Add macro mt_async

Author: oschulz

src/onthreads.jl

@@ -193,3 +193,33 @@ function ThreadLocal{T}(f::Base.Callable) where {T}
     @onthreads allthreads() result.value[threadid()] = f()
     result
 end
+
+
+"""
+    @mt_async expr
+
+Spawn a Julia task running `expr` asynchronously.
+
+Compatible with `@sync`. Uses a multi-threaded task scheduler if available (on
+Julia >= v1.3).
+
+Equivalent to `Base.@async` on Julia <= v1.2, equivalent to
+`Base.Threads.@spawn` on Julia >= v1.3.
+"""
+macro mt_async(expr)
+    # Code taken from Base.@async and Base.Threads.@spawn:
+    thunk = esc(:(()->($expr)))
+    var = esc(Base.sync_varname)
+    quote
+        local task = Task($thunk)
+        @static if VERSION >= v"1.3.0-alpha.0"
+            task.sticky = false
+        end
+        if $(Expr(:isdefined, var))
+            push!($var, task)
+        end
+        schedule(task)
+        task
+    end
+end
+export @mt_async

test/test_onthreads.jl

@@ -11,6 +11,22 @@ using Base.Threads
         @warn "JULIA multithreading not enabled"
     end
 
+
+    function do_work(n)
+        if n < 0
+            throw(ArgumentError("n must be >= 0"))
+        end
+        s::Float64 = 0
+        for i in 1:n
+            if n % 1000 == 0
+                yield()
+            end
+            s += log(abs(asin(sin(Complex(log(i), log(i))))) + 1)
+        end
+        s
+    end
+
+
     @testset "macro onthreads" begin
         @test (begin
             tl = ThreadLocal(0)
@@ -19,6 +35,20 @@ using Base.Threads
         end) == 1:nthreads()
     end
 
+    @testset "macro mt_async" begin
+        @test begin
+            n = 128
+            A = zeros(n)
+            @sync for i in eachindex(A)
+                @mt_async begin
+                    do_work(10^3)
+                    A[i] = log(i)
+                end
+            end
+            A == log.(1:n)
+        end
+    end
+
     @testset "Examples" begin
         @testset "Example 1" begin
             tlsum = ThreadLocal(0.0)