Refactor the IOCP event loop (timers, ...) (#15238)

Upgrades the IOCP event loop for Windows to be on par with the Polling event loops (epoll, kqueue) on UNIX. After a few low hanging fruits (enqueue multiple fibers on each call, for example) the last commit completely rewrites the `#run` method:

- store events in pairing heaps;
- high resolution timers (`CreateWaitableTimer`);
- block forever/never (no need for timeout);
- cancelling timeouts (no more dead fibers);
- thread safety (parallel timer de/enqueues) for [RFC #2];
- interrupt run using completion key instead of an UserAPC for [RFC #2] (untested).

[RFC #2]: crystal-lang/rfcs#2

.github/workflows/mingw-w64.yml

@@ -80,7 +80,7 @@ jobs:
           cc crystal.obj -o .build/crystal.exe -municode \
             $(pkg-config bdw-gc libpcre2-8 iconv zlib libffi --libs) \
             $(llvm-config --libs --system-libs --ldflags) \
-            -lole32 -lWS2_32 -Wl,--stack,0x800000
+            -lole32 -lWS2_32 -lntdll -Wl,--stack,0x800000
 
       - name: Package Crystal
         shell: msys2 {0}

spec/std/crystal/event_loop/polling/timers_spec.cr → spec/std/crystal/event_loop/timers_spec.cr

@@ -1,13 +1,26 @@
-{% skip_file unless Crystal::EventLoop.has_constant?(:Polling) %}
-
 require "spec"
+require "crystal/event_loop/timers"
+
+private struct Timer
+  include Crystal::PointerPairingHeap::Node
+
+  property! wake_at : Time::Span
+
+  def initialize(timeout : Time::Span? = nil)
+    @wake_at = Time.monotonic + timeout if timeout
+  end
+
+  def heap_compare(other : Pointer(self)) : Bool
+    wake_at < other.value.wake_at
+  end
+end
 
-describe Crystal::EventLoop::Polling::Timers do
+describe Crystal::EventLoop::Timers do
   it "#empty?" do
-    timers = Crystal::EventLoop::Polling::Timers.new
+    timers = Crystal::EventLoop::Timers(Timer).new
     timers.empty?.should be_true
 
-    event = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 7.seconds)
+    event = Timer.new(7.seconds)
     timers.add(pointerof(event))
     timers.empty?.should be_false
 
@@ -17,13 +30,13 @@ describe Crystal::EventLoop::Polling::Timers do
 
   it "#next_ready?" do
     # empty
-    timers = Crystal::EventLoop::Polling::Timers.new
+    timers = Crystal::EventLoop::Timers(Timer).new
     timers.next_ready?.should be_nil
 
     # with events
-    event1s = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 1.second)
-    event3m = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 3.minutes)
-    event5m = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 5.minutes)
+    event1s = Timer.new(1.second)
+    event3m = Timer.new(3.minutes)
+    event5m = Timer.new(5.minutes)
 
     timers.add(pointerof(event5m))
     timers.next_ready?.should eq(event5m.wake_at?)
@@ -36,24 +49,24 @@ describe Crystal::EventLoop::Polling::Timers do
   end
 
   it "#dequeue_ready" do
-    timers = Crystal::EventLoop::Polling::Timers.new
+    timers = Crystal::EventLoop::Timers(Timer).new
 
-    event1 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 0.seconds)
-    event2 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 0.seconds)
-    event3 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 1.minute)
+    event1 = Timer.new(0.seconds)
+    event2 = Timer.new(0.seconds)
+    event3 = Timer.new(1.minute)
 
     # empty
     called = 0
     timers.dequeue_ready { called += 1 }
     called.should eq(0)
 
     # add events in non chronological order
-    timers = Crystal::EventLoop::Polling::Timers.new
+    timers = Crystal::EventLoop::Timers(Timer).new
     timers.add(pointerof(event1))
     timers.add(pointerof(event3))
     timers.add(pointerof(event2))
 
-    events = [] of Crystal::EventLoop::Polling::Event*
+    events = [] of Timer*
     timers.dequeue_ready { |event| events << event }
 
     events.should eq([
@@ -64,12 +77,12 @@ describe Crystal::EventLoop::Polling::Timers do
   end
 
   it "#add" do
-    timers = Crystal::EventLoop::Polling::Timers.new
+    timers = Crystal::EventLoop::Timers(Timer).new
 
-    event0 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current)
-    event1 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 0.seconds)
-    event2 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 2.minutes)
-    event3 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 1.minute)
+    event0 = Timer.new
+    event1 = Timer.new(0.seconds)
+    event2 = Timer.new(2.minutes)
+    event3 = Timer.new(1.minute)
 
     # add events in non chronological order
     timers.add(pointerof(event1)).should be_true # added to the head (next ready)
@@ -81,13 +94,13 @@ describe Crystal::EventLoop::Polling::Timers do
   end
 
   it "#delete" do
-    event1 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 0.seconds)
-    event2 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 0.seconds)
-    event3 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 1.minute)
-    event4 = Crystal::EventLoop::Polling::Event.new(:sleep, Fiber.current, timeout: 4.minutes)
+    event1 = Timer.new(0.seconds)
+    event2 = Timer.new(0.seconds)
+    event3 = Timer.new(1.minute)
+    event4 = Timer.new(4.minutes)
 
     # add events in non chronological order
-    timers = Crystal::EventLoop::Polling::Timers.new
+    timers = Crystal::EventLoop::Timers(Timer).new
     timers.add(pointerof(event1))
     timers.add(pointerof(event3))
     timers.add(pointerof(event2))