From 7bd41994480c17db71fdc07e3447ade929eaa386 Mon Sep 17 00:00:00 2001 From: schneems Date: Mon, 6 Jun 2016 11:26:22 -0500 Subject: EventedFileUpdateChecker boots once per process We need one file checker booted per process as talked about in #24990. Before we do a check to see if any updates have been registered by the listener we first check to make sure that the current process has booted a listener. We are intentionally not starting a listener when the checker is created. This way we can avoid #25259 in which puma warns of multiple threads created before fork. As written the listener for each process will be invoked by the `ActionDispatch::Executor` middleware when the `updated?` method is called. This is the first middleware on the stack and will be invoked before application code is read into memory. The downside of this approach is that the API is a little less obvious. I.e. that you have to call `updated?` to get the listener to start is not intuitive. We could make `boot!` not private if we want to make the API a little nicer. Alternatively we could boot when the checker is initialized however this reintroduces the puma threads warning, and also means that in cases of `rails server` or when using `preload!` that we have extra threads notifying of changes on a process that we don't care about. [close #24990] [close #25259] --- activesupport/test/evented_file_update_checker_test.rb | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'activesupport/test') diff --git a/activesupport/test/evented_file_update_checker_test.rb b/activesupport/test/evented_file_update_checker_test.rb index bc3f77bd54..ce2e05da2c 100644 --- a/activesupport/test/evented_file_update_checker_test.rb +++ b/activesupport/test/evented_file_update_checker_test.rb @@ -11,7 +11,8 @@ class EventedFileUpdateCheckerTest < ActiveSupport::TestCase end def new_checker(files = [], dirs = {}, &block) - ActiveSupport::EventedFileUpdateChecker.new(files, dirs, &block).tap do + ActiveSupport::EventedFileUpdateChecker.new(files, dirs, &block).tap do |c| + c.updated? wait end end -- cgit v1.2.3 From 7d733b9f0f847d67d8759421f6820ebc57567647 Mon Sep 17 00:00:00 2001 From: schneems Date: Wed, 8 Jun 2016 15:52:02 -0500 Subject: Test how evented file checker handles forks Pretty proud of this. We are testing distributed processes synchronized via pipes which makes it deterministic. Pretty cool. We boot a listener in the parent process we then fork. Before we touch the file we verify the fork is booted using pipes. Then the parent process will touch the file while the fork waits on a pipe. Once the parent process signals that the file has been touched we continue inside of the fork. --- .../test/evented_file_update_checker_test.rb | 43 +++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) (limited to 'activesupport/test') diff --git a/activesupport/test/evented_file_update_checker_test.rb b/activesupport/test/evented_file_update_checker_test.rb index ce2e05da2c..2cb2d8167f 100644 --- a/activesupport/test/evented_file_update_checker_test.rb +++ b/activesupport/test/evented_file_update_checker_test.rb @@ -12,7 +12,6 @@ class EventedFileUpdateCheckerTest < ActiveSupport::TestCase def new_checker(files = [], dirs = {}, &block) ActiveSupport::EventedFileUpdateChecker.new(files, dirs, &block).tap do |c| - c.updated? wait end end @@ -35,6 +34,48 @@ class EventedFileUpdateCheckerTest < ActiveSupport::TestCase super wait end + + test 'notifies forked processes' do + FileUtils.touch(tmpfiles) + + checker = new_checker(tmpfiles) { } + assert !checker.updated? + + # Pipes used for flow controll across fork. + boot_reader, boot_writer = IO.pipe + touch_reader, touch_writer = IO.pipe + + pid = fork do + assert checker.updated? + + # Clear previous check value. + checker.execute + assert !checker.updated? + + # Fork is booted, ready for file to be touched + # notify parent process. + boot_writer.write("booted") + + # Wait for parent process to signal that file + # has been touched. + IO.select([touch_reader]) + + assert checker.updated? + end + + assert pid + + # Wait for fork to be booted before touching files. + IO.select([boot_reader]) + touch(tmpfiles) + + # Notify fork that files have been touched. + touch_writer.write("touched") + + assert checker.updated? + + Process.wait(pid) + end end class EventedFileUpdateCheckerPathHelperTest < ActiveSupport::TestCase -- cgit v1.2.3