GitHub user agoodm opened a pull request:
https://github.com/apache/zeppelin/pull/1470
ZEPPELIN-1423 - Allow users to specify pre/post-execute hooks for
interpreters
### What is this PR for?
See #1439. This is a second attempt based on prior feedback, particularly
from @Leemoonsoo who advised that it would be better to contain all of the code
inside of the Interpreter Process. Aside from this, the major changes since the
previous PR are:
- The terminology "hooks" is used instead of "callbacks". Since the
information being passed to the interpreter isn't actually a "callback",
strictly speaking, the more general term "hook" is probably a better choice.
All variable / class names were updated correspondingly.
- The registry is now keyed by class name rather than the `replName`
specified by the magic on top of the paragraph. The interface provided by
`ZeppelinContext` allows for a `replName` to be converted to `className`
through an internal mapping.
- Two new event codes, "PRE_EXEC_DEV" and "POST_EXEC_DEV" have been added.
This is primarily intended to separate use cases for the interpreter
maintainers (via subclasses of `Interpreter`) and the notebook users (via the
`ZeppelinContext` class), as otherwise user attempts at registering a hook
would overwrite that set by the interpreter maintainer.
- Global scope for hook registration is supported for the developer use
cases.
### What type of PR is it?
New Feature
### What is the Jira issue?
[ZEPPELIN-1423](https://issues.apache.org/jira/browse/ZEPPELIN-1423)
### How should this be tested?
In a new note, add the following lines of code to a paragraph:
```python
%pyspark
z.registerCallback("post_exec", "print 'This code should be executed before
the parapgraph code!'")
z.registerCallback("pre_exec", "print 'This code should be executed after
the paragraph code!'")
```
Then run any other paragraph in the note containing some other code, eg
```python
%pyspark
print "This code should be entered into the paragraph by the user!"
```
The output should be:
```
This code should be executed before the paragraph code!
This code should be entered into the paragraph by the user!
This code should be executed after the paragraph code!
```
You should also test out the other two methods (`getCallback()` and
`unregisterCallback()`) specified in `ZeppelinContext.java`.
One final caveat that should be mentioned: If there are errors in the code
you specify for a pre-execute event, it will render the interpreter useless
since the current implementation prepends the the code specified in `pre_exec`
directly to the paragraph entered code before calling `interpret()`. The
current workaround for this would be to either restart the interpreter group or
call `unregisterCallback()` via a different REPL within the interpreter group
(eg, `z.unregisterCallback("pre_exec", "pyspark")` from the spark interpreter).
I would appreciate if anyone here would be willing to share any better
approaches here.
### Questions:
* Does the licenses files need update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? Yes
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/agoodm/zeppelin ZEPPELIN-1423v2
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/zeppelin/pull/1470.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1470
----
commit 8fad93674420da1faf4d63ed3f4902c630f2ca26
Author: Alex Goodman <ago...@users.noreply.github.com>
Date: 2016-09-28T19:27:12Z
Added Interpreter Hooks to Interpreter Process
commit 07cac65e99f643971b171756d26e7e8da92b76d3
Author: Alex Goodman <ago...@users.noreply.github.com>
Date: 2016-09-29T00:28:50Z
Implemented user-defined hook registry system for spark/pyspark interpreters
commit 1331fe1bd3d89394f74d5f7a0543a56911138f0b
Author: Alex Goodman <ago...@users.noreply.github.com>
Date: 2016-09-29T00:38:49Z
Update interpreters.md
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