[HDFS-12380] Simplify dataQueue.wait condition logical operation in DataStreamer::run()

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-beta1
• Fix Version/s: 3.0.0-beta1
• Component/s: hdfs-client

Environment

cluster: 3 nodes
os:(Red Hat 2.6.33.20, Red Hat 3.10.0-514.6.1.el7.x86_64, Ubuntu4.4.0-31-generic)
hadoop version: hadoop-3.0.0-beta1
operation: Code review

• Hadoop Flags: Reviewed
• Assignee: liaoyuxiangqin
• Reporter: liaoyuxiangqin
• Created: 31/Aug/17 07:32
• Updated: 01/Sep/17 06:36
• Resolved: 01/Sep/17 06:20

Description

When i read the run() of DataStream class in hdfs-client, i found the following condition code could be more simplify and easy to understand.

DataStreamer.java

// wait for a packet to be sent.
long now = Time.monotonicNow();
while ((!shouldStop() && dataQueue.size() == 0 &&
     (stage != BlockConstructionStage.DATA_STREAMING ||
      stage == BlockConstructionStage.DATA_STREAMING &&
            now - lastPacket < halfSocketTimeout)) || doSleep ) {

as described above code segmet, i find the code of stage !=DATA_STREAMING and stage==DATA_STREAMING appear at the same time in one condition, so i think this condition logical not good understanding and should simplify more.