[HDFS-6803] Documenting DFSClient#DFSInputStream expectations reading and preading in concurrent context

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.1
• Fix Version/s: 2.7.0
• Component/s: hdfs-client
• Assignee: Michael Stack
• Reporter: Michael Stack
• Created: 01/Aug/14 05:17
• Updated: 24/Apr/15 23:23
• Resolved: 26/Nov/14 11:44

Description

Reviews of the patch posted the parent task suggest that we be more explicit about how DFSIS is expected to behave when being read by contending threads. It is also suggested that presumptions made internally be made explicit documenting expectations.

Before we put up a patch we've made a document of assertions we'd like to make into tenets of DFSInputSteam. If agreement, we'll attach to this issue a patch that weaves the assumptions into DFSIS as javadoc and class comments.

Issue Links

• is related to: HADOOP-10938 Remove thread-safe description in PositionedReadable javadoc
• is related to: HADOOP-10930 HarFsInputStream should implement PositionedReadable with thead-safe.
• is related to: HDFS-6813 WebHdfsFileSystem#OffsetUrlInputStream should implement PositionedReadable with thead-safe.
• relates to: HADOOP-9361 Strictly define the expected behavior of filesystem APIs and write tests to verify compliance