add missing wait during Timer and AsyncCondition close (#51847)

Can cause spurious warnings about not closing these properly and
unexpected events to appear after `close` returns.

Author: vtjnash

base/asyncevent.jl

@@ -118,22 +118,26 @@ end
 unsafe_convert(::Type{Ptr{Cvoid}}, t::Timer) = t.handle
 unsafe_convert(::Type{Ptr{Cvoid}}, async::AsyncCondition) = async.handle
 
+# if this returns true, the object has been signaled
+# if this returns false, the object is closed
 function _trywait(t::Union{Timer, AsyncCondition})
     set = t.set
     if set
         # full barrier now for AsyncCondition
         t isa Timer || Core.Intrinsics.atomic_fence(:acquire_release)
     else
-        t.isopen || return false
-        t.handle == C_NULL && return false
+        if !isopen(t)
+            close(t) # wait for the close to complete
+            return false
+        end
         iolock_begin()
         set = t.set
         if !set
             preserve_handle(t)
             lock(t.cond)
             try
                 set = t.set
-                if !set && t.isopen && t.handle != C_NULL
+                if !set && t.handle != C_NULL # wait for set or handle, but not the isopen flag
                     iolock_end()
                     set = wait(t.cond)
                     unlock(t.cond)
@@ -160,10 +164,28 @@ end
 isopen(t::Union{Timer, AsyncCondition}) = t.isopen && t.handle != C_NULL
 
 function close(t::Union{Timer, AsyncCondition})
+    t.handle == C_NULL && return # short-circuit path
     iolock_begin()
-    if isopen(t)
-        @atomic :monotonic t.isopen = false
-        ccall(:jl_close_uv, Cvoid, (Ptr{Cvoid},), t)
+    if t.handle != C_NULL
+        if t.isopen
+            @atomic :monotonic t.isopen = false
+            ccall(:jl_close_uv, Cvoid, (Ptr{Cvoid},), t)
+        end
+        # implement _trywait here without the auto-reset function, just waiting for the final close signal
+        preserve_handle(t)
+        lock(t.cond)
+        try
+            while t.handle != C_NULL
+                iolock_end()
+                wait(t.cond)
+                unlock(t.cond)
+                iolock_begin()
+                lock(t.cond)
+            end
+        finally
+            unlock(t.cond)
+            unpreserve_handle(t)
+        end
     end
     iolock_end()
     nothing
@@ -220,7 +242,10 @@ function uv_timercb(handle::Ptr{Cvoid})
         @atomic :monotonic t.set = true
         if ccall(:uv_timer_get_repeat, UInt64, (Ptr{Cvoid},), t) == 0
             # timer is stopped now
-            close(t)
+            if t.isopen
+                @atomic :monotonic t.isopen = false
+                ccall(:jl_close_uv, Cvoid, (Ptr{Cvoid},), t)
+            end
         end
         notify(t.cond, true)
     finally

test/channels.jl

@@ -457,8 +457,8 @@ end
         Sys.iswindows() && Base.process_events() # schedule event (windows?)
         close(async) # and close
         @test !isopen(async)
-        @test tc[] == 2
-        @test tc[] == 2
+        @test tc[] == 3
+        @test tc[] == 3
         yield() # consume event & then close
         @test tc[] == 3
         sleep(0.1) # no further events
@@ -479,7 +479,7 @@ end
         close(async)
         @test !isopen(async)
         Base.process_events() # and close
-        @test tc[] == 0
+        @test tc[] == 1
         yield() # consume event & then close
         @test tc[] == 1
         sleep(0.1) # no further events