ch20 examples

ramalho · ramalho · commit 7b193e0c13d7 · 2021-02-12T23:41:11.000-03:00
diff --git a/20-concurrency/primes/spinner_async_nap.py b/20-concurrency/primes/spinner_async_nap.py
diff --git a/20-concurrency/spinner_async.py b/20-concurrency/spinner_async.py
@@ -0,0 +1,41 @@
+# spinner_async.py
+
+# credits: Example by Luciano Ramalho inspired by
+# Michele Simionato's multiprocessing example in the python-list:
+# https://mail.python.org/pipermail/python-list/2009-February/675659.html
+
+# tag::SPINNER_ASYNC_TOP[]
+import asyncio
+import itertools
+
+async def spin(msg: str) -> None:  # <1>
+    for char in itertools.cycle(r'\|/-'):
+        status = f'\r{char} {msg}'
+        print(status, flush=True, end='')
+        try:
+            await asyncio.sleep(.1)  # <2>
+        except asyncio.CancelledError:  # <3>
+            break
+    blanks = ' ' * len(status)
+    print(f'\r{blanks}\r', end='')
+
+async def slow() -> int:
+    await asyncio.sleep(3)  # <4>
+    return 42
+# end::SPINNER_ASYNC_TOP[]
+
+# tag::SPINNER_ASYNC_START[]
+def main() -> None:  # <1>
+    result = asyncio.run(supervisor())  # <2>
+    print('Answer:', result)
+
+async def supervisor() -> int:  # <3>
+    spinner = asyncio.create_task(spin('thinking!'))  # <4>
+    print('spinner object:', spinner)  # <5>
+    result = await slow()  # <6>
+    spinner.cancel()  # <7>
+    return result
+
+if __name__ == '__main__':
+    main()
+# end::SPINNER_ASYNC_START[]
diff --git a/20-concurrency/spinner_async_experiment.py b/20-concurrency/spinner_async_experiment.py
@@ -6,8 +6,7 @@
 
 import asyncio
 import itertools
-
-import primes
+import time
 
 async def spin(msg: str) -> None:
     for char in itertools.cycle(r'\|/-'):
@@ -21,7 +20,7 @@ async def spin(msg: str) -> None:
 
 # tag::SPINNER_ASYNC_EXPERIMENT[]
 async def slow() -> int:
-    primes.is_prime(5_000_111_000_222_021)  # <4>
+    time.sleep(3)  # <4>
     return 42
 
 async def supervisor() -> int:
diff --git a/20-concurrency/spinner_proc.py b/20-concurrency/spinner_proc.py
@@ -0,0 +1,47 @@
+# spinner_proc.py
+
+# credits: Adapted from Michele Simionato's
+# multiprocessing example in the python-list:
+# https://mail.python.org/pipermail/python-list/2009-February/675659.html
+
+# tag::SPINNER_PROC_IMPORTS[]
+from multiprocessing import Process, Event  # <1>
+from multiprocessing import synchronize     # <2>
+import itertools
+import time
+
+def spin(msg: str, done: synchronize.Event) -> None:  # <3>
+# end::SPINNER_PROC_IMPORTS[]
+    for char in itertools.cycle(r'\|/-'):
+        status = f'\r{char} {msg}'
+        print(status, end='', flush=True)
+        if done.wait(.1):
+            break
+    blanks = ' ' * len(status)
+    print(f'\r{blanks}\r', end='')
+
+def slow() -> int:
+    time.sleep(3)
+    return 42
+
+# tag::SPINNER_PROC_SUPER[]
+def supervisor() -> int:
+    done = Event()
+    spinner = Process(target=spin,               # <4>
+                      args=('thinking!', done))
+    print('spinner object:', spinner)            # <5>
+    spinner.start()
+    result = slow()
+    done.set()
+    spinner.join()
+    return result
+# end::SPINNER_PROC_SUPER[]
+
+def main() -> None:
+    result = supervisor()
+    print('Answer:', result)
+
+
+if __name__ == '__main__':
+    main()
+
diff --git a/20-concurrency/spinner_thread.py b/20-concurrency/spinner_thread.py
@@ -7,8 +7,7 @@
 # tag::SPINNER_THREAD_TOP[]
 from threading import Thread, Event
 import itertools
-
-from primes import is_prime
+import time
 
 def spin(msg: str, done: Event) -> None:  # <1>
     for char in itertools.cycle(r'\|/-'):  # <2>
@@ -20,7 +19,7 @@ def spin(msg: str, done: Event) -> None:  # <1>
     print(f'\r{blanks}\r', end='')  # <6>
 
 def slow() -> int:
-    is_prime(5_000_111_000_222_021)  # <7>
+    time.sleep(3)  # <7>
     return 42
 # end::SPINNER_THREAD_TOP[]
 
