perf hists browser: Implement printing snapshots to files

To avoid having to resort to --stdio, that expands everything, instead
allow the user to go on expanding the relevant callchains and then press
'P' to print that view.

As the hists browser is used for both static (report) and dynamic (top)
views, it prints to a 'perf.hists.N' sequence, i.e. multiple snapshots
can be taken in report and top.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-wr9xx4ba0utrynu5j6wotd79@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/hists.c

@@ -23,6 +23,7 @@ struct hist_browser {
 	struct hists	    *hists;
 	struct hist_entry   *he_selection;
 	struct map_symbol   *selection;
+	int		     print_seq;
 	bool		     has_symbols;
 };
 
@@ -800,6 +801,196 @@ do_offset:
 	}
 }
 
+static int hist_browser__fprintf_callchain_node_rb_tree(struct hist_browser *browser,
+							struct callchain_node *chain_node,
+							u64 total, int level,
+							FILE *fp)
+{
+	struct rb_node *node;
+	int offset = level * LEVEL_OFFSET_STEP;
+	u64 new_total, remaining;
+	int printed = 0;
+
+	if (callchain_param.mode == CHAIN_GRAPH_REL)
+		new_total = chain_node->children_hit;
+	else
+		new_total = total;
+
+	remaining = new_total;
+	node = rb_first(&chain_node->rb_root);
+	while (node) {
+		struct callchain_node *child = rb_entry(node, struct callchain_node, rb_node);
+		struct rb_node *next = rb_next(node);
+		u64 cumul = callchain_cumul_hits(child);
+		struct callchain_list *chain;
+		char folded_sign = ' ';
+		int first = true;
+		int extra_offset = 0;
+
+		remaining -= cumul;
+
+		list_for_each_entry(chain, &child->val, list) {
+			char ipstr[BITS_PER_LONG / 4 + 1], *alloc_str;
+			const char *str;
+			bool was_first = first;
+
+			if (first)
+				first = false;
+			else
+				extra_offset = LEVEL_OFFSET_STEP;
+
+			folded_sign = callchain_list__folded(chain);
+
+			alloc_str = NULL;
+			str = callchain_list__sym_name(chain, ipstr, sizeof(ipstr));
+			if (was_first) {
+				double percent = cumul * 100.0 / new_total;
+
+				if (asprintf(&alloc_str, "%2.2f%% %s", percent, str) < 0)
+					str = "Not enough memory!";
+				else
+					str = alloc_str;
+			}
+
+			printed += fprintf(fp, "%*s%c %s\n", offset + extra_offset, " ", folded_sign, str);
+			free(alloc_str);
+			if (folded_sign == '+')
+				break;
+		}
+
+		if (folded_sign == '-') {
+			const int new_level = level + (extra_offset ? 2 : 1);
+			printed += hist_browser__fprintf_callchain_node_rb_tree(browser, child, new_total,
+										new_level, fp);
+		}
+
+		node = next;
+	}
+
+	return printed;
+}
+
+static int hist_browser__fprintf_callchain_node(struct hist_browser *browser,
+						struct callchain_node *node,
+						int level, FILE *fp)
+{
+	struct callchain_list *chain;
+	int offset = level * LEVEL_OFFSET_STEP;
+	char folded_sign = ' ';
+	int printed = 0;
+
+	list_for_each_entry(chain, &node->val, list) {
+		char ipstr[BITS_PER_LONG / 4 + 1], *s;
+
+		folded_sign = callchain_list__folded(chain);
+		s = callchain_list__sym_name(chain, ipstr, sizeof(ipstr));
+		printed += fprintf(fp, "%*s%c %s\n", offset, " ", folded_sign, s);
+	}
+
+	if (folded_sign == '-')
+		printed += hist_browser__fprintf_callchain_node_rb_tree(browser, node,
+									browser->hists->stats.total_period,
