implement get set functinality

app/main.py

@@ -1,22 +1,74 @@
 import asyncio
+import io
+import app.redis_db as redis_db
+
+def parse_wire_protocol(message):
+    return _parse_wire_protocol(io.BytesIO(message))
+
+def _parse_wire_protocol(msg_buffer):
+    current_line = msg_buffer.readline()
+    msg_type, remaining = chr(current_line[0]), current_line[1:]
+    if msg_type == '+':
+        return remaining.rstrip(b'\r\n').decode()
+    elif msg_type == ':':
+        return int(remaining)
+    elif msg_type == '$':
+        msg_length = int(remaining)
+        if msg_length == -1:
+            return None
+        result = msg_buffer.read(msg_length)
+        msg_buffer.readline() # move past \r\n
+        return result
+    elif msg_type == '*':
+        array_length = int(remaining)
+        return [_parse_wire_protocol(msg_buffer) for _ in range(array_length)]
+
+def serialize_to_wire(value):
+    if isinstance(value, str):
+        return ('+%s' % value).encode() + b'\r\n'
+    elif isinstance(value, bool) and value:
+        return b"+OK\r\n"
+    elif isinstance(value, int):
+        return (':%s' % value).encode() + b'\r\n'
+    elif isinstance(value, bytes):
+        return (b'$' + str(len(value)).encode() +
+                b'\r\n' + value + b'\r\n')
+    elif value is None:
+        return b'$-1\r\n'
+    elif isinstance(value, list):
+        base = b'*' + str(len(value)).encode() + b'\r\n'
+        for item in value:
+            base += serialize_to_wire(item)
+        return base
 
 class RedisServerProtocol(asyncio.Protocol):
+    def __init__(self, db):
+        self._db = db
+        self.transport = None
+
     def connection_made(self, transport):
         self.transport = transport
 
     def data_received(self, data):
-        message = data.decode()
-        if 'GET' in message:
-            self.transport.write(b"$3\r\n")
-            self.transport.write(b"BAZ\r\n")
-        else:
-            self.transport.write(b"-ERR unknown command\r\n")
-
-def main():
+        parsed = parse_wire_protocol(data)
+        command = parsed[0].decode().lower()
+        if command == 'get':
+            response = self._db.get(parsed[1])
+        elif command == 'set':
+            response = self._db.set(parsed[1], parsed[2])
+
+        wire_response = serialize_to_wire(response)
+        self.transport.write(wire_response)
+
+def main(hostname='localhost', port=6379):
     loop = asyncio.get_event_loop()
-    coro = loop.create_server(RedisServerProtocol, '127.0.0.1', 6379)
-    server = loop.run_until_complete(coro)
+    db = redis_db.DB()
+    protocol_factory = lambda: RedisServerProtocol(db)
 
+    coro = loop.create_server(protocol_factory,
+                              hostname, port)
+    server = loop.run_until_complete(coro)
+    print("Listening on port {}".format(port))
     try:
         loop.run_forever()
     except KeyboardInterrupt:

app/my_redis.py

@@ -0,0 +1,82 @@
+import asyncio
+import io
+
+def parse_wire_protocol(message):
+    return _parse_wire_protocol(io.BytesIO(message))
+
+def _parse_wire_protocol(msg_buffer):
+    current_line = msg_buffer.readline()
+    msg_type, remaining = chr(current_line[0]), current_line[1:]
+    if msg_type == '+':
+        return remaining.rstrip(b'\r\n').decode()
+    elif msg_type == ':':
+        return int(remaining)
+    elif msg_type == '$':
+        msg_length = int(remaining)
+        if msg_length == -1:
+            return None
+        result = msg_buffer.read(msg_length)
+        # There's a '\r\n' that comes after a bulk string
+        # so we .readline() to move passed that crlf.
+        msg_buffer.readline()
+        return result
+    elif msg_type == '*':
+        array_length = int(remaining)
+        return [_parse_wire_protocol(msg_buffer) for _ in range(array_length)]
+
+def serialize_to_wire(value):
+    if isinstance(value, str):
+        return ('+%s' % value).encode() + b'\r\n'
+    elif isinstance(value, bool) and value:
+        return b"+OK\r\n"
+    elif isinstance(value, int):
+        return (':%s' % value).encode() + b'\r\n'
+    elif isinstance(value, bytes):
+        return (b'$' + str(len(value)).encode() +
+                b'\r\n' + value + b'\r\n')
+    elif value is None:
+        return b'$-1\r\n'
+    elif isinstance(value, list):
+        base = b'*' + str(len(value)).encode() + b'\r\n'
+        for item in value:
+            base += serialize_to_wire(item)
+        return base
+
+class RedisServerProtocol(asyncio.Protocol):
+    def __init__(self, redis):
+        self._redis = redis
+        self.transport = None
+
+    def connection_made(self, transport):
+        self.transport = transport
+
+    def data_received(self, data):
+        parsed = parse_wire_protocol(data)
+        # parsed is an array of [command, *args]
+        command = parsed[0].decode().lower()
+        try:
+            method = getattr(self._redis, command)
+        except AttributeError:
+            self.transport.write(
+                b"-ERR unknown command " + parsed[0] + b"\r\n")
+            return
+        result = method(*parsed[1:])
+        serialized = serialize_to_wire(result)
+        self.transport.write(serialized)
+
+class WireRedisConverter(object):
+    def __init__(self, redis):
+        self._redis = redis
+
+    def lrange(self, name, start, end):
+        return self._redis.lrange(name, int(start), int(end))
+
+    def hmset(self, name, *args):
+        converted = {}
+        iter_args = iter(list(args))
+        for key, val in zip(iter_args, iter_args):
+            converted[key] = val
+        return self._redis.hmset(name, converted)
+
+    def __getattr__(self, name):
+        return getattr(self._redis, name)

app/redis_db.py

@@ -0,0 +1,12 @@
+class DB:
+    def __init__(self, db=None):
+        if db is None:
+            db = {}
+        self._db = db
+
+    def get(self, item):
+        return self._db.get(item)
+
+    def set(self, item, value):
+        self._db[item] = value
+        return True