apply suggestions

kong/plugins/opentelemetry/handler.lua

@@ -36,11 +36,33 @@ local default_headers = {
   ["Content-Type"] = "application/x-protobuf",
 }
 
--- worker-level spans cache
-local spans_cache = new_tab(5000, 0)
+-- worker-level spans queue
+local spans_queue = new_tab(5000, 0)
 local headers_cache = setmetatable({}, { __mode = "k" })
 local last_run_cache = setmetatable({}, { __mode = "k" })
 
+local function get_cached_headers(conf_headers)
+  -- cache http headers
+  local headers = default_headers
+  if conf_headers then
+    headers = headers_cache[conf_headers]
+  end
+
+  if not headers then
+    headers = clone(default_headers)
+    if conf_headers and conf_headers ~= null then
+      for k, v in pairs(conf_headers) do
+        headers[k] = v and v[1]
+      end
+    end
+
+    headers_cache[conf_headers] = headers
+  end
+
+  return headers
+end
+
+
 local function http_export_request(conf, pb_data, headers)
   local httpc = http.new()
   httpc:set_timeouts(conf.connect_timeout, conf.send_timeout, conf.read_timeout)
@@ -63,55 +85,40 @@ local function http_export(premature, conf)
     return
   end
 
-  local spans = spans_cache
-  local spans_n = #spans
+  local spans_n = #spans_queue
   if spans_n == 0 then
     return
   end
 
   local start = ngx_now()
-
-  -- cache http headers
-  local headers = default_headers
-  if conf.headers then
-    headers = headers_cache[conf.headers]
-  end
-
-  if not headers then
-    headers = clone(default_headers)
-    if conf.headers and conf.headers ~= null then
-      for k, v in pairs(conf.headers) do
-        headers[k] = v and v[1]
-      end
-    end
-    headers_cache[conf.headers] = headers
-  end
+  local headers = conf.headers and get_cached_headers(conf.headers) or default_headers
 
   -- batch send spans
-  local batch_spans = tablepool_fetch(POOL_BATCH_SPANS, conf.batch_span_count, 0)
+  local spans_buffer = tablepool_fetch(POOL_BATCH_SPANS, conf.batch_span_count, 0)
 
-  for i = 1, spans_cache.n do
-    local len = (batch_spans.n or 0) + 1
-    batch_spans[len] = spans_cache[i]
-    batch_spans.n = len
+  for i = 1, spans_n do
+    local len = (spans_buffer.n or 0) + 1
+    spans_buffer[len] = spans_queue[i]
+    spans_buffer.n = len
 
     if len >= conf.batch_span_count then
-      local pb_data = encode_traces(batch_spans, conf.resource_attributes)
-      clear(batch_spans)
+      local pb_data = encode_traces(spans_buffer, conf.resource_attributes)
+      clear(spans_buffer)
 
       http_export_request(conf, pb_data, headers)
     end
   end
 
   -- remain spans
-  if spans_cache.n and spans_cache.n > 0 then
-    local pb_data = encode_traces(batch_spans, conf.resource_attributes)
+  if spans_queue.n and spans_queue.n > 0 then
+    local pb_data = encode_traces(spans_buffer, conf.resource_attributes)
     http_export_request(conf, pb_data, headers)
   end
 
-  clear(spans_cache)
+  -- clear the queue
+  clear(spans_queue)
 
-  tablepool_release(POOL_BATCH_SPANS, batch_spans)
+  tablepool_release(POOL_BATCH_SPANS, spans_buffer)
 
   ngx_update_time()
   local duration = ngx_now() - start
@@ -135,20 +142,23 @@ local function process_span(span)
 
   local pb_span = transform_span(span)
 
-  local len = spans_cache.n or 0
+  local len = spans_queue.n or 0
   len = len + 1
 
-  spans_cache[len] = pb_span
-  spans_cache.n = len
+  spans_queue[len] = pb_span
+  spans_queue.n = len
 end
 
 function OpenTelemetryHandler:rewrite()
   local headers = ngx_get_headers()
   local root_span = ngx.ctx.KONG_SPANS and ngx.ctx.KONG_SPANS[1]
-  -- tracing instrumetation not enabled
+
+  -- make propagation running with tracing instrumetation not enabled
   if not root_span then
     local tracer = kong.tracing.new("otel")
-    root_span = tracer.start_span("otel")
+    root_span = tracer.start_span("root")
+
+    -- the span created only for the propagation and will be bypassed to the exporter
     kong.ctx.plugin.should_sample = false
   end
 
@@ -163,6 +173,7 @@ function OpenTelemetryHandler:rewrite()
     kong.ctx.plugin.trace_id = trace_id
   end
 
+  -- overwrite root span's parent_id
   if span_id then
     root_span.parent_id = span_id
   end

spec/helpers.lua

@@ -3019,6 +3019,7 @@ end
   udp_server = udp_server,
   kill_tcp_server = kill_tcp_server,
   http_server = http_server,
+  kill_http_server = kill_http_server,
   get_proxy_ip = get_proxy_ip,
   get_proxy_port = get_proxy_port,
   proxy_client = proxy_client,