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// Copyright 2019 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.
#ifndef COMPONENTS_PREVIEWS_CONTENT_HINT_CACHE_STORE_H_
#define COMPONENTS_PREVIEWS_CONTENT_HINT_CACHE_STORE_H_
#include <map>
#include <string>
#include <unordered_set>
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/optional.h"
#include "base/sequence_checker.h"
#include "base/version.h"
#include "components/leveldb_proto/public/proto_database.h"
#include "components/previews/content/hint_update_data.h"
namespace base {
class SequencedTaskRunner;
} // namespace base
namespace optimization_guide {
namespace proto {
class Hint;
} // namespace proto
} // namespace optimization_guide
namespace previews {
namespace proto {
class StoreEntry;
} // namespace proto
// The HintCache backing store, which is responsible for storing all hints that
// are locally available. While the HintCache itself may retain some hints in a
// memory cache, all of its hints are initially loaded asynchronously by the
// store. All calls to this store must be made from the same thread.
class HintCacheStore {
public:
using HintLoadedCallback = base::OnceCallback<void(
const std::string&,
std::unique_ptr<optimization_guide::proto::Hint>)>;
using EntryKey = std::string;
using StoreEntryProtoDatabase =
leveldb_proto::ProtoDatabase<previews::proto::StoreEntry>;
// Status of the store. The store begins in kUninitialized, transitions to
// kInitializing after Initialize() is called, and transitions to kAvailable
// if initialization successfully completes. In the case where anything fails,
// the store transitions to kFailed, at which point it is fully purged and
// becomes unusable.
//
// Keep in sync with PreviewsHintCacheLevelDBStoreStatus in
// tools/metrics/histograms/enums.xml.
enum class Status {
kUninitialized = 0,
kInitializing = 1,
kAvailable = 2,
kFailed = 3,
kMaxValue = kFailed,
};
HintCacheStore(const base::FilePath& database_dir,
scoped_refptr<base::SequencedTaskRunner> store_task_runner);
HintCacheStore(const base::FilePath& database_dir,
std::unique_ptr<StoreEntryProtoDatabase> database);
~HintCacheStore();
// Initializes the hint cache store. If |purge_existing_data| is set to true,
// then the cache is purged during initialization and starts in a fresh state.
// When initialization completes, the provided callback is run asynchronously.
void Initialize(bool purge_existing_data, base::OnceClosure callback);
// Creates and returns a HintUpdateData object for component hints. This
// object is used to collect hints within a component in a format usable on a
// background thread and is later returned to the store in
// UpdateComponentHints(). The HintUpdateData object is only created when the
// provided component version is newer than the store's version, indicating
// fresh hints. If the component's version is not newer than the store's
// version, then no HintUpdateData is created and nullptr is returned. This
// prevents unnecessary processing of the component's hints by the caller.
std::unique_ptr<HintUpdateData> MaybeCreateUpdateDataForComponentHints(
const base::Version& version) const;
// Creates and returns a HintsUpdateData object for Fetched Hints.
// This object is used to collect a batch of hints in a format that is usable
// to update the store on a background thread. This is always created when
// hints have been successfully fetched from the remote Optimization Guide
// Service so the store can expire old hints, remove hints specified by the
// server, and store the fresh hints.
std::unique_ptr<HintUpdateData> CreateUpdateDataForFetchedHints(
base::Time update_time) const;
// Updates the component hints and version contained within the store. When
// this is called, all pre-existing component hints within the store is purged
// and only the new hints are retained. After the store is fully updated with
// the new component hints, the callback is run asynchronously.
void UpdateComponentHints(std::unique_ptr<HintUpdateData> component_data,
base::OnceClosure callback);
// Updates the fetched hints contained in the store, including the
// metadata entry. The callback is run asynchronously after the database
// stores the hints.
