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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_CODE_CACHE_SIMPLE_LRU_CACHE_H_
#define CONTENT_BROWSER_CODE_CACHE_SIMPLE_LRU_CACHE_H_
#include <stdint.h>
#include <map>
#include <optional>
#include <string>
#include <vector>
#include "base/containers/span.h"
#include "base/time/time.h"
#include "base/types/strong_alias.h"
#include "content/common/content_export.h"
#include "content/common/features.h"
#include "mojo/public/cpp/base/big_buffer.h"
namespace content {
// A simple LRU cache, to measure the potential performance impact of
// memory-backed code cache.
class CONTENT_EXPORT SimpleLruCache {
public:
explicit SimpleLruCache(uint64_t capacity);
~SimpleLruCache();
SimpleLruCache(const SimpleLruCache&) = delete;
SimpleLruCache& operator=(const SimpleLruCache&) = delete;
struct CONTENT_EXPORT GetResult {
GetResult(base::Time response_time, mojo_base::BigBuffer data);
~GetResult();
GetResult(const GetResult&) = delete;
GetResult& operator=(const GetResult&) = delete;
GetResult(GetResult&&);
GetResult& operator=(GetResult&&);
base::Time response_time;
mojo_base::BigBuffer data;
};
// Returns the contents of the entry for `key`, if any. The `data` member of
// GetResult is filled only when features::kInMemoryCodeCache is enabled.
// This updates the entry access time.
std::optional<GetResult> Get(const std::string& key);
// Returns whether there is an entry for `key`. This updates the entry access
// time.
bool Has(const std::string& key);
// Puts an entry.
void Put(const std::string& key,
base::Time response_time,
base::span<const uint8_t> data);
// Deletes an entry for `key` in the cache. If there is no such an entry, this
// does nothing.
void Delete(const std::string& key);
// Returns the total size of the cache.
uint64_t GetSize() const;
// Clears all the entries.
void Clear();
static constexpr uint32_t kEmptyEntrySize = 1024;
private:
using Age = base::StrongAlias<class AgeTag, uint32_t>;
using Key = std::string;
struct Value final {
Value(Age age, base::Time response_time, uint32_t size);
Value(Age age,
base::Time response_time,
uint32_t size,
base::span<const uint8_t> data);
~Value();
Value(const Value&) = delete;
Value& operator=(const Value&) = delete;
Value(Value&&);
Value& operator=(Value&&);
Age age;
base::Time response_time;
uint32_t size;
// This is used when features::kInMemoryCodeCache is enabled.
std::vector<uint8_t> data;
};
bool GetInternal(const std::string& key,
base::Time* response_time,
mojo_base::BigBuffer* data);
Age GetNextAge() { return Age(age_source_++); }
void Evict();
const uint64_t capacity_;
std::map<Key, Value> entries_;
std::map<Age, Key> access_list_;
uint32_t age_source_ = 0;
uint64_t size_ = 0;
};
} // namespace content
#endif // CONTENT_BROWSER_CODE_CACHE_SIMPLE_LRU_CACHE_H_
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