Merge branch 'main' into fix-060

1 files changed, 54 insertions, 0 deletions

diff --git a/exercises/086_async2.zig b/exercises/086_async2.zig
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+++ b/exercises/086_async2.zig
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+//
+// Now that we know how to get an Io value, let's use it for
+// asynchronous execution!
+//
+// io.async() launches a function and returns a Future. The result
+// won't necessarily be available until you call .await() on it:
+//
+//     var future = io.async(someFunction, .{ arg1, arg2 });
+//     const result = future.await(io);
+//
+// The function *may* run immediately or on another thread -
+// your code doesn't need to care! That's the beauty of the
+// Io abstraction.
+//
+// IMPORTANT: Every Future MUST be either .await()ed or .cancel()ed.
+// Failing to do so leaks resources! A safe pattern is:
+//
+//     var future = io.async(myFn, .{});
+//     defer _ = future.cancel(io);  // safety net
+//     // ... later, if we want the result:
+//     const result = future.await(io);
+//     // (await after cancel is fine — it just returns the result)
+//
+// Both .await() and .cancel() block until the task finishes and
+// return the result. The difference is that .cancel() also
+// requests the task to stop at its next cancellation point.
+// Calling either one more than once is safe — subsequent calls
+// just return a copy of the result.
+//
+// Fix this program so that computeAnswer runs asynchronously
+// and its result is properly awaited.
+//
+const std = @import("std");
+const print = std.debug.print;
+
+pub fn main(init: std.process.Init) !void {
+    const io = init.io;
+
+    // Launch computeAnswer asynchronously.
+    var future = io.async(computeAnswer, .{ 6, 7 });
+    defer _ = future.cancel(io); // always clean up!
+
+    print("Computing... ", .{});
+
+    // Now collect the result. What method on Future gives us
+    // the value, blocking until it's ready?
+    const answer = future.???(io);
+
+    print("The answer is: {}\n", .{answer});
+}
+
+fn computeAnswer(a: u32, b: u32) u32 {
+    return a * b;
+}