//
// TODO(mcrouse): When called, fetched hints in the store that have expired
// specified by |expiry_time_secs| will be purged and only the new hints and
// non-expired hints are retained.
void UpdateFetchedHints(std::unique_ptr<HintUpdateData> fetched_hints_data,
base::OnceClosure callback);
// Finds a hint entry key associated with the specified host suffix. Returns
// true if a hint entry key is found, in which case |out_hint_entry_key| is
// populated with the key.
bool FindHintEntryKey(const std::string& host_suffix,
EntryKey* out_hint_entry_key) const;
// Loads the hint specified by |hint_entry_key|.
// After the load finishes, the hint data is passed to |callback|. In the case
// where the hint cannot be loaded, the callback is run with a nullptr.
// Depending on the load result, the callback may be synchronous or
// asynchronous.
void LoadHint(const EntryKey& hint_entry_key, HintLoadedCallback callback);
// Returns the time that the fetched hints in the store can be updated. If
// |this| is not available, base::Time() is returned.
base::Time FetchedHintsUpdateTime() const;
private:
friend class HintCacheStoreTest;
friend class HintUpdateData;
using EntryKeyPrefix = std::string;
using EntryKeySet = std::unordered_set<EntryKey>;
using EntryVector =
leveldb_proto::ProtoDatabase<previews::proto::StoreEntry>::KeyEntryVector;
using EntryMap = std::map<EntryKey, previews::proto::StoreEntry>;
// Entry types within the store appear at the start of the keys of entries.
// These values are converted into strings within the key: a key starting with
// "1_" signifies a metadata entry and one starting with "2_" signifies a
// component hint entry. Adding this to the start of the key allows the store
// to quickly perform operations on all entries of a specific key type. Given
// that entry type comparisons may be performed many times, the entry type
// string is kept as small as possible.
// Example metadata entry type key:
// "[EntryType::kMetadata]_[MetadataType::kSchema]" ==> "1_1"
// Example component hint entry type key:
// "[EntryType::kComponentHint]_[component_version]_[host]"
// ==> "2_55_foo.com"
// NOTE: The order and value of the existing entry types within the enum
// cannot be changed, but new types can be added to the end.
enum class EntryType {
kMetadata = 1,
kComponentHint = 2,
kFetchedHint = 3,
};
// Metadata types within the store. The metadata type appears at the end of
// metadata entry keys. These values are converted into strings within the
// key.
// Example metadata type keys:
// "[EntryType::kMetadata]_[MetadataType::kSchema]" ==> "1_1"
// "[EntryType::kMetadata]_[MetadataType::kComponent]" ==> "1_2"
// NOTE: The order and value of the existing metadata types within the enum
// cannot be changed, but new types can be added to the end.
enum class MetadataType {
kSchema = 1,
kComponent = 2,
kFetched = 3,
};
// Current schema version of the hint cache store. When this is changed,
// pre-existing store data from an earlier version is purged.
static const char kStoreSchemaVersion[];
// Returns prefix in the key of every metadata entry type entry: "1_"
static EntryKeyPrefix GetMetadataEntryKeyPrefix();
// Returns entry key for the specified metadata type entry: "1_[MetadataType]"
static EntryKey GetMetadataTypeEntryKey(MetadataType metadata_type);
// Returns prefix in the key of every component hint entry: "2_"
static EntryKeyPrefix GetComponentHintEntryKeyPrefixWithoutVersion();
// Returns prefix in the key of component hint entries for the specified
// component version: "2_[component_version]_"
static EntryKeyPrefix GetComponentHintEntryKeyPrefix(
const base::Version& component_version);
// Returns prefix of the key of every fetched hint entry: "3_".
static EntryKeyPrefix GetFetchedHintEntryKeyPrefix();
// Updates the status of the store to the specified value, validates the
// transition, and destroys the database in the case where the status
// transitions to Status::kFailed.
void UpdateStatus(Status new_status);
// Returns true if the current status is Status::kAvailable.
bool IsAvailable() const;
// Asynchronously purges all existing entries from the database and runs the
// callback after it completes. This should only be run during initialization.
void PurgeDatabase(base::OnceClosure callback);
// Updates |component_version_| and |component_hint_entry_key_prefix_| for
// the new component version. This must be called rather than directly
// modifying |component_version_|, as it ensures that both member variables
// are updated in sync.
