[LLDB][GUI] Expand selected thread tree item by default

This patch expands the tree item that corresponds to the selected thread
by default in the Threads window. Additionally, the tree root item is
always expanded, which is the process in the Threads window.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D100243

lldb/source/Core/IOHandlerCursesGUI.cpp

@@ -3361,8 +3361,13 @@ public:
 
   virtual void TreeDelegateDrawTreeItem(TreeItem &item, Window &window) = 0;
   virtual void TreeDelegateGenerateChildren(TreeItem &item) = 0;
+  virtual void TreeDelegateUpdateSelection(TreeItem &root, int &selection_index,
+                                           TreeItem *&selected_item) {
+    return;
+  }
   virtual bool TreeDelegateItemSelected(
       TreeItem &item) = 0; // Return true if we need to update views
+  virtual bool TreeDelegateExpandRootByDefault() { return false; }
 };
 
 typedef std::shared_ptr<TreeDelegate> TreeDelegateSP;
@@ -3372,7 +3377,10 @@ public:
   TreeItem(TreeItem *parent, TreeDelegate &delegate, bool might_have_children)
       : m_parent(parent), m_delegate(delegate), m_user_data(nullptr),
         m_identifier(0), m_row_idx(-1), m_children(),
-        m_might_have_children(might_have_children), m_is_expanded(false) {}
+        m_might_have_children(might_have_children), m_is_expanded(false) {
+    if (m_parent == nullptr)
+      m_is_expanded = m_delegate.TreeDelegateExpandRootByDefault();
+  }
 
   TreeItem &operator=(const TreeItem &rhs) {
     if (this != &rhs) {
@@ -3601,6 +3609,8 @@ public:
       const int num_visible_rows = NumVisibleRows();
       m_num_rows = 0;
       m_root.CalculateRowIndexes(m_num_rows);
+      m_delegate_sp->TreeDelegateUpdateSelection(m_root, m_selected_row_idx,
+                                                 m_selected_item);
 
       // If we unexpanded while having something selected our total number of
       // rows is less than the num visible rows, then make sure we show all the
@@ -3902,7 +3912,7 @@ class ThreadsTreeDelegate : public TreeDelegate {
 public:
   ThreadsTreeDelegate(Debugger &debugger)
       : TreeDelegate(), m_thread_delegate_sp(), m_debugger(debugger),
-        m_stop_id(UINT32_MAX) {
+        m_stop_id(UINT32_MAX), m_update_selection(false) {
     FormatEntity::Parse("process ${process.id}{, name = ${process.name}}",
                         m_format);
   }
@@ -3930,6 +3940,7 @@ public:
 
   void TreeDelegateGenerateChildren(TreeItem &item) override {
     ProcessSP process_sp = GetProcess();
+    m_update_selection = false;
     if (process_sp && process_sp->IsAlive()) {
       StateType state = process_sp->GetState();
       if (StateIsStoppedState(state, true)) {
@@ -3938,6 +3949,7 @@ public:
           return; // Children are already up to date
 
         m_stop_id = stop_id;
+        m_update_selection = true;
 
         if (!m_thread_delegate_sp) {
           // Always expand the thread item the first time we show it
@@ -3949,11 +3961,15 @@ public:
         TreeItem t(&item, *m_thread_delegate_sp, false);
         ThreadList &threads = process_sp->GetThreadList();
         std::lock_guard<std::recursive_mutex> guard(threads.GetMutex());
+        ThreadSP selected_thread = threads.GetSelectedThread();
         size_t num_threads = threads.GetSize();
         item.Resize(num_threads, t);
         for (size_t i = 0; i < num_threads; ++i) {
-          item[i].SetIdentifier(threads.GetThreadAtIndex(i)->GetID());
+          ThreadSP thread = threads.GetThreadAtIndex(i);
+          item[i].SetIdentifier(thread->GetID());
           item[i].SetMightHaveChildren(true);
+          if (selected_thread->GetID() == thread->GetID())
+            item[i].Expand();
         }
         return;
       }
@@ -3961,12 +3977,42 @@ public:
     item.ClearChildren();
   }
 
