Merge pull request ifwe#3 from ifwe/ha_with_sentinel_rebase_new

Merge latest andyqzb patch

Author: mishan

README.md

@@ -111,9 +111,10 @@ Twemproxy can be configured through a YAML file specified by the -c or --conf-fi
 + **server_retry_timeout**: The timeout value in msec to wait for before retrying on a temporarily ejected server, when auto_eject_host is set to true. Defaults to 30000 msec.
 + **server_failure_limit**: The number of consecutive failures on a server that would lead to it being temporarily ejected when auto_eject_host is set to true. Defaults to 2.
 + **servers**: A list of server address, port and weight (name:port:weight or ip:port:weight) for this server pool.
++ **sentinels**: A list of redis sentinel address, port and weight (name:port:weight or ip:port:weight) for this server pool. Weight of sentinel is not used.
 
 
-For example, the configuration file in [conf/nutcracker.yml](conf/nutcracker.yml), also shown below, configures 5 server pools with names - _alpha_, _beta_, _gamma_, _delta_ and omega. Clients that intend to send requests to one of the 10 servers in pool delta connect to port 22124 on 127.0.0.1. Clients that intend to send request to one of 2 servers in pool omega connect to unix path /tmp/gamma. Requests sent to pool alpha and omega have no timeout and might require timeout functionality to be implemented on the client side. On the other hand, requests sent to pool beta, gamma and delta timeout after 400 msec, 400 msec and 100 msec respectively when no response is received from the server. Of the 5 server pools, only pools alpha, gamma and delta are configured to use server ejection and hence are resilient to server failures. All the 5 server pools use ketama consistent hashing for key distribution with the key hasher for pools alpha, beta, gamma and delta set to fnv1a_64 while that for pool omega set to hsieh. Also only pool beta uses [nodes names](notes/recommendation.md#node-names-for-consistent-hashing) for consistent hashing, while pool alpha, gamma, delta and omega use 'host:port:weight' for consistent hashing. Finally, only pool alpha and beta can speak the redis protocol, while pool gamma, deta and omega speak memcached protocol.
+For example, the configuration file in [conf/nutcracker.yml](conf/nutcracker.yml), also shown below, configures 5 server pools with names - _alpha_, _beta_, _gamma_, _delta_ and omega. Clients that intend to send requests to one of the 10 servers in pool delta connect to port 22124 on 127.0.0.1. Clients that intend to send request to one of 2 servers in pool omega connect to unix path /tmp/gamma. Requests sent to pool alpha and omega have no timeout and might require timeout functionality to be implemented on the client side. On the other hand, requests sent to pool beta, gamma and delta timeout after 400 msec, 400 msec and 100 msec respectively when no response is received from the server. Of the 5 server pools, only pools alpha, gamma and delta are configured to use server ejection and hence are resilient to server failures. All the 5 server pools use ketama consistent hashing for key distribution with the key hasher for pools alpha, beta, gamma and delta set to fnv1a_64 while that for pool omega set to hsieh. Also only pool beta uses [nodes names](notes/recommendation.md#node-names-for-consistent-hashing) for consistent hashing, while pool alpha, gamma, delta and omega use 'host:port:weight' for consistent hashing. Finally, pool alpha, beta and sigma can speak the redis protocol, while pool gamma, deta and omega speak memcached protocol.
 
     alpha:
       listen: 127.0.0.1:22121
@@ -183,6 +184,22 @@ For example, the configuration file in [conf/nutcracker.yml](conf/nutcracker.yml
        - 127.0.0.1:11214:100000
        - 127.0.0.1:11215:1
 
+    sigma:
+      listen: 127.0.0.1:22125
+      hash: fnv1a_64
+      distribution: ketama
+      auto_eject_hosts: false
+      redis: true
+      server_retry_timeout: 2000
+      server_failure_limit: 1
+      servers:
+        - 127.0.0.1:6379:1 server1
+        - 127.0.0.1:6380:1 server2
+      sentinels:
+        - 127.0.0.1:26379:1
+        - 127.0.0.1:26380:1
+        - 127.0.0.1:26381:1
+
 Finally, to make writing a syntactically correct configuration file easier, twemproxy provides a command-line argument -t or --test-conf that can be used to test the YAML configuration file for any syntax error.
 
 ## Observability

conf/nutcracker.yml

@@ -65,3 +65,19 @@ omega:
   servers:
    - 127.0.0.1:11214:100000
    - 127.0.0.1:11215:1
+
+sigma:
+  listen: 127.0.0.1:22125
+  hash: fnv1a_64
+  distribution: ketama
+  auto_eject_hosts: false
+  redis: true
+  server_retry_timeout: 2000
+  server_failure_limit: 1
+  servers:
+    - 127.0.0.1:6379:1 server1
+    - 127.0.0.1:6380:1 server2
+  sentinels:
+    - 127.0.0.1:26379:1
+    - 127.0.0.1:26380:1
+    - 127.0.0.1:26381:1

notes/redis.md

@@ -460,4 +460,28 @@
     + *MUST* set all redis with a same passwd, and all twemproxy with the same passwd
     + Length of password should less than 256 
 
+## redis-sentinel feature
+
++ You can configure sentinel for a pool with 'sentinels' to let twemproxy works with sentinel:
+
+        sigma:
+          listen: 127.0.0.1:22125
+          hash: fnv1a_64
+          distribution: ketama
+          auto_eject_hosts: false
+          redis: true
+          server_retry_timeout: 2000
+          server_failure_limit: 1
+          servers:
+            - 127.0.0.1:6379:1 server1
+            - 127.0.0.1:6380:1 server2
+          sentinels:
+            - 127.0.0.1:26379:1
+            - 127.0.0.1:26380:1
+            - 127.0.0.1:26381:1
+
++ notice:
+    + You should configure all the sentinels you used. Twemproxy will connect to the alive sentinels when some are down
+    + Weight of sentinel is not used. Twemproxy keep it because of server load code reuse
+
 

src/Makefile.am

@@ -38,6 +38,7 @@ nutcracker_SOURCES =			\
 	nc_connection.c nc_connection.h	\
 	nc_client.c nc_client.h		\
 	nc_server.c nc_server.h		\
+	nc_sentinel.c nc_sentinel.h	\
 	nc_proxy.c nc_proxy.h		\
 	nc_message.c nc_message.h	\
 	nc_request.c			\