Add pub sub server

ipc_unix/pubsub.py

@@ -0,0 +1,66 @@
+import select
+import socket
+
+import ujson
+from ipc_unix.utils import read_payload
+
+
+class Subscriber:
+    def __init__(self, socket_path):
+        self.socket_path = socket_path
+        self.socket = socket.socket(
+            socket.AF_UNIX, type=socket.SOCK_STREAM | socket.SOCK_NONBLOCK
+        )
+        self.socket.connect(self.socket_path)
+
+    def listen(self):
+        while True:
+            yield self.get_message()
+
+    def get_message(self):
+        return read_payload(self.socket)
+
+    def close(self):
+        self.socket.close()
+
+
+class Publisher:
+    def __init__(self, socket_path):
+        self.socket_path = socket_path
+        self.master_socket = socket.socket(
+            socket.AF_UNIX, type=socket.SOCK_STREAM | socket.SOCK_NONBLOCK
+        )
+        self.master_socket.bind(self.socket_path)
+        self.master_socket.listen()
+        self.connections = []
+
+    def close(self):
+        self.master_socket.close()
+        self.connections.clear()
+
+    def accept_new_connection(self):
+        readable, _, _ = select.select([self.master_socket], [], [], 1)
+
+        if self.master_socket in readable:
+            new_socket, _ = self.master_socket.accept()
+            self.connections.append(new_socket)
+
+    def write(self, message):
+        self.accept_new_connection()
+
+        _, writable, errorable = select.select([], self.connections, [], 1)
+
+        dead_sockets = []
+
+        if writable:
+            data = ujson.dumps(message).encode() + b"\n"
+            for sock in writable:
+                try:
+                    sock.send(data)
+                except BrokenPipeError:
+                    dead_sockets.append(sock)
+
+        for sock in dead_sockets:
+            if sock in self.connections:
+                self.connections.remove(sock)
+            sock.close()

ipc_unix/utils.py

@@ -4,7 +4,7 @@ import ujson
 def read_payload(payload):
     data = b""
     while b"\n" not in data:
-        message = payload.recv(4096)
+        message = payload.recv(2)
         if message == b"":
             break
         data += message

tests/__init__.py

@@ -8,7 +8,7 @@ class EchoServer(server.Server):
         return request
 
 
-def get_random_path() -> str:
+def get_temp_file_path() -> str:
     _, temp_file_path = tempfile.mkstemp()
     os.remove(temp_file_path)
     return temp_file_path

tests/test_pubsub.py

@@ -0,0 +1,28 @@
+from unittest import TestCase
+
+from ipc_unix import pubsub
+from tests import get_temp_file_path
+
+
+class PubSubTestCase(TestCase):
+    def setUp(self):
+        self.socket_path = get_temp_file_path()
+        self.publisher = pubsub.Publisher(self.socket_path)
+        self.subscriber = pubsub.Subscriber(self.socket_path)
+
+    def tearDown(self):
+        self.publisher.close()
+        self.subscriber.close()
+
+    def test_transmits(self):
+        self.publisher.write({"foo": "bar"})
+        response = self.subscriber.get_message()
+        self.assertEqual(response, {"foo": "bar"})
+
+    def test_buffers_messages(self):
+        for i in range(5):
+            self.publisher.write(i)
+        messages = []
+        for i in range(5):
+            messages.append(self.subscriber.get_message())
+        self.assertEqual(messages, [0, 1, 2, 3, 4])

tests/test_server.py

@@ -2,12 +2,12 @@ from functools import partial
 from unittest import TestCase
 
 from ipc_unix import client
-from tests import EchoServer, get_random_path
+from tests import EchoServer, get_temp_file_path
 
 
 class BasicServerTestCase(TestCase):
     def setUp(self):
-        self.socket_path = get_random_path()
+        self.socket_path = get_temp_file_path()
         self.server = EchoServer(self.socket_path)
         self.server.serve_in_thread()
         self.send_to_client = partial(client.send_to, self.socket_path)
@@ -20,8 +20,8 @@ class BasicServerTestCase(TestCase):
         response = self.send_to_client(data)
         self.assertEqual(response, data)
 
-    def test_sending_array(self):
+    def test_sending_string(self):
-        data = ["foo", "bar"]
+        data = "foo"
         response = self.send_to_client(data)
         self.assertEqual(response, data)