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libudev: queue - add comments for queue format

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udev/udev.pc
This commit is contained in:
Kay Sievers 2009-06-22 00:32:26 +02:00
parent 7567ca34aa
commit f86ac6e170
1 changed files with 12 additions and 9 deletions
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21
libudev/libudev-queue-private.c
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@ -19,19 +19,22 @@
*
* When a new event is queued, its details are appended to the log.
* When the event finishes, a second record is appended to the log
* with the same sequence number but a null devpath.
* with the same sequence number but a devpath len of 0.
*
* Example:
* {1, "/devices/virtual/mem/null" },
* {2, "/devices/virtual/mem/zero" },
* {1, "" },
* Event 2 is still queued, but event 1 has been finished
* { 0x0000000000000001 }
* { 0x0000000000000001, 0x0019, "/devices/virtual/mem/null" },
* { 0x0000000000000002, 0x001b, "/devices/virtual/mem/random" },
* { 0x0000000000000001, 0x0000 },
* { 0x0000000000000003, 0x0019, "/devices/virtual/mem/zero" },
*
* The queue does not grow indefinitely. It is periodically re-created
* to remove finished events. Atomic rename() makes this transparent to readers.
* Events 2 and 3 are still queued, but event 1 has finished.
*
* The queue does not grow indefinitely. It is periodically re-created
* to remove finished events. Atomic rename() makes this transparent to readers.
*
* The queue file starts with a single sequence number which specifies the
* minimum sequence number in the log that follows. Any events prior to this
* minimum sequence number in the log that follows. Any events prior to this
* sequence number have already finished.
*/
@ -349,7 +352,7 @@ static int update_queue(struct udev_queue_export *udev_queue_export,
return -1;
}
/* when the queue files grow too large, they must be garbage collected and rebuilt */
/* when the queue file grows too large, garbage-collect and rebuild it */
bytes = ftell(udev_queue_export->queue_file) + queue_record_size(devpath_len);
/* if we're removing the last event from the queue, that's the best time to rebuild it */