storage: close idle open FDs via FileManager

src/manager.cc

@@ -110,6 +110,7 @@ Manager::receive_tick() {
 
   m_resource_manager->receive_tick();
   m_chunk_manager->periodic_sync();
+  m_file_manager->periodic_close_idle();
 
   // To ensure the downloads get equal chance over time at using
   // various limited resources, like sockets for handshakes, cycle the

src/torrent/data/file_manager.cc

@@ -111,4 +111,30 @@ FileManager::close_least_active() {
     close(least);
 }
 
+void
+FileManager::periodic_close_idle() {
+  if (m_close_idle == 0 || empty())
+    return;
+
+  auto now  = this_thread::cached_time();
+  auto idle = std::chrono::seconds(m_close_idle);
+
+  size_type i = 0;
+  while (i < size()) {
+    File* f = base_type::operator[](i);
+
+    if (!f->is_open()) {
+      ++i;
+      continue;
+    }
+
+    auto touched = std::chrono::microseconds(f->last_touched());
+
+    if (touched <= now && now - touched >= idle)
+      close(f);
+    else
+      ++i;
+  }
+}
+
 } // namespace torrent

src/torrent/data/file_manager.h

@@ -36,12 +36,15 @@ class LIBTORRENT_EXPORT FileManager : private std::vector<File*> {
   bool                advise_random_hashing() const         { return m_advise_random_hashing; }
   void                set_advise_random_hashing(bool state) { m_advise_random_hashing = state; }
 
+  // Idle seconds before closing open FDs; 0 disables.
+  uint32_t            close_idle() const                    { return m_close_idle; }
+  void                set_close_idle(uint32_t seconds)      { m_close_idle = seconds; }
+
   bool                open(value_type file, bool hashing, int prot, int flags);
   void                close(value_type file);
 
-  // TODO: Close all files held by a download after hashing. Also flush all memory chunks.
-
   void                close_least_active();
+  void                periodic_close_idle();
 
   // Statistics:
   uint64_t            files_opened_counter() const { return m_files_opened_counter; }
@@ -53,6 +56,7 @@ class LIBTORRENT_EXPORT FileManager : private std::vector<File*> {
   FileManager& operator=(const FileManager&) = delete;
 
   size_type           m_max_open_files{0};
+  uint32_t            m_close_idle{60};
   bool                m_advise_random{false};
   bool                m_advise_random_hashing{false};