perf newt: Make <- zoom out filters

After we use the filters to zoom into DSOs or threads, we can use <-
(left arrow) to zoom out from the last filter applied.

It is still possible to zoom out of order by using the popup menu.

With this we now have the zoom out operation on the browsing fast path,
by allowing fast navigation using just the four arrors and the enter key
to expand collapse callchains.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile

@@ -416,6 +416,7 @@ LIB_H += util/thread.h
 LIB_H += util/trace-event.h
 LIB_H += util/probe-finder.h
 LIB_H += util/probe-event.h
+LIB_H += util/pstack.h
 LIB_H += util/cpumap.h
 
 LIB_OBJS += $(OUTPUT)util/abspath.o
@@ -451,6 +452,7 @@ LIB_OBJS += $(OUTPUT)util/callchain.o
 LIB_OBJS += $(OUTPUT)util/values.o
 LIB_OBJS += $(OUTPUT)util/debug.o
 LIB_OBJS += $(OUTPUT)util/map.o
+LIB_OBJS += $(OUTPUT)util/pstack.o
 LIB_OBJS += $(OUTPUT)util/session.o
 LIB_OBJS += $(OUTPUT)util/thread.o
 LIB_OBJS += $(OUTPUT)util/trace-event-parse.o

tools/perf/util/newt.c

@@ -9,6 +9,7 @@
 
 #include "cache.h"
 #include "hist.h"
+#include "pstack.h"
 #include "session.h"
 #include "sort.h"
 #include "symbol.h"
@@ -750,6 +751,7 @@ static int hist_browser__populate(struct hist_browser *self, struct hists *hists
 	newtFormAddHotKey(self->form, 'A');
 	newtFormAddHotKey(self->form, 'a');
 	newtFormAddHotKey(self->form, NEWT_KEY_RIGHT);
+	newtFormAddHotKey(self->form, NEWT_KEY_LEFT);
 	newtFormAddComponents(self->form, self->tree, NULL);
 	self->selection = newt__symbol_tree_get_current(self->tree);
 
@@ -801,6 +803,7 @@ static int hist_browser__title(char *bf, size_t size, const char *input_name,
 int hists__browse(struct hists *self, const char *helpline, const char *input_name)
 {
 	struct hist_browser *browser = hist_browser__new();
+	struct pstack *fstack = pstack__new(2);
 	const struct thread *thread_filter = NULL;
 	const struct dso *dso_filter = NULL;
 	struct newtExitStruct es;
@@ -810,12 +813,16 @@ int hists__browse(struct hists *self, const char *helpline, const char *input_na
 	if (browser == NULL)
 		return -1;
 
+	fstack = pstack__new(2);
+	if (fstack == NULL)
+		goto out;
+
 	ui_helpline__push(helpline);
 
 	hist_browser__title(msg, sizeof(msg), input_name,
 			    dso_filter, thread_filter);
 	if (hist_browser__populate(browser, self, msg) < 0)
-		goto out;
+		goto out_free_stack;
 
 	while (1) {
 		const struct thread *thread;
@@ -836,6 +843,19 @@ int hists__browse(struct hists *self, const char *helpline, const char *input_na
 				else
 					continue;
 			}
+
+			if (es.u.key == NEWT_KEY_LEFT) {
+				const void *top;
+
+				if (pstack__empty(fstack))
+					continue;
+				top = pstack__pop(fstack);
+				if (top == &dso_filter)
+					goto zoom_out_dso;
+				if (top == &thread_filter)
+					goto zoom_out_thread;
+				continue;
+			}
 		}
 
