mon: compact trimmed range, not entire prefix

This will reduce the work that leveldb is asked to do by only triggering
compaction of the keys that were just trimmed.

We ma want to further reduce the work by compacting less frequently, but
this is at least a step in that direction.

Signed-off-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 6da4b20ca53fc8161485c8a99a6b333e23ace30e)

2 files changed, 12 insertions, 11 deletions

diff --git a/src/mon/Paxos.cc b/src/mon/Paxos.cc
index bfb9ed4f5dd..7ff5edbd0a9 100644
--- a/src/mon/Paxos.cc
+++ b/src/mon/Paxos.cc
@@ -21,6 +21,7 @@
 
 #include "common/config.h"
 #include "include/assert.h"
+#include "include/stringify.h"
 #include "common/Formatter.h"
 
 #define dout_subsys ceph_subsys_paxos
@@ -959,14 +960,13 @@ void Paxos::trim_to(MonitorDBStore::Transaction *t,
   dout(10) << __func__ << " from " << from << " to " << to << dendl;
   assert(from < to);
 
-  while (from < to) {
-    dout(10) << "trim " << from << dendl;
-    t->erase(get_name(), from);
-    from++;
+  for (version_t v = from; v < to; ++v) {
+    dout(10) << "trim " << v << dendl;
+    t->erase(get_name(), v);
   }
   if (g_conf->mon_compact_on_trim) {
-    dout(10) << " compacting prefix" << dendl;
-    t->compact_prefix(get_name());
+    dout(10) << " compacting trimmed range" << dendl;
+    t->compact_range(get_name(), stringify(from), stringify(to));
   }
 }
 
diff --git a/src/mon/PaxosService.cc b/src/mon/PaxosService.cc
index 8f421ab3d81..3402cf7e76f 100644
--- a/src/mon/PaxosService.cc
+++ b/src/mon/PaxosService.cc
@@ -314,11 +314,12 @@ void PaxosService::trim(MonitorDBStore::Transaction *t,
 {
   dout(10) << __func__ << " from " << from << " to " << to << dendl;
   assert(from != to);
-  for (; from < to; from++) {
-    dout(20) << __func__ << " " << from << dendl;
-    t->erase(get_service_name(), from);
 
-    string full_key = mon->store->combine_strings("full", from);
+  for (version_t v = from; v < to; ++v) {
+    dout(20) << __func__ << " " << v << dendl;
+    t->erase(get_service_name(), v);
+
+    string full_key = mon->store->combine_strings("full", v);
     if (mon->store->exists(get_service_name(), full_key)) {
       dout(20) << __func__ << " " << full_key << dendl;
       t->erase(get_service_name(), full_key);
@@ -326,7 +327,7 @@ void PaxosService::trim(MonitorDBStore::Transaction *t,
   }
   if (g_conf->mon_compact_on_trim) {
     dout(20) << " compacting prefix " << get_service_name() << dendl;
-    t->compact_prefix(get_service_name());
+    t->compact_range(get_service_name(), stringify(from), stringify(to));
   }
 }