Pref service: Batch pref updates.

services/preferences/public/cpp/persistent_pref_store_client.cc

 // Copyright 2017 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 "services/preferences/public/cpp/persistent_pref_store_client.h"
 
 #include <utility>
 
 #include "base/values.h"
 #include "components/prefs/pref_registry.h"
 #include "mojo/public/cpp/bindings/sync_call_restrictions.h"
 #include "services/preferences/public/cpp/pref_registry_serializer.h"
 
 namespace prefs {
 
 PersistentPrefStoreClient::PersistentPrefStoreClient(
     mojom::PrefStoreConnectorPtr connector,
     scoped_refptr<PrefRegistry> pref_registry,
     std::vector<PrefValueStore::PrefStoreType> already_connected_types)
     : connector_(std::move(connector)),
       pref_registry_(std::move(pref_registry)),
-      already_connected_types_(std::move(already_connected_types)) {
+      already_connected_types_(std::move(already_connected_types)),
+      weak_factory_(this) {
   DCHECK(connector_);
 }
 
 PersistentPrefStoreClient::PersistentPrefStoreClient(
-    mojom::PersistentPrefStoreConnectionPtr connection) {
+    mojom::PersistentPrefStoreConnectionPtr connection)
+    : weak_factory_(this) {
   OnConnect(std::move(connection),
             std::unordered_map<PrefValueStore::PrefStoreType,
                                prefs::mojom::PrefStoreConnectionPtr>());
 }
 
 void PersistentPrefStoreClient::SetValue(const std::string& key,
                                          std::unique_ptr<base::Value> value,
                                          uint32_t flags) {
   base::Value* old_value = nullptr;
   GetMutableValues().Get(key, &old_value);
@@ skipping 12 matching lines @@
 bool PersistentPrefStoreClient::GetMutableValue(const std::string& key,
                                                 base::Value** result) {
   return GetMutableValues().Get(key, result);
 }
 
 void PersistentPrefStoreClient::ReportValueChanged(const std::string& key,
                                                    uint32_t flags) {
   DCHECK(pref_store_);
   const base::Value* local_value = nullptr;
   GetMutableValues().Get(key, &local_value);
-  pref_store_->SetValue(
-      key, local_value ? local_value->CreateDeepCopy() : nullptr, flags);
+
+  QueueWrite(key, flags);
   ReportPrefValueChanged(key);
 }
 
 void PersistentPrefStoreClient::SetValueSilently(
     const std::string& key,
     std::unique_ptr<base::Value> value,
     uint32_t flags) {
   DCHECK(pref_store_);
-  pref_store_->SetValue(key, value->CreateDeepCopy(), flags);
+  QueueWrite(key, flags);
   GetMutableValues().Set(key, std::move(value));
 }
 
 bool PersistentPrefStoreClient::ReadOnly() const {
   return read_only_;
 }
 
 PersistentPrefStore::PrefReadError PersistentPrefStoreClient::GetReadError()
     const {
   return read_error_;
@@ skipping 20 matching lines @@
   error_delegate_.reset(error_delegate);
   connector_->Connect(SerializePrefRegistry(*pref_registry_),
                       already_connected_types_,
                       base::Bind(&PersistentPrefStoreClient::OnConnect,
                                  base::Unretained(this)));
   pref_registry_ = nullptr;
 }
 
 void PersistentPrefStoreClient::CommitPendingWrite() {
   DCHECK(pref_store_);
+  if (!pending_writes_.empty())
+    FlushPendingWrites();
   pref_store_->CommitPendingWrite();
 }
 
 void PersistentPrefStoreClient::SchedulePendingLossyWrites() {
   DCHECK(pref_store_);
   return pref_store_->SchedulePendingLossyWrites();
 }
 
 void PersistentPrefStoreClient::ClearMutableValues() {
   DCHECK(pref_store_);
   return pref_store_->ClearMutableValues();
 }
 
 PersistentPrefStoreClient::~PersistentPrefStoreClient() {
   if (!pref_store_)
     return;
 
-  pref_store_->CommitPendingWrite();
+  CommitPendingWrite();
 }
 
 void PersistentPrefStoreClient::OnConnect(
     mojom::PersistentPrefStoreConnectionPtr connection,
     std::unordered_map<PrefValueStore::PrefStoreType,
                        prefs::mojom::PrefStoreConnectionPtr>
         other_pref_stores) {
   connector_.reset();
   read_error_ = connection->read_error;
   read_only_ = connection->read_only;
   pref_store_ = std::move(connection->pref_store);
   if (error_delegate_ && read_error_ != PREF_READ_ERROR_NONE)
     error_delegate_->OnError(read_error_);
   error_delegate_.reset();
 
   if (connection->pref_store_connection) {
     Init(std::move(connection->pref_store_connection->initial_prefs), true,
          std::move(connection->pref_store_connection->observer));
   } else {
     Init(nullptr, false, nullptr);
   }
 }
 
+void PersistentPrefStoreClient::QueueWrite(const std::string& key,
+                                           uint32_t flags) {
+  if (pending_writes_.empty()) {
+    // Use a weak pointer since a pending write should not prolong the life of
+    // |this|. Instead, the destruction of |this| will flush any pending writes.
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&PersistentPrefStoreClient::FlushPendingWrites,
+                              weak_factory_.GetWeakPtr()));
+  }
+  pending_writes_.insert(std::make_pair(key, flags));
+}
+
+void PersistentPrefStoreClient::FlushPendingWrites() {
+  std::vector<mojom::PrefUpdatePtr> updates;
+  for (const auto& pref : pending_writes_) {
+    const base::Value* value = nullptr;
+    if (GetValue(pref.first, &value)) {
+      updates.push_back(mojom::PrefUpdate::New(
+          pref.first, value->CreateDeepCopy(), pref.second));
+    } else {
+      updates.push_back(
+          mojom::PrefUpdate::New(pref.first, nullptr, pref.second));
+    }
+  }
+  pref_store_->SetValues(std::move(updates));
+  pending_writes_.clear();
+}
+
 }  // namespace prefs