void SetComponentVersion(const base::Version& component_version);
// Resets |component_version_| and |component_hint_entry_key_prefix_| back to
// their default state. Called after the database is destroyed.
void ClearComponentVersion();
// Asynchronously loads the hint entry keys from the store, populates
// |hint_entry_keys_| with them, and runs the provided callback after they
// finish loading. In the case where there is currently an in-flight component
// update, this does nothing, as the hint entry keys will be loaded after the
// component update completes.
void MaybeLoadHintEntryKeys(base::OnceClosure callback);
// Returns the total hint entry keys contained within the store.
size_t GetHintEntryKeyCount() const;
// Callback that runs after the database finishes being initialized. If
// |purge_existing_data| is true, then unconditionally purges the database;
// otherwise, triggers loading of the metadata.
void OnDatabaseInitialized(bool purge_existing_data,
base::OnceClosure callback,
bool success);
// Callback that is run after the database finishes being destroyed.
void OnDatabaseDestroyed(bool success);
// Callback that runs after the metadata finishes being loaded. This
// validates the schema version, sets the component version, and either purges
// the store (on a schema version mismatch) or loads all hint entry keys (on
// a schema version match).
void OnLoadMetadata(base::OnceClosure callback,
bool success,
std::unique_ptr<EntryMap> metadata_entries);
// Callback that runs after the database is purged during initialization.
void OnPurgeDatabase(base::OnceClosure callback, bool success);
// Callback that runs after the hints data within the store is fully
// updated. If the update was successful, it attempts to load all of the hint
// entry keys contained within the database.
void OnUpdateHints(base::OnceClosure callback, bool success);
// Callback that runs after the hint entry keys are fully loaded. If there's
// currently an in-flight component update, then the hint entry keys will be
// loaded again after the component update completes, so the results are
// tossed; otherwise, |hint_entry_keys| is moved into |hint_entry_keys_|.
// Regardless of the outcome of loading the keys, the callback always runs.
void OnLoadHintEntryKeys(std::unique_ptr<EntryKeySet> hint_entry_keys,
base::OnceClosure callback,
bool success,
std::unique_ptr<EntryMap> unused);
// Callback that runs after a hint entry is loaded from the database. If
// there's currently an in-flight component update, then the hint is about to
// be invalidated, so results are tossed; otherwise, the hint is released into
// the callback, allowing the caller to own the hint without copying it.
// Regardless of the success or failure of retrieving the key, the callback
// always runs (it simply runs with a nullptr on failure).
void OnLoadHint(const EntryKey& entry_key,
HintLoadedCallback callback,
bool success,
std::unique_ptr<previews::proto::StoreEntry> entry);
// Path to the directory for the profile using this store.
const base::FilePath database_dir_;
// Proto database used by the store.
const std::unique_ptr<StoreEntryProtoDatabase> database_;
// The current status of the store. It should only be updated through
// UpdateStatus(), which validates status transitions and triggers
// accompanying logic.
Status status_;
// The current component version of the store. This should only be updated
// via SetComponentVersion(), which ensures that both |component_version_|
// and |component_hint_key_prefix_| are updated at the same time.
base::Optional<base::Version> component_version_;
// The current entry key prefix shared by all component hints containd within
// the store. While this could be generated on the fly using
// |component_version_|, it is retaind separately as an optimization, as it
// is needed often.
EntryKeyPrefix component_hint_entry_key_prefix_;
// If a component data update is in the middle of being processed; when this
// is true, keys and hints will not be returned by the store.
bool data_update_in_flight_;
// The next update time for the fetched hints that are currently in the
// store.
base::Time fetched_update_time_;
// The keys of the hints available within the store.
std::unique_ptr<EntryKeySet> hint_entry_keys_;
SEQUENCE_CHECKER(sequence_checker_);
base::WeakPtrFactory<HintCacheStore> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(HintCacheStore);
};
} // namespace previews
#endif // COMPONENTS_PREVIEWS_CONTENT_HINT_CACHE_STORE_H_