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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_PERSISTENT_CACHE_BACKEND_PARAMS_MANAGER_H_
#define COMPONENTS_PERSISTENT_CACHE_BACKEND_PARAMS_MANAGER_H_
#include <type_traits>
#include <unordered_map>
#include "base/component_export.h"
#include "base/containers/lru_cache.h"
#include "base/files/file_path.h"
#include "base/functional/callback.h"
#include "base/hash/hash.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "components/persistent_cache/backend_params.h"
namespace persistent_cache {
// Use to retrieve or create BackendParams to open a PersistentCache. Existing
// params are cached so that they can be retrieved synchronously when possible.
//
// Example:
// BackendParamsManager params_manager(GetPath());
// params_manager.GetParamsSyncOrCreateAsync(BackendType::kSqlite, "key",
// AccessRights::kReadOnly,
// std::move(callback));
// // `callback` called synchronously and result can be used right away.
// // ... or
// // `callback` will be invoked asynchronously to return result.
//
class COMPONENT_EXPORT(PERSISTENT_CACHE) BackendParamsManager {
public:
enum class AccessRights { kReadonly, kReadWrite };
// `top_directory` is the where BackendParamsManager will try to find existing
// files and create new ones.
explicit BackendParamsManager(base::FilePath top_directory);
~BackendParamsManager();
using CompletedCallback = base::OnceCallback<void(const BackendParams&)>;
// Use to get backend params matching parameters through `callback`.
void GetParamsSyncOrCreateAsync(BackendType backend_type,
const std::string& key,
AccessRights access_rights,
CompletedCallback callback);
BackendParams GetOrCreateParamsSync(BackendType backend_type,
const std::string& key,
AccessRights access_rights);
// Delete all managed files.
void DeleteAllFiles();
// Use to reduce the total size of files on disk until it's equal or smaller
// than `target_footprint`. Use when enforcing a quota or proactively saving
// space. If the goal is to get rid of all files use `DeleteAllFiles()`
// instead. Returns the number of bytes deleted.
int64_t BringDownTotalFootprintOfFiles(int64_t target_footprint);
private:
struct BackendParamsKey {
BackendType backend_type;
std::string key;
};
struct BackendParamsKeyHash {
BackendParamsKeyHash() = default;
~BackendParamsKeyHash() = default;
std::size_t operator()(const BackendParamsKey& k) const {
size_t hash = 0;
return base::HashCombine(hash, k.backend_type, k.key);
}
};
struct BackendParamsKeyEqual {
bool operator()(const BackendParamsKey& lhs,
const BackendParamsKey& rhs) const {
return lhs.backend_type == rhs.backend_type && lhs.key == rhs.key;
}
};
static BackendParams CreateParamsSync(base::FilePath directory,
BackendType backend_type,
const std::string& key,
AccessRights access_rights);
// Saves params for later retrieval.
void SaveParams(const std::string& key,
CompletedCallback callback,
BackendParams backend_params);
base::HashingLRUCache<BackendParamsKey,
BackendParams,
BackendParamsKeyHash,
BackendParamsKeyEqual>
backend_params_map_ GUARDED_BY_CONTEXT(sequence_checker_);
const base::FilePath top_directory_;
SEQUENCE_CHECKER(sequence_checker_);
base::WeakPtrFactory<BackendParamsManager> weak_factory_{this};
};
} // namespace persistent_cache
#endif // COMPONENTS_PERSISTENT_CACHE_BACKEND_PARAMS_MANAGER_H_
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