IIRC, I read in your code that composed signals means the next
delegate must have the (logger, signal) {...} form.
Why?
I can (not must) have the form, the delegate params are tested
independently from signal composition.
Is that the standard behavior for daemons in OSes?
Most signals are simply ignored (except termination ones).
You could have the daemon stopped, after logging the unhandled
signal.
Or you could also block compilation if a daemon does not handle
all signals...
Some signals could be sent without any reason: sighup or
interrogate in windows.
Ignoring most signals is a better strategy, the exception could
be done for terminating signals - their default handlers should
set `shouldExit` flag to true.
Or have a 'catch-all' delegate, as std.concurrency.receive,
which uses
a (Variant v) {...} delegate at the end.
See:
http://dlang.org/library/std/concurrency/receive.html
Good idea, it will be implemented.
(btw, signals could also be types and you could have a handling
syntax
similar to receive).
Ohh, that is much more complicated feature as it may seem.
Signaling in both OSes are very limited. We need an additional
channel to pass arbitrary memory between processes and also
restrict data to be serializable. If I continue to move in that
direction, the D will occasionally obtain a library for
distributed cluster computing (like Cloud Haskell) ;).
On Sunday, 31 August 2014 at 19:45:32 UTC, Philippe Sigaud via
Digitalmars-d-announce wrote:
Does the user sees/uses this name in any way afterwards?
Because I
think you could also produce a unique string at compile-time
(by using
__FILE__ and __LINE__, unless someone has a better idea), if
the user
does not provide one. Maybe he just wants an anonymous
daemon, or
doesn't care, whatever.
Yes, the name is used in windows service manager (you can
start/stop the
daemon by control panel) and for default locations of .pid and
.lock files.
OK.
Auto generated name will prevent sending signals and could be
ugly displayed
in service manager. The feature is useful for simple daemons,
I will play
around with that idea to find out if it worth.
Great.
I will add the approach in next release (it requires some more
additional
templates to wrap all the mess) thanks to arguments "grammar"
has no
ambiguities.
Yes, the grammar is simple, use it to simplify the life of your
users.
Is the idea that, if the delegate has two arguments, then the
second
is the signal that will be passed to it, and if it has only
one
argument, only the logger will be passed?
Yes
OK.
IIRC, I read in your code that composed signals means the next
delegate must have the (logger, signal) {...} form.
Why?
What if the user does not want a logger? Is a daemon always
associated
to a log file in OSes?
It is a general rule as the stderr and stdout files are
closed. At next
version I want to use duck typing for logger (or sink approach
same as
toString uses) and add a feature to reopen stderr/stdout to
another file.
OK.
Concerning the DaemonClient template, could you not ask for
Daemon to
generate it on demand? Or is DaemonClient always used in
another
module?
DaemonClient is designed to be used in another module, you can
send signals
with full Daemon template.
OK. I'd have thought that just having the name of the daemon
would be
enough to send it signals.
What happens when an unhandled signal is passed to a daemon?
The event is logged down and ignored.
Is that the standard behavior for daemons in OSes?
You could have the daemon stopped, after logging the unhandled
signal.
Or you could also block compilation if a daemon does not handle
all signals...
Or have a 'catch-all' delegate, as std.concurrency.receive,
which uses
a (Variant v) {...} delegate at the end.
See:
http://dlang.org/library/std/concurrency/receive.html
(btw, signals could also be types and you could have a handling
syntax
similar to receive).
