feat: stream audio to CB

Uses PyAudio and ZeroMQ to publish audio chunks.

ref: N25B-119

state.py

@@ -0,0 +1,47 @@
+import signal
+import threading
+
+
+class State(object):
+    """
+    Do not create an instance of this class directly: use the instance `state` below. This state must be initiated once,
+    probably when your program starts.
+
+    This class is used to share state between threads. For example, when the program is quit, that all threads can
+    detect this via the `exit_event` property being set.
+    """
+    def __init__(self):
+        self.is_initialized = False
+        self.exit_event = None
+
+    def initialize(self):
+        if self.is_initialized:
+            print("Already initialized")
+            return
+
+        self.exit_event = threading.Event()
+        def handle_exit(_, __):
+            print("Exiting.")
+            self.exit_event.set()
+        signal.signal(signal.SIGINT, handle_exit)
+        signal.signal(signal.SIGTERM, handle_exit)
+
+        self.is_initialized = True
+
+    def deinitialize(self):
+        if not self.is_initialized: return
+        self.is_initialized = False
+
+    def __getattribute__(self, name):
+        # Enforce that the state is initialized before accessing any property (aside from the basic ones)
+        if name in ("initialize", "deinitialize", "is_initialized", "__dict__", "__class__"):
+            return object.__getattribute__(self, name)
+
+        if not self.is_initialized:
+            raise RuntimeError("State must be initialized before accessing '%s'" % name)
+
+        return object.__getattribute__(self, name)
+
+
+# Must call `.initialize` before use
+state = State()