Use OncePerProcess when possible (#483)

Author: christiangnrd

lib/mtl/buffer.jl

@@ -49,12 +49,18 @@ function MTLBuffer(dev::MTLDevice, bytesize::Integer, ptr::Ptr;
     return MTLBuffer(ptr)
 end
 
-const _page_size::Ref{Int} = Ref{Int}(0)
-function page_size()
-    if _page_size[] == 0
-        _page_size[] = Int(ccall(:getpagesize, Cint, ()))
+@static if isdefined(Base, :OncePerProcess) # VERSION >= v"1.12.0-DEV.1421"
+    const page_size = OncePerProcess{Int}() do
+        Int(ccall(:getpagesize, Cint, ()))
+    end
+else
+    const _page_size::Ref{Int} = Ref{Int}(0)
+    function page_size()
+        if _page_size[] == 0
+            _page_size[] = Int(ccall(:getpagesize, Cint, ()))
+        end
+        _page_size[]
     end
-    _page_size[]
 end
 
 function can_alloc_nocopy(ptr::Ptr, bytesize::Integer)

src/initialization.jl

@@ -1,15 +1,27 @@
-# Starts at `nothing`. Only false when it's determined
-const _functional = Ref{Union{Nothing,Bool}}(false)
+@static if isdefined(Base, :OncePerProcess) # VERSION >= v"1.12.0-DEV.1421"
+    const functional = OncePerProcess{Bool}() do
+        try
+            dev = device()
+            return supports_family(dev, MTL.MTLGPUFamilyApple7) &&
+            supports_family(dev, MTL.MTLGPUFamilyMetal3)
+        catch
+            return false
+        end
+    end
+else
+    # Becomes `nothing` once it has been determined that the device is on macOS
+    const _functional = Ref{Union{Nothing,Bool}}(false)
 
-function functional()
-    if isnothing(_functional[])
-        dev = device()
+    function functional()
+        if isnothing(_functional[])
+            dev = device()
 
-        _functional[] =
-            supports_family(dev, MTL.MTLGPUFamilyApple7) &&
-            supports_family(dev, MTL.MTLGPUFamilyMetal3)
+            _functional[] =
+                supports_family(dev, MTL.MTLGPUFamilyApple7) &&
+                supports_family(dev, MTL.MTLGPUFamilyMetal3)
+        end
+        _functional[]
     end
-    _functional[]
 end
 
 function __init__()
@@ -51,7 +63,9 @@ function __init__()
 
         # Successful loading of CoreGraphics means there's a
         # chance the graphics device is supported
-        _functional[] = nothing
+        if @isdefined _functional
+            _functional[] = nothing  # VERSION <= v"1.12.0-DEV.1421"
+        end
     catch err
         @error "Failed to load Metal" exception=(err,catch_backtrace())
         return

src/version.jl

@@ -15,35 +15,46 @@
     parse(VersionNumber, verstr)
 end
 
-const _darwin_version = Ref{VersionNumber}()
-"""
+@static if isdefined(Base, :OncePerProcess) # VERSION >= v"1.12.0-DEV.1421"
+    const darwin_version = OncePerProcess{VersionNumber}() do
+        _syscall_version("kern.osrelease")
+    end
+    const macos_version = OncePerProcess{VersionNumber}() do
+        _syscall_version("kern.osproductversion")
+    end
+else
+    const _darwin_version = Ref{VersionNumber}()
+    function darwin_version()
+        if !isassigned(_darwin_version)
+            _darwin_version[] = _syscall_version("kern.osrelease")
+        end
+        _darwin_version[]
+    end
+
+    const _macos_version = Ref{VersionNumber}()
+    function macos_version()
+        if !isassigned(_macos_version)
+            _macos_version[] = _syscall_version("kern.osproductversion")
+        end
+        _macos_version[]
+    end
+end
+
+@doc """
     Metal.darwin_version() -> VersionNumber
 
 Returns the host Darwin kernel version.
 
 See also [`Metal.macos_version`](@ref).
-"""
-function darwin_version()
-    if !isassigned(_darwin_version)
-        _darwin_version[] = _syscall_version("kern.osrelease")
-    end
-    _darwin_version[]
-end
+""" darwin_version
 
-const _macos_version = Ref{VersionNumber}()
-"""
+@doc """
     Metal.macos_version() -> VersionNumber
 
 Returns the host macOS version.
 
 See also [`Metal.darwin_version`](@ref).
-"""
-function macos_version()
-    if !isassigned(_macos_version)
-        _macos_version[] = _syscall_version("kern.osproductversion")
-    end
-    _macos_version[]
-end
+""" macos_version
 
 
 ## support queries