[PATCH 1/2] perf evlist: Add a method to return the list of evsels as a string

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <a...@redhat.com>

Add a 'scnprintf' method to obtain the list of evsels in a evlist as a
string, excluding the "dummy" event used for things like receiving
metadata events (PERF_RECORD_FORK, MMAP, etc) when synthesizing
preexisting threads.

Will be used to improve the error message for workload failure in 'perf
record.

Cc: Adrian Hunter <adrian.hun...@intel.com>
Cc: Ian Rogers <irog...@google.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Namhyung Kim <namhy...@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
 tools/perf/util/evlist.c | 19 +++++++++++++++++++
 tools/perf/util/evlist.h |  2 ++
 2 files changed, 21 insertions(+)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index f1c79ecf81073f74..d29a8a118973c71c 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -2138,3 +2138,22 @@ struct evsel *evlist__find_evsel(struct evlist *evlist, 
int idx)
        }
        return NULL;
 }
+
+int evlist__scnprintf_evsels(struct evlist *evlist, size_t size, char *bf)
+{
+       struct evsel *evsel;
+       int printed = 0;
+
+       evlist__for_each_entry(evlist, evsel) {
+               if (evsel__is_dummy_event(evsel))
+                       continue;
+               if (size > (strlen(evsel__name(evsel)) + (printed ? 2 : 1))) {
+                       printed += scnprintf(bf + printed, size - printed, 
"%s%s", printed ? "," : "", evsel__name(evsel));
+               } else {
+                       printed += scnprintf(bf + printed, size - printed, 
"%s...", printed ? "," : "");
+                       break;
+               }
+       }
+
+       return printed;
+}
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index b695ffaae519a5d0..a8b97b50cceb7e43 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -365,4 +365,6 @@ int evlist__ctlfd_ack(struct evlist *evlist);
 #define EVLIST_DISABLED_MSG "Events disabled\n"
 
 struct evsel *evlist__find_evsel(struct evlist *evlist, int idx);
+
+int evlist__scnprintf_evsels(struct evlist *evlist, size_t size, char *bf);
 #endif /* __PERF_EVLIST_H */
-- 
2.26.2