feature: support cosocket and other yieldable APIs in init_worker_by_lua*

README.md

@@ -139,6 +139,8 @@ behavior.
 * [init_by_lua_file](https://github.com/openresty/lua-nginx-module#init_by_lua_file)
 * [init_worker_by_lua_block](https://github.com/openresty/lua-nginx-module#init_worker_by_lua_block)
 * [init_worker_by_lua_file](https://github.com/openresty/lua-nginx-module#init_worker_by_lua_file)
+* [lua_init_worker_timeout](https://github.com/openresty/lua-nginx-module#lua_init_worker_timeout)
+* [lua_init_worker_abort_on_error](https://github.com/openresty/lua-nginx-module#lua_init_worker_abort_on_error)
 * [preread_by_lua_block](#preread_by_lua_block)
 * [preread_by_lua_file](#preread_by_lua_file)
 * [content_by_lua_block](https://github.com/openresty/lua-nginx-module#content_by_lua_block)
@@ -179,6 +181,19 @@ behavior.
 * [lua_capture_error_log](https://github.com/openresty/lua-nginx-module#lua_capture_error_log)
 * [preread_by_lua_no_postpone](#preread_by_lua_no_postpone)
 
+Cosockets (and other yieldable APIs) are supported in `init_worker_by_lua*`.
+When a cosocket operation yields (for example, during a `connect` or
+`receive` call), the module runs a lightweight event pump that drives the
+Nginx event loop until the operation completes. See
+[lua_init_worker_timeout](https://github.com/openresty/lua-nginx-module#lua_init_worker_timeout)
+and
+[lua_init_worker_abort_on_error](https://github.com/openresty/lua-nginx-module#lua_init_worker_abort_on_error)
+in ngx_http_lua for the directives that bound how long the init code may
+block worker startup and how Lua runtime errors are handled.
+
+Note that `ngx.timer.at` callbacks registered during `init_worker_by_lua*`
+are deferred: they will not run until the init code finishes.
+
 The [send_timeout](https://nginx.org/r/send_timeout) directive in the Nginx
 "http" subsystem is missing in the "stream" subsystem. As such,
 ngx_stream_lua_module uses the `lua_socket_send_timeout` directive for this

src/ngx_stream_lua_common.h

@@ -239,6 +239,10 @@ struct ngx_stream_lua_main_conf_s {
     ngx_stream_lua_main_conf_handler_pt          init_worker_handler;
     ngx_str_t                                    init_worker_src;
 
+    ngx_msec_t           init_worker_timeout;
+    ngx_flag_t           init_worker_abort_on_error;
+    ngx_queue_t          deferred_timers;
+
     ngx_stream_lua_balancer_peer_data_t          *balancer_peer_data;
                     /* neither yielding nor recursion is possible in
                      * balancer_by_lua*, so there cannot be any races among