Offload the isc_http response processing to worker thread

Prepare the statistics channel data in the offloaded worker thread, so
the networking thread is not blocked by the process gathering data from
various data structures.  Only the netmgr send is then run on the
networkin thread when all the data is already there.

diff --git a/lib/isc/httpd.c b/lib/isc/httpd.c
index 57cc0fd943ce824ab2c6b50a4d1306757c3cd060..d2084ae1800a693cfe07d3d6d2ae75da6582f041 100644 (file)
--- a/lib/isc/httpd.c
+++ b/lib/isc/httpd.c
@@ -598,6 +598,12 @@ isc__httpd_sendreq_new(isc_httpd_t *httpd) {
 
        isc_buffer_initnull(&req->bodybuffer);
 
+       /*
+        * We don't need to attach to httpd here because it gets only cleaned
+        * when the last handle has been detached
+        */
+       req->httpd = httpd;
+
        return (req);
 }
 
@@ -749,10 +755,11 @@ httpd_compress(isc_httpd_sendreq_t *req) {
 #endif /* ifdef HAVE_ZLIB */
 
 static void
-prepare_response(isc_httpdmgr_t *mgr, isc_httpd_t *httpd,
-                isc_httpd_sendreq_t **reqp) {
-       isc_httpd_sendreq_t *req = NULL;
-       isc_time_t now;
+prepare_response(void *arg) {
+       isc_httpd_sendreq_t *req = arg;
+       isc_httpd_t *httpd = req->httpd;
+       isc_httpdmgr_t *mgr = httpd->mgr;
+       isc_time_t now = isc_time_now();
        char datebuf[ISC_FORMATHTTPTIMESTAMP_SIZE];
        const char *path = "/";
        size_t path_len = 1;
@@ -761,9 +768,8 @@ prepare_response(isc_httpdmgr_t *mgr, isc_httpd_t *httpd,
        isc_result_t result;
 
        REQUIRE(VALID_HTTPD(httpd));
-       REQUIRE(reqp != NULL && *reqp == NULL);
+       REQUIRE(req != NULL);
 
-       now = isc_time_now();
        isc_time_formathttptimestamp(&now, datebuf, sizeof(datebuf));
 
        if (httpd->up.field_set & (1 << ISC_UF_PATH)) {
@@ -779,8 +785,6 @@ prepare_response(isc_httpdmgr_t *mgr, isc_httpd_t *httpd,
        }
        UNLOCK(&mgr->lock);
 
-       req = isc__httpd_sendreq_new(httpd);
-
        if (url == NULL) {
                result = mgr->render_404(httpd, NULL, NULL, &req->retcode,
                                         &req->retmsg, &req->mimetype,
@@ -874,14 +878,20 @@ prepare_response(isc_httpdmgr_t *mgr, isc_httpd_t *httpd,
        }
        httpd->recvlen -= httpd->consume;
        httpd->consume = 0;
+}
+
+static void
+prepare_response_done(void *arg) {
+       isc_region_t r;
+       isc_httpd_sendreq_t *req = arg;
+       isc_httpd_t *httpd = req->httpd;
 
        /*
-        * We don't need to attach to httpd here because it gets only cleaned
-        * when the last handle has been detached
+        * Determine total response size.
         */
-       req->httpd = httpd;
+       isc_buffer_usedregion(req->sendbuffer, &r);
 
-       *reqp = req;
+       isc_nm_send(httpd->handle, &r, httpd_senddone, req);
 }
 
 static void
@@ -889,8 +899,6 @@ httpd_request(isc_nmhandle_t *handle, isc_result_t eresult,
              isc_region_t *region, void *arg) {
        isc_httpd_t *httpd = arg;
        isc_httpdmgr_t *mgr = httpd->mgr;
-       isc_httpd_sendreq_t *req = NULL;
-       isc_region_t r;
        size_t last_len = 0;
        isc_result_t result;
 
@@ -941,15 +949,10 @@ httpd_request(isc_nmhandle_t *handle, isc_result_t eresult,
                goto close_readhandle;
        }
 
-       prepare_response(mgr, httpd, &req);
-
-       /*
-        * Determine total response size.
-        */
-       isc_buffer_usedregion(req->sendbuffer, &r);
-
+       isc_httpd_sendreq_t *req = isc__httpd_sendreq_new(httpd);
        isc_nmhandle_ref(handle);
-       isc_nm_send(handle, &r, httpd_senddone, req);
+       isc_work_enqueue(isc_loop(), prepare_response, prepare_response_done,
+                        req);
        return;
 
 close_readhandle: