diff options
Diffstat (limited to 'lib/std/Thread.zig')
| -rw-r--r-- | lib/std/Thread.zig | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/lib/std/Thread.zig b/lib/std/Thread.zig index 77277bd154..b9a69d151f 100644 --- a/lib/std/Thread.zig +++ b/lib/std/Thread.zig @@ -165,18 +165,32 @@ pub const SpawnError = error{ Unexpected, }; -/// caller must call wait on the returned thread -/// fn startFn(@TypeOf(context)) T -/// where T is u8, noreturn, void, or !void -/// caller must call wait on the returned thread -pub fn spawn(context: anytype, comptime startFn: anytype) SpawnError!*Thread { +// Given `T`, the type of the thread startFn, extract the expected type for the +// context parameter. +fn SpawnContextType(comptime T: type) type { + const TI = @typeInfo(T); + if (TI != .Fn) + @compileError("expected function type, found " ++ @typeName(T)); + + if (TI.Fn.args.len != 1) + @compileError("expected function with single argument, found " ++ @typeName(T)); + + return TI.Fn.args[0].arg_type orelse + @compileError("cannot use a generic function as thread startFn"); +} + +/// Spawns a new thread executing startFn, returning an handle for it. +/// Caller must call wait on the returned thread. +/// The `startFn` function must take a single argument of type T and return a +/// value of type u8, noreturn, void or !void. +/// The `context` parameter is of type T and is passed to the spawned thread. +pub fn spawn(comptime startFn: anytype, context: SpawnContextType(@TypeOf(startFn))) SpawnError!*Thread { if (builtin.single_threaded) @compileError("cannot spawn thread when building in single-threaded mode"); // TODO compile-time call graph analysis to determine stack upper bound // https://github.com/ziglang/zig/issues/157 const default_stack_size = 16 * 1024 * 1024; const Context = @TypeOf(context); - comptime assert(@typeInfo(@TypeOf(startFn)).Fn.args[0].arg_type.? == Context); if (std.Target.current.os.tag == .windows) { const WinThread = struct { |