sbt/main
Ethan Atkins 272508596a Use one observer for all aggregated watch tasks
There was a bug where sometimes a source file change would not trigger a
new build if the change occurred during a build. Based on the logs, it
seemed to be because a number of redundant events were generated for the
same path and they triggered the anti-entropy constraint of the file
event monitor.

To fix this, I consolidated a number of observers of the global file
tree repository into a single observer. This way, I am able to ensure
that only one event is generated per file event.

I also reworked the onEvent callback to only stamp the file once. It was
previously stamping the modified source file for all of the aggregated
tasks. In the sbt project running `~compile` meant that we were stamping
a source file 22 times whenever the file changed.

This actually uncovered a zinc issue though as well. Zinc computes and
writes the hash of the source file to the analysis file after
compilation has completed. If a source file is modified during
compilation, then the new hash is written to the analysis file even when
the compilation may have been made against the previous version of the
file. Zinc will then refuse to re-compile that file until another change
is made.

I manually verified that in the sbt project if I ran `~compile` before
this change and modified a file during compilation, then no event was
triggered (there was a log message about the event being dropped due to
the anti-entropy constraint though). After this change, if I changed a
file during compilation, it seemed to always trigger, but due to the
zinc bug, it didn't always re-compile.
2019-07-15 14:21:14 -07:00
..
src Use one observer for all aggregated watch tasks 2019-07-15 14:21:14 -07:00
NOTICE Add, configure & enforce file headers 2017-10-05 09:03:40 +01:00