Fdinfo engine - Revision history

Stenbom: Spelling and grammar fixes

2018-12-28T12:55:40Z

Spelling and grammar fixes

Ktkhai: /* Dependencies */

2017-04-25T16:02:18Z

Dependencies

Ktkhai at 15:34, 25 April 2017

2017-04-25T15:34:41Z

Ktkhai: /* Per-process files restore */

2017-04-25T15:10:46Z

Per-process files restore

Ktkhai: /* Notes */

2017-04-25T09:15:09Z

Notes

Ktkhai at 09:06, 25 April 2017

2017-04-25T09:06:21Z

Ktkhai: /* Masters and slaves */

2017-04-25T08:59:20Z

Masters and slaves

Xemul at 08:52, 25 April 2017

2017-04-25T08:52:21Z

Ktkhai at 08:49, 25 April 2017

2017-04-25T08:49:28Z

Xemul: Xemul moved page Fdinfo-engine to Fdinfo engine: No dash in name

2016-09-21T10:24:14Z

Xemul moved page Fdinfo-engine to Fdinfo engine: No dash in name

@@ Line 1: / Line 1: @@
 = Masters and slaves =
-# A file may be referred by several file descriptors. The descriptors may belong to a single process or to several processes.
+# A file may be referred to by several file descriptors. The descriptors may belong to a single process or to several processes.
-# Group of descriptors referring to the same file is called shared. One of the descriptors is named master, others are slaves.
+# A group of descriptors referring to the same file is called shared. One of the descriptors is named master, others are slaves.
-# Every descriptor is discribed via struct fdinfo_list_entry (fle).
+# Every descriptor is described via struct fdinfo_list_entry (fle).
-# One process opens a master fle of a file, while other processes, sharing the file, obtain it using scm_rights. See send_fds() and receive_fds() for the details.
+# One process opens a master fle of a file, while other processes, sharing the file, obtain it using scm_rights. See send_fds() and receive_fds() for details.
-= Per-process files restore =
+= Per-process file restore =
-Every file types is described via structure file_desc. We sequentially call file_desc::ops::open(struct file_desc *d, int *new_fd) method for every master file of a process until all masters are restored. The open methods may return three values:
+Every file type is described via structure file_desc. We sequentially call file_desc::ops::open(struct file_desc *d, int *new_fd) method for every master file of a process until all masters are restored. The open methods may return three values:
 *  0  -- restore of the master file is successefuly finished;
 *  1  -- restore is in progress or it can't be started yet, because of it depends on another files, so the method should be called once again;
 * -1 -- restore failed.
-Right after a file is open at first time, the open method must return fd value in new_fd argument. This allows the common code to send this master to other processes to reopen the master as a slave as soon as possible. The same time, returning of not-negative new_fd does not mean, that the master is restored. The open() callback may return not-negative new_fd and "1" as return value at the same time.
+Right after a file is opened for the first time, the open method must return the fd value in the new_fd argument. This allows the common code to send this master to other processes to reopen the master as a slave as soon as possible. At the same time, returning a non-negative new_fd does not mean that the master is restored. The open() callback may return a non-negative new_fd and "1" as return value at the same time.
 Example. Restore of connected unix socket by open() method.

@@ Line 25: / Line 25: @@
 = Dependencies =
-# Slave TTY can only be created after respective master peer are restored. But now we wait even more -- till all masters are restored.
+# Slave TTY can only be created after respective master peer is restored. But now we wait even more -- till all masters are restored.
 # CTTY must be created after all other TTYs are restored. For all tty dependencies see tty_deps_restored() for the details.
-# Epoll can be created in any time, but it can add a fd in its polling list, after the corresponding fle is completely restored. The only exception is a epoll listening other epoll. In this case we wait till listened fle is just created (not restored). See epoll_not_ready_tfd().
+# Epoll can be created in any time, but it can add a fd in its polling list after the corresponding fle is completely restored. The only exception is a epoll listening other epoll. In this case we wait till listened fle is just created (not restored). See epoll_not_ready_tfd().
 # Unix socket must wait a peer before connect to it. See peer_is_not_prepared() for the details.
 # TCP sockets have a counter on address use.

@@ Line 23: / Line 23: @@
 *1)bind(<peer name>);
 *2)set_fds_event(<socket pid>);
 = Notes =
 # Pipes (and fifos), unix sockets and TTYs generate two fds in their ->open callbacls, the 2nd one can conflict with some other fd the task restores and (!) this "2nd one" may require sending to some other task.
 [[Category:Under the hood]]
 [[Category:Files]]

← Older revision		Revision as of 15:10, 25 April 2017
Line 19:		Line 19:

	Note: it's also possible to go to step "2" right after new_fd is written.		Note: it's also possible to go to step "2" right after new_fd is written.
		+
		+	The peer, which bind() the socket waits in "2", must notify the socket, when it is bound:
		+	*1)bind(<peer name>);
		+	*2)set_fds_event(<socket pid>);

	= Notes =		= Notes =

@@ Line 21: / Line 21: @@
 = Notes =
-# Pipes (and fifos), unix sockets and TTYs generate two fds in their ->open callbacls, the 2nd one can conflict with some other fd the task restores and (!) this "2nd one" may require sending to some other task. This imposes another requirement on the 3-stages engine described above.
+# Pipes (and fifos), unix sockets and TTYs generate two fds in their ->open callbacls, the 2nd one can conflict with some other fd the task restores and (!) this "2nd one" may require sending to some other task.
-# Some actions can only be done only after file is created, served out    and moved to proper position. E.g. epoll configuration and scheduling    TCP repair off. Thus the ->post_open call :( and separate queue for   epoll fds.
+# Some actions can only be done only after file is created, served out and moved to proper position. E.g. epoll configuration and scheduling TCP repair off.
-# Slave TTYs can only be restored after respective master peers. Take into account the issue #2, this results in 3rd queue for slave TTYs.
+# Slave TTYs can only be restored after respective master peers.
-# CTTYs should be __created__ after all other TTYs are created, configured and served out. Thus separate stages (not only queue) for CTTYs.
+# CTTYs should be __created__ after all other TTYs are created, configured and served out.
 [[Category:Under the hood]]
 [[Category:Files]]

← Older revision		Revision as of 08:52, 25 April 2017
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	[[Category:Under the hood]]		[[Category:Under the hood]]
	[[Category:Files]]		[[Category:Files]]
−	~~[[Category:Empty articles]]~~