updated chapter 4 and appendix-A files

appendix-A/arcfour_futures.py

@@ -0,0 +1,46 @@
+import sys
+import time
+from concurrent import futures
+from random import randrange
+from arcfour import arcfour
+
+JOBS = 12
+SIZE = 2**18
+
+KEY = b"'Twas brillig, and the slithy toves\nDid gyre"
+STATUS = '{} workers, elapsed time: {:.2f}s'
+
+
+def arcfour_test(size, key):
+    in_text = bytearray(randrange(256) for i in range(size))
+    cypher_text = arcfour(key, in_text)
+    out_text = arcfour(key, cypher_text)
+    assert in_text == out_text, 'Failed arcfour_test'
+    return size
+
+
+def main(workers=None):
+    if workers:
+        workers = int(workers)
+    t0 = time.time()
+
+    with futures.ProcessPoolExecutor(workers) as executor:
+        actual_workers = executor._max_workers
+        to_do = []
+        for i in range(JOBS, 0, -1):
+            size = SIZE + int(SIZE / JOBS * (i - JOBS/2))
+            job = executor.submit(arcfour_test, size, KEY)
+            to_do.append(job)
+
+        for future in futures.as_completed(to_do):
+            res = future.result()
+            print('{:.1f} KB'.format(res/2**10))
+
+    print(STATUS.format(actual_workers, time.time() - t0))
+
+if __name__ == '__main__':
+    if len(sys.argv) == 2:
+        workers = int(sys.argv[1])
+    else:
+        workers = None
+    main(workers)