ConsoleReader should be blocking in sbt 1.4+ since System.in already is non-blocking

[mkurz]

Fixes #11032

In #9420 we made the run command interruptible by adding a couple of sleep statements, so that when hitting CTRL+C sbt had the chance to interrupt the thread.
To fix #10864 Greg now switched from FileDescriptor.in to System.in in #10890, which totally make sense, however it isn't that easy. Starting with sbt 1.4 System.in is non-blocking, therefore the patch introduced in #9420 makes the sbt console hang when waiting for an input. The problem is that read() recursively calls itself in the same thread that is supposed to read data from System.in, but because of the endless loop it never has the chance to do so.
Anyway, this comment confirms exactly what I debugged:

They shouldn't need to create a non blocking input stream reader because sbt makes System.in non-blocking starting with 1.4.0.

To solve this we create the exact same (legacy) ConsoleReader when using sbt <=1.3, that already was used before Greg's patch, and yes it still uses FileDescriptor.in, but that does not matter because until sbt 1.4.x that was totally ok, because there was not client mode yet.
For sbt 1.4+ we now create a blocking ConsoleReader which just wraps System.in/System.out, basically the solution Greg referred to in his pull request.

[mkurz]

@Mergifyio backport master

[mergify]

backport master

🟠 Waiting for conditions to match

• merged [:pushpin: backport requirement]

[mkurz]

BTW: I tested this with sbt

• 1.2.8
• 1.3.13
• 1.4.0
• 1.5.7
• 1.6.0-RC2

[mkurz]

@Mergifyio backport 2.7.x

[mergify]

backport 2.7.x

🟠 Waiting for conditions to match

• merged [:pushpin: backport requirement]

[gmethvin]

Nice! Thanks for fixing this

[mergify]

backport master

✅ Backports have been created

• #11065 ConsoleReader should be blocking in sbt 1.4+ since System.in already is non-blocking (backport #11061) has been created for branch master

[mergify]

backport 2.7.x

✅ Backports have been created

• #11066 ConsoleReader should be blocking in sbt 1.4+ since System.in already is non-blocking (backport #11061) has been created for branch 2.7.x

[mkurz]

Thanks Greg!