cpython: f8c49a930015 (original) (raw)

Mercurial > cpython

changeset 69935:f8c49a930015

Issue #8407: The signal handler writes the signal number as a single byte instead of a nul byte into the wakeup file descriptor. So it is possible to wait more than one signal and know which signals were raised. [#8407]

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--- a/Doc/library/signal.rst +++ b/Doc/library/signal.rst @@ -262,13 +262,17 @@ The :mod:signal module defines the fol .. function:: set_wakeup_fd(fd)

• Set the wakeup fd to fd. When a signal is received, a '\0' byte is
• written to the fd. This can be used by a library to wakeup a poll or select
• call, allowing the signal to be fully processed.

• Set the wakeup file descriptor to fd. When a signal is received, the
• signal number is written as a single byte into the fd. This can be used by
• a library to wakeup a poll or select call, allowing the signal to be fully
• processed. The old wakeup fd is returned. fd must be non-blocking. It is up to the library to remove any bytes before calling poll or select again.
• Use for example struct.unpack('%uB' % len(data), data) to decode the
• signal numbers list. + When threads are enabled, this function can only be called from the main thread; attempting to call it from other threads will cause a :exc:ValueError exception to be raised.

--- a/Doc/whatsnew/3.3.rst +++ b/Doc/whatsnew/3.3.rst @@ -131,6 +131,10 @@ signal

• :func:~signal.sigpending: examine pending functions ;
• :func:~signal.sigwait: wait a signal. +* The signal handler writes the signal number as a single byte instead of

• a nul byte into the wakeup file descriptor. So it is possible to wait more
• than one signal and know which signals were raised. + Optimizations =============

--- a/Lib/test/test_signal.py +++ b/Lib/test/test_signal.py @@ -5,6 +5,7 @@ import gc import pickle import select import signal +import struct import subprocess import traceback import sys, os, time, errno @@ -236,6 +237,11 @@ class WakeupSignalTests(unittest.TestCas TIMEOUT_FULL = 10 TIMEOUT_HALF = 5

• def check_signum(self, *signals):

•    data = os.read(self.read, len(signals)+1)[](#l3.16)

•    raised = struct.unpack('%uB' % len(data), data)[](#l3.17)

•    self.assertSequenceEqual(raised, signals)[](#l3.18)

+ def test_wakeup_fd_early(self): import select @@ -249,6 +255,7 @@ class WakeupSignalTests(unittest.TestCas select.select([self.read], [], [], self.TIMEOUT_FULL) after_time = time.time() self.assertTrue(after_time - mid_time < self.TIMEOUT_HALF)

•    self.check_signum(signal.SIGALRM)[](#l3.27)

def test_wakeup_fd_during(self): import select @@ -260,6 +267,14 @@ class WakeupSignalTests(unittest.TestCas [self.read], [], [], self.TIMEOUT_FULL) after_time = time.time() self.assertTrue(after_time - before_time < self.TIMEOUT_HALF)

•    self.check_signum(signal.SIGALRM)[](#l3.35)

+

• def test_signum(self):

•    old_handler = signal.signal(signal.SIGUSR1, lambda x,y:None)[](#l3.38)

•    self.addCleanup(signal.signal, signal.SIGUSR1, old_handler)[](#l3.39)

•    os.kill(os.getpid(), signal.SIGUSR1)[](#l3.40)

•    os.kill(os.getpid(), signal.SIGALRM)[](#l3.41)

•    self.check_signum(signal.SIGUSR1, signal.SIGALRM)[](#l3.42)

def setUp(self): import fcntl

--- a/Misc/NEWS +++ b/Misc/NEWS @@ -140,6 +140,10 @@ Core and Builtins Library ------- +- Issue #8407: The signal handler writes the signal number as a single byte

• instead of a nul byte into the wakeup file descriptor. So it is possible to
• wait more than one signal and know which signals were raised. +

• Issue #8407: Add pthread_kill(), sigpending() and sigwait() functions to the signal module.

--- a/Modules/signalmodule.c +++ b/Modules/signalmodule.c @@ -176,6 +176,7 @@ checksignals_witharg(void * unused) static void trip_signal(int sig_num) {

• unsigned char byte; Handlers[sig_num].tripped = 1; if (is_tripped) return;

@@ -183,8 +184,10 @@ trip_signal(int sig_num) cleared in PyErr_CheckSignals() before .tripped. */ is_tripped = 1; Py_AddPendingCall(checksignals_witharg, NULL);

• if (wakeup_fd != -1)

•    write(wakeup_fd, "\0", 1);[](#l5.16)

• if (wakeup_fd != -1) {

•    byte = (unsigned char)sig_num;[](#l5.18)

•    write(wakeup_fd, &byte, 1);[](#l5.19)

• }

} static void