rt: Add a function for configuring task notification

Author: brson

src/rt/rust_builtin.cpp

@@ -481,6 +481,16 @@ drop_task(rust_task *target) {
     }
 }
 
+extern "C" CDECL void
+rust_task_config_notify(rust_task_id task_id, chan_handle *chan) {
+    rust_task *task = rust_task_thread::get_task();
+    rust_task *target = task->kernel->get_task_by_id(task_id);
+    A(task->thread, target != NULL,
+      "This function should only be called when we know the task exists");
+    target->config_notify(*chan);
+    target->deref();
+}
+
 extern "C" CDECL rust_task *
 get_task_pointer(rust_task_id id) {
     rust_task *task = rust_task_thread::get_task();

src/rt/rust_task.cpp

@@ -713,6 +713,12 @@ rust_task::check_stack_canary() {
     ::check_stack_canary(stk);
 }
 
+void
+rust_task::config_notify(chan_handle chan) {
+    user.notify_enabled = true;
+    user.notify_chan = chan;
+}
+
 //
 // Local Variables:
 // mode: C++

src/rt/rust_task.h

@@ -181,6 +181,8 @@ rust_task : public kernel_owned<rust_task>, rust_cond
     void reset_stack_limit();
     bool on_rust_stack();
     void check_stack_canary();
+
+    void config_notify(chan_handle chan);
 };
 
 //

src/rt/rustrt.def.in

@@ -49,6 +49,7 @@ rust_env_pairs
 rust_task_yield
 rust_task_is_unwinding
 rust_get_task
+rust_task_config_notify
 sched_threads
 shape_log_str
 squareroot