Asynchronously watches a remote file, then notifies a callback function when a change occurs. More...

#include <remote_watcher.hpp>

Public Types
enum	file_action { CREATED = 0, CHANGED = 1, DELETED = 2 }
	The actions that remote_watcher can monitor. More...
typedef boost::function< void(file_action action, const std::string &url)>	callback_t
Public Member Functions
	remote_watcher (int sleep_ms=10000, int timeout_ms=2000)
	~remote_watcher ()
	Destructor.
void	insert (const std::string &url, const callback_t &callback)
	Adds path to the list of monitored paths.
void	clear ()
	clear the whole list
void	erase (const std::string &url)
	Removes path from the list of monitored paths.
void	start ()
	Starts the asynchronous monitor thread.
void	stop ()
	Stops the asynchronous monitor thread.
Static Public Member Functions
static bool	connect (boost::asio::ip::tcp::iostream &s, std::string url, int timeout_ms, bool skip_header=false)
	Connects to the given url. Will put the connection in the passed stream.
Private Member Functions
std::time_t	get_time ()
std::string	last_write_time (const std::string &url)
	we cannot assume that if a file exists, it will exist in the following moment that we check its file size
void	run ()
	Entry point for the asynchronous monitor thread.
Private Attributes
std::map< std::string, callback_t >	m_file_callback
	The map that associates watched files to the callbacks that should be launched.
std::map< std::string, std::string >	m_file_modified
	The map that associates watched files with their last known modification times.
boost::mutex	m_file_mutex
	Mutex to make modifications to remote_watcher::m_file_callback and remote_watcher::m_file_modified thread-safe.
boost::shared_ptr< boost::thread >	m_pthread
	Shared pointer to the thread that is constantly checking the files for modifications.
bool	m_run
	Whether the watcher thread is running.
boost::mutex	m_run_mutex
	Mutex that must be locked when we are changing remote_watcher::m_run.
boost::condition	m_run_cond
	Condition to notify threads blocking on the remote_watcher watcher thread.
int	m_sleep_ms
int	m_timeout_ms

Detailed Description

Asynchronously watches a remote file, then notifies a callback function when a change occurs.

After a remote_watcher is instantiated, you must call remote_watcher::start() to start up the asynchronous thread.

Definition at line 61 of file remote_watcher.hpp.

Member Typedef Documentation

typedef boost::function<void(file_action action, const std::string & url)> moost::io::remote_watcher::callback_t

Definition at line 73 of file remote_watcher.hpp.

Member Enumeration Documentation

enum moost::io::remote_watcher::file_action

The actions that remote_watcher can monitor.

Enumerator:

CREATED	File creation.
CHANGED	File modification.
DELETED

Definition at line 66 of file remote_watcher.hpp.

Constructor & Destructor Documentation

moost::io::remote_watcher::remote_watcher	(	int	sleep_ms = `10000`,
		int	timeout_ms = `2000`
	)		`[inline]`

Constructs an empty remote_watcher that is not running and not watching anything

Parameters:

sleep_ms,: the number of milliseconds to sleep in between checking files

Definition at line 186 of file remote_watcher.hpp.

moost::io::remote_watcher::~remote_watcher ( ) [inline]

Destructor.

This method takes care of properly setting remote_watcher::m_run to false using the remote_watcher::m_run_mutex mutex, and it also waits until the watcher thread exits.

Definition at line 197 of file remote_watcher.hpp.

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Member Function Documentation

void moost::io::remote_watcher::clear ( ) [inline]

clear the whole list

Definition at line 221 of file remote_watcher.hpp.

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static bool moost::io::remote_watcher::connect	(	boost::asio::ip::tcp::iostream &	s,
		std::string	url,
		int	timeout_ms,
		bool	skip_header = `false`
	)		`[inline, static]`

Connects to the given url. Will put the connection in the passed stream.

Returns:: false if the connection did not succeed

Definition at line 278 of file remote_watcher.hpp.

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void moost::io::remote_watcher::erase ( const std::string & url ) [inline]

Removes path from the list of monitored paths.

Parameters:

path	the path to stop monitoring

Definition at line 233 of file remote_watcher.hpp.

std::time_t moost::io::remote_watcher::get_time ( ) [inline, private]

Definition at line 116 of file remote_watcher.hpp.

void moost::io::remote_watcher::insert	(	const std::string &	url,
		const callback_t &	callback
	)		`[inline]`

Adds path to the list of monitored paths.

Parameters:

url	the url to monitor
callback	the callback to notify if the file at url changes

Definition at line 206 of file remote_watcher.hpp.

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std::string moost::io::remote_watcher::last_write_time ( const std::string & url ) [inline, private]

we cannot assume that if a file exists, it will exist in the following moment that we check its file size

Definition at line 124 of file remote_watcher.hpp.

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void moost::io::remote_watcher::run ( ) [inline, private]

Entry point for the asynchronous monitor thread.

Definition at line 353 of file remote_watcher.hpp.

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void moost::io::remote_watcher::start ( ) [inline]

Starts the asynchronous monitor thread.

Exceptions:

std::invalid_argument if the thread is already started start will NOT call the callback function straight away!!!

Definition at line 245 of file remote_watcher.hpp.

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void moost::io::remote_watcher::stop ( ) [inline]

Stops the asynchronous monitor thread.

Exceptions:

std::invalid_argument if the thread is already stopped

Definition at line 258 of file remote_watcher.hpp.

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Member Data Documentation

std::map<std::string, callback_t > moost::io::remote_watcher::m_file_callback [private]

The map that associates watched files to the callbacks that should be launched.

Definition at line 78 of file remote_watcher.hpp.

std::map<std::string, std::string > moost::io::remote_watcher::m_file_modified [private]

The map that associates watched files with their last known modification times.

We actually track the last two modification times. Ideally, we want to send a notification only when the file was modified and the modifying process already closed the file, therefore we fire a CHANGED event only if the previous previous modification time is different from the previous modification time but the previous modification time equals the modification time we read from the file. Otherwise we just "shift" the pair (drop the previous previous modification, move the previous to the first position that is empty and push the file's last modification obtained from the filesystem to the second element of the pair).

Definition at line 90 of file remote_watcher.hpp.

boost::mutex moost::io::remote_watcher::m_file_mutex [private]

Mutex to make modifications to remote_watcher::m_file_callback and remote_watcher::m_file_modified thread-safe.

Definition at line 94 of file remote_watcher.hpp.

boost::shared_ptr< boost::thread> moost::io::remote_watcher::m_pthread [private]

Shared pointer to the thread that is constantly checking the files for modifications.

Definition at line 97 of file remote_watcher.hpp.

bool moost::io::remote_watcher::m_run [private]

Whether the watcher thread is running.

Definition at line 103 of file remote_watcher.hpp.

boost::condition moost::io::remote_watcher::m_run_cond [private]

Condition to notify threads blocking on the remote_watcher watcher thread.

Definition at line 111 of file remote_watcher.hpp.

boost::mutex moost::io::remote_watcher::m_run_mutex [private]

Mutex that must be locked when we are changing remote_watcher::m_run.

This is because remote_watcher::m_run can be modified from the watcher thread itself and also from the thread that originally constructed this remote_watcher.

Definition at line 109 of file remote_watcher.hpp.

int moost::io::remote_watcher::m_sleep_ms [private]

Definition at line 113 of file remote_watcher.hpp.

int moost::io::remote_watcher::m_timeout_ms [private]

Definition at line 114 of file remote_watcher.hpp.

The documentation for this class was generated from the following file:

/home/mhx/git/github/libmoost/include/moost/io/remote_watcher.hpp

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation