From 95673cb2c203d464e2dbb8749f0f9eec26b57965 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krist=C3=B3f=20T=C3=B3th?= <kristof.toth@avatao.com>
Date: Thu, 13 Dec 2018 22:06:13 +0100
Subject: [PATCH] Initial commit

---
 pipe_io_server.py | 100 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 pipe_io_server.py

diff --git a/pipe_io_server.py b/pipe_io_server.py
new file mode 100644
index 0000000..934811f
--- /dev/null
+++ b/pipe_io_server.py
@@ -0,0 +1,100 @@
+from threading import Thread
+from queue import Queue
+from os import mkfifo, remove
+from os.path import exists, join
+from signal import signal, SIGTERM, SIGINT
+from secrets import token_urlsafe
+
+
+class PipeWriterThread(Thread):
+    def __init__(self, to_write_queue, pipe_path):
+        super().__init__()
+        self._to_write_queue = to_write_queue
+        self._pipe_path = pipe_path
+
+    def run(self):
+        while True:
+            message = self._to_write_queue.get(block=True)
+            if message is None:
+                break
+            with open(self._pipe_path, 'wb') as pipe:
+                pipe.write(message)
+
+    def stop(self):
+        self._to_write_queue.put(None)
+        self.join()
+
+
+class PipeReaderThread(Thread):
+    _stop_sequence = b'stop_reading'
+
+    def __init__(self, results_queue, pipe_path):
+        super().__init__()
+        self._results_queue = results_queue
+        self._pipe_path = pipe_path
+
+    def run(self):
+        while True:
+            with open(self._pipe_path, 'rb') as pipe:
+                message = pipe.read()
+            if message == self._stop_sequence:
+                break
+            self._results_queue.put(message, block=True)
+
+    def stop(self):
+        with open(self._pipe_path, 'wb') as pipe:
+            pipe.write(self._stop_sequence)
+        self.join()
+
+
+class PipeHandler:
+    def __init__(self, pipe_path):
+        self._pipe_path = pipe_path
+
+    def recreate(self):
+        self.remove()
+        mkfifo(self._pipe_path)
+
+    def remove(self):
+        if exists(self._pipe_path):
+            remove(self._pipe_path)
+
+
+class PipeIOServer:
+    def __init__(self, in_pipe=None, out_pipe=None):
+        self.in_pipe, self.out_pipe = in_pipe, out_pipe
+        self._create_pipes()
+
+        self._message_queue = Queue()
+        self._io_threads = {
+            'reader': PipeReaderThread(self._message_queue, self.in_pipe),
+            'writer': PipeWriterThread(self._message_queue, self.out_pipe)
+        }
+
+    def _create_pipes(self):
+        if not self.in_pipe or not self.out_pipe:
+            pipe_id = token_urlsafe(6)
+            self.in_pipe = join('/tmp', f'in_pipe_{pipe_id}')
+            self.out_pipe = join('/tmp', f'out_pipe_{pipe_id}')
+        PipeHandler(self.in_pipe).recreate()
+        PipeHandler(self.out_pipe).recreate()
+
+    def run(self):
+        for thread in self._io_threads.values():
+            thread.start()
+
+    def stop(self):
+        for thread in self._io_threads.values():
+            thread.stop()
+        PipeHandler(self.in_pipe).remove()
+        PipeHandler(self.out_pipe).remove()
+
+
+if __name__ == "__main__":
+    pipe_io = PipeIOServer()
+    signal(SIGTERM, lambda a, b: pipe_io.stop())
+    signal(SIGINT, lambda a, b: pipe_io.stop())
+    pipe_io.run()
+    print('Running pipe IO server with named pipes:')
+    print(f'Input:  {pipe_io.in_pipe}')
+    print(f'Output: {pipe_io.out_pipe}')