+  void TreeDelegateUpdateSelection(TreeItem &root, int &selection_index,
+                                   TreeItem *&selected_item) override {
+    if (!m_update_selection)
+      return;
+
+    ProcessSP process_sp = GetProcess();
+    if (!(process_sp && process_sp->IsAlive()))
+      return;
+
+    StateType state = process_sp->GetState();
+    if (!StateIsStoppedState(state, true))
+      return;
+
+    ThreadList &threads = process_sp->GetThreadList();
+    std::lock_guard<std::recursive_mutex> guard(threads.GetMutex());
+    ThreadSP selected_thread = threads.GetSelectedThread();
+    size_t num_threads = threads.GetSize();
+    for (size_t i = 0; i < num_threads; ++i) {
+      ThreadSP thread = threads.GetThreadAtIndex(i);
+      if (selected_thread->GetID() == thread->GetID()) {
+        selected_item = &root[i][thread->GetSelectedFrameIndex()];
+        selection_index = selected_item->GetRowIndex();
+        return;
+      }
+    }
+  }
+
   bool TreeDelegateItemSelected(TreeItem &item) override { return false; }
 
+  bool TreeDelegateExpandRootByDefault() override { return true; }
+
 protected:
   std::shared_ptr<ThreadTreeDelegate> m_thread_delegate_sp;
   Debugger &m_debugger;
   uint32_t m_stop_id;
+  bool m_update_selection;
   FormatEntity::Entry m_format;
 };
 

lldb/test/API/commands/gui/expand-threads-tree/Makefile

@@ -0,0 +1,3 @@
+C_SOURCES := main.c
+ENABLE_THREADS := YES
+include Makefile.rules

lldb/test/API/commands/gui/expand-threads-tree/TestGuiExpandThreadsTree.py

@@ -0,0 +1,55 @@
+"""
+Test the 'gui' default thread tree expansion.
+The root process tree item and the tree item corresponding to the selected
+thread should be expanded by default.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.lldbpexpect import PExpectTest
+
+class TestGuiExpandThreadsTree(PExpectTest):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    # PExpect uses many timeouts internally and doesn't play well
+    # under ASAN on a loaded machine..
+    @skipIfAsan
+    @skipIfCursesSupportMissing
+    def test_gui(self):
+        self.build()
+
+        self.launch(executable=self.getBuildArtifact("a.out"), dimensions=(100,500))
+        self.expect("breakpoint set -r thread_start_routine", substrs=["Breakpoint 1", "address ="])
+        self.expect("run", substrs=["stop reason ="])
+
+        escape_key = chr(27).encode()
+
+        # Start the GUI and close the welcome window.
+        self.child.sendline("gui")
+        self.child.send(escape_key)
+        self.child.expect_exact("Threads")
+
+        # The thread running thread_start_routine should be expanded.
+        self.child.expect_exact("frame #0: thread_start_routine")
+
+        # Exit GUI.
+        self.child.send(escape_key)
+        self.expect_prompt()
+
+        # Select the main thread.
+        self.child.sendline("thread select 1")
+
+        # Start the GUI.
+        self.child.sendline("gui")
+        self.child.expect_exact("Threads")
+
+        # The main thread should be expanded.
+        self.child.expect("frame #\d+: main")
+
+        # Quit the GUI
+        self.child.send(escape_key)
+
+        self.expect_prompt()
+        self.quit()

lldb/test/API/commands/gui/expand-threads-tree/main.c

@@ -0,0 +1,10 @@
+#include <pthread.h>
+
+void *thread_start_routine(void *arg) { return NULL; }
+
+int main() {
+  pthread_t thread;
+  pthread_create(&thread, NULL, thread_start_routine, NULL);
+  pthread_join(thread, NULL);
+  return 0;
+}