[Offline] Creates metadata store interface for offline pages

components/offline_pages/offline_page_metadata_store_impl.cc

+// Copyright 2015 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 "components/offline_pages/offline_page_metadata_store_impl.h"

[Dmitry Titov, 2015/06/04 00:25:53]

If we move the dependency on leveldb to embedder, this file will likely live
under chrome/browser/offline_pages...

[fgorski, 2015/06/05 21:28:42]

Done.

+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/location.h"
+#include "base/sequenced_task_runner.h"
+#include "base/thread_task_runner_handle.h"
+#include "components/offline_pages/offline_page_item.h"
+#include "components/offline_pages/proto/offline_pages.pb.h"
+#include "third_party/leveldatabase/env_chromium.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+namespace {
+
+const char kOffinePageKeyStart[] = "offline-page1-";
+const char kOffinePageKeyEnd[] = "offline-page2-";
+
+// Note: leveldb::Slice keeps a pointer to the data in |s|, which must therefore
+// outlive the slice.
+// For example: MakeSlice(MakeOutgoingKey(x)) is invalid.
+leveldb::Slice MakeSlice(const base::StringPiece& s) {
+  return leveldb::Slice(s.begin(), s.size());
+}
+
+std::string MakeKey(const std::string& key) {
+  return kOffinePageKeyStart + key;
+}
+
+std::string SerializeOfflinePage(const OfflinePageItem& item) {
+  offline_pages_proto::OfflinePageItem item_proto;
+  item_proto.set_url(item.url.spec());
+  item_proto.set_title(item.title);
+  item_proto.set_version(item.version);
+  item_proto.set_file_path(item.file_path.value());
+  item_proto.set_file_size(item.file_size);
+  item_proto.set_creation_time(item.creation_time.ToInternalValue());
+  item_proto.set_last_access_time(item.last_access_time.ToInternalValue());
+  return item_proto.SerializeAsString();
+}
+
+bool DeserializeOfflinePage(const std::string& serialized,
+                            OfflinePageItem* item) {
+  offline_pages_proto::OfflinePageItem item_proto;
+  if (!item_proto.ParseFromString(serialized)) {
+    LOG(ERROR) << "Failed to parse serialized offline page metadata.";
+    return false;
+  }
+  if (!item) {
+    LOG(ERROR) << "Item pointer should be initialized.";
+    return false;
+  }
+
+  item->url = GURL(item_proto.url());
+  item->title = item_proto.title();
+  item->version = item_proto.version();
+  item->file_path = base::FilePath(item_proto.file_path());
+  if (item_proto.has_file_size()) {
+    item->file_size = item_proto.file_size();
+  }
+  if (item_proto.has_creation_time()) {
+    item->creation_time =
+        base::Time::FromInternalValue(item_proto.creation_time());
+  }
+  if (item_proto.has_last_access_time()) {
+    item->last_access_time =
+        base::Time::FromInternalValue(item_proto.last_access_time());
+  }
+  return true;
+}
+
+}  // namespace
+
+class OfflinePageMetadataStoreImpl::Backend
+    : public base::RefCountedThreadSafe<OfflinePageMetadataStoreImpl::Backend> {
+ public:
+  Backend(const base::FilePath& path,
+          scoped_refptr<base::SequencedTaskRunner> foreground_task_runner);
+
+  void Close();
+
+  // Blocking implementations methods.
+  void Load(const LoadCallback& callback);
+  void AddOfflinePage(const OfflinePageItem& offline_page_item,
+                      const UpdateCallback& callback);
+  void RemoveOfflinePage(const GURL& page_url, const UpdateCallback& callback);
+  void Destroy(const UpdateCallback& callback);
+
+ private:
+  friend class base::RefCountedThreadSafe<Backend>;
+  ~Backend();
+
+  Status EnsureStoreIsOpen();
+
+  bool LoadOfflinePages(std::vector<std::string>* serialized_offline_pages);
+
+  const base::FilePath path_;
