Create a Lock API for Datasets

[NolanRogers]

In ways that are appropriate to the purpose of being able to read, write, delete, rename datasets & members.

Need foundational **locking service ** to implement write(s) in ZSS:

• to lock a resource
• to free/unlock a resource
• to check if lock exists
• to calculate or get content hash

Some more research done in this regard:

• optimistic locking approach

An optimistic locking approach:

• fetch content, and calculate content hash
• append content hast to response headers as e-tag
• let user modify content
• fetch and calculate content hash again, and compare it with e-tag of modified file
• if same, grab lock , else throw error
• replace content with modified content, and save
• and free, lock

RSE Dataset locking mechanism:
https://www.ibm.com/support/knowledgecenter/en/SSBDYH_3.2/com.ibm.zexpl.config.hostconfigref.doc/topics/dataset_lock_owner.html

[1000TurquoisePogs]

This ticket was premature, and a solution that plays well with ispf is needed. More tickets will be made.

[NakulManchanda]

Progress is being tracked with story
#498
Locking functionality is implemented

• Work is being done on releasing lock on configurable timeout
  Release remaining dataset locks when file editor stops #570