From d637937d48ecb527d2c15c38c1a1fdd35e32b4d1 Mon Sep 17 00:00:00 2001
From: Casey Bodley <cbodley@redhat.com>
Date: Fri, 29 Mar 2019 10:27:56 -0400
Subject: [PATCH] rgw: data sync checks empty next_marker for datalog

RGWReadRemoteDataLogShardCR tracks the marker and next_marker
separately, because next_marker will be empty when it reaches the end

this allows RGWDataSyncShardCR to avoid clearing its sync_marker and
restarting datalog listing from the beginning

Fixes: http://tracker.ceph.com/issues/39033

Signed-off-by: Casey Bodley <cbodley@redhat.com>
(cherry picked from commit 2ff63778342282ab5c676529f6e7d90f30e6da1a)
---
 src/rgw/rgw_data_sync.cc | 42 +++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/src/rgw/rgw_data_sync.cc b/src/rgw/rgw_data_sync.cc
index 6cd55eece17e5..90eb6bc234410 100644
--- a/src/rgw/rgw_data_sync.cc
+++ b/src/rgw/rgw_data_sync.cc
@@ -249,24 +249,24 @@ struct read_remote_data_log_response {
 class RGWReadRemoteDataLogShardCR : public RGWCoroutine {
   RGWDataSyncEnv *sync_env;
 
-  RGWRESTReadResource *http_op;
+  RGWRESTReadResource *http_op = nullptr;
 
   int shard_id;
-  string *pmarker;
+  const std::string& marker;
+  string *pnext_marker;
   list<rgw_data_change_log_entry> *entries;
   bool *truncated;
 
   read_remote_data_log_response response;
 
 public:
-  RGWReadRemoteDataLogShardCR(RGWDataSyncEnv *_sync_env,
-                              int _shard_id, string *_pmarker, list<rgw_data_change_log_entry> *_entries, bool *_truncated) : RGWCoroutine(_sync_env->cct),
-                                                      sync_env(_sync_env),
-                                                      http_op(NULL),
-                                                      shard_id(_shard_id),
-                                                      pmarker(_pmarker),
-                                                      entries(_entries),
-                                                      truncated(_truncated) {
+  RGWReadRemoteDataLogShardCR(RGWDataSyncEnv *_sync_env, int _shard_id,
+                              const std::string& marker, string *pnext_marker,
+                              list<rgw_data_change_log_entry> *_entries,
+                              bool *_truncated)
+    : RGWCoroutine(_sync_env->cct), sync_env(_sync_env),
+      shard_id(_shard_id), marker(marker), pnext_marker(pnext_marker),
+      entries(_entries), truncated(_truncated) {
   }
   ~RGWReadRemoteDataLogShardCR() override {
     if (http_op) {
@@ -281,7 +281,7 @@ public:
 	snprintf(buf, sizeof(buf), "%d", shard_id);
         rgw_http_param_pair pairs[] = { { "type" , "data" },
 	                                { "id", buf },
-	                                { "marker", pmarker->c_str() },
+	                                { "marker", marker.c_str() },
 	                                { "extra-info", "true" },
 	                                { NULL, NULL } };
 
@@ -307,7 +307,7 @@ public:
         }
         entries->clear();
         entries->swap(response.entries);
-        *pmarker = response.marker;
+        *pnext_marker = response.marker;
         *truncated = response.truncated;
         return set_cr_done();
       }
@@ -1081,6 +1081,7 @@ class RGWDataSyncShardCR : public RGWCoroutine {
 
   RGWDataSyncShardMarkerTrack *marker_tracker;
 
+  std::string next_marker;
   list<rgw_data_change_log_entry> log_entries;
   list<rgw_data_change_log_entry>::iterator log_iter;
   bool truncated;
@@ -1127,7 +1128,7 @@ class RGWDataSyncShardCR : public RGWCoroutine {
 public:
   RGWDataSyncShardCR(RGWDataSyncEnv *_sync_env,
                      rgw_pool& _pool,
-		     uint32_t _shard_id, rgw_data_sync_marker& _marker,
+		     uint32_t _shard_id, const rgw_data_sync_marker& _marker,
                      RGWSyncTraceNodeRef& _tn,
                      bool *_reset_backoff) : RGWCoroutine(_sync_env->cct),
                                                       sync_env(_sync_env),
@@ -1377,7 +1378,8 @@ public:
 #define INCREMENTAL_MAX_ENTRIES 100
         tn->log(20, SSTR("shard_id=" << shard_id << " sync_marker=" << sync_marker.marker));
         spawned_keys.clear();
-        yield call(new RGWReadRemoteDataLogShardCR(sync_env, shard_id, &sync_marker.marker, &log_entries, &truncated));
+        yield call(new RGWReadRemoteDataLogShardCR(sync_env, shard_id, sync_marker.marker,
+                                                   &next_marker, &log_entries, &truncated));
         if (retcode < 0) {
           tn->log(0, SSTR("ERROR: failed to read remote data log info: ret=" << retcode));
           stop_spawned_services();
@@ -1426,7 +1428,13 @@ public:
           }
         }
 
-        tn->log(20, SSTR("shard_id=" << shard_id << " sync_marker=" << sync_marker.marker << " truncated=" << truncated));
+        tn->log(20, SSTR("shard_id=" << shard_id << " sync_marker=" << sync_marker.marker
+                         << " next_marker=" << next_marker << " truncated=" << truncated));
+        if (!next_marker.empty()) {
+          sync_marker.marker = next_marker;
+        } else if (!log_entries.empty()) {
+          sync_marker.marker = log_entries.back().log_id;
+        }
         if (!truncated) {
           // we reached the end, wait a while before checking for more
           tn->unset_flag(RGW_SNS_FLAG_ACTIVE);
@@ -2204,6 +2212,7 @@ class RGWReadPendingBucketShardsCoroutine : public RGWCoroutine {
   rgw_data_sync_marker* sync_marker;
   int count;
 
+  std::string next_marker;
   list<rgw_data_change_log_entry> log_entries;
   bool truncated;
 
@@ -2239,7 +2248,8 @@ int RGWReadPendingBucketShardsCoroutine::operate()
     marker = sync_marker->marker;
     count = 0;
     do{
-      yield call(new RGWReadRemoteDataLogShardCR(sync_env, shard_id, &marker, &log_entries, &truncated));
+      yield call(new RGWReadRemoteDataLogShardCR(sync_env, shard_id, marker,
+                                                 &next_marker, &log_entries, &truncated));
 
       if (retcode == -ENOENT) {
         break;
-- 
2.39.5