perf annotate: Cycle thru sorted lines with samples

The annotate TUI now starts centered on the line with most samples, i.e.
the hottest line in the annotated function. Pressing TAB will center on
the second hottest function and so on. Shift+TAB goes in the other
direction.

This way one can more easily sift thru the function hotspots.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/ui/browsers/annotate.c

@@ -17,6 +17,7 @@ static void ui__error_window(const char *fmt, ...)
 struct annotate_browser {
 	struct ui_browser b;
 	struct rb_root	  entries;
+	struct rb_node	  *curr_hot;
 };
 
 struct objdump_line_rb_node {
@@ -110,12 +111,83 @@ static void objdump__insert_line(struct rb_root *self,
 	rb_insert_color(&line->rb_node, self);
 }
 
+static void annotate_browser__set_top(struct annotate_browser *self,
+				      struct rb_node *nd)
+{
+	struct objdump_line_rb_node *rbpos;
+	struct objdump_line *pos;
+	unsigned back;
+
+	ui_browser__refresh_dimensions(&self->b);
+	back = self->b.height / 2;
+	rbpos = rb_entry(nd, struct objdump_line_rb_node, rb_node);
+	pos = ((struct objdump_line *)rbpos) - 1;
+	self->b.top_idx = self->b.index = rbpos->idx;
+
+	while (self->b.top_idx != 0 && back != 0) {
+		pos = list_entry(pos->node.prev, struct objdump_line, node);
+
+		--self->b.top_idx;
+		--back;
+	}
+
+	self->b.top = pos;
+	self->curr_hot = nd;
+}
+
+static int annotate_browser__run(struct annotate_browser *self,
+				 struct newtExitStruct *es)
+{
+	struct rb_node *nd;
+	struct hist_entry *he = self->b.priv;
+
+	if (ui_browser__show(&self->b, he->ms.sym->name) < 0)
+		return -1;
+
+	ui_helpline__fpush("<- or ESC: exit, TAB/shift+TAB: cycle thru samples");
+	newtFormAddHotKey(self->b.form, NEWT_KEY_LEFT);
+
+	nd = self->curr_hot;
+	if (nd) {
+		newtFormAddHotKey(self->b.form, NEWT_KEY_TAB);
+		newtFormAddHotKey(self->b.form, NEWT_KEY_UNTAB);
+	}
+
+	while (1) {
+		ui_browser__run(&self->b, es);
+
+		if (es->reason != NEWT_EXIT_HOTKEY)
+			break;
+
+		switch (es->u.key) {
+		case NEWT_KEY_TAB:
+			nd = rb_prev(nd);
+			if (nd == NULL)
+				nd = rb_last(&self->entries);
+			annotate_browser__set_top(self, nd);
+			break;
+		case NEWT_KEY_UNTAB:
+			nd = rb_next(nd);
+			if (nd == NULL)
+				nd = rb_first(&self->entries);
+			annotate_browser__set_top(self, nd);
+			break;
+		default:
+			goto out;
+		}
+	}
+out:
+	newtFormDestroy(self->b.form);
+	newtPopWindow();
+	ui_helpline__pop();
+	return 0;
+}
+
 int hist_entry__tui_annotate(struct hist_entry *self)
 {
 	struct newtExitStruct es;
 	struct objdump_line *pos, *n;
 	struct objdump_line_rb_node *rbpos;
-	struct rb_node *nd;
 	LIST_HEAD(head);
 	struct annotate_browser browser = {
 		.b = {
@@ -156,35 +228,15 @@ int hist_entry__tui_annotate(struct hist_entry *self)
 	/*
 	 * Position the browser at the hottest line.
 	 */
-	nd = rb_last(&browser.entries);
-	if (nd != NULL) {
-		unsigned back;
-
-		ui_browser__refresh_dimensions(&browser.b);
-		back = browser.b.height / 2;
-		rbpos = rb_entry(nd, struct objdump_line_rb_node, rb_node);
-		pos = ((struct objdump_line *)rbpos) - 1;
-		browser.b.top_idx = browser.b.index = rbpos->idx;
-
-		while (browser.b.top_idx != 0 && back != 0) {
-			pos = list_entry(pos->node.prev, struct objdump_line, node);
-
-			--browser.b.top_idx;
-			--back;
-		}
-
-		browser.b.top = pos;
-	}
+	browser.curr_hot = rb_last(&browser.entries);
+	if (browser.curr_hot)
+		annotate_browser__set_top(&browser, browser.curr_hot);
 
 	browser.b.width += 18; /* Percentage */
-	ui_browser__show(&browser.b, self->ms.sym->name);
-	ret = ui_browser__run(&browser.b, &es);
-	newtFormDestroy(browser.b.form);
-	newtPopWindow();
+	ret = annotate_browser__run(&browser, &es);
 	list_for_each_entry_safe(pos, n, &head, node) {
 		list_del(&pos->node);
 		objdump_line__free(pos);
 	}
-	ui_helpline__pop();
 	return ret;
 }