Merge pull request #5 from JuliaFolds2/atomic

Atomic storage, threadpool support

.github/workflows/CI.yml

@@ -10,7 +10,6 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - '1.6'
           - '1.9'
           - '1.10.0'
           - 'nightly'

Project.toml

@@ -4,7 +4,7 @@ authors = ["Mason Protter <mason.protter@icloud.com>"]
 version = "0.1.3"
 
 [compat]
-julia = "1.6"
+julia = "1.9"
 
 [extras]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"

README.md

@@ -2,8 +2,7 @@
 
 StableTasks is a simple package with one main API `StableTasks.@spawn` (not exported by default). 
 
-It works like `Threads.@spawn`, except it is *type stable* to `fetch` from (and it does not yet support threadpools
-other than the default threadpool).
+It works like `Threads.@spawn`, except it is *type stable* to `fetch` from.
 
 ``` julia
 julia> Core.Compiler.return_type(() -> fetch(StableTasks.@spawn 1 + 1), Tuple{})

src/StableTasks.jl

@@ -3,10 +3,16 @@ module StableTasks
 macro spawn end
 macro spawnat end
 
-using Base: RefValue
+mutable struct AtomicRef{T}
+    @atomic x::T
+    AtomicRef{T}() where {T} = new{T}()
+    AtomicRef(x::T) where {T} = new{T}(x)
+    AtomicRef{T}(x) where {T} = new{T}(convert(T, x))
+end
+
 struct StableTask{T}
     t::Task
-    ret::RefValue{T}
+    ret::AtomicRef{T}
 end
 
 include("internals.jl")

src/internals.jl

@@ -1,6 +1,9 @@
 module Internals
 
-import StableTasks: @spawn, @spawnat, StableTask
+import StableTasks: @spawn, @spawnat, StableTask, AtomicRef
+
+Base.getindex(r::AtomicRef) = @atomic r.x
+Base.setindex!(r::AtomicRef{T}, x) where {T} = @atomic r.x = convert(T, x)
 
 function Base.fetch(t::StableTask{T}) where {T}
     fetch(t.t)
@@ -25,41 +28,58 @@ Base.schedule(t::StableTask) = (schedule(t.t); t)
 Base.schedule(t, val; error=false) = (schedule(t.t, val; error); t)
 
 """
-Similar to `Threads.@spawn` but type-stable. Creates a `Task` and schedules it to run on any available thread in the `:default` threadpool.
+    @spawn [:default|:interactive] expr
+
+Similar to `Threads.@spawn` but type-stable. Creates a `Task` and schedules it to run on any available
+thread in the specified threadpool (defaults to the `:default` threadpool).
 """
-macro spawn(ex)
+macro spawn(args...)
+    tp = QuoteNode(:default)
+    na = length(args)
+    if na == 2
+        ttype, ex = args
+        if ttype isa QuoteNode
+            ttype = ttype.value
+            if ttype !== :interactive && ttype !== :default
+                throw(ArgumentError("unsupported threadpool in StableTasks.@spawn: $ttype"))
+            end
+            tp = QuoteNode(ttype)
+        else
+            tp = ttype
+        end
+    elseif na == 1
+        ex = args[1]
+    else
+        throw(ArgumentError("wrong number of arguments in @spawn"))
+    end
+
     letargs = _lift_one_interp!(ex)
 
     thunk = replace_linenums!(:(() -> ($(esc(ex)))), __source__)
     var = esc(Base.sync_varname) # This is for the @sync macro which sets a local variable whose name is
     # the symbol bound to Base.sync_varname
     # I asked on slack and this is apparently safe to consider a public API
-    set_pool = if VERSION < v"1.9"
-        nothing
-    else
-        :(Threads._spawn_set_thrpool(task, :default))
-    end
     quote
         let $(letargs...)
             f = $thunk
             T = Core.Compiler.return_type(f, Tuple{})
-            ref = Ref{T}()
+            ref = AtomicRef{T}()
             f_wrap = () -> (ref[] = f(); nothing)
             task = Task(f_wrap)
             task.sticky = false
-            $set_pool
+            Threads._spawn_set_thrpool(task, $(esc(tp)))
             if $(Expr(:islocal, var))
                 put!($var, task) # Sync will set up a Channel, and we want our task to be in there.
             end
             schedule(task)
-            StableTask(task, ref)
+            StableTask{T}(task, ref)
         end
     end
 end
 
 """
 Similar to `StableTasks.@spawn` but creates a **sticky** `Task` and schedules it to run on the thread with the given id (`thrdid`).
-The task is guaranteed to stay on this thread (it won't migrate to another thread). 
+The task is guaranteed to stay on this thread (it won't migrate to another thread).
 """
 macro spawnat(thrdid, ex)
     letargs = _lift_one_interp!(ex)
@@ -81,7 +101,7 @@ macro spawnat(thrdid, ex)
         let $(letargs...)
             thunk = $thunk
             RT = Core.Compiler.return_type(thunk, Tuple{})
-            ret = Ref{RT}()
+            ret = AtomicRef{RT}()
             thunk_wrap = () -> (ret[] = thunk(); nothing)
             local task = Task(thunk_wrap)
             task.sticky = true

test/runtests.jl

@@ -6,6 +6,15 @@ using StableTasks: @spawn, @spawnat
     t = @eval @spawn inv([1 2 ; 3 4])
     @test inv([1 2 ; 3 4]) == @inferred fetch(t)
 
+    @test 2 == @inferred fetch(@spawn :interactive 1 + 1)
+    t = @eval @spawn :interactive inv([1 2 ; 3 4])
+    @test inv([1 2 ; 3 4]) == @inferred fetch(t)
+
+    s = :default
+    @test 2 == @inferred fetch(@spawn s 1 + 1)
+    t = @eval @spawn $(QuoteNode(s)) inv([1 2 ; 3 4])
+    @test inv([1 2 ; 3 4]) == @inferred fetch(t)
+
     @test 2 == @inferred fetch(@spawnat 1 1 + 1)
     t = @eval @spawnat 1 inv([1 2 ; 3 4])
     @test inv([1 2 ; 3 4]) == @inferred fetch(t)