fix: transparently support blocking work without worker threads

include/lnm/http/loop.h

@@ -32,23 +32,16 @@ lnm_err lnm_http_loop_init(lnm_http_loop **out, void *c_gctx,
                            lnm_http_ctx_reset_fn ctx_reset,
                            lnm_http_ctx_free_fn ctx_free);
 
-/**
- * Initialize a new step.
- *
- * @param out where to store pointer to new `lnm_http_step`
- * @param fn step function
- */
-lnm_err lnm_http_step_init(lnm_http_step **out, lnm_http_step_fn fn);
-
 /**
  * Append the given step fn to the step.
  *
- * @param out where to store pointer to new `lnm_http_step`
- * @param step step to append new step to
+ * @param out both the previous step to append the new step to, and the output
+ * variable to which the new step is appended
  * @param fn step function
+ * @param blocking whether the step is blocking or not
  */
-lnm_err lnm_http_step_append(lnm_http_step **out, lnm_http_step *step,
-                             lnm_http_step_fn fn);
+lnm_err lnm_http_step_append(lnm_http_step **out, lnm_http_step_fn fn,
+                             bool blocking);
 
 /**
  * Initialize a new route of type literal.

include/lnm/loop.h

@@ -106,6 +106,26 @@ lnm_err lnm_loop_run(lnm_loop *l);
 lnm_err lnm_loop_run_multi(lnm_loop *l, size_t epoll_threads,
                            size_t worker_threads);
 
+/**
+ * Advance the processing of the given connection.
+ *
+ * Behavior of this function depends on both the connection state and whether
+ * worker threads are enabled.
+ *
+ * For IO states, this function will perform network I/O along with executing
+ * the loop's respective processing functions.
+ *
+ * For work states, the respective processing functions are executed without
+ * performing any network I/O. If no worker queue is present, this function
+ * performs all blocking work until an I/O or the end state is reached. If there
+ * is a worker queue present, only one block of work is done before exiting,
+ * allowing further blocks of work to be scheduled on other worker threads.
+ *
+ * If no worker queue is present, this function will only exit once an I/O or
+ * end state is reached.
+ */
+void lnm_loop_conn_advance(lnm_loop *l, lnm_loop_conn *conn);
+
 /**
  * Reschedule the given connection, either on the event loop for network IO or
  * on a worker thread for blocking work. Connections are terminated as needed.