 		if (browser->selection->sym != NULL &&
@@ -888,12 +908,15 @@ do_annotate:
 			hist_entry__annotate_browser(he);
 		} else if (choice == zoom_dso) {
 			if (dso_filter) {
+				pstack__remove(fstack, &dso_filter);
+zoom_out_dso:
 				ui_helpline__pop();
 				dso_filter = NULL;
 			} else {
-				ui_helpline__fpush("To zoom out press -> + \"Zoom out of %s DSO\"",
+				ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s DSO\"",
 						   dso->kernel ? "the Kernel" : dso->short_name);
 				dso_filter = dso;
+				pstack__push(fstack, &dso_filter);
 			}
 			hists__filter_by_dso(self, dso_filter);
 			hist_browser__title(msg, sizeof(msg), input_name,
@@ -902,13 +925,16 @@ do_annotate:
 				goto out;
 		} else if (choice == zoom_thread) {
 			if (thread_filter) {
+				pstack__remove(fstack, &thread_filter);
+zoom_out_thread:
 				ui_helpline__pop();
 				thread_filter = NULL;
 			} else {
-				ui_helpline__fpush("To zoom out press -> + \"Zoom out of %s(%d) thread\"",
+				ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s(%d) thread\"",
 						   thread->comm_set ? thread->comm : "",
 						   thread->pid);
 				thread_filter = thread;
+				pstack__push(fstack, &thread_filter);
 			}
 			hists__filter_by_thread(self, thread_filter);
 			hist_browser__title(msg, sizeof(msg), input_name,
@@ -918,6 +944,8 @@ do_annotate:
 		}
 	}
 	err = 0;
+out_free_stack:
+	pstack__delete(fstack);
 out:
 	hist_browser__delete(browser);
 	return err;

tools/perf/util/pstack.c

@@ -0,0 +1,75 @@
+/*
+ * Simple pointer stack
+ *
+ * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
+ */
+
+#include "util.h"
+#include "pstack.h"
+#include <linux/kernel.h>
+#include <stdlib.h>
+
+struct pstack {
+	unsigned short	top;
+	unsigned short	max_nr_entries;
+	void		*entries[0];
+};
+
+struct pstack *pstack__new(unsigned short max_nr_entries)
+{
+	struct pstack *self = zalloc((sizeof(*self) +
+				     max_nr_entries * sizeof(void *)));
+	if (self != NULL)
+		self->max_nr_entries = max_nr_entries;
+	return self;
+}
+
+void pstack__delete(struct pstack *self)
+{
+	free(self);
+}
+
+bool pstack__empty(const struct pstack *self)
+{
+	return self->top == 0;
+}
+
+void pstack__remove(struct pstack *self, void *key)
+{
+	unsigned short i = self->top, last_index = self->top - 1;
+
+	while (i-- != 0) {
+		if (self->entries[i] == key) {
+			if (i < last_index)
+				memmove(self->entries + i,
+					self->entries + i + 1,
+					(last_index - i) * sizeof(void *));
+			--self->top;
+			return;
+		}
+	}
+	pr_err("%s: %p not on the pstack!\n", __func__, key);
+}
+
+void pstack__push(struct pstack *self, void *key)
+{
+	if (self->top == self->max_nr_entries) {
+		pr_err("%s: top=%d, overflow!\n", __func__, self->top);
+		return;
+	}
+	self->entries[self->top++] = key;
+}
+
+void *pstack__pop(struct pstack *self)
+{
+	void *ret;
+
+	if (self->top == 0) {
+		pr_err("%s: underflow!\n", __func__);
+		return NULL;
+	}
+
+	ret = self->entries[--self->top];
+	self->entries[self->top] = NULL;
+	return ret;
+}

tools/perf/util/pstack.h

@@ -0,0 +1,12 @@
+#ifndef _PERF_PSTACK_
+#define _PERF_PSTACK_
+
+struct pstack;
+struct pstack *pstack__new(unsigned short max_nr_entries);
+void pstack__delete(struct pstack *self);
+bool pstack__empty(const struct pstack *self);
+void pstack__remove(struct pstack *self, void *key);
+void pstack__push(struct pstack *self, void *key);
+void *pstack__pop(struct pstack *self);
+
+#endif /* _PERF_PSTACK_ */