zookeeper(3)——watcher
zookeeper(3)——watcher
羊羽shine
发布于 2019-05-29 16:37:54
发布于 2019-05-29 16:37:54
针对每个节点的操作，都会有一个监督者 watcher。 当监控的某个对象znode发生了变化，就会触发watcher事件 zk中的watch是一次性的，触发后立即销毁。 父节点，子节点增删改都能触发其watcher 针对不同类型的操作，触发的watcher事件也不同 1 节点创建事件 2 节点删除事件 3 节点数据变化事件
作用场景
统一资源配置
创建父节点触发
[zk: localhost:2181(CONNECTED) 59] stat /test watch
Node does not exist: /test
[zk: localhost:2181(CONNECTED) 60] create /test testd-data
WATCHER::
Created /test
WatchedEvent state:SyncConnected type:NodeCreated path:/test修改父节点
[zk: localhost:2181(CONNECTED) 64] get /test watch
testd-data
cZxid = 0x1d
ctime = Wed May 08 19:06:40 CST 2019
mZxid = 0x1d
mtime = Wed May 08 19:06:40 CST 2019
pZxid = 0x1d
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 10
numChildren = 0
[zk: localhost:2181(CONNECTED) 65] set /test newdata
WATCHER::
WatchedEvent state:SyncConnected type:NodeDataChanged path:/testcZxid = 0x1d
ctime = Wed May 08 19:06:40 CST 2019
mZxid = 0x1e
mtime = Wed May 08 19:12:27 CST 2019
pZxid = 0x1d
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 0删除父节点
[zk: localhost:2181(CONNECTED) 66] get /test watch
newdata
cZxid = 0x1d
ctime = Wed May 08 19:06:40 CST 2019
mZxid = 0x1e
mtime = Wed May 08 19:12:27 CST 2019
pZxid = 0x1d
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 0
[zk: localhost:2181(CONNECTED) 67] delete /test
WATCHER::
WatchedEvent state:SyncConnected type:NodeDeleted path:/test子节点创建
[zk: localhost:2181(CONNECTED) 78] ls /test watch
[]
[zk: localhost:2181(CONNECTED) 79] create /test/sub test
WATCHER::Created /test/sub
WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/tes修改子节点
依然触发的是NodeDataChanged事件
[zk: localhost:2181(CONNECTED) 83] get /test/sub watch
test
cZxid = 0x26
ctime = Wed May 08 19:30:32 CST 2019
mZxid = 0x26
mtime = Wed May 08 19:30:32 CST 2019
pZxid = 0x26
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 4
numChildren = 0
[zk: localhost:2181(CONNECTED) 84] set /test/sub testdata
WATCHER::
WatchedEvent state:SyncConnected type:NodeDataChanged path:/test/subcZxid = 0x26
ctime = Wed May 08 19:30:32 CST 2019
mZxid = 0x27
mtime = Wed May 08 19:30:54 CST 2019
pZxid = 0x26
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 8
numChildren = 0删除子节点
[zk: localhost:2181(CONNECTED) 80] ls /test watch
[sub]
[zk: localhost:2181(CONNECTED) 81] delete /test/sub
[zk: localhost:2181(CONNECTED) 82]
WATCHER::
WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/test本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2019.05.08 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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