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/** |
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* This file is part of the CernVM File System. |
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*/ |
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#ifndef CVMFS_FILE_WATCHER_H_ |
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#define CVMFS_FILE_WATCHER_H_ |
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#include <pthread.h> |
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#include <map> |
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#include <string> |
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namespace file_watcher { |
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enum Event { |
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kModified, |
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kRenamed, |
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kAttributes, |
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kHardlinked, |
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kDeleted, |
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kIgnored, |
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kInvalid |
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}; |
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class EventHandler { |
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public: |
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EventHandler(); |
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virtual ~EventHandler(); |
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/** |
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* Handle function called per event |
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* |
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* @param file_path - the path of the file this event corresponds to |
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* @param event - the type of event |
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* @param clear_handler - (output) set this to true to have the event |
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* handler remove from the loop after this call |
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* |
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* Should return false in case of failure. |
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* |
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* Setting the clear_handler parameter to false means that the FileWatcher |
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* object will attempt to re-register the handler for the same file name |
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* in the case a file was delete - useful for continuously watching a file |
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* which may be deleted and recreated |
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*/ |
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virtual bool Handle(const std::string& file_path, |
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Event event, |
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bool* clear_handler) = 0; |
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}; |
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struct WatchRecord { |
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WatchRecord() : file_path_(), handler_(NULL) {} |
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WatchRecord(const std::string& path, |
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file_watcher::EventHandler* h) |
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: file_path_(path), |
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handler_(h) {} |
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std::string file_path_; |
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file_watcher::EventHandler* handler_; |
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}; |
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class FileWatcher { |
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public: |
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typedef std::map<std::string, EventHandler*> HandlerMap; |
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FileWatcher(); |
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virtual ~FileWatcher(); |
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static FileWatcher *Create(); |
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void RegisterHandler(const std::string& file_path, |
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EventHandler* handler); |
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bool Spawn(); |
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void Stop(); |
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protected: |
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// Delays controlling the backoff throttle when registering new watches |
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static const unsigned kInitialDelay; |
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static const unsigned kMaxDelay; |
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static const unsigned kResetDelay; |
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void RegisterFilter(const std::string& file_path, |
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EventHandler* handler); |
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virtual bool RunEventLoop(const HandlerMap& handler_map, |
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int read_pipe, int write_pipe) = 0; |
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virtual int TryRegisterFilter(const std::string& file_path) = 0; |
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std::map<int, WatchRecord> watch_records_; |
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private: |
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static void* BackgroundThread(void* d); |
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HandlerMap handler_map_; |
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int control_pipe_to_back_[2]; |
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int control_pipe_to_front_[2]; |
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pthread_t thread_; |
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bool started_; |
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}; |
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} // namespace file_watcher |
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#endif // CVMFS_FILE_WATCHER_H_ |
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