Copyright (c) 2000 Artur Grabowski <art@openbsd.org>
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.Dd $Mdocdate: September 22 2016 $ .Dt TIMEOUT_SET 9 .Os .Sh NAME .Nm timeout_set , .Nm timeout_set_proc , .Nm timeout_add , .Nm timeout_add_sec , .Nm timeout_add_msec , .Nm timeout_add_nsec , .Nm timeout_add_usec , .Nm timeout_add_tv , .Nm timeout_add_ts , .Nm timeout_add_bt , .Nm timeout_del , .Nm timeout_barrier , .Nm timeout_pending , .Nm timeout_initialized , .Nm timeout_triggered , .Nm TIMEOUT_INITIALIZER .Nd execute a function after a specified period of time .Sh SYNOPSIS n sys/types.h n sys/timeout.h .Ft void .Fn timeout_set "struct timeout *to" "void (*fn)(void *)" "void *arg" .Ft void .Fn timeout_set_proc "struct timeout *to" "void (*fn)(void *)" "void *arg" .Ft int .Fn timeout_add "struct timeout *to" "int ticks" .Ft int .Fn timeout_del "struct timeout *to" .Ft void .Fn timeout_barrier "struct timeout *to" .Ft int .Fn timeout_pending "struct timeout *to" .Ft int .Fn timeout_initialized "struct timeout *to" .Ft int .Fn timeout_triggered "struct timeout *to" .Ft int .Fn timeout_add_tv "struct timeout *to" "struct timeval *" .Ft int .Fn timeout_add_ts "struct timeout *to" "struct timespec *" .Ft int .Fn timeout_add_bt "struct timeout *to" "struct bintime *" .Ft int .Fn timeout_add_sec "struct timeout *to" "int sec" .Ft int .Fn timeout_add_msec "struct timeout *to" "int msec" .Ft int .Fn timeout_add_usec "struct timeout *to" "int usec" .Ft int .Fn timeout_add_nsec "struct timeout *to" "int nsec" .Fn TIMEOUT_INITIALIZER "void (*fn)(void *)" "void *arg" .Sh DESCRIPTION The .Nm timeout API provides a mechanism to execute a function at a given time. The granularity of the time is limited by the granularity of the .Xr hardclock 9 timer which executes .Xr hz 9 times a second.
p It is the responsibility of the caller to provide these functions with pre-allocated timeout structures.
p The functions .Fn timeout_set and .Fn timeout_set_proc prepare the timeout structure .Fa to to be used in future calls to .Fn timeout_add and .Fn timeout_del . The timeout will be prepared to call the function specified by the .Fa fn argument with a .Fa void * argument given in the .Fa arg argument. Once initialized, the .Fa to structure can be used repeatedly in .Fn timeout_add and .Fn timeout_del and does not need to be reinitialized unless the function called and/or its argument must change.
p The function .Fn timeout_add schedules the execution of the .Fa to timeout in at least .Fa ticks Ns /hz seconds. Negative values of .Fa ticks are illegal. If the value is .Sq 0 it will, in the current implementation, be treated as .Sq 1 , but in the future it might cause an immediate timeout. The timeout in the .Fa to argument must be already initialized by .Fn timeout_set or .Fn timeout_set_proc and may not be used in calls to .Fn timeout_set or .Fn timeout_set_proc until it has timed out or been removed with .Fn timeout_del . If the timeout in the .Fa to argument is already scheduled, the old execution time will be replaced by the new one.
p The function .Fn timeout_del will cancel the timeout in the argument .Fa to . If the timeout has already executed or has never been added the call will have no effect.
p .Fn timeout_barrier ensures that any current execution of the timeout in the argument .Fa to has completed before returning. If the timeout .Fa to has been initialised with .Fn timeout_set it will take the kernel lock.
p The .Fn timeout_pending macro can be used to check if a timeout is scheduled to run.
p The .Fn timeout_initialized macro can be used to check if a timeout has been initialized.
p The .Fn timeout_triggered macro can be used to check if a timeout is running or has been run. The .Fn timeout_add and .Fn timeout_del functions clear the triggered state for that timeout.
p When possible, use the .Fn timeout_add_tv , .Fn timeout_add_ts , .Fn timeout_add_bt , .Fn timeout_add_sec , .Fn timeout_add_msec , .Fn timeout_add_usec , and .Fn timeout_add_nsec functions instead of .Fn timeout_add . Those functions add a timeout whilst converting the time specified by the respective types. They also defer the timeout handler for at least one tick if called with a positive value.
p A timeout declaration can be initialised with the .Fn TIMEOUT_INITIALIZER macro. The timeout will be prepared to call the function specified by the .Fa fn argument with the .Fa void * argument given in .Fa arg . .Sh CONTEXT .Fn timeout_set and .Fn timeout_set_proc can be called during autoconf, from process context, or from interrupt context.
p .Fn timeout_add , .Fn timeout_add_sec , .Fn timeout_add_msec , .Fn timeout_add_nsec , .Fn timeout_add_usec , .Fn timeout_add_tv , .Fn timeout_add_ts , .Fn timeout_add_bt , .Fn timeout_del , .Fn timeout_pending , .Fn timeout_initialized , .Fn timeout_triggered can be called during autoconf, from process context, or from any interrupt context at or below .Dv IPL_CLOCK .
p .Fn timeout_barrier can be called from process context.
p When the timeout runs, the .Fa fn argument to .Fn timeout_set or .Fn timeout_set_proc will be called in an interrupt context at .Dv IPL_SOFTCLOCK or a process context, respectively. .Sh RETURN VALUES .Fn timeout_add , .Fn timeout_add_sec , .Fn timeout_add_msec , .Fn timeout_add_nsec , .Fn timeout_add_usec , .Fn timeout_add_tv , .Fn timeout_add_ts , and .Fn timeout_add_bt will return 1 if the timeout .Fa to was added to the timeout schedule or 0 if it was already queued.
p .Fn timeout_del will return 1 if the timeout .Fa to was removed from the pending timeout schedule or 0 if it was not currently queued. .Sh CODE REFERENCES These functions are implemented in the file
a sys/kern/kern_timeout.c . .Sh SEE ALSO .Xr hz 9 , .Xr splclock 9 , .Xr tsleep 9 , .Xr tvtohz 9