[HDFS-3144] Refactor DatanodeID#getName by use

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0-alpha
• Component/s: datanode
• Hadoop Flags: Incompatible change, Reviewed
• Release Note: This change modifies DatanodeID, which is part of the client to server protocol, therefore clients must be upgraded with servers.
• Assignee: Eli Collins
• Reporter: Eli Collins
• Created: 24/Mar/12 23:56
• Updated: 28/Sep/15 20:58
• Resolved: 01/Apr/12 22:16

Description

DatanodeID#getName, which returns a string containing the IP:xferPort of a Datanode, is used in a variety of contexts:

1. Putting the ID in a log message
2. Connecting to the DN for data transfer
3. Getting a string to use as a key (eg for comparison)
4. Using as a hostname, eg for excludes/includes, topology files

Same for DatanodeID#getHost, which returns just the IP part, and sometimes we use it as a key, sometimes we tack on the IPC port, etc.

Let's have a method for each use, eg toString can be used for #1, a new method (eg getDataXferAddr) for #2, a new method (eg getKey) for #3, new method (eg getHostID) for #4, etc. Aside from the code being more clear, we can change the value for particular uses, eg we can change the format in a log message without changing the address used that clients connect to the DN, or modify the address used for data transfer without changing the other uses.

Issue Links

• depends upon: HDFS-3171 The DatanodeID "name" field is overloaded
• relates to: HDFS-5449 WebHdfs compatibility broken between 2.2 and 1.x / 23.x
• relates to: HDFS-3224 Bug in check for DN re-registration with different storage ID