Merge pull request #10 from Borkason/master

Various suggestions and code improvements, fixed one possible mistake

Author: andrewgodwin

asgi_ipc.py

@@ -1,9 +1,7 @@
 from __future__ import unicode_literals
+
 import mmap
 import msgpack
-import os
-import pkg_resources
-import posix_ipc
 import random
 import six
 import string
@@ -12,6 +10,8 @@
 import time
 from asgiref.base_layer import BaseChannelLayer
 
+import pkg_resources
+import posix_ipc
 
 __version__ = pkg_resources.require('asgi_ipc')[0].version
 MB = 1024 * 1024
@@ -31,7 +31,9 @@ class IPCChannelLayer(BaseChannelLayer):
     little... heavier than that.
     """
 
-    def __init__(self, prefix="asgi", expiry=60, group_expiry=86400, capacity=10, channel_capacity=None, channel_memory=100*MB, group_memory=20*MB):
+    def __init__(self, prefix="asgi", expiry=60, group_expiry=86400,
+                 capacity=10, channel_capacity=None,
+                 channel_memory=100 * MB, group_memory=20 * MB):
         super(IPCChannelLayer, self).__init__(
             expiry=expiry,
             group_expiry=group_expiry,
@@ -40,16 +42,24 @@ def __init__(self, prefix="asgi", expiry=60, group_expiry=86400, capacity=10, ch
         )
         self.thread_lock = threading.Lock()
         self.prefix = prefix
-        self.channel_store = MemoryDict("/%s-chan" % self.prefix, size=channel_memory)
+        self.channel_store = MemoryDict(
+            "/%s-chan" % self.prefix,
+            size=channel_memory
+        )
         # Set containing all groups to flush
-        self.group_store = MemoryDict("/%s-group" % self.prefix, size=group_memory)
+        self.group_store = MemoryDict(
+            "/%s-group" % self.prefix,
+            size=group_memory
+        )
 
-    ### ASGI API ###
+    # --------
+    # ASGI API
+    # --------
 
     extensions = ["flush", "groups"]
 
     def send(self, channel, message):
-        # Typecheck
+        # Type check
         assert isinstance(message, dict), "message is not a dict"
         assert self.valid_channel_name(channel), "channel name not valid"
         # Write message into the correct message queue
@@ -61,17 +71,20 @@ def send(self, channel, message):
                 channel_list.append([message, time.time() + self.expiry])
                 self.channel_store[channel] = channel_list
 
-    def receive(self, channels, block=False):
+    def receive(self, channels):
         if not channels:
             return None, None
         channels = list(channels)
-        assert all(self.valid_channel_name(channel) for channel in channels), "one or more channel names invalid"
+        assert all(
+            self.valid_channel_name(channel) for channel in channels
+        ), "one or more channel names invalid"
         random.shuffle(channels)
         # Try to pop off all of the named channels
         with self.thread_lock:
             for channel in channels:
                 channel_list = self.channel_store.get(channel, [])
-                # Keep looping on the channel until we hit no messages or an unexpired one
+                # Keep looping on the channel until
+                # we hit no messages or an unexpired one
                 while True:
                     try:
                         # Popleft equivalent
@@ -83,16 +96,16 @@ def receive(self, channels, block=False):
                         return channel, message
                     except IndexError:
                         break
-                    # If the channel is now empty, delete its key
-                    if not channel_list and channel in self.channel_store:
-                        del self.channel_store[channel]
+                # If the channel is now empty, delete its key
+                if not channel_list and channel in self.channel_store:
+                    del self.channel_store[channel]
         return None, None
 
     def new_channel(self, pattern):
         assert isinstance(pattern, six.text_type)
         # Keep making channel names till one isn't present.
         while True:
-            random_string = "".join(random.choice(string.ascii_letters) for i in range(12))
+            random_string = "".join(random.sample(string.ascii_letters, 12))
             assert pattern.endswith("!") or pattern.endswith("?")
             new_name = pattern + random_string
             # To see if it's present we open the queue without O_CREAT
@@ -102,7 +115,9 @@ def new_channel(self, pattern):
                 else:
                     continue
 
-    ### Groups extension ###
+    # ----------------
+    # Groups extension
+    # ----------------
 
     def group_add(self, group, channel):
         """
@@ -154,7 +169,9 @@ def send_group(self, group, message):
             except self.ChannelFull:
                 pass
 
-    ### Flush extension ###
+    # ---------------
+    # Flush extension
+    # ---------------
 
     def flush(self):
         """
@@ -165,7 +182,7 @@ def flush(self):
             self.group_store.flush()
 
     def __str__(self):
-        return "%s(hosts=%s)" % (self.__class__.__name__, self.hosts)
+        return "%s(prefix=%s)" % (self.__class__.__name__, self.prefix)
 
 
 class MemoryDatastructure(object):
@@ -209,7 +226,8 @@ def __init__(self, path, size=None):
             )
         except ValueError as e:
             raise ValueError(
-                "Unable to allocate shared memory segment (potentially out of memory).\n" +
+                "Unable to allocate shared memory segment"
+                "(potentially out of memory).\n"
                 "Error was: %s" % e
             )
         self.mmap = mmap.mmap(self.shm.fd, self.size)