os.system breaks event detection - Matt Kimball (issue 127)

CHANGELOG.txt

@@ -1,9 +1,10 @@
 Change Log
 ==========
 
-0.6.3a0
+0.6.3a1
 -------
 - Fix code so it builds under PyPy (Gasper Zejn)
+- os.system breaks event detection - Matt Kimball (issue 127)
 
 0.6.2
 -----

RPi/GPIO/__init__.py

@@ -22,4 +22,4 @@
 
 from RPi._GPIO import *
 
-VERSION = '0.6.3a0'
+VERSION = '0.6.3a1'

debian_jessie/changelog

@@ -1,8 +1,8 @@
-rpi.gpio (0.6.3a0~jessie-1) unstable; urgency=low
+rpi.gpio (0.6.3a1~jessie-1) unstable; urgency=low
 
-  * To match new Python package 0.6.3a0
+  * To match new Python package 0.6.3a1
 
- -- Ben Croston <ben@croston.org>  Sat, 15 Oct 2016 19:10:13 +0100
+ -- Ben Croston <ben@croston.org>  Sat, 30 Oct 2016 20:10:13 +0000
 
 rpi.gpio (0.6.2~jessie-1) unstable; urgency=low
 

debian_wheezy/changelog

@@ -1,8 +1,8 @@
-rpi.gpio (0.6.3a0~wheezy-1) unstable; urgency=low
+rpi.gpio (0.6.3a1~wheezy-1) unstable; urgency=low
 
-  * To match new Python package 0.6.3a0
+  * To match new Python package 0.6.3a1
 
- -- Ben Croston <ben@croston.org>  Sat, 15 Oct 2016 19:13:25 +0100
+ -- Ben Croston <ben@croston.org>  Sat, 30 Oct 2016 20:13:25 +0000
 
 rpi.gpio (0.6.2~wheezy-1) unstable; urgency=low
 

make_deb

@@ -3,7 +3,7 @@
 # There may be dependencies I've forgotten to mention!
 # Version numbers may change as well!
 
-VERSION=0.6.3a0
+VERSION=0.6.3a1
 DISTRO=`lsb_release -sc`
 #DEBFULLNAME="Ben Croston"
 #DEBEMAIL="ben@croston.org"

setup.py

@@ -33,7 +33,7 @@
                'Topic :: System :: Hardware']
 
 setup(name             = 'RPi.GPIO',
-      version          = '0.6.3a0',
+      version          = '0.6.3a1',
       author           = 'Ben Croston',
       author_email     = 'ben@croston.org',
       description      = 'A module to control Raspberry Pi GPIO channels',

source/event_gpio.c

@@ -24,6 +24,7 @@ SOFTWARE.
 #include <sys/epoll.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <string.h>
@@ -331,10 +332,7 @@ void *poll_thread(void *threadarg)
 
     thread_running = 1;
     while (thread_running) {
-        if ((n = epoll_wait(epfd_thread, &events, 1, -1)) == -1) {
-            thread_running = 0;
-            pthread_exit(NULL);
-        }
+        n = epoll_wait(epfd_thread, &events, 1, -1);
         if (n > 0) {
             lseek(events.data.fd, 0, SEEK_SET);
             if (read(events.data.fd, &buf, 1) != 1) {
@@ -353,6 +351,15 @@ void *poll_thread(void *threadarg)
                     run_callbacks(g->gpio);
                 }
             }
+        } else if (n == -1) {
+            /*  If a signal is received while we are waiting,
+                epoll_wait will return with an EINTR error.
+                Just try again in that case.  */
+            if (errno == EINTR) {
+                continue;
+            }
+            thread_running = 0;
+            pthread_exit(NULL);
         }
     }
     thread_running = 0;
@@ -534,7 +541,14 @@ int blocking_wait_for_edge(unsigned int gpio, unsigned int edge, int bouncetime,
 
     // wait for edge
     while (!finished) {
-        if ((n = epoll_wait(epfd_blocking, &events, 1, timeout)) == -1) {
+        n = epoll_wait(epfd_blocking, &events, 1, timeout);
+        if (n == -1) {
+            /*  If a signal is received while we are waiting,
+                epoll_wait will return with an EINTR error.
+                Just try again in that case.  */
+            if (errno == EINTR) {
+                continue;
+            }
             epoll_ctl(epfd_blocking, EPOLL_CTL_DEL, g->value_fd, &ev);
             return -2;
         }

test/test.py

@@ -29,6 +29,8 @@
 LOOP_OUT = 22
 """
 
+import os
+import subprocess
 import sys
 import warnings
 import time
@@ -395,6 +397,54 @@ def setUp(self):
         GPIO.setup(LOOP_IN, GPIO.IN)
         GPIO.setup(LOOP_OUT, GPIO.OUT)
 
+    #  Running a shell command with os.sytem has caused problems
+    #  with sending SIGCHLD to the polling thread, causing it
+    #  to exit.  Test for that.
+    def testShellCmdWithWaitForEdge(self):
+        self.finished = False
+        def shellcmd():
+            for i in range(50):
+                os.system('sleep 0')
+                subprocess.call('sleep 0', shell=True)
+            self.finished = True
+        def makehigh():
+            GPIO.output(LOOP_OUT, GPIO.HIGH)
+
+        GPIO.output(LOOP_OUT, GPIO.LOW)
+        t1 = Timer(0.1, shellcmd)
+        t2 = Timer(0.5, makehigh)
+        t1.start()
+        t2.start()
+        starttime = time.time()
+        channel = GPIO.wait_for_edge(LOOP_IN, GPIO.RISING, timeout=1000)
+        endtime = time.time()
+        self.assertGreater(endtime - starttime, 0.5)
+        self.assertLess(endtime - starttime, 0.6)
+        self.assertEqual(channel, LOOP_IN)
+
+        # make sure tasks in this test have finished before continuing
+        while not self.finished:
+            time.sleep(0.1)
+
+    def testShellCmdWithEventCallback(self):
+        self.run_cb = False
+
+        def cb(channel):
+            self.run_cb = True
+
+        GPIO.output(LOOP_OUT, GPIO.LOW)
+        GPIO.add_event_detect(LOOP_IN, GPIO.RISING, callback=cb)
+        time.sleep(0.01)
+
+        for i in range(50):
+            os.system('sleep 0')
+            subprocess.call('sleep 0', shell=True)
+
+        GPIO.output(LOOP_OUT, GPIO.HIGH)
+        time.sleep(0.01)
+        GPIO.remove_event_detect(LOOP_IN)
+        self.assertEqual(self.run_cb, True)
+
     def testWaitForEdgeInLoop(self):
         def makelow():
             GPIO.output(LOOP_OUT, GPIO.LOW)
@@ -405,7 +455,11 @@ def makelow():
         while True:
             t = Timer(0.1, makelow)
             t.start()
-            GPIO.wait_for_edge(LOOP_IN, GPIO.FALLING)
+            starttime = time.time()
+            channel = GPIO.wait_for_edge(LOOP_IN, GPIO.FALLING, timeout=200)
+            endtime = time.time()
+            self.assertLess(endtime-starttime, 0.12)
+            self.assertEqual(channel, LOOP_IN)
             GPIO.output(LOOP_OUT, GPIO.HIGH)
             count += 1
             if time.time() - timestart > 5 or count > 150: