FileSystemWatcher.h

#pragma once
 
#include <ToolsFoundation/ToolsFoundationDLL.h>
 
#if PL_ENABLED(PL_SUPPORTS_DIRECTORY_WATCHER)
 
#  include <Foundation/Application/Config/FileSystemConfig.h>
#  include <Foundation/IO/DirectoryWatcher.h>
#  include <Foundation/Threading/TaskSystem.h>
 
class plTask;
 
struct plFileSystemWatcherEvent
{
  enum class Type
  {
    FileAdded,
    FileRemoved,
    FileChanged,
    DirectoryAdded,
    DirectoryRemoved,
  };
 
  plStringView m_sPath;
  Type m_Type;
};
 
class PL_TOOLSFOUNDATION_DLL plFileSystemWatcher
{
public:
  plFileSystemWatcher(const plApplicationFileSystemConfig& fileSystemConfig);
  ~plFileSystemWatcher();
 
  void Initialize();
 
  void Deinitialize();
 
  void MainThreadTick();
 
public:
  plEvent<const plFileSystemWatcherEvent&, plMutex> m_Events;
 
private:
  // On file move / rename operations we want the new file to be seen first before the old file delete event so that we can correctly detect this as a move instead of a delete operation. We achieve this by delaying each event by a fixed number of frames.
  static constexpr plUInt32 s_AddedFrameDelay = 5;
  static constexpr plUInt32 s_RemovedFrameDelay = 10;
  // Sometimes moving a file triggers a modified event on the old file. To prevent this from triggering the removal to be seen before the addition, we also delay modified events by the same amount as remove events.
  static constexpr plUInt32 s_ModifiedFrameDelay = 10;
 
  struct WatcherResult
  {
    plString m_sFile;
    plDirectoryWatcherAction m_Action;
    plDirectoryWatcherType m_Type;
  };
 
  struct PendingUpdate
  {
    plString m_sAbsPath;
    plUInt32 m_uiFrameDelay = 0;
  };
 
  void HandleWatcherChange(const WatcherResult& res);
  void NotifyChanges();
  void AddEntry(plDynamicArray<PendingUpdate>& container, const plStringView sAbsPath, plUInt32 uiFrameDelay);
  void ConsumeEntry(plDynamicArray<PendingUpdate>& container, plFileSystemWatcherEvent::Type type, const plDelegate<void(const plString& sAbsPath, plFileSystemWatcherEvent::Type type)>& consume);
 
private:
  // Immutable data after StartInitialize
  plApplicationFileSystemConfig m_FileSystemConfig;
 
  // Watchers
  mutable plMutex m_WatcherMutex;
  plHybridArray<plDirectoryWatcher*, 6> m_Watchers;
  plSharedPtr<plTask> m_pWatcherTask;
  plSharedPtr<plTask> m_pNotifyTask;
  plTaskGroupID m_WatcherGroup;
  plTaskGroupID m_NotifyGroup;
  plAtomicBool m_bShutdown = false;
 
  // Pending ops
  plHybridArray<PendingUpdate, 4> m_FileAdded;
  plHybridArray<PendingUpdate, 4> m_FileRemoved;
  plHybridArray<PendingUpdate, 4> m_FileChanged;
  plHybridArray<PendingUpdate, 4> m_DirectoryAdded;
  plHybridArray<PendingUpdate, 4> m_DirectoryRemoved;
};
 
#endif