Add directory.watch.ready for safe torrent watch folders

src/utils/file_status_cache.cc

@@ -21,13 +21,16 @@ FileStatusCache::insert(const std::string& path) {
 
   std::pair<iterator, bool> result = base_type::insert(value_type(path, file_status()));
 
-  // Return false if the file hasn't been modified since last time. We
-  // use 'equal to' instead of 'greater than' since the file might
-  // have been replaced by another file, and thus should be re-tried.
-  if (!result.second && result.first->second.m_mtime == (uint32_t)fs.modified_time())
+  // Return false if the file hasn't changed since last time. We use
+  // 'equal to' instead of 'greater than' since the file might have
+  // been replaced by another file, and thus should be re-tried.
+  if (!result.second &&
+      result.first->second.m_mtime == (uint32_t)fs.modified_time() &&
+      result.first->second.m_size == (int64_t)fs.size())
     return false;
 
   result.first->second.m_flags = 0;
+  result.first->second.m_size  = (int64_t)fs.size();
   result.first->second.m_mtime = fs.modified_time();
 
   return true;
@@ -41,7 +44,9 @@ FileStatusCache::prune() {
     torrent::utils::FileStat fs;
     iterator tmp = itr++;
 
-    if (!fs.update(expand_path(tmp->first)) || tmp->second.m_mtime != (uint32_t)fs.modified_time())
+    if (!fs.update(expand_path(tmp->first)) ||
+        tmp->second.m_mtime != (uint32_t)fs.modified_time() ||
+        tmp->second.m_size != (int64_t)fs.size())
       base_type::erase(tmp);
   }
 }

src/utils/file_status_cache.h

@@ -9,6 +9,7 @@ namespace utils {
 
 struct file_status {
   int      m_flags;
+  int64_t  m_size;
   uint32_t m_mtime;
 };
 
@@ -32,14 +33,14 @@ public:
 
   using base_type::erase;
 
-  // Insert and return true if the entry does not exist or the new
-  // file's mtime is more recent.
+  // Insert and return true if the entry does not exist or the file's
+  // status has changed.
   bool                insert(const std::string& path);
 
   // Add a function for pruning a sorted list of paths.
 
   // Function for pruning entries that no longer points to a file, or
-  // has a different mtime.
+  // has different status.
   void                prune();
 };
 

src/utils/watch_ready_queue.cc

@@ -0,0 +1,158 @@
+#include "config.h"
+
+#include "utils/watch_ready_queue.h"
+
+#include <algorithm>
+#include <torrent/utils/file_stat.h>
+#include <torrent/utils/log.h>
+
+#include "globals.h"
+#include "rpc/rpc_manager.h"
+
+namespace utils {
+
+namespace {
+
+auto compare_next_time = [](const auto* lhs, const auto* rhs) {
+  return lhs->next_time > rhs->next_time;
+};
+
+}
+
+WatchReadyQueue::WatchReadyQueue() {
+  m_task_process.slot() = [this]() { process(); };
+}
+
+WatchReadyQueue::~WatchReadyQueue() {
+  torrent::this_thread::scheduler()->erase(&m_task_process);
+}
+
+void
+WatchReadyQueue::push(const std::string& command, const std::string& path) {
+  if (!m_active)
+    return;
+
+  auto result = m_entries.emplace(path, Entry());
+  auto& entry = result.first->second;
+
+  if (result.second) {
+    entry.path = path;
+    entry.first_seen = torrent::this_thread::cached_time();
+  }
+
+  entry.command = command;
+  entry.last_changed = torrent::this_thread::cached_time();
+  update_status(&entry);
+
+  if (result.second) {
+    update_next_time(&entry);
+    push_entry(&entry);
+  } else {
+    update_entry(&entry);
+  }
+
+  schedule();
+}
+
+void
+WatchReadyQueue::shutdown() {
+  m_active = false;
+  m_entries.clear();
+  m_entry_queue.clear();
+  torrent::this_thread::scheduler()->erase(&m_task_process);
+}
+
+void
+WatchReadyQueue::push_entry(Entry* entry) {
+  m_entry_queue.push_back(entry);
+  std::push_heap(m_entry_queue.begin(), m_entry_queue.end(), compare_next_time);
+}
+
+void
+WatchReadyQueue::update_entry(Entry* entry) {
+  update_next_time(entry);
+  std::make_heap(m_entry_queue.begin(), m_entry_queue.end(), compare_next_time);
+}
+
+void
+WatchReadyQueue::update_next_time(Entry* entry) {
+  if (entry->regular && entry->size > 0) {
+    entry->next_time = entry->last_changed + quiet_time;
+    return;
+  }
+
+  entry->next_time = std::min(torrent::this_thread::cached_time() + retry_time,
+                              entry->first_seen + stale_time);
+}
+
+void
+WatchReadyQueue::update_status(Entry* entry) {
+  torrent::utils::FileStat fs;
+  bool regular = false;
+  int64_t size = -1;
+  time_t mtime = 0;
+
+  if (fs.update(expand_path(entry->path))) {
+    regular = fs.is_regular();
+    size = fs.size();
+    mtime = fs.modified_time();
+  }
+
+  if (entry->regular != regular || entry->size != size || entry->mtime != mtime) {
+    entry->regular = regular;
+    entry->size = size;
+    entry->mtime = mtime;
+    entry->last_changed = torrent::this_thread::cached_time();
+  }
+}
+
+void
+WatchReadyQueue::process() {
+  ready_list ready;
+
+  while (!m_entry_queue.empty() && m_entry_queue.front()->next_time <= torrent::this_thread::cached_time()) {
+    std::pop_heap(m_entry_queue.begin(), m_entry_queue.end(), compare_next_time);
+    Entry* entry = m_entry_queue.back();
+    m_entry_queue.pop_back();
+
+    update_status(entry);
+
+    bool unchanged_entry = torrent::this_thread::cached_time() - entry->last_changed >= quiet_time;
+    bool stale_entry = torrent::this_thread::cached_time() - entry->first_seen >= stale_time;
+    bool nonempty_regular = entry->regular && entry->size > 0;
+
+    if (nonempty_regular && unchanged_entry) {
+      ready.emplace_back(entry->command, entry->path);
+      std::string path = entry->path;
+      m_entries.erase(path);
+      continue;
+    }
+
+    if (!nonempty_regular && stale_entry) {
+      std::string path = entry->path;
+      lt_log_print(torrent::LOG_SYSTEM, "system: Dropped unready watch file after timeout: \"%s\"", path.c_str());
+      m_entries.erase(path);
+      continue;
+    }
+
+    update_next_time(entry);
+    push_entry(entry);
+  }
+
+  schedule();
+
+  for (const auto& item : ready)
+    rpc::commands.call_catch(item.first.c_str(), rpc::make_target(), item.second);
+}
+
+void
+WatchReadyQueue::schedule() {
+  if (m_entry_queue.empty()) {
+    torrent::this_thread::scheduler()->erase(&m_task_process);
+    return;
+  }
+
+  torrent::this_thread::scheduler()->update_wait_until(&m_task_process, m_entry_queue.front()->next_time);
+}
+
+}

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