Add directory.watch.ready for safe torrent watch folders

src/utils/watch_ready_queue.h

@@ -0,0 +1,60 @@
+#ifndef RTORRENT_UTILS_WATCH_READY_QUEUE_H
+#define RTORRENT_UTILS_WATCH_READY_QUEUE_H
+
+#include <chrono>
+#include <cstdint>
+#include <ctime>
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <torrent/utils/scheduler.h>
+
+namespace utils {
+
+class WatchReadyQueue {
+public:
+  WatchReadyQueue();
+  ~WatchReadyQueue();
+
+  void                push(const std::string& command, const std::string& path);
+  void                shutdown();
+  bool                empty() const { return m_entries.empty(); }
+
+private:
+  using time_type = std::chrono::microseconds;
+
+  static constexpr auto quiet_time = std::chrono::milliseconds(500);
+  static constexpr auto retry_time = std::chrono::milliseconds(250);
+  static constexpr auto stale_time = std::chrono::seconds(10);
+
+  using ready_list = std::vector<std::pair<std::string, std::string>>;
+
+  struct Entry {
+    std::string command;
+    std::string path;
+    bool        regular{};
+    int64_t     size{-1};
+    time_t      mtime{};
+    time_type   first_seen{};
+    time_type   last_changed{};
+    time_type   next_time{};
+  };
+
+  void               process();
+  void               push_entry(Entry* entry);
+  void               update_entry(Entry* entry);
+  void               update_next_time(Entry* entry);
+  void               update_status(Entry* entry);
+  void               schedule();
+
+  std::map<std::string, Entry>   m_entries;
+  std::vector<Entry*>            m_entry_queue;
+  torrent::utils::SchedulerEntry m_task_process;
+  bool                           m_active{true};
+};
+
+}
+
+#endif