lp:~vojtech-horky/helenos/logging
Attempt for low-overhead logging mechanism.
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- 1608. By Vojtech Horky
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Logger processes the messages asynchronously
See description of the problem in previous commit and detailed
description in the diff (write_to_log() function). - 1607. By Vojtech Horky
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MinixFS uses standard logging interface (BROKEN)
Using logger from inside a file system driver revealed a deadlock and
so this revision will not work when debugging is turned on inside mfs.The deadlock is probably somewhere in VFS and is caused by following
chain of events:
* VFS asks MFS to mount some block device (backed by file on FAT)
* MFS sends a debug message to the logger
* logger accepts the message and prints it to the console
* logger also wants to print that message to the file /log/mfs (on FAT)
* logger tries to open that file and there it fails
(if writing to a file is commented out in the logger, all works well)Summary is that one cannot write to a file while mount is in progress.
Possible solutions:
* break the lock in VFS & co. into smaller ones
(I am not sure whether this is possible at all)
* make logger asynchronous - i.e. copy the messages to some internal
queue and process them later
(note that simply not waiting for answer in log_msg() does not work) - 1606. By Vojtech Horky
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Add no-op log_destroy() for destroying logs
The implementation will be added later, currently it exists only for
symmetry to log_create().
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