Fix tests on Mac

Author: user202729

src/sage/doctest/util.py

@@ -762,28 +762,27 @@ def ensure_interruptible_after(seconds: float, max_wait_after_interrupt: float =
     EXAMPLES::
 
         sage: from sage.doctest.util import ensure_interruptible_after
-        sage: with ensure_interruptible_after(1) as data: sleep(3r)
+        sage: with ensure_interruptible_after(1) as data: sleep(3)
 
     ``as data`` is optional, but if it is used, it will contain a few useful values::
 
-        sage: data  # abs tol 0.01
+        sage: data  # abs tol 1
         {'alarm_raised': True, 'elapsed': 1.0}
 
     ``max_wait_after_interrupt`` can be passed if the function may take longer than usual to be interrupted::
 
+        sage: # needs sage.misc.cython
         sage: cython(r'''
-        ....: from posix.time cimport clock_gettime, CLOCK_REALTIME, timespec
+        ....: from posix.time cimport clock_gettime, CLOCK_REALTIME, timespec, time_t
         ....: from cysignals.signals cimport sig_check
-        ....: from time import time as walltime
         ....:
         ....: cpdef void uninterruptible_sleep(double seconds):
         ....:     cdef timespec start_time, target_time
-        ....:     start_walltime = walltime()
         ....:     clock_gettime(CLOCK_REALTIME, &start_time)
         ....:
-        ....:     cdef int floor_seconds = <int>seconds
+        ....:     cdef time_t floor_seconds = <time_t>seconds
         ....:     target_time.tv_sec = start_time.tv_sec + floor_seconds
-        ....:     target_time.tv_nsec = start_time.tv_nsec + <int>((seconds - floor_seconds) * 1e9)
+        ....:     target_time.tv_nsec = start_time.tv_nsec + <long>((seconds - floor_seconds) * 1e9)
         ....:     if target_time.tv_nsec >= 1000000000:
         ....:         target_time.tv_nsec -= 1000000000
         ....:         target_time.tv_sec += 1
@@ -808,23 +807,44 @@ def ensure_interruptible_after(seconds: float, max_wait_after_interrupt: float =
 
     TESTS::
 
-        sage: # we use 1r instead of 1 to avoid unexplained slowdown
-        sage: with ensure_interruptible_after(2) as data: sleep(1r)
+        sage: with ensure_interruptible_after(2) as data: sleep(1)
         Traceback (most recent call last):
         ...
-        RuntimeError: Function terminates early after 1.00... < 2.0000 seconds
-        sage: data  # abs tol 0.01
+        RuntimeError: Function terminates early after 1... < 2.0000 seconds
+        sage: data  # abs tol 1
         {'alarm_raised': False, 'elapsed': 1.0}
-        sage: with ensure_interruptible_after(1) as data: raise ValueError
-        Traceback (most recent call last):
-        ...
-        ValueError
-        sage: data  # abs tol 0.01
-        {'alarm_raised': False, 'elapsed': 0.0}
 
-    ::
+    The test above requires a large tolerance, because both ``time.sleep`` and
+    ``from posix.unistd cimport usleep`` may have slowdown on the order of 0.1s on Mac,
+    likely because the system is idle and GitHub CI switches the program out,
+    and context switch back takes time. So we use busy wait instead::
 
         sage: # needs sage.misc.cython
+        sage: cython(r'''
+        ....: from posix.time cimport clock_gettime, CLOCK_REALTIME, timespec, time_t
+        ....: from cysignals.signals cimport sig_check
+        ....:
+        ....: cpdef void interruptible_sleep(double seconds):
+        ....:     cdef timespec start_time, target_time
+        ....:     clock_gettime(CLOCK_REALTIME, &start_time)
+        ....:
+        ....:     cdef time_t floor_seconds = <time_t>seconds
+        ....:     target_time.tv_sec = start_time.tv_sec + floor_seconds
+        ....:     target_time.tv_nsec = start_time.tv_nsec + <long>((seconds - floor_seconds) * 1e9)
+        ....:     if target_time.tv_nsec >= 1000000000:
+        ....:         target_time.tv_nsec -= 1000000000
+        ....:         target_time.tv_sec += 1
+        ....:
+        ....:     while True:
+        ....:         sig_check()
+        ....:         clock_gettime(CLOCK_REALTIME, &start_time)
+        ....:         if start_time.tv_sec > target_time.tv_sec or (start_time.tv_sec == target_time.tv_sec and start_time.tv_nsec >= target_time.tv_nsec):
+        ....:             break
+        ....: ''')
+        sage: with ensure_interruptible_after(2) as data: interruptible_sleep(1)
+        Traceback (most recent call last):
+        ...
+        RuntimeError: Function terminates early after 1.00... < 2.0000 seconds
         sage: with ensure_interruptible_after(1) as data: uninterruptible_sleep(2)
         Traceback (most recent call last):
         ...
@@ -837,6 +857,15 @@ def ensure_interruptible_after(seconds: float, max_wait_after_interrupt: float =
         RuntimeError: Function is not interruptible within 1.0000 seconds, only after 2.00... seconds
         sage: data  # abs tol 0.01
         {'alarm_raised': True, 'elapsed': 2.0}
+
+    ::
+
+        sage: with ensure_interruptible_after(1) as data: raise ValueError
+        Traceback (most recent call last):
+        ...
+        ValueError
+        sage: data  # abs tol 0.01
+        {'alarm_raised': False, 'elapsed': 0.0}
     """
     seconds = float(seconds)
     max_wait_after_interrupt = float(max_wait_after_interrupt)