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os::NodeMonitor Class Reference

Filesystem node monitor. More...

#include <nodemonitor.h>

List of all members.

Public Methods
	NodeMonitor ()
	NodeMonitor (const std::string &cPath, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
	NodeMonitor (const std::string &cPath, uint32 nFlags, const Messenger &cTarget)
	NodeMonitor (const Directory &cDir, const std::string &cPath, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
	NodeMonitor (const Directory &cDir, const std::string &cPath, uint32 nFlags, const Messenger &cTarget)
	NodeMonitor (const FileReference &cRef, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
	NodeMonitor (const FileReference &cRef, uint32 nFlags, const Messenger &cTarget)
	NodeMonitor (const FSNode *pcNode, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
	NodeMonitor (const FSNode *pcNode, uint32 nFlags, const Messenger &cTarget)
	~NodeMonitor ()
bool	IsValid () const
status_t	Unset ()
status_t	SetTo (const std::string &cPath, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
status_t	SetTo (const std::string &cPath, uint32 nFlags, const Messenger &cTarget)
status_t	SetTo (const Directory &cDir, const std::string &cPath, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
status_t	SetTo (const Directory &cDir, const std::string &cPath, uint32 nFlags, const Messenger &cTarget)
status_t	SetTo (const FileReference &cRef, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
status_t	SetTo (const FileReference &cRef, uint32 nFlags, const Messenger &cTarget)
status_t	SetTo (const FSNode *pcNode, uint32 nFlags, const Handler *pcHandler, const Looper *pcLooper=NULL)
status_t	SetTo (const FSNode *pcNode, uint32 nFlags, const Messenger &cTarget)
int	GetMonitor () const

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Detailed Description

Description:

The node monitor allow you to monitor changes done in the filesystem. This is very useful for the desktop manager, file requesters and other things that display the content of a directory to the user since it makes it possible to keep the directory list in sync with the actual directory without any need for polling. It might also be useful for other purposes like a daemon who want to monitor it's config file and reload it whenever it has changed.

You can monitor file creations and deletions as well as file renaming inside a directory. You can also monitor a file or directory for changes to the attributes or stat info (size, time-stamps, etc etc).

A node monitor will produce asyncronous events that will be sendt to a os::Looper whenever a relevant change is made to the node it is monitoring. When creating a NodeMonitor you must provide a bit-mask telling what event's you are interrested in and what os::Looper/os::Handler should receive the event message.

Here is a list of the flags controlling what to monitor:

• NWATCH_NAME Notify if the name of the watched node is changed.
• NWATCH_STAT Notify if the information returned by the stat() function on the watched node changes.
• NWATCH_ATTR Notify if a attribute on the watched node is created, deleted, or modified.
• NWATCH_DIR Notify if the content of a directory changes. This include creation and deletion of files as well as renaming files within the directory or moving files to or from the directory. This flag will have no effect if applied to a file.
• NWATCH_ALL A convinient combination of all the above.
• NWATCH_FULL_DST_PATH This can be used in conjunction with the NWATCH_NAME and NWATCH_DIR flag to include the full path of one of the directories involved in the rename operation. Which directory depends on wether a node watched with NWATCH_NAME was renamed or wether the file was moved to or from a directory watched with NWATCH_DIR. Don't set this flag unless you really needs it. Retrieving the path of a directory can be a very expensive operation.
• NWATCH_MOUNT Notify when filesystems are mounted and unmounted.
• NWATCH_WORLD Whatch for all file creations, deletions and renamings on all filesystem mounted (NOT IMPLEMENTED YET).

When a relevant change happens to the filesystem one of the following messages are sendt to the target of the monitor:

All messages contain at least 3 elements:

Field	Type	Description
"event"	T_INT32	One of the NWEVENT_* event codes
"device"	T_INT32	The dev_t device number of the FS containing the affected node(s)
"node"	T_INT64	The ino_t i-node number of the affected node

NWEVENT_CREATED

Sendt when a file is created in a directory watched with NWATCH_DIR.

