Implement async HTTP responses

Sometimes, library users cannot return a HTTP response as soon as the
request is received, or the operations that are required to generate it
can take a long time.

In order to solve this, libweb adds a new member to struct
http_response, namely step, which must be assigned to a function
whenever a HTTP response should be generated in a non-blocking manner.
Leaving the function pointer as null will fall back to the default
behaviour.

1 files changed, 14 insertions, 1 deletions

diff --git a/handler.c b/handler.c
index 9ae9b10..8a777fa 100644
--- a/handler.c
+++ b/handler.c
@@ -28,6 +28,7 @@ struct handler
         struct handler *h;
         struct server_client *c;
         struct http_ctx *http;
+        int (*fn)(const struct http_payload *, struct http_response *, void *);
         struct client *next;
     } *clients;
 
@@ -59,7 +60,19 @@ static int on_payload(const struct http_payload *const p,
         const struct elem *const e = &h->elem[i];
 
         if (e->op == p->op && !wildcard_cmp(p->resource, e->url, true))
-            return e->f(p, r, e->user);
+        {
+            int ret;
+
+            if (c->fn)
+                ret = c->fn(p, r, e->user);
+            else
+                ret = e->f(p, r, e->user);
+
+            if (!ret)
+                c->fn = r->step;
+
+            return ret;
+        }
     }
 
     fprintf(stderr, "Not found: %s\n", p->resource);