第 16 章： Sentinel ========================= Sentinel 状态以及已连接的两个 Sentinel 实例结构。 .. graphviz:: digraph { label = "\n 图 16-5 master1 的实例结构"; rankdir = LR; node [shape = record]; // master1 [label = " sentinelRedisInstance | flags \n SRI_MASTER | name \n \"master1\" | runid \n \"ee07959afc9d061233191c0f5bfe29580dfad0f4\" | config_epoch \n 0 | addr | down_after_period \n 30000 | quorum \n 2 | parallel_syncs \n 1 | failover_timeout \n 900000 | ... "]; addr [label = " sentinelAddr | ip \n \"127.0.0.1\" | port \n 6379 "]; // master1:addr -> addr:head; } .. graphviz:: digraph { label = "\n 图 16-6 master2 的实例结构"; rankdir = LR; node [shape = record]; // master2 [label = " sentinelRedisInstance | flags \n SRI_MASTER | name \n \"master2\" | runid \n \"a68408b775438a5dee54a638b3a6f3461920158a\" | config_epoch \n 0 | addr | down_after_period \n 50000 | quorum \n 5 | parallel_syncs \n 5 | failover_timeout \n 450000 | ... "]; addr [label = " sentinelAddr | ip \n \"127.0.0.1\" | port \n 12345 "]; // master2:addr -> addr:head; } .. graphviz:: digraph { label = "\n 图 16-7 Sentinel 状态以及 masters 字典"; rankdir = LR; node [shape = record]; // sentinelState [label = " sentinelState | masters | ... "]; masters [label = " dict | \"master1\" | \"master2\" "]; master1 [label = " sentinelRedisInstance | ... | name \n \"master1\" | ... "]; master2 [label = " sentinelRedisInstance | ... | name \n \"master2\" | ... "]; // sentinelState:masters -> masters:head; masters:master1 -> master1:head; masters:master2 -> master2:head; } ---- Sentinel 通过向主服务器发送 ``INFO`` 命令来获得从服务器的信息。 .. graphviz:: digraph { label = "\n 图 16-9 Sentinel 向带有三个从服务器的主服务器发送 INFO 命令"; sentinel [label = "Sentinel", shape = box, width = 4.5, height = 1.0]; master [shape = doublecircle]; node [shape = circle]; edge [dir = none]; master -> slave0; master -> slave1; master -> slave2; edge [dir = forward]; sentinel -> master [label = "INFO"]; } 以及 Sentinel 为这个主服务器以及三个从服务器创建的信息结构。 .. graphviz:: digraph { label = "\n 图 16-10 主服务器和它的三个从服务器"; rankdir = LR; node [shape = record]; master [label = " sentinelRedisInstance | flags \n SRI_MASTER | run_id \n \"7611c59dc3a29aa6fa0609f841bb6a1019008a9c\" | name \n \"master\" | ... | slaves | ... "]; slaves [label = " dict | \"127.0.0.1:11111\" | \"127.0.0.1:22222\" | \"127.0.0.1:33333\" "]; slave0 [label = " sentinelRedisInstance | flags \n SRI_SLAVE | name \n \"127.0.0.1:11111\" | ... "]; slave1 [label = " sentinelRedisInstance | flags \n SRI_SLAVE | name \n \"127.0.0.1:22222\" | ... "]; slave2 [label = " sentinelRedisInstance | flags \n SRI_SLAVE | name \n \"127.0.0.1:33333\" | ... "]; master:slaves -> slaves:head; slaves:slave0 -> slave0:head; slaves:slave1 -> slave1:head; slaves:slave2 -> slave2:head; } ---- Sentinel 通过命令连接向频道发送信息， 并通过订阅连接从频道中获取信息。 .. graphviz:: digraph { label = "\n 图 16-13 Sentinel 同时向服务器发送和接收信息"; rankdir = LR; sentinel [label = "Sentinel", shape = box, height = 1.8]; master [label = "服务器", shape = circle]; sentinel -> master [label = "通过命令连接\n发送信息到频道"]; sentinel -> master [dir = back, label = "通过订阅连接\n从频道中接收信息"]; } ---- 示例：一个 Sentinel 向包括它自己在内的三个 Sentinel 发送信息。 .. graphviz:: digraph { label = "\n 图 16-14 向服务器发送信息"; node [shape = box]; sentinel1 [label = "sentinel1", width = 2.0]; sentinel2 [label = "sentinel2", width = 2.0]; sentinel3 [label = "sentinel3", width = 2.0]; server [label = "服务器", shape = circle]; edge [label = "发送信息\n（命令连接）"]; sentinel1 -> server; edge [style = dashed]; edge [dir = back, label = "接收信息\n（订阅连接）"]; sentinel1 -> server; sentinel2 -> server; sentinel3 -> server; } ---- Redis Sentinel 执行故障转移的整个过程。 .. graphviz:: digraph { label = "\n 图 16-22 将 server2 升级为主服务器"; subgraph cluster_servers { style = invis; node [shape = circle, width = 1.2]; edge [dir = none, style = dashed]; server1 [label = "server1", shape = doublecircle, style = dashed]; server2 [label = "server2"]; server3 [label = "server3"]; server4 [label = "server4"]; server1 -> server2; server1 -> server3; server1 -> server4; } sentinel_system [label = "领头 Sentinel", shape = box, width = 5.0, height = 1.0]; edge [label = "监视"]; sentinel_system -> server1 [style = dashed, label = "已下线", dir = none]; sentinel_system -> server2 [label = "发送命令\nSLAVEOF no one"]; sentinel_system -> server3 [dir = none]; sentinel_system -> server4 [dir = none]; } .. graphviz:: digraph { label = "\n 图 16-23 server2 成功升级为主服务器"; subgraph cluster_servers { style = invis; node [shape = circle, width = 1.2]; edge [dir = none, style = dashed]; server1 [label = "server1", shape = doublecircle, style = dashed]; server2 [label = "server2", shape = doublecircle]; server3 [label = "server3"]; server4 [label = "server4"]; server1 -> server3; server1 -> server4; } sentinel_system [label = "领头 Sentinel", shape = box, width = 5.0, height = 1.0]; edge [label = "监视", dir = none]; sentinel_system -> server1 [style = dashed, label = "已下线"]; sentinel_system -> server2; sentinel_system -> server3; sentinel_system -> server4; } .. graphviz:: digraph { label = "\n 图 16-24 让从服务器复制新的主服务器"; subgraph cluster_servers { style = invis; node [shape = circle, width = 1.2]; edge [dir = none, style = dashed]; server1 [label = "server1", shape = doublecircle, style = dashed]; server2 [label = "server2", shape = doublecircle]; server3 [label = "server3"]; server4 [label = "server4"]; server1 -> server3; server1 -> server4; } sentinel_system [label = "领头 Sentinel", shape = box, width = 5.0, height = 1.0]; sentinel_system -> server1 [style = dashed, label = "已下线", dir = none]; sentinel_system -> server2 [label = "监视", dir = none]; edge [label = "发送命令\nSLAVEOF\n\n"]; sentinel_system -> server3; sentinel_system -> server4; } .. graphviz:: digraph { label = "\n 图 16-25 server3 和 server4 成为 server2 的从服务器"; subgraph cluster_servers { style = invis; node [shape = circle, width = 1.2]; edge [dir = none]; server1 [label = "server1", shape = doublecircle, style = dashed]; server2 [label = "server2", shape = doublecircle]; server3 [label = "server3"]; server4 [label = "server4"]; server2 -> server3; server2 -> server4; } sentinel_system [label = "领头 Sentinel", shape = box, width = 5.0, height = 1.0]; sentinel_system -> server1 [style = dashed, label = "已下线", dir = none]; edge [label = "监视", dir = none]; sentinel_system -> server2; sentinel_system -> server3; sentinel_system -> server4; } .. graphviz:: digraph { label = "\n 图 16-26 server1 被设置为新主服务器的从服务器"; subgraph cluster_servers { style = invis; node [shape = circle, width = 1.2]; edge [dir = none]; server1 [label = "server1", shape = circle, style = dashed]; server2 [label = "server2", shape = doublecircle]; server3 [label = "server3"]; server4 [label = "server4"]; server2 -> server1 [style = dashed]; server2 -> server3; server2 -> server4; } sentinel_system [label = "Sentinel 系统", shape = box, width = 5.0, height = 1.0]; edge [dir = none]; sentinel_system -> server1 [style = dashed, label = "已下线"]; edge [label = "监视"]; sentinel_system -> server2; sentinel_system -> server3; sentinel_system -> server4; } .. graphviz:: digraph { label = "\n 图 16-27 server1 重新上线并成为 server2 的从服务器"; subgraph cluster_servers { style = invis; node [shape = circle, width = 1.2]; edge [dir = none]; server1 [label = "server1"]; server2 [label = "server2", shape = doublecircle]; server3 [label = "server3"]; server4 [label = "server4"]; server2 -> server1; server2 -> server3; server2 -> server4; } sentinel_system [label = "Sentinel 系统", shape = box, width = 5.0, height = 1.0]; edge [label = "监视", dir = none]; sentinel_system -> server1; sentinel_system -> server2; sentinel_system -> server3; sentinel_system -> server4; }