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)

Conflicts:
	src/rgw/rgw_admin.cc

Cherry-pick notes:
- Confict caused by reshard.list not having dout prefix provider arg in Pacific

diff --git a/qa/workunits/rgw/test_rgw_reshard.py b/qa/workunits/rgw/test_rgw_reshard.py
index 14f4fe509946989e2e8f6ad59b78ad928cbea207..d3e407d8b4428c50f8e4547cc510c801126eb885 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 2e306fe7e84715d6ce207b1065ec7c26ba2a4dfb..57067625b54393e02bb9f9217d844003fdee5b93 100644 (file)
--- a/src/cls/rgw/cls_rgw_types.cc
+++ b/src/cls/rgw/cls_rgw_types.cc
@@ -722,8 +722,7 @@ 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 7928867648e292d03066a4922b33777ac228ec93..d585153688d6938cd081b96a0bed78334bdaa676 100644 (file)
--- a/src/rgw/rgw_admin.cc
+++ b/src/rgw/rgw_admin.cc
@@ -7003,7 +7003,6 @@ next:
   }
 
   if (opt_cmd == OPT::RESHARD_LIST) {
-    list<cls_rgw_reshard_entry> entries;
     int ret;
     int count = 0;
     if (max_entries < 0) {
@@ -7018,19 +7017,20 @@ 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(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);
@@ -7042,6 +7042,7 @@ next:
 
     formatter->close_section();
     formatter->flush(cout);
+
     return 0;
   }