rgw: paginate ListTopics

rename read_topics()/write_topics() to 'v1' and only call them from
internal v1 call paths

public get_topics() now calls read_topics_v1() for the v1 case, and does
the paginated listing with driver->meta_list_keys_next() for v2

RGWPSListTopicsOp now uses the NextToken request/response params with
the paginated get_topics(), limiting responses to 100 entries like AWS

'radosgw-admin topic list' also paginates the listing according to
--max-entries to avoid reading everything into memory at once

Signed-off-by: Casey Bodley <cbodley@redhat.com>

1 files changed, 11 insertions, 9 deletions

diff --git a/src/rgw/rgw_pubsub.h b/src/rgw/rgw_pubsub.h
index ed785672175..519c1053ab3 100644
--- a/src/rgw/rgw_pubsub.h
+++ b/src/rgw/rgw_pubsub.h
@@ -562,10 +562,10 @@ class RGWPubSub
   const std::string tenant;
   bool use_notification_v2 = false;
 
-  int read_topics(const DoutPrefixProvider *dpp, rgw_pubsub_topics& result, 
-      RGWObjVersionTracker* objv_tracker, optional_yield y) const;
-  int write_topics(const DoutPrefixProvider *dpp, const rgw_pubsub_topics& topics,
-			RGWObjVersionTracker* objv_tracker, optional_yield y) const;
+  int read_topics_v1(const DoutPrefixProvider *dpp, rgw_pubsub_topics& result,
+                     RGWObjVersionTracker* objv_tracker, optional_yield y) const;
+  int write_topics_v1(const DoutPrefixProvider *dpp, const rgw_pubsub_topics& topics,
+                      RGWObjVersionTracker* objv_tracker, optional_yield y) const;
 
 public:
   RGWPubSub(rgw::sal::Driver* _driver, const std::string& tenant);
@@ -620,11 +620,13 @@ public:
     int remove_notifications(const DoutPrefixProvider *dpp, optional_yield y) const;
   };
 
-  // get the list of topics
-  // return 0 on success or if no topic was associated with the bucket, error code otherwise
-  int get_topics(const DoutPrefixProvider *dpp, rgw_pubsub_topics& result, optional_yield y) const {
-    return read_topics(dpp, result, nullptr, y);
-  }
+  // get a paginated list of topics
+  // return 0 on success, error code otherwise
+  int get_topics(const DoutPrefixProvider* dpp,
+                 const std::string& start_marker, int max_items,
+                 rgw_pubsub_topics& result, std::string& next_marker,
+                 optional_yield y) const;
+
   // get a topic with by its name and populate it into "result"
   // return -ENOENT if the topic does not exists
   // return 0 on success, error code otherwise.