Implement getting the cluster nodes list from nodes

Periodically call a user-defined Lua function on the current node to
obtain or refresh the full cluster nodes list.

Resolves: #134

Author: msiomkin

tarantool/connection.py

@@ -126,6 +126,7 @@ def __init__(self, host, port,
         self.encoding = encoding
         self.call_16 = call_16
         self.connection_timeout = connection_timeout
+        self.authenticated = False
         if connect_now:
             self.connect()
 
@@ -200,9 +201,11 @@ def connect(self):
         :raise: `NetworkError`
         '''
         try:
+            self.authenticated = False
             self.connect_basic()
             self.handshake()
             self.load_schema()
+            self.authenticated = True
         except Exception as e:
             self.connected = False
             raise NetworkError(e)
@@ -370,14 +373,33 @@ def call(self, func_name, *args):
 
         :rtype: `Response` instance
         '''
-        assert isinstance(func_name, str)
 
         # This allows to use a tuple or list as an argument
         if len(args) == 1 and isinstance(args[0], (list, tuple)):
             args = args[0]
 
+        return self.call_ex(func_name, args, True)
+
+    def call_ex(self, func_name, args=[], reconnect=True):
+        '''
+        Execute CALL request. Call stored Lua function.
+
+        :param func_name: stored Lua function name
+        :type func_name: str
+        :param args: list of function arguments
+        :type args: list or tuple
+        :param reconnect: reconnect before call
+        :type reconnect: boolean
+
+        :rtype: `Response` instance
+        '''
+        assert isinstance(func_name, str)
+
         request = RequestCall(self, func_name, args, self.call_16)
-        response = self._send_request(request)
+        if reconnect:
+            response = self._send_request(request)
+        else:
+            response = self._send_request_wo_reconnect(request)
         return response
 
     def eval(self, expr, *args):
@@ -391,14 +413,33 @@ def eval(self, expr, *args):
 
         :rtype: `Response` instance
         '''
-        assert isinstance(expr, str)
 
         # This allows to use a tuple or list as an argument
         if len(args) == 1 and isinstance(args[0], (list, tuple)):
             args = args[0]
 
+        return self.eval_ex(expr, args, True)
+
+    def eval_ex(self, expr, args=[], reconnect=True):
+        '''
+        Execute EVAL request. Eval Lua expression.
+
+        :param expr: Lua expression
+        :type expr: str
+        :param args: list of function arguments
+        :type args: list or tuple
+        :param reconnect: reconnect before call
+        :type reconnect: boolean
+
+        :rtype: `Response` instance
+        '''
+        assert isinstance(expr, str)
+
         request = RequestEval(self, expr, args)
-        response = self._send_request(request)
+        if reconnect:
+            response = self._send_request(request)
+        else:
+            response = self._send_request_wo_reconnect(request)
         return response
 
     def replace(self, space_name, values):

tarantool/const.py

@@ -86,3 +86,5 @@
 RECONNECT_MAX_ATTEMPTS = 10
 # Default delay between attempts to reconnect (seconds)
 RECONNECT_DELAY = 0.1
+# Default cluster nodes list refresh interval (seconds)
+NODES_REFRESH_INTERVAL = 300

tarantool/mesh_connection.py

@@ -4,13 +4,15 @@
 between tarantool instances and basic Round-Robin strategy.
 '''
 
+import time
 from tarantool.connection import Connection
 from tarantool.error import NetworkError
 from tarantool.utils import ENCODING_DEFAULT
 from tarantool.const import (
     SOCKET_TIMEOUT,
     RECONNECT_MAX_ATTEMPTS,
-    RECONNECT_DELAY
+    RECONNECT_DELAY,
+    NODES_REFRESH_INTERVAL
 )
 
 
@@ -34,12 +36,15 @@ def __init__(self, addrs,
                  reconnect_delay=RECONNECT_DELAY,
                  connect_now=True,
                  encoding=ENCODING_DEFAULT,
-                 strategy_class=RoundRobinStrategy):
+                 strategy_class=RoundRobinStrategy,
+                 nodes_refresh_interval=NODES_REFRESH_INTERVAL):
         self.nattempts = 2 * len(addrs) + 1
         self.strategy = strategy_class(addrs)
         addr = self.strategy.getnext()
         host = addr['host']
         port = addr['port']
+        self.nodes_refresh_interval = nodes_refresh_interval
+        self.last_nodes_refresh = 0
         super(MeshConnection, self).__init__(host=host,
                                              port=port,
                                              user=user,
@@ -63,3 +68,28 @@ def _opt_reconnect(self):
                 self.port = addr['port']
         else:
             raise NetworkError
+
+        if self.authenticated:
+            now = time.time()
+            if now - self.last_nodes_refresh > self.nodes_refresh_interval:
+                self.refresh_nodes(now)
+
+    def refresh_nodes(self, cur_time):
+        resp = super(MeshConnection, self).eval_ex('return get_nodes ~= nil',
+                                                   [], reconnect=False)
+        if not (resp.data and resp.data[0]):
+            return
+
+        resp = super(MeshConnection, self).call_ex('get_nodes', [],
+                                                   reconnect=False)
+
+        if not (resp.data and resp.data[0]):
+            return
+
+        addrs = resp.data[0]
+        if type(addrs) is list:
+            self.strategy.addrs = addrs
+            self.strategy.pos = 0
+            self.last_nodes_refresh = cur_time
+            if not {'host': self.host, 'port': self.port} in addrs:
+                self._opt_reconnect()