Revert 141514 - Remove CachingValueStore in favor of an async ValueStoreFrontend.

chrome/browser/value_store/value_store_frontend.cc

-// Copyright (c) 2012 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 "chrome/browser/value_store/value_store_frontend.h"
-
-#include "chrome/browser/value_store/leveldb_value_store.h"
-#include "content/public/browser/browser_thread.h"
-
-using content::BrowserThread;
-
-class ValueStoreFrontend::Backend : public base::RefCountedThreadSafe<Backend> {
- public:
-  explicit Backend(const FilePath& db_path) : storage_(NULL) {
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-        base::Bind(&ValueStoreFrontend::Backend::InitOnFileThread,
-                   this, db_path));
-  }
-
-  void Get(const std::string& key,
-           const ValueStoreFrontend::ReadCallback& callback) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    ValueStore::ReadResult result = storage_->Get(key);
-
-    // Extract the value from the ReadResult and pass ownership of it to the
-    // callback.
-    base::Value* value = NULL;
-    if (!result->HasError())
-      result->settings()->RemoveWithoutPathExpansion(key, &value);
-
-    scoped_ptr<base::Value> passed_value(value);
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-        base::Bind(&ValueStoreFrontend::Backend::RunCallback,
-                   this, callback, base::Passed(passed_value.Pass())));
-  }
-
-  void Set(const std::string& key, scoped_ptr<base::Value> value) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    // We don't need the old value, so skip generating changes.
-    storage_->Set(ValueStore::IGNORE_QUOTA | ValueStore::NO_GENERATE_CHANGES,
-                  key, *value.get());
-  }
-
-  void Remove(const std::string& key) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    storage_->Remove(key);
-  }
-
- private:
-  friend class base::RefCountedThreadSafe<Backend>;
-
-  virtual ~Backend() {
-    if (BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
-      delete storage_;
-    } else {
-      BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, storage_);
-    }
-  }
-
-  void InitOnFileThread(const FilePath& db_path) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-    DCHECK(!storage_);
-    storage_ = LeveldbValueStore::Create(db_path);
-  }
-
-  void RunCallback(const ValueStoreFrontend::ReadCallback& callback,
-                   scoped_ptr<base::Value> value) {
-    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-    callback.Run(value.Pass());
-  }
-
-  // The actual ValueStore that handles persisting the data to disk. Used
-  // exclusively on the FILE thread.
-  LeveldbValueStore* storage_;
-
-  DISALLOW_COPY_AND_ASSIGN(Backend);
-};
-
-ValueStoreFrontend::ValueStoreFrontend(const FilePath& db_path)
-    : backend_(new Backend(db_path)) {
-}
-
-ValueStoreFrontend::~ValueStoreFrontend() {
-  DCHECK(CalledOnValidThread());
-}
-
-void ValueStoreFrontend::Get(const std::string& key,
-                             const ReadCallback& callback) {
-  DCHECK(CalledOnValidThread());
-
-  BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-      base::Bind(&ValueStoreFrontend::Backend::Get,
-                 backend_, key, callback));
-}
-
-void ValueStoreFrontend::Set(const std::string& key,
-                             scoped_ptr<base::Value> value) {
-  DCHECK(CalledOnValidThread());
-
-  BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-      base::Bind(&ValueStoreFrontend::Backend::Set,
-                 backend_, key, base::Passed(value.Pass())));
-}
-
-void ValueStoreFrontend::Remove(const std::string& key) {
-  DCHECK(CalledOnValidThread());
-
-  BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-      base::Bind(&ValueStoreFrontend::Backend::Remove,
-                 backend_, key));
-}