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dmeventd is 'scanning' statuses in loop (most usually in 10sec
intervals) - and meanwhile it sleeps within:
pthread_cond_timedwait()
However this function call tends to wakeup sometimes a short amount of
time sooner - and our code still believe the 'right time' has not yet
arrived and basically for a moment 'busy-looped' on calling this
function - so for systems with 'clock_gettime()' present we obtain
time and we go 10ms to the future second - this avoids unneeded
repeated invocation of our time scheduling loop.
TODO: monitoring during 1 hour 'time-change'...
When _daemon_read()/_client_read() fails during the read,
ensure memory allocated withing function is also release here
(so caller does not need to care). Also improve code readbility a bit
a for same functionality use more similar code.
Since configure.h is a generated header and it's missing traditional
ifdefs preambule - it can be included & parsed multiple times.
Normally compiler is fine when defines have same value and there is
no warning - yet we don't need to parse this several times
and by adding -include directive we can ensure every file
in the package is rightly compile with configure.h as the
first header file.
Since dmeventd is 'libdm' based project, it needs to link
libdm library instead of its internal version
An external users may provide plugins loadeable by dmeventd.
So external user of libdevmapper-event library has no other option
then to link with released libdevmapper library.
The complexity comes with lvm2 plugins.
The lvm2 plugin itself uses internal version of device_mapper,
but libdevmapper-event usage is libdm based - so there needs to be avoided
any breakage on compatibility of internal i.e. dm_task_run structures.
TODO: most likely dmeventd itself should be moved into libdm/dm-tools dir,
and only lvm2 plugins should be created as part of lvm project,
but those still need to link with libdevmapper.
The device-mapper directory now holds a copy of libdm source. At
the moment this code is identical to libdm. Over time code will
migrate out to appropriate places (see doc/refactoring.txt).
The libdm directory still exists, and contains the source for the
libdevmapper shared library, which we will continue to ship (though
not neccessarily update).
All code using libdm should now use the version in device-mapper.
As we start refactoring the code to break dependencies (see doc/refactoring.txt),
I want us to use full paths in the includes (eg, #include "base/data-struct/list.h").
This makes it more obvious when we're breaking abstraction boundaries, eg, including a file in
metadata/ from base/
When dmeventd receives SIGTERM/INT/HUP/QUIT it validates if exit is possible.
If there was any device still monitored, such exit request used to
be ignored/refused. This 'usually' worked reasonably well, however if there
is very short time period between last device is unmonitored and signal
reception - there was possibility such EXIT was ignored, as dmeventd has
not yet got into idle state even commands like 'vgchange -an' has already
finished.
This patch changes logic towards scheduling EXIT to the nearest
point when there is no monitored device.
EXIT is never forgotten.
NOTE: if there is only a single monitored device and someone sends
SIGTERM and later someone uses i.e. 'lvchange --refresh' after
unmonitoring dmeventd will exit and new instance needs to be
started.
Some archs can use even 64K pages and then lvm2 runs into trouble if
the stack is 'too small' to fit extra page capturing stack overwrite.
So when lvm2 limits stack - add extra mem page - be it 4K or 64K.
Relates to ppc64le bug: https://bugzilla.redhat.com/1387279
Ensure different logging function for dmeventd.c logging
and dm and lvm library.
We can recognize we want to show every log_info() and
log_notice() message from dmeventd.c code while not
exposing those from libdm/libdevmapper-event
Also switch to use log with errno - it's not changing
anything and doesn't bring any more features yet to dmeventd
logging but we just properly pass dm_errno_or_class properly
through the whole code stack for possible future use
(i.e. support of class logging for dmeventd).
Integrate back _unblock_sigalrm() and check for error code of
pthread_sigmask() function so we do not use uninitialized
sigmask_t on error path (Coverity).
If an existing fifo has the wrong attributes it cannot be trusted
so we must unlink it and recreate it correctly.
(Replaces 2c8d6f5c90: if the other end of
the fifo already got opened while its mode was insecure, delaying the
chmod isn't going to make any difference!)
Use fputs() when printing plain string,
easier then fprintf which needs to parse it.
Also check fd before close is >= 0 -
it is - but coverity fail to see it, so eliminate
this false-positive warning.
Put calls related to fifo opening into a single function.
Fix Time-Of-Check-Time-Of-Use and use fstat()
and fchmod() on already opened fd instead of
checking first path and then risking to open something
different.
Improve event string parser to avoid unneeded alloc+free.
Daemon talk function uses '-' to mark NULL/missing field.
So restore the NULL pointer back on parser.
This should have made old tools like 'dmevent_tool' work again.
As now 'uuid' or 'dso' could become NULL and then be
properly used in _want_registered_device() function.
Since lvm2 always fill these parameters, this change should
have no effect on lvm2.
Older pthread library was missing 'trick'
in pthread_cleanup_pop() which lead to
compilation error:
error: label at end of compound statement
Use explicit ';' to fix it.
Implementing exit when 'dmeventd' is idle.
Default idle timeout set to 1 hour - after this time period
dmeventd will cleanly exit.
On systems with 'systemd' - service is automatically started with
next contact on dmeventd communication socket/fifo.
On other systems - new dmeventd starts again when lvm2 command detects
its missing and monitoring is needed.
Add support to unmonitor device when monitor recognizes there is
nothing to monitor anymore.
TODO: possibly API change with return value could be also used.
Redesign threading code:
- plugin registration runs within its new created thread for
improved parallel usage.
- wait task is created just once and used during whole plugin lifetime.
- event thread is based over 'events' filter being set - when
filter is 0, such thread is 'unused'.
- event loop is simplified.
- timeout thread is never signaling 'processing' thread.
- pending of events filter cnange is properly reported and
running event thread is signalled when possible.
- helgrind is not reporting problems.
Need here to keep control device opened while there is 'any' dso
plugin loaded - otherwise there would a race closing controlfd
inside lvm2 plugin while some other monitoring thread would
tried to execute another WAITEVENT task.
Move all DSO related function in front, so they could be easily
referenced from rest of code.
Add proper error paths with logging and error reporting.
Drop mutex locking when releasing DSO - since DSO is always
allocated and released in main 'event' processing thread.
Rework thread creation code to better use resources.
New code will not leak 'timeout' registered thread on error path.
Also if the thread already exist - avoid creation of thread
object and it's later destruction.
If the race is noticed during adding new monitoring thread,
such thread is put on cleanup list and -EEXIST is reported.