Field	Type	Description
"event"	T_INT32	NWEVENT_CREATED
"device"	T_INT32	The dev_t device number of the FS where the file was created.
"node"	T_INT64	The ino_t i-node number of the new node
"dir_node"	T_INT64	The ino_t of the directory where the node was created.
"name"	T_STRING	The name of the new node

NWEVENT_DELETED

Sendt when a file watched with NWATCH_NAME or that lives in a directory watched with NWATCH_DIR is deleted.

Field	Type	Description
"event"	T_INT32	NWEVENT_DELETED
"device"	T_INT32	The dev_t device number of the FS where the file was deleted.
"node"	T_INT64	The ino_t i-node number of the node that was deleted.
"dir_node"	T_INT64	The ino_t of the directory from where the node was deleted.
"name"	T_STRING	The name of the deleted node

NWEVENT_MOVED

Sendt when a file watched with NWATCH_NAME or that lives in a directory watched with NWATCH_DIR is deleted.

Field	Type	Description
"event"	T_INT32	NWEVENT_MOVED
"device"	T_INT32	The dev_t device number of the FS containing the moved/renamed file.
"node"	T_INT64	The ino_t i-node number of the node that was moved/renamed.
"old_dir"	T_INT64	The ino_t i-node number of the directory the file was moved from.
"new_dir"	T_INT64	The ino_t i-node number of the directory the file was moved to. If this is the same as "old_dir" the file was only renamed and not moved.
"name"	T_STRING	The new file name.
"old_path"	T_STRING	Only present if the NWATCH_FULL_DST_PATH was set and the file was moved into a directory watched with NWATCH_DIR. The string contain the full path of the directory the file was moved from.
"new_path"	T_STRING	Only present if the NWATCH_FULL_DST_PATH was set and the file was moved out of a directory watched with NWATCH_DIR or the moved/renamed file itself was watched with NWATCH_NAME (and NWATCH_FULL_DST_PATH)

• NWEVENT_STAT_CHANGED
• NWEVENT_ATTR_WRITTEN
• NWEVENT_ATTR_DELETED
• NWEVENT_FS_MOUNTED
• NWEVENT_FS_UNMOUNTED

See also:

os::Looper, os::Handler, os::FSNode

Author:

Kurt Skauen (kurt@atheos.cx)

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Constructor & Destructor Documentation

NodeMonitor::NodeMonitor (  )

NodeMonitor::NodeMonitor (  const std::string & cPath, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

NodeMonitor::NodeMonitor (  const std::string & cPath, uint32 nFlags, const Messenger & cTarget )

NodeMonitor::NodeMonitor (  const Directory & cDir, const std::string & cPath, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

NodeMonitor::NodeMonitor (  const Directory & cDir, const std::string & cPath, uint32 nFlags, const Messenger & cTarget )

NodeMonitor::NodeMonitor (  const FileReference & cRef, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

NodeMonitor::NodeMonitor (  const FileReference & cRef, uint32 nFlags, const Messenger & cTarget )

NodeMonitor::NodeMonitor (  const FSNode * pcNode, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

NodeMonitor::NodeMonitor (  const FSNode * pcNode, uint32 nFlags, const Messenger & cTarget )

NodeMonitor::~NodeMonitor (  )

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Member Function Documentation

int NodeMonitor::GetMonitor (  )  const

bool os::NodeMonitor::IsValid (  void )  const

status_t NodeMonitor::SetTo (  const FSNode * pcNode, uint32 nFlags, const Messenger & cTarget )

status_t NodeMonitor::SetTo (  const FSNode * pcNode, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

status_t NodeMonitor::SetTo (  const FileReference & cRef, uint32 nFlags, const Messenger & cTarget )

status_t NodeMonitor::SetTo (  const FileReference & cRef, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

status_t NodeMonitor::SetTo (  const Directory & cDir, const std::string & cPath, uint32 nFlags, const Messenger & cTarget )

status_t NodeMonitor::SetTo (  const Directory & cDir, const std::string & cPath, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

status_t NodeMonitor::SetTo (  const std::string & cPath, uint32 nFlags, const Messenger & cTarget )

status_t NodeMonitor::SetTo (  const std::string & cPath, uint32 nFlags, const Handler * pcHandler, const Looper * pcLooper = NULL )

status_t NodeMonitor::Unset (  )

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