fs_cache_client.hpp

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#pragma once
 
/// @file userver/fs/fs_cache_client.hpp
/// @brief @copybref fs::FsCacheClient
 
#include <userver/engine/io/sys_linux/inotify.hpp>
#include <userver/fs/read.hpp>
#include <userver/rcu/rcu_map.hpp>
#include <userver/utils/periodic_task.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace fs {
 
/// @ingroup userver_clients
///
/// @brief Class client for storing files in memory
/// Usually retrieved from `components::FsCache`
class FsCacheClient final {
public:
    /// @brief Fills the cache and starts periodic update
    /// @param dir directory to cache files from
    /// @param update_period time (0 - fill the cache only at startup), not used
    /// in Linux
    /// @param tp task processor to do filesystem operations
    FsCacheClient(std::string_view dir, std::chrono::milliseconds update_period, engine::TaskProcessor& tp);
 
    /// @brief get file from memory
    /// @param path to file
    /// @return file info and content ; `nullptr` if no file with specified name
    /// on FS
    FileInfoWithDataConstPtr TryGetFile(std::string_view path) const;
 
    /// @brief Concurrency-safe cache update
    void UpdateCache();
 
private:
#ifdef __linux__
    void InotifyWork();
 
    void HandleDelete(const std::string& path);
 
    static void HandleDeleteDirectory(engine::io::sys_linux::Inotify& inotify, const std::string& path);
 
    void HandleCreate(const std::string& path);
 
    void HandleCreateDirectory(engine::io::sys_linux::Inotify& inotify, const std::string& path);
 
    void HandleCreateDirectoryBlocking(engine::io::sys_linux::Inotify& inotify, const std::string& path);
#endif
 
    const std::string dir_;
    const std::chrono::milliseconds update_period_;
    engine::TaskProcessor& tp_;
#ifndef __linux__
    utils::PeriodicTask cache_updater_;
#endif
    rcu::RcuMap<std::string, const fs::FileInfoWithData> data_;
 
#ifdef __linux__
    engine::Task inotify_task_;
#endif
};
 
}  // namespace fs
 
USERVER_NAMESPACE_END