rgw: in bucket reshard list, clarify new num shards is tentative

With dynamic bucket index resharding, when the average number of
objects per shard exceeds the configured value, that bucket is
scheduled for reshard. That bucket may receive more new objects before
the resharding takes place. As a result, the existing code
re-calculates the number of new shards just prior to resharding,
rather than waste a resharding opportunity with too low a value.

The same holds true for a user-scheduled resharding.

A user reported confusion that the number reported in `radosgw-admin
reshard list` wasn't the number that the reshard operation ultimately
used. This commit makes it clear that the new number of shards is
"tentative". And test_rgw_reshard.py is updated to reflect this
altered output.

Additionally this commit adds some modernization and efficiency to the
"reshard list" subcommand.

Signed-off-by: J. Eric Ivancich <ivancich@redhat.com>
(cherry picked from commit aa0071ce8b8594b92c0bed2be7a9bf35bfff8cac)

diff --git a/qa/workunits/rgw/test_rgw_reshard.py b/qa/workunits/rgw/test_rgw_reshard.py
index 092a002b2bd7f03daed6472a5f4c901bcaf89433..61e92b990459790906b5115130e8e36530befd61 100755 (executable)
--- a/qa/workunits/rgw/test_rgw_reshard.py
+++ b/qa/workunits/rgw/test_rgw_reshard.py
@@ -149,7 +149,7 @@ def main():
     json_op = json.loads(cmd)
     log.debug('bucket name %s', json_op[0]['bucket_name'])
     assert json_op[0]['bucket_name'] == BUCKET_NAME1
-    assert json_op[0]['new_num_shards'] == num_shards_expected
+    assert json_op[0]['tentative_new_num_shards'] == num_shards_expected
 
     # TESTCASE 'reshard-process','reshard','','process bucket resharding','succeeds'
     log.debug(' test: reshard process')
@@ -174,7 +174,7 @@ def main():
     json_op = json.loads(cmd)
     log.debug('bucket name %s', json_op[0]['bucket_name'])
     assert json_op[0]['bucket_name'] == BUCKET_NAME1
-    assert json_op[0]['new_num_shards'] == num_shards_expected
+    assert json_op[0]['tentative_new_num_shards'] == num_shards_expected
 
     # TESTCASE 'reshard process ,'reshard','process','reshard non empty bucket','succeeds'
     log.debug(' test: reshard process non empty bucket')

diff --git a/src/cls/rgw/cls_rgw_types.cc b/src/cls/rgw/cls_rgw_types.cc
index 91ebe86eb432fceec584359c5c2e3f6c5ed3c919..67535841e2fc2831801c7501e6bda191f115f70c 100644 (file)
--- a/src/cls/rgw/cls_rgw_types.cc
+++ b/src/cls/rgw/cls_rgw_types.cc
@@ -721,8 +721,7 @@ void cls_rgw_reshard_entry::dump(Formatter *f) const
   encode_json("bucket_id", bucket_id, f);
   encode_json("new_instance_id", new_instance_id, f);
   encode_json("old_num_shards", old_num_shards, f);
-  encode_json("new_num_shards", new_num_shards, f);
-
+  encode_json("tentative_new_num_shards", new_num_shards, f);
 }
 
 void cls_rgw_reshard_entry::generate_test_instances(list<cls_rgw_reshard_entry*>& ls)

diff --git a/src/rgw/rgw_admin.cc b/src/rgw/rgw_admin.cc
index 6d10387fb3598a8199bd70c4cff5c90de475d093..3ce6874eaccf0431c42192c1e7ee7fa018dd383d 100644 (file)
--- a/src/rgw/rgw_admin.cc
+++ b/src/rgw/rgw_admin.cc
@@ -7563,7 +7563,6 @@ next:
   }
 
   if (opt_cmd == OPT::RESHARD_LIST) {
-    list<cls_rgw_reshard_entry> entries;
     int ret;
     int count = 0;
     if (max_entries < 0) {
@@ -7578,19 +7577,20 @@ next:
     formatter->open_array_section("reshard");
     for (int i = 0; i < num_logshards; i++) {
       bool is_truncated = true;
-      string marker;
+      std::string marker;
       do {
-        entries.clear();
+       std::list<cls_rgw_reshard_entry> entries;
         ret = reshard.list(dpp(), i, marker, max_entries - count, entries, &is_truncated);
         if (ret < 0) {
           cerr << "Error listing resharding buckets: " << cpp_strerror(-ret) << std::endl;
           return ret;
         }
-        for (auto iter=entries.begin(); iter != entries.end(); ++iter) {
-          cls_rgw_reshard_entry& entry = *iter;
+        for (const auto& entry : entries) {
           encode_json("entry", entry, formatter.get());
-          entry.get_key(&marker);
         }
+       if (is_truncated) {
+         entries.crbegin()->get_key(&marker); // last entry's key becomes marker
+       }
         count += entries.size();
         formatter->flush(cout);
       } while (is_truncated && count < max_entries);
@@ -7602,6 +7602,7 @@ next:
 
     formatter->close_section();
     formatter->flush(cout);
+
     return 0;
   }