+  scoped_refptr<base::SequencedTaskRunner> foreground_task_runner_;
+  scoped_ptr<leveldb::DB> db_;
+};
+
+OfflinePageMetadataStoreImpl::Backend::Backend(
+    const base::FilePath& path,
+    scoped_refptr<base::SequencedTaskRunner> foreground_task_runner)
+    : path_(path), foreground_task_runner_(foreground_task_runner) {
+}
+
+OfflinePageMetadataStoreImpl::Backend::~Backend() {
+}
+
+void OfflinePageMetadataStoreImpl::Backend::Load(const LoadCallback& callback) {
+  if (EnsureStoreIsOpen() == FAILED_TO_OPEN_STORE) {
+    foreground_task_runner_->PostTask(
+        FROM_HERE, base::Bind(callback, FAILED_TO_OPEN_STORE,
+                              std::vector<OfflinePageItem>()));
+    return;
+  }
+
+  std::vector<std::string> serialized_offline_pages;
+  if (!LoadOfflinePages(&serialized_offline_pages)) {
+    foreground_task_runner_->PostTask(
+        FROM_HERE, base::Bind(callback, FAILED_TO_LOAD_STORE,
+                              std::vector<OfflinePageItem>()));
+    return;
+  }
+
+  std::vector<OfflinePageItem> result;
+  for (auto iter = serialized_offline_pages.cbegin();
+       iter != serialized_offline_pages.cend(); ++iter) {
+    OfflinePageItem item;
+    if (!DeserializeOfflinePage(*iter, &item)) {
+      foreground_task_runner_->PostTask(
+          FROM_HERE, base::Bind(callback, FAILED_TO_DESERIALIZE,
+                                std::vector<OfflinePageItem>()));
+      return;
+    }
+    result.push_back(item);
+  }
+
+  foreground_task_runner_->PostTask(FROM_HERE,
+                                    base::Bind(callback, SUCCESS, result));
+}
+
+OfflinePageMetadataStore::Status
+OfflinePageMetadataStoreImpl::Backend::EnsureStoreIsOpen() {
+  if (!db_.get()) {
+    leveldb::Options options;
+    options.create_if_missing = true;
+    options.reuse_logs = leveldb_env::kDefaultLogReuseOptionValue;
+    leveldb::DB* db;
+    leveldb::Status status =
+        leveldb::DB::Open(options, path_.AsUTF8Unsafe(), &db);
+    if (!status.ok()) {
+      LOG(ERROR) << "Failed to open database " << path_.value() << ": "
+                 << status.ToString();
+      return FAILED_TO_OPEN_STORE;
+    }
+    db_.reset(db);
+  }
+
+  return SUCCESS;
+}
+
+void OfflinePageMetadataStoreImpl::Backend::Close() {
+  DVLOG(1) << "Closing the offline page metadata store.";
+  db_.reset();
+}
+
+void OfflinePageMetadataStoreImpl::Backend::AddOfflinePage(
+    const OfflinePageItem& offline_page_item,
+    const UpdateCallback& callback) {
+  DVLOG(1) << "Saving an entry in offline pages store with URL: "
+           << offline_page_item.url.spec();
+  Status status = EnsureStoreIsOpen();
+  if (status == FAILED_TO_OPEN_STORE) {
+    LOG(ERROR) << "OfflinePage store is not open.";
+    foreground_task_runner_->PostTask(FROM_HERE, base::Bind(callback, status));
+    return;
+  }
+
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+
+  std::string key = MakeKey(offline_page_item.url.spec());
+  leveldb::Slice key_slice = MakeSlice(key);
+
+  std::string serialized_value = SerializeOfflinePage(offline_page_item);
+  leveldb::Slice value_slice = MakeSlice(serialized_value);
+
+  leveldb::Status s = db_->Put(write_options, key_slice, value_slice);
+  if (!s.ok()) {
+    LOG(ERROR) << "Offline page store level DB Put failed for: "
+               << offline_page_item.url.spec() << " Status: " << s.ToString();
+  }
+
+  status = s.ok() ? SUCCESS : FAILED_TO_UPDATE_STORE;
+  foreground_task_runner_->PostTask(FROM_HERE, base::Bind(callback, status));
+}
+
+void OfflinePageMetadataStoreImpl::Backend::RemoveOfflinePage(
+    const GURL& page_url,
+    const UpdateCallback& callback) {
+  DVLOG(1) << "Deleting an entry in offline pages store with URL: "