+									level + 1,  fp);
+	return printed;
+}
+
+static int hist_browser__fprintf_callchain(struct hist_browser *browser,
+					   struct rb_root *chain, int level, FILE *fp)
+{
+	struct rb_node *nd;
+	int printed = 0;
+
+	for (nd = rb_first(chain); nd; nd = rb_next(nd)) {
+		struct callchain_node *node = rb_entry(nd, struct callchain_node, rb_node);
+
+		printed += hist_browser__fprintf_callchain_node(browser, node, level, fp);
+	}
+
+	return printed;
+}
+
+static int hist_browser__fprintf_entry(struct hist_browser *browser,
+				       struct hist_entry *he, FILE *fp)
+{
+	char s[8192];
+	double percent;
+	int printed = 0;
+	char folded_sign = ' ';
+
+	if (symbol_conf.use_callchain)
+		folded_sign = hist_entry__folded(he);
+
+	hist_entry__snprintf(he, s, sizeof(s), browser->hists);
+	percent = (he->period * 100.0) / browser->hists->stats.total_period;
+
+	if (symbol_conf.use_callchain)
+		printed += fprintf(fp, "%c ", folded_sign);
+
+	printed += fprintf(fp, " %5.2f%%", percent);
+
+	if (symbol_conf.show_nr_samples)
+		printed += fprintf(fp, " %11u", he->nr_events);
+
+	if (symbol_conf.show_total_period)
+		printed += fprintf(fp, " %12" PRIu64, he->period);
+
+	printed += fprintf(fp, "%s\n", rtrim(s));
+
+	if (folded_sign == '-')
+		printed += hist_browser__fprintf_callchain(browser, &he->sorted_chain, 1, fp);
+
+	return printed;
+}
+
+static int hist_browser__fprintf(struct hist_browser *browser, FILE *fp)
+{
+	struct rb_node *nd = hists__filter_entries(rb_first(browser->b.entries));
+	int printed = 0;
+
+	while (nd) {
+		struct hist_entry *h = rb_entry(nd, struct hist_entry, rb_node);
+
+		printed += hist_browser__fprintf_entry(browser, h, fp);
+		nd = hists__filter_entries(rb_next(nd));
+	}
+
+	return printed;
+}
+
+static int hist_browser__dump(struct hist_browser *browser)
+{
+	char filename[64];
+	FILE *fp;
+
+	while (1) {
+		scnprintf(filename, sizeof(filename), "perf.hist.%d", browser->print_seq);
+		if (access(filename, F_OK))
+			break;
+		/*
+ 		 * XXX: Just an arbitrary lazy upper limit
+ 		 */
+		if (++browser->print_seq == 8192) {
+			ui_helpline__fpush("Too many perf.hist.N files, nothing written!");
+			return -1;
+		}
+	}
+
+	fp = fopen(filename, "w");
+	if (fp == NULL) {
+		char bf[64];
+		strerror_r(errno, bf, sizeof(bf));
+		ui_helpline__fpush("Couldn't write to %s: %s", filename, bf);
+		return -1;
+	}
+
+	++browser->print_seq;
+	hist_browser__fprintf(browser, fp);
+	fclose(fp);
+	ui_helpline__fpush("%s written!", filename);
+
+	return 0;
+}
+
 static struct hist_browser *hist_browser__new(struct hists *hists)
 {
 	struct hist_browser *browser = zalloc(sizeof(*browser));
@@ -937,6 +1128,9 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 			    browser->selection->map->dso->annotate_warned)
 				continue;
 			goto do_annotate;
+		case 'P':
+			hist_browser__dump(browser);
+			continue;
 		case 'd':
 			goto zoom_dso;
 		case 't':
@@ -969,6 +1163,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 					"E             Expand all callchains\n"
 					"d             Zoom into current DSO\n"
 					"t             Zoom into current Thread\n"
+					"P             Print histograms to perf.hist.N\n"
 					"/             Filter symbol by name");
 			continue;
 		case K_ENTER: