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From "Naveen Gangam (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-19700) Workaround for JLine issue with UnsupportedTerminal
Date Thu, 24 May 2018 21:24:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-19700?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Naveen Gangam updated HIVE-19700:
---------------------------------
    Status: Patch Available  (was: Open)

[~aihuaxu] [~ychena] Could you please review the patch? Thanks

> Workaround for JLine issue with UnsupportedTerminal
> ---------------------------------------------------
>
>                 Key: HIVE-19700
>                 URL: https://issues.apache.org/jira/browse/HIVE-19700
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Naveen Gangam
>            Assignee: Naveen Gangam
>            Priority: Major
>             Fix For: 2.2.1
>
>         Attachments: HIVE-19700.patch
>
>
> From the JLine's ConsoleReader, readLine(prompt, mask) calls the following beforeReadLine()
method.
> {code}
>         try {
>             // System.out.println("is terminal supported " + terminal.isSupported());
>             if (!terminal.isSupported()) {
>                 beforeReadLine(prompt, mask);
>             }
> {code}
> So specifically when using UnsupportedTerminal {{-Djline.terminal}} and {{prompt=null}}
and {{mask!=null}}, a "null" string gets printed to the console before and after the query
result. {{UnsupportedTerminal}} is required to be used when running beeline as a background
process, hangs otherwise.
> {code}
>     private void beforeReadLine(final String prompt, final Character mask) {
>         if (mask != null && maskThread == null) {
>             final String fullPrompt = "\r" + prompt
>                 + "                 "
>                 + "                 "
>                 + "                 "
>                 + "\r" + prompt;
>             maskThread = new Thread()
>             {
>                 public void run() {
>                     while (!interrupted()) {
>                         try {
>                             Writer out = getOutput();
>                             out.write(fullPrompt);
> {code}
> So the {{prompt}} is null and {{mask}} is NOT in atleast 2 scenarios in beeline. 
> when beeline's silent=true, prompt is null
> * https://github.com/apache/hive/blob/master/beeline/src/java/org/apache/hive/beeline/BeeLine.java#L1264
> when running multiline queries
> * https://github.com/apache/hive/blob/master/beeline/src/java/org/apache/hive/beeline/Commands.java#L1093
> When executing beeline in script mode (commands in a file), there should not be any masking
while reading lines from the script file. aka, entire line should be a beeline command or
part of a multiline hive query.
> So it should be safe to use a null mask instead of {{ConsoleReader.NULL_MASK}} when using
UnsupportedTerminal as jline terminal.



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