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rails--rails/activesupport/test/evented_file_update_checker_test.rb
Jonathan Hefner eba1534939 Listen on fork in EventedFileUpdateChecker
The Listen gem does not notify across process forks, and so forked
processes must re-create their listeners.  `EventedFileUpdateChecker`
handled this in `updated?` by checking if `Process.pid` was different.
Because file updates may have occurred after the start of the fork but
before the call to `updated?`, `updated?` would always return true in
this case.

However, the above approach can result in unnecessary application
reloading, particularly when using Spring.  That, in turn, can cause
unexpected and problematic behavior: #39431, #37591.  This commit
changes listener re-creation to occur immediately after fork, and
changes `updated?` to return true only when necessary.
2020-09-26 16:35:28 -05:00

152 lines
3.7 KiB
Ruby

# frozen_string_literal: true
require_relative "abstract_unit"
require "pathname"
require "weakref"
require_relative "file_update_checker_shared_tests"
class EventedFileUpdateCheckerTest < ActiveSupport::TestCase
include FileUpdateCheckerSharedTests
def setup
skip if ENV["LISTEN"] == "0"
require "listen"
super
end
def new_checker(files = [], dirs = {}, &block)
ActiveSupport::EventedFileUpdateChecker.new(files, dirs, &block).tap do |c|
wait
end
end
def teardown
super
Listen.stop
end
def wait
sleep 1
end
def touch(files)
super
wait # wait for the events to fire
end
test "notifies forked processes" do
skip "Forking not available" unless Process.respond_to?(:fork)
FileUtils.touch(tmpfiles)
checker = new_checker(tmpfiles) { }
assert_not_predicate checker, :updated?
# Pipes used for flow control across fork.
boot_reader, boot_writer = IO.pipe
touch_reader, touch_writer = IO.pipe
pid = fork do
assert_not_predicate 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_predicate 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_predicate checker, :updated?
Process.wait(pid)
end
test "can be garbage collected" do
previous_threads = Thread.list
checker_ref = WeakRef.new(ActiveSupport::EventedFileUpdateChecker.new([], tmpdir => ".rb") { })
listener_threads = Thread.list - previous_threads
wait # Wait for listener thread to start processing events.
GC.start
assert_not_predicate checker_ref, :weakref_alive?
assert_empty Thread.list & listener_threads
end
test "should detect changes through symlink" do
actual_dir = File.join(tmpdir, "actual")
linked_dir = File.join(tmpdir, "linked")
Dir.mkdir(actual_dir)
FileUtils.ln_s(actual_dir, linked_dir)
checker = new_checker([], linked_dir => ".rb") { }
assert_not_predicate checker, :updated?
FileUtils.touch(File.join(actual_dir, "a.rb"))
wait
assert_predicate checker, :updated?
assert checker.execute_if_updated
end
test "updated should become true when nonexistent directory is added later" do
watched_dir = File.join(tmpdir, "app")
unwatched_dir = File.join(tmpdir, "node_modules")
not_exist_watched_dir = File.join(tmpdir, "test")
Dir.mkdir(watched_dir)
Dir.mkdir(unwatched_dir)
checker = new_checker([], watched_dir => ".rb", not_exist_watched_dir => ".rb") { }
FileUtils.touch(File.join(watched_dir, "a.rb"))
wait
assert_predicate checker, :updated?
assert checker.execute_if_updated
Dir.mkdir(not_exist_watched_dir)
wait
assert_predicate checker, :updated?
assert checker.execute_if_updated
FileUtils.touch(File.join(unwatched_dir, "a.rb"))
wait
assert_not_predicate checker, :updated?
assert_not checker.execute_if_updated
end
test "does not stop other checkers when nonexistent directory is added later" do
dir1 = File.join(tmpdir, "app")
dir2 = File.join(tmpdir, "test")
Dir.mkdir(dir2)
checker1 = new_checker([], dir1 => ".rb") { }
checker2 = new_checker([], dir2 => ".rb") { }
Dir.mkdir(dir1)
touch(File.join(dir1, "a.rb"))
assert_predicate checker1, :updated?
assert_not_predicate checker2, :updated?
touch(File.join(dir2, "a.rb"))
assert_predicate checker2, :updated?
end
end