rt: Run a single-threaded scheduler on the main thread

1 files changed, 30 insertions, 9 deletions

diff --git a/src/rt/rust_kernel.cpp b/src/rt/rust_kernel.cpp
index 5062e4de3c3..d65837a47d6 100644
--- a/src/rt/rust_kernel.cpp
+++ b/src/rt/rust_kernel.cpp
@@ -1,6 +1,7 @@
 #include "rust_internal.h"
 #include "rust_util.h"
 #include "rust_scheduler.h"
+#include "rust_sched_launcher.h"
 
 #include <vector>
 
@@ -18,8 +19,15 @@ rust_kernel::rust_kernel(rust_srv *srv) :
     rval(0),
     max_sched_id(0),
     sched_reaper(this),
+    osmain_driver(NULL),
     env(srv->env)
 {
+    // Create the single threaded scheduler that will run on the platform's
+    // main thread
+    rust_manual_sched_launcher_factory launchfac;
+    osmain_scheduler = create_scheduler(&launchfac, 1, false);
+    osmain_driver = launchfac.get_driver();
+    sched_reaper.start();
 }
 
 void
@@ -59,24 +67,25 @@ void rust_kernel::free(void *mem) {
 
 rust_sched_id
 rust_kernel::create_scheduler(size_t num_threads) {
+    rust_thread_sched_launcher_factory launchfac;
+    return create_scheduler(&launchfac, num_threads, true);
+}
+
+rust_sched_id
+rust_kernel::create_scheduler(rust_sched_launcher_factory *launchfac,
+                              size_t num_threads, bool allow_exit) {
     rust_sched_id id;
     rust_scheduler *sched;
     {
         scoped_lock with(sched_lock);
-        // If this is the first scheduler then we need to launch
-        // the scheduler reaper.
-        bool start_reaper = sched_table.empty();
         id = max_sched_id++;
         K(srv, id != INTPTR_MAX, "Hit the maximum scheduler id");
         sched = new (this, "rust_scheduler")
-            rust_scheduler(this, srv, num_threads, id, true);
+            rust_scheduler(this, srv, num_threads, id, allow_exit, launchfac);
         bool is_new = sched_table
             .insert(std::pair<rust_sched_id,
                               rust_scheduler*>(id, sched)).second;
         A(this, is_new, "Reusing a sched id?");
-        if (start_reaper) {
-            sched_reaper.start();
-        }
     }
     sched->start_task_threads();
     return id;
@@ -123,6 +132,15 @@ rust_kernel::wait_for_schedulers()
             sched_table.erase(iter);
             sched->join_task_threads();
             delete sched;
+            if (sched_table.size() == 1) {
+                KLOG_("Allowing osmain scheduler to exit");
+                sched_lock.unlock();
+                // It's only the osmain scheduler left. Tell it to exit
+                rust_scheduler *sched = get_scheduler_by_id(osmain_scheduler);
+                assert(sched != NULL);
+                sched_lock.lock();
+                sched->allow_exit();
+            }
         }
         if (!sched_table.empty()) {
             sched_lock.wait();
@@ -130,9 +148,12 @@ rust_kernel::wait_for_schedulers()
     }
 }
 
-/* Called on the main thread to wait for the kernel to exit */
+/* Called on the main thread to run the osmain scheduler to completion,
+   then wait for schedulers to exit */
 int
-rust_kernel::wait_for_exit() {
+rust_kernel::run() {
+    assert(osmain_driver != NULL);
+    osmain_driver->start_main_loop();
     sched_reaper.join();
     return rval;
 }