntityTracker::EntityTracker(const std::string& id,
const std::string& client_tag_hash,
int64 highest_commit_response_version,
int64 highest_gu_response_version,
bool is_commit_pending,
int64 sequence_number,
int64 base_version,
base::Time ctime,
base::Time mtime,
const std::string& non_unique_name,
bool deleted,
const sync_pb::EntitySpecifics& specifics)
: id_(id),
client_tag_hash_(client_tag_hash),
highest_commit_response_version_(highest_commit_response_version),
highest_gu_response_version_(highest_gu_response_version),
is_commit_pending_(is_commit_pending),
sequence_number_(sequence_number),
base_version_(base_version),
ctime_(ctime),
mtime_(mtime),
non_unique_name_(non_unique_name),
deleted_(deleted),
specifics_(specifics) {
}
EntityTracker::~EntityTracker() {
}
bool EntityTracker::IsCommitPending() const {
return is_commit_pending_;
}
void EntityTracker::PrepareCommitProto(sync_pb::SyncEntity* commit_entity,
int64* sequence_number) const {
// Set ID if we have a server-assigned ID. Otherwise, it will be up to
// our caller to assign a client-unique initial ID.
if (base_version_ != kUncommittedVersion) {
commit_entity->set_id_string(id_);
}
commit_entity->set_client_defined_unique_tag(client_tag_hash_);
commit_entity->set_version(base_version_);
commit_entity->set_deleted(deleted_);
commit_entity->set_folder(false);
commit_entity->set_name(non_unique_name_);
if (!deleted_) {
commit_entity->set_ctime(TimeToProtoTime(ctime_));
commit_entity->set_mtime(TimeToProtoTime(mtime_));
commit_entity->mutable_specifics()->CopyFrom(specifics_);
}
*sequence_number = sequence_number_;
}
void EntityTracker::RequestCommit(const std::string& id,
const std::string& client_tag_hash,
int64 sequence_number,
int64 base_version,
base::Time ctime,
base::Time mtime,
const std::string& non_unique_name,
bool deleted,
const sync_pb::EntitySpecifics& specifics) {
DCHECK_GE(base_version, base_version_)
<< "Base version should never decrease";
DCHECK_GE(sequence_number, sequence_number_)
<< "Sequence number should never decrease";
// Update our book-keeping counters.
base_version_ = base_version;
sequence_number_ = sequence_number;
// Do our counter values indicate a conflict? If so, don't commit.
//
// There's no need to inform the model thread of the conflict. The
// conflicting update has already been posted to its task runner; it will
// figure it out as soon as it runs that task.
is_commit_pending_ = true;
if (IsInConflict()) {
ClearPendingCommit();
return;
}
// We don't commit deletions of server-unknown items.
if (deleted && !IsServerKnown()) {
ClearPendingCommit();
return;
}
// Otherwise, we should store the data associated with this pending commit
// so we're ready to commit at the next possible opportunity.
// We intentionally don't update the id_ here. Good ID values come from the
// server and always pass through the sync thread first. There's no way the
// model thread could have a better ID value than we do.
// This entity is identified by its client tag. That value can never change.
DCHECK_EQ(client_tag_hash_, client_tag_hash);
// Set the fields for the pending commit.
ctime_ = ctime;
mtime_ = mtime;
non_unique_name_ = non_unique_name;
deleted_ = deleted;
specifics_ = specifics;
}
void EntityTracker::ReceiveCommitResponse(const std::string& response_id,
int64 response_version,
int64 sequence_number) {
// Commit responses, especially after the first commit, can update our ID.
id_ = response_id;
DCHECK_GT(response_version, highest_commit_response_version_)
<< "Had expected higher response version."
<< " id: " << id_;
// Commits are synchronous, so there's no reason why the sequence numbers
// wouldn't match.
DCHECK_EQ(sequence_number_, sequence_number)
<< "Unexpected sequence number mismatch."
<< " id: " << id_;
highest_commit_response_version_ = response_version;
// Because an in-progress commit blocks the sync thread, we can assume that
// the item we just committed successfully is exactly the one we have now.
// Nothing changed it while the commit was happening. Since we're now in
// sync with the server, we can clear the pending commit.
ClearPendingCommit();
}
void EntityTracker::ReceiveUpdate(int64 version) {
highest_gu_response_version_ =
std::max(highest_gu_response_version_, version);
if (IsInConflict()) {
// Incoming update clobbers the pending commit on the sync thread.
// The model thread can re-request this commit later if it wants to.
ClearPendingCommit();
}
}
bool EntityTracker::IsInConflict() const {
if (!is_commit_pending_)
return false;
if (highest_gu_response_version_ <= highest_commit_response_version_) {
// The most recent server state was created in a commit made by this
// client. We're fully up to date, and therefore not in conflict.
return false;
} else {
// The most recent server state was written by someone else.
// Did the model thread have the most up to date version when it issued the
// commit request?
if (base_version_ >= highest_gu_response_version_) {
return false; // Yes.
} else {
return true; // No.
}
}
}
bool EntityTracker::IsServerKnown() const {
return base_version_ != kUncommittedVersion;
}
void EntityTracker::ClearPendingCommit() {
is_commit_pending_ = false;
// Clearing the specifics might free up some memory. It can't hurt to try.
specifics_.Clear();
}
} // namespace syncer
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