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Diffstat (limited to 'Doc/library/signal.rst')
| -rw-r--r-- | Doc/library/signal.rst | 67 |
1 files changed, 60 insertions, 7 deletions
diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst index 2e5cae5..94863e1 100644 --- a/Doc/library/signal.rst +++ b/Doc/library/signal.rst @@ -39,12 +39,13 @@ rules for working with signals and their handlers: * Some care must be taken if both signals and threads are used in the same program. The fundamental thing to remember in using signals and threads simultaneously is: always perform :func:`signal` operations in the main thread - of execution. Any thread can perform an :func:`alarm`, :func:`getsignal`, or - :func:`pause`; only the main thread can set a new signal handler, and the main - thread will be the only one to receive signals (this is enforced by the Python - :mod:`signal` module, even if the underlying thread implementation supports - sending signals to individual threads). This means that signals can't be used - as a means of inter-thread communication. Use locks instead. + of execution. Any thread can perform an :func:`alarm`, :func:`getsignal`, + :func:`pause`, :func:`setitimer` or :func:`getitimer`; only the main thread + can set a new signal handler, and the main thread will be the only one to + receive signals (this is enforced by the Python :mod:`signal` module, even + if the underlying thread implementation supports sending signals to + individual threads). This means that signals can't be used as a means of + inter-thread communication. Use locks instead. The variables defined in the :mod:`signal` module are: @@ -78,6 +79,36 @@ The variables defined in the :mod:`signal` module are: One more than the number of the highest signal number. + +.. data:: ITIMER_REAL + + Decrements interval timer in real time, and delivers SIGALRM upon expiration. + + +.. data:: ITIMER_VIRTUAL + + Decrements interval timer only when the process is executing, and delivers + SIGVTALRM upon expiration. + + +.. data:: ITIMER_PROF + + Decrements interval timer both when the process executes and when the + system is executing on behalf of the process. Coupled with ITIMER_VIRTUAL, + this timer is usually used to profile the time spent by the application + in user and kernel space. SIGPROF is delivered upon expiration. + + +The :mod:`signal` module defines one exception: + +.. exception:: ItimerError + + Raised to signal an error from the underlying :func:`setitimer` or + :func:`getitimer` implementation. Expect this error if an invalid + interval timer or a negative time is passed to :func:`setitimer`. + This error is a subtype of :exc:`IOError`. + + The :mod:`signal` module defines the following functions: @@ -110,6 +141,29 @@ The :mod:`signal` module defines the following functions: :manpage:`signal(2)`.) +.. function:: setitimer(which, seconds[, interval]) + + Sets given itimer (one of :const:`signal.ITIMER_REAL`, + :const:`signal.ITIMER_VIRTUAL` or :const:`signal.ITIMER_PROF`) especified + by *which* to fire after *seconds* (float is accepted, different from + :func:`alarm`) and after that every *interval* seconds. The interval + timer specified by *which* can be cleared by setting seconds to zero. + + The old values are returned as a tuple: (delay, interval). + + Attempting to pass an invalid interval timer will cause a + :exc:`ItimerError`. + + .. versionadded:: 2.6 + + +.. function:: getitimer(which) + + Returns current value of a given itimer especified by *which*. + + .. versionadded:: 2.6 + + .. function:: set_wakeup_fd(fd) Set the wakeup fd to *fd*. When a signal is received, a ``'\0'`` byte is @@ -124,7 +178,6 @@ The :mod:`signal` module defines the following functions: exception to be raised. - .. function:: siginterrupt(signalnum, flag) Change system call restart behaviour: if *flag* is :const:`False`, system calls |