rt: Only wake up all schedulers when no tasks are left

At the moment there's not really any reason to be raising this signal,
since they schedulers wake up periodically anyway, but once we remove
the timer this will be how the schedulers know to exit.

1 files changed, 17 insertions, 4 deletions

diff --git a/src/rt/rust_scheduler.cpp b/src/rt/rust_scheduler.cpp
index 5a6cbd241ae..9005680dcc6 100644
--- a/src/rt/rust_scheduler.cpp
+++ b/src/rt/rust_scheduler.cpp
@@ -32,7 +32,8 @@ rust_scheduler::rust_scheduler(rust_kernel *kernel,
     kernel(kernel),
     id(id),
     min_stack_size(kernel->env->min_stack_size),
-    env(kernel->env)
+    env(kernel->env),
+    should_exit(false)
 {
     LOGPTR(this, "new dom", (uintptr_t)this);
     isaac_init(this, &rctx);
@@ -160,8 +161,12 @@ rust_scheduler::reap_dead_tasks(int id) {
         rust_task *task = dead_tasks_copy[i];
         if (task) {
             task->deref();
-            sync::decrement(kernel->live_tasks);
-            kernel->wakeup_schedulers();
+            int live_tasks = sync::decrement(kernel->live_tasks);
+            if (live_tasks == 0) {
+                // There are no more tasks and there never will be.
+                // Tell all the schedulers to exit.
+                kernel->exit_schedulers();
+            }
         }
     }
     srv->free(dead_tasks_copy);
@@ -236,7 +241,7 @@ rust_scheduler::start_main_loop() {
 
     DLOG(this, dom, "started domain loop %d", id);
 
-    while (kernel->live_tasks > 0) {
+    while (!should_exit) {
         A(this, kernel->is_deadlocked() == false, "deadlock");
 
         DLOG(this, dom, "worker %d, number_of_live_tasks = %d, total = %d",
@@ -375,6 +380,14 @@ rust_scheduler::get_task() {
 }
 #endif
 
+void
+rust_scheduler::exit() {
+    A(this, !lock.lock_held_by_current_thread(), "Shouldn't have lock");
+    scoped_lock with(lock);
+    should_exit = true;
+    lock.signal_all();
+}
+
 //
 // Local Variables:
 // mode: C++