Zig 0.17.0-dev (Split by item)

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concurrent

Calls function with args, such that the return value of the function is not guaranteed to be available until await is called, allowing the caller to progress while waiting for any Io operations.

This has stronger guarantee than async, placing restrictions on what kind of Io implementations are supported. By calling async instead, one allows, for example, stackful single-threaded blocking I/O.

Io.concurrent

pub fn concurrent(
    io: Io,
    function: anytype,
    args: std.meta.ArgsTuple(@TypeOf(function)),
) ConcurrentError!Future(@typeInfo(@TypeOf(function)).@"fn".return_type.?)

File

lib/std/Io.zig:2446

Code

pub fn concurrent(
    io: Io,
    function: anytype,
    args: std.meta.ArgsTuple(@TypeOf(function)),
) ConcurrentError!Future(@typeInfo(@TypeOf(function)).@"fn".return_type.?) {
    const Result = @typeInfo(@TypeOf(function)).@"fn".return_type.?;
    const Args = @TypeOf(args);
    const TypeErased = struct {
        fn start(context: *const anyopaque, result: *anyopaque) void {
            const args_casted: *const Args = @ptrCast(@alignCast(context));
            const result_casted: *Result = @ptrCast(@alignCast(result));
            result_casted.* = @call(.auto, function, args_casted.*);
        }
    };
    var future: Future(Result) = undefined;
    future.any_future = try io.vtable.concurrent(
        io.userdata,
        @sizeOf(Result),
        .of(Result),
        @ptrCast(&args),
        .of(Args),
        TypeErased.start,
    );
    return future;
}