fix(clustering/sync): delta.version may be null

kong/clustering/services/sync/rpc.lua

@@ -93,7 +93,7 @@ function _M:init_cp(manager)
     end
 
     -- is the node empty? If so, just do a full sync to bring it up to date faster
-    if default_namespace_version == 0 or latest_version == ngx_null or
+    if default_namespace_version == 0 or
        latest_version - default_namespace_version > FULL_SYNC_THRESHOLD
     then
       -- we need to full sync because holes are found
@@ -295,8 +295,10 @@ local function do_sync()
     crud_events_n = crud_events_n + 1
     crud_events[crud_events_n] = ev
 
-    -- XXX TODO: could delta.version be nil or ngx.null
-    if type(delta.version) == "number" and delta.version ~= version then
+    -- delta.version should not be nil or ngx.null
+    assert(type(delta.version) == "number")
+
+    if delta.version ~= version then
       version = delta.version
     end
   end -- for _, delta

kong/clustering/services/sync/strategies/postgres.lua

@@ -8,6 +8,7 @@ local buffer = require("string.buffer")
 
 local string_format = string.format
 local cjson_encode = cjson.encode
+local ngx_null = ngx.null
 local ngx_log = ngx.log
 local ngx_ERR = ngx.ERR
 local ngx_DEBUG = ngx.DEBUG
@@ -99,7 +100,12 @@ function _M:get_latest_version()
     return nil, err
   end
 
-  return res[1] and res[1].max_version
+  local ver = res[1] and res[1].max_version
+  if ver == ngx_null then
+    return 0
+  end
+
+  return ver
 end
 
 

kong/db/declarative/export.lua

@@ -124,7 +124,11 @@ local function export_from_db_impl(emitter, skip_ws, skip_disabled_entities, exp
       return nil, err
     end
 
+    -- it will be ngx.null when the table clustering_sync_version is empty
     sync_version = assert(ok[1].max)
+    if sync_version == null then
+      sync_version = 0
+    end
   end
 
   emitter:emit_toplevel({