+           << page_url.spec();
+  Status status = EnsureStoreIsOpen();
+  if (status == FAILED_TO_OPEN_STORE) {
+    LOG(ERROR) << "OfflinePage store is not open.";
+    foreground_task_runner_->PostTask(FROM_HERE, base::Bind(callback, status));
+    return;
+  }
+
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+
+  std::string key = MakeKey(page_url.spec());
+  leveldb::Slice key_slice = MakeSlice(key);
+  leveldb::Status s = db_->Delete(write_options, key_slice);
+  if (!s.ok()) {
+    LOG(ERROR) << "Offline page store LevelDB Delete failed for: "
+               << page_url.spec() << " Status: " << s.ToString();
+  }
+
+  status = s.ok() ? SUCCESS : FAILED_TO_UPDATE_STORE;
+  foreground_task_runner_->PostTask(FROM_HERE, base::Bind(callback, status));
+}
+
+bool OfflinePageMetadataStoreImpl::Backend::LoadOfflinePages(
+    std::vector<std::string>* serialized_offline_pages) {
+  leveldb::ReadOptions read_options;
+  read_options.verify_checksums = true;
+
+  scoped_ptr<leveldb::Iterator> iter(db_->NewIterator(read_options));
+  leveldb::Slice from_key = MakeSlice(kOffinePageKeyStart);
+  for (iter->Seek(from_key);
+       iter->Valid() && iter->key().ToString() < kOffinePageKeyEnd;
+       iter->Next()) {
+    if (iter->value().empty()) {
+      LOG(ERROR) << "Error reading offline page metadata with key "
+                 << iter->key().ToString();
+      return false;
+    }
+    DVLOG(1) << "Found incoming message with URL " << iter->key().ToString();
+    serialized_offline_pages->push_back(iter->value().ToString());
+  }
+
+  return true;
+}
+
+void OfflinePageMetadataStoreImpl::Backend::Destroy(
+    const UpdateCallback& callback) {
+  DVLOG(1) << "Destroying Offline Page Metadata store.";
+  db_.reset();
+  const leveldb::Status s =
+      leveldb::DestroyDB(path_.AsUTF8Unsafe(), leveldb::Options());
+  if (!s.ok())
+    LOG(ERROR) << "Destroy failed: " << s.ToString();
+
+  Status status = s.ok() ? SUCCESS : FAILED_TO_DESTROY_STORE;
+  foreground_task_runner_->PostTask(FROM_HERE, base::Bind(callback, status));
+}
+
+OfflinePageMetadataStoreImpl::OfflinePageMetadataStoreImpl(
+    const base::FilePath& path,
+    scoped_refptr<base::SequencedTaskRunner> blocking_task_runner)
+    : backend_(new Backend(path, base::ThreadTaskRunnerHandle::Get())),
+      blocking_task_runner_(blocking_task_runner) {
+}
+
+OfflinePageMetadataStoreImpl::~OfflinePageMetadataStoreImpl() {
+}
+
+void OfflinePageMetadataStoreImpl::AddOfflinePage(
+    const OfflinePageItem& offline_page_item,
+    const UpdateCallback& callback) {
+  blocking_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreImpl::Backend::AddOfflinePage,
+                 backend_, offline_page_item, callback));
+}
+
+void OfflinePageMetadataStoreImpl::RemoveOfflinePage(
+    const GURL& page_url,
+    const UpdateCallback& callback) {
+  blocking_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreImpl::Backend::RemoveOfflinePage,
+                 backend_, page_url, callback));
+}
+
+void OfflinePageMetadataStoreImpl::Load(const LoadCallback& callback) {
+  blocking_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&OfflinePageMetadataStoreImpl::Backend::Load,
+                            backend_, callback));
+}
+
+void OfflinePageMetadataStoreImpl::Destroy(const UpdateCallback& callback) {
+  blocking_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&OfflinePageMetadataStoreImpl::Backend::Destroy,
+                            backend_, callback));
+}
+
+void OfflinePageMetadataStoreImpl::Close() {
+  blocking_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&OfflinePageMetadataStoreImpl::Backend::Close, backend_));
+}
+
+}  // namespace offline_pages