[debugger] Properly close debugger thread when connection hangs

When we detach from the debugger, we reset the state by starting a new debugger thread (why don't we just use the existing thread?). As per commit https://github.com/mono/mono/commit/mono/mono@540ef385faa230bc226c7a83bfabd0730520911e we should shut down the debugger thread when the connection drops. However, since that commit was acting as a Dispose command was sent instead, it would end up relentlessly spawning and closing new debugger threads up until the runtime is shut down. This commit makes sure we don't respawn once the connection hangs.

Commit migrated from https://github.com/mono/mono/commit/f5bb650f784f7d9021178633e7da3b7984122b68

diff --git a/src/mono/mono/mini/debugger-agent.c b/src/mono/mono/mini/debugger-agent.c
index 1253032..a9bd9a3 100644 (file)
--- a/src/mono/mono/mini/debugger-agent.c
+++ b/src/mono/mono/mini/debugger-agent.c
@@ -1646,7 +1646,8 @@ start_debugger_thread (MonoError *error)
 
        thread = mono_thread_create_internal (mono_get_root_domain (), (gpointer)debugger_thread, NULL, MONO_THREAD_CREATE_FLAGS_DEBUGGER, error);
        return_if_nok (error);
-       
+
+       /* Is it possible for the thread to be dead alreay ? */
        debugger_thread_handle = mono_threads_open_thread_handle (thread->handle);
        g_assert (debugger_thread_handle);
        
@@ -6284,6 +6285,23 @@ clear_types_for_assembly (MonoAssembly *assembly)
        mono_loader_unlock ();
 }
 
+static void
+dispose_vm (void)
+{
+       /* Clear all event requests */
+       mono_loader_lock ();
+       while (event_requests->len > 0) {
+               EventRequest *req = (EventRequest *)g_ptr_array_index (event_requests, 0);
+
+               clear_event_request (req->id, req->event_kind);
+       }
+       mono_loader_unlock ();
+
+       while (suspend_count > 0)
+               resume_vm ();
+       disconnected = TRUE;
+       vm_start_event_sent = FALSE;
+}
 
 static void
 count_thread_check_gc_finalizer (gpointer key, gpointer value, gpointer user_data)
@@ -6893,19 +6911,7 @@ vm_commands (int command, int id, guint8 *p, guint8 *end, Buffer *buf)
                clear_suspended_objs ();
                break;
        case CMD_VM_DISPOSE:
-               /* Clear all event requests */
-               mono_loader_lock ();
-               while (event_requests->len > 0) {
-                       EventRequest *req = (EventRequest *)g_ptr_array_index (event_requests, 0);
-
-                       clear_event_request (req->id, req->event_kind);
-               }
-               mono_loader_unlock ();
-
-               while (suspend_count > 0)
-                       resume_vm ();
-               disconnected = TRUE;
-               vm_start_event_sent = FALSE;
+               dispose_vm ();
                break;
        case CMD_VM_EXIT: {
                MonoInternalThread *thread;
@@ -9994,11 +10000,10 @@ debugger_thread (void *arg)
                /* This will break if the socket is closed during shutdown too */
                if (res != HEADER_LENGTH) {
                        DEBUG_PRINTF (1, "[dbg] transport_recv () returned %d, expected %d.\n", res, HEADER_LENGTH);
-                       len = HEADER_LENGTH;
-                       id = 0;
-                       flags = 0;
-                       command_set = CMD_SET_VM;
-                       command = CMD_VM_DISPOSE;
+                       command_set = (CommandSet)0;
+                       command = 0;
+                       dispose_vm ();
+                       break;
                } else {
                        p = header;
                        end = header + HEADER_LENGTH;