Imported from /home/lorry/working-area/delta_python-packages_posix-ipc-tarball/posix_ipc-0.9.8.tar.gz.HEADposix_ipc-0.9.8master

1 files changed, 86 insertions, 0 deletions

diff --git a/demo/conclusion.py b/demo/conclusion.py
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+# Python modules
+import time
+import mmap
+import os
+import sys
+PY_MAJOR_VERSION = sys.version_info[0]
+# hashlib is only available in Python >= 2.5. I still want to support 
+# older Pythons so I import md5 if hashlib is not available. Fortunately
+# md5 can masquerade as hashlib for my purposes.
+try:
+    import hashlib
+except ImportError:
+    import md5 as hashlib
+
+# 3rd party modules
+import posix_ipc
+
+# Utils for this demo
+import utils
+
+
+PY_MAJOR_VERSION = sys.version_info[0]
+
+utils.say("Oooo 'ello, I'm Mrs. Conclusion!")
+
+params = utils.read_params()
+
+# Mrs. Premise has already created the semaphore and shared memory. 
+# I just need to get handles to them.
+memory = posix_ipc.SharedMemory(params["SHARED_MEMORY_NAME"])
+semaphore = posix_ipc.Semaphore(params["SEMAPHORE_NAME"])
+
+# MMap the shared memory
+mapfile = mmap.mmap(memory.fd, memory.size)
+
+# Once I've mmapped the file descriptor, I can close it without 
+# interfering with the mmap. This also demonstrates that os.close() is a
+# perfectly legitimate alternative to the SharedMemory's close_fd() method.
+os.close(memory.fd)
+
+what_i_wrote = ""
+
+for i in range(0, params["ITERATIONS"]):
+    utils.say("iteration %d" % i)
+    if not params["LIVE_DANGEROUSLY"]:
+        # Wait for Mrs. Premise to free up the semaphore.
+        utils.say("Waiting to acquire the semaphore")
+        semaphore.acquire()
+
+    s = utils.read_from_memory(mapfile)
+
+    while s == what_i_wrote:
+        if not params["LIVE_DANGEROUSLY"]:
+            # Release the semaphore...
+            utils.say("Releasing the semaphore")
+            semaphore.release()
+            # ...and wait for it to become available again.
+            utils.say("Waiting to acquire the semaphore")
+            semaphore.acquire()
+
+        s = utils.read_from_memory(mapfile)
+
+    if what_i_wrote:
+        if PY_MAJOR_VERSION > 2:
+            what_i_wrote = what_i_wrote.encode()
+        try:
+            assert(s == hashlib.md5(what_i_wrote).hexdigest())
+        except AssertionError:
+            utils.raise_error(AssertionError, 
+                              "Shared memory corruption after %d iterations." % i)
+
+    if PY_MAJOR_VERSION > 2:
+        s = s.encode()
+    what_i_wrote = hashlib.md5(s).hexdigest()
+
+    utils.write_to_memory(mapfile, what_i_wrote)
+    
+    if not params["LIVE_DANGEROUSLY"]:
+        utils.say("Releasing the semaphore")
+        semaphore.release()
+
+semaphore.close()
+mapfile.close()
+
+utils.say("")
+utils.say("%d iterations complete" % (i + 1))