Implement reconnection strategy class

Add built-in reconnect strategy class based on Round Robin.
@params:
  peers
  nattempts

Return next connection or error if all URIs are unavailable.

Closes #106

Author: Konstantin Belyavskiy

client.py

@@ -0,0 +1,97 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import sys
+import time
+
+from tarantool.connection import Connection
+from tarantool.const import (
+    SOCKET_TIMEOUT,
+    RECONNECT_MAX_ATTEMPTS,
+    RECONNECT_DELAY,
+)
+
+from tarantool.error import (
+    Error,
+    DatabaseError,
+    NetworkError,
+    NetworkWarning,
+)
+
+from tarantool.schema import (
+    Schema,
+    SchemaError
+)
+
+from tarantool.utils import (
+    ENCODING_DEFAULT
+)
+
+class MeshConnection(Connection):
+    def __init__(self, addrs, user, password, connect_now, encoding):
+        self.addrs = addrs
+        self.nattempts = 2 * len(addrs) + 1
+        self.pos = 0
+        host = addrs[self.pos]['host']
+        port = addrs[self.pos]['port']
+        super(MeshConnection, self).__init__(host=host,
+                                             port=port,
+                                             user=user,
+                                             password=password,
+                                             connect_now=connect_now,
+                                             encoding=encoding)
+
+    def _opt_reconnect(self):
+        ntries = self.nattempts
+        print "QQQ MeshConnection:_opt_reconnect", ntries, self.pos, len(self.addrs)
+        while ntries > 0:
+            try:
+                super(MeshConnection, self)._opt_reconnect()
+                print "MeshConnection: success"
+                break
+            except NetworkError:
+                print "MeshConnection: gocha!"
+            ntries -= 1
+            self.pos = (self.pos + 1) % len(self.addrs)
+            self.host = self.addrs[self.pos]['host']
+            self.port = self.addrs[self.pos]['port']
+        else:
+            print "MeshConnection: failure"
+            raise NetworkError
+        print "MeshConnection: reconnect done"
+
+def connectmesh(addrs=({'host': 'localhost', 'port': 3301},), user=None,
+                password=None, connect_now=True, encoding=ENCODING_DEFAULT):
+    '''
+    Create a connection to the Tarantool server.
+
+    :param str host: Server hostname or IP-address
+    :param int port: Server port
+
+    :rtype: :class:`~tarantool.connection.Connection`
+
+    :raise: `NetworkError`
+    '''
+
+    return MeshConnection(addrs=addrs,
+                          user=user,
+                          password=password,
+                          connect_now=connect_now,
+                          encoding=encoding)
+
+addrs=(
+    {'host': 'localhost', 'port': 3301},
+    {'host': 'localhost', 'port': 3304},
+)
+
+con = connectmesh(addrs)
+
+while True:
+    try:
+        print con.ping()
+    except NetworkError:
+        print 'NetworkError !'
+        break
+    except Exception as e:
+        print e
+    time.sleep(1)

tarantool/connection.py

@@ -335,6 +335,7 @@ def check():  # Check that connection is alive
         try:
             self.inconnect = True
             self.handshake()
+            self.inconnect = False
         except:
             self.inconnect = False
             raise