Add Timer args to struct and add show method (#57081)

Author: IanButterworth

NEWS.md

@@ -128,6 +128,7 @@ New library features
 certain compiler plugin workflows ([#56660]).
 * `sort` now supports `NTuple`s ([#54494])
 * `map!(f, A)` now stores the results in `A`, like `map!(f, A, A)`. or `A .= f.(A)` ([#40632]).
+* `Timer` now has readable `timeout` and `interval` properties, and a more descriptive show method ([#57081])
 
 Standard library changes
 ------------------------

base/asyncevent.jl

@@ -74,7 +74,24 @@ Create a timer that wakes up tasks waiting for it (by calling [`wait`](@ref) on
 Waiting tasks are woken after an initial delay of at least `delay` seconds, and then repeating after
 at least `interval` seconds again elapse. If `interval` is equal to `0`, the timer is only triggered
 once. When the timer is closed (by [`close`](@ref)) waiting tasks are woken with an error. Use
-[`isopen`](@ref) to check whether a timer is still active.
+[`isopen`](@ref) to check whether a timer is still active. Use `t.timeout` and `t.interval` to read
+the setup conditions of a `Timer` `t`.
+
+```julia-repl
+julia> t = Timer(1.0; interval=0.5)
+Timer (open, timeout: 1.0 s, interval: 0.5 s) @0x000000010f4e6e90
+
+julia> isopen(t)
+true
+
+julia> t.timeout
+1.0
+
+julia> close(t)
+
+julia> isopen(t)
+false
+```
 
 !!! note
     `interval` is subject to accumulating time skew. If you need precise events at a particular
@@ -84,12 +101,17 @@ once. When the timer is closed (by [`close`](@ref)) waiting tasks are woken with
     A `Timer` requires yield points to update its state. For instance, `isopen(t::Timer)` cannot be
     used to timeout a non-yielding while loop.
 
+!!! compat "Julia 1.12
+    The `timeout` and `interval` readable properties were added in Julia 1.12.
+
 """
 mutable struct Timer
     @atomic handle::Ptr{Cvoid}
     cond::ThreadSynchronizer
     @atomic isopen::Bool
     @atomic set::Bool
+    timeout_ms::UInt64
+    interval_ms::UInt64
 
     function Timer(timeout::Real; interval::Real = 0.0)
         timeout ≥ 0 || throw(ArgumentError("timer cannot have negative timeout of $timeout seconds"))
@@ -99,7 +121,7 @@ mutable struct Timer
         intervalms = ceil(UInt64, interval * 1000)
         loop = eventloop()
 
-        this = new(Libc.malloc(_sizeof_uv_timer), ThreadSynchronizer(), true, false)
+        this = new(Libc.malloc(_sizeof_uv_timer), ThreadSynchronizer(), true, false, timeoutms, intervalms)
         associate_julia_struct(this.handle, this)
         iolock_begin()
         err = ccall(:uv_timer_init, Cint, (Ptr{Cvoid}, Ptr{Cvoid}), loop, this)
@@ -114,6 +136,24 @@ mutable struct Timer
         return this
     end
 end
+function getproperty(t::Timer, f::Symbol)
+    if f == :timeout
+        t.timeout_ms == 0 && return 0.0
+        return (t.timeout_ms - 1) / 1000 # remove the +1ms compensation from the constructor
+    elseif f == :interval
+        return t.interval_ms / 1000
+    else
+        return getfield(t, f)
+    end
+end
+propertynames(::Timer) = (:handle, :cond, :isopen, :set, :timeout, :timeout_ms, :interval, :interval_ms)
+
+function show(io::IO, t::Timer)
+    state = isopen(t) ? "open" : "closed"
+    interval = t.interval
+    interval_str = interval > 0 ? ", interval: $(t.interval) s" : ""
+    print(io, "Timer ($state, timeout: $(t.timeout) s$interval_str) @0x$(string(convert(UInt, pointer_from_objref(t)), base = 16, pad = Sys.WORD_SIZE>>2))")
+end
 
 unsafe_convert(::Type{Ptr{Cvoid}}, t::Timer) = t.handle
 unsafe_convert(::Type{Ptr{Cvoid}}, async::AsyncCondition) = async.handle

test/channels.jl

@@ -621,6 +621,16 @@ let a = Ref(0)
     @test a[] == 1
 end
 
+@testset "Timer properties" begin
+    t = Timer(1.0, interval = 0.5)
+    @test t.timeout == 1.0
+    @test t.interval == 0.5
+    close(t)
+    @test !isopen(t)
+    @test t.timeout == 1.0
+    @test t.interval == 0.5
+end
+
 # trying to `schedule` a finished task
 let t = @async nothing
     wait(t)