brave-sampler-zookeeper

This package contains additional trace samplers. They are put in a separate project because they might rely on external libraries (eg ZooKeeper) that you might not want to use.

ZooKeeperSampler

com.github.kristofa.brave.sampler.ZooKeeperSampler is a trace sampler that accesses ZooKeeper to get sample rate. It will also get updated in case sample rate is updated in ZooKeeper. This means it supports updating sample rate and switching tracing on/off at runtime.

Below is an example of using zkCLi to create a znode (/brave/samplerate) which starts with sample rate value of 0.2f (20%) and is than updated to value 0.25f (25%). If you set the sample rate to 0.0f tracing will be disabled.

[zk: localhost:2181(CONNECTED) 15] create /brave null
Created /brave
[zk: localhost:2181(CONNECTED) 16] create /brave/samplerate 0.2
Created /brave/samplerate
[zk: localhost:2181(CONNECTED) 17] get /brave/samplerate
0.2
cZxid = 0x7f
ctime = Sun Oct 27 17:42:10 CET 2013
mZxid = 0x7f
mtime = Sun Oct 27 17:42:10 CET 2013
pZxid = 0x7f
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 2
numChildren = 0
[zk: localhost:2181(CONNECTED) 18] set /brave/samplerate 0.25
cZxid = 0x7f
ctime = Sun Oct 27 17:42:10 CET 2013
mZxid = 0x80
mtime = Sun Oct 27 17:42:47 CET 2013
pZxid = 0x7f
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 2
numChildren = 0
[zk: localhost:2181(CONNECTED) 19] get /brave/samplerate
0.25
cZxid = 0x7f
ctime = Sun Oct 27 17:42:10 CET 2013
mZxid = 0x80
mtime = Sun Oct 27 17:42:47 CET 2013
pZxid = 0x7f
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 2
numChildren = 0
[zk: localhost:2181(CONNECTED) 20]