perf hist: Introduce hists class and move lots of methods to it

In cbbc79a we introduced support for multiple events by introducing a
new "event_stat_id" struct and then made several perf_session methods
receive a point to it instead of a pointer to perf_session, and kept the
event_stats and hists rb_tree in perf_session.

While working on the new newt based browser, I realised that it would be
better to introduce a new class, "hists" (short for "histograms"),
renaming the "event_stat_id" struct and the perf_session methods that
were really "hists" methods, as they manipulate only struct hists
members, not touching anything in the other perf_session members.

Other optimizations, such as calculating the maximum lenght of a symbol
name present in an hists instance will be possible as we add them,
avoiding a re-traversal just for finding that information.

The rationale for the name "hists" to replace "event_stat_id" is that we
may have multiple sets of hists for the same event_stat id, as, for
instance, the 'perf diff' tool has, so event stat id is not what
characterizes what this struct and the functions that manipulate it do.

Cc: Eric B Munson <ebmunson@us.ibm.com>
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>

1 files changed, 9 insertions, 3 deletions

diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 242d528bfae2..46190f94b547 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -1,6 +1,7 @@
 #ifndef __PERF_SESSION_H
 #define __PERF_SESSION_H
 
+#include "hist.h"
 #include "event.h"
 #include "header.h"
 #include "symbol.h"
@@ -28,11 +29,16 @@ struct perf_session {
         struct thread           *last_match;
         struct machine          host_machine;
         struct rb_root          machines;
-        struct events_stats     events_stats;
-        struct rb_root          stats_by_id;
+        struct rb_root          hists_tree;
         unsigned long           event_total[PERF_RECORD_MAX];
         unsigned long           unknown_events;
-        struct rb_root          hists;
+        /*
+         * FIXME: should point to the first entry in hists_tree and
+         *        be a hists instance. Right now its only 'report'
+         *        that is using ->hists_tree while all the rest use
+         *        ->hists.
+         */
+        struct hists            hists;
         u64                     sample_type;
         int                     fd;
         bool                    fd_pipe;