*) core: adding a new hook and method to the API:

     create_secondary_connection and ap_create_secondary_connection()
     to setup connections related to a "master" one, as used in
     the HTTP/2 protocol implementation.

  *) mod_http2: using the new API calls to get rid of knowledge
     about how the core handles conn_rec specifics.
     Improvements in pollset stream handling to use less sets.
     Using atomic read/writes instead of volatiles now.
     Keeping a reserve of "transit" pools and bucket_allocs for
     use on secondary connections to avoid repeated setup/teardowns.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1899032 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 68 insertions, 0 deletions

diff --git a/server/connection.c b/server/connection.c
index a7a51cf741..f32a1f3712 100644
--- a/server/connection.c
+++ b/server/connection.c
@@ -35,6 +35,7 @@ APR_HOOK_STRUCT(
             APR_HOOK_LINK(process_connection)
             APR_HOOK_LINK(pre_connection)
             APR_HOOK_LINK(pre_close_connection)
+            APR_HOOK_LINK(create_secondary_connection)
 )
 AP_IMPLEMENT_HOOK_RUN_FIRST(conn_rec *,create_connection,
                             (apr_pool_t *p, server_rec *server, apr_socket_t *csd, long conn_id, void *sbh, apr_bucket_alloc_t *alloc),
@@ -42,6 +43,9 @@ AP_IMPLEMENT_HOOK_RUN_FIRST(conn_rec *,create_connection,
 AP_IMPLEMENT_HOOK_RUN_FIRST(int,process_connection,(conn_rec *c),(c),DECLINED)
 AP_IMPLEMENT_HOOK_RUN_ALL(int,pre_connection,(conn_rec *c, void *csd),(c, csd),OK,DECLINED)
 AP_IMPLEMENT_HOOK_RUN_ALL(int,pre_close_connection,(conn_rec *c),(c),OK,DECLINED)
+AP_IMPLEMENT_HOOK_RUN_FIRST(conn_rec *,create_secondary_connection,
+                            (apr_pool_t *p, conn_rec *master, apr_bucket_alloc_t *alloc),
+                            (p, master, alloc), NULL)
 
 AP_DECLARE(conn_rec *) ap_create_connection(apr_pool_t *p,
                                             server_rec *server,
@@ -66,6 +70,13 @@ AP_DECLARE(conn_rec *) ap_create_connection(apr_pool_t *p,
     return c;
 }
 
+AP_DECLARE(conn_rec *) ap_create_secondary_connection(apr_pool_t *p,
+                                                      conn_rec *master,
+                                                      apr_bucket_alloc_t *alloc)
+{
+    return ap_run_create_secondary_connection(p, master, alloc);
+}
+
 /*
  * More machine-dependent networking gooo... on some systems,
  * you've got to be *really* sure that all the packets are acknowledged
diff --git a/server/core.c b/server/core.c
index 1730ceee44..e3953f231a 100644
--- a/server/core.c
+++ b/server/core.c
@@ -147,6 +147,8 @@ typedef struct {
     struct ap_logconf log;
 } conn_log_config;
 
+static apr_socket_t *dummy_socket;
+
 static void *create_core_dir_config(apr_pool_t *a, char *dir)
 {
     core_dir_config *conf;
@@ -5517,6 +5519,54 @@ static conn_rec *core_create_conn(apr_pool_t *ptrans, server_rec *s,
     return c;
 }
 
+static conn_rec *core_create_secondary_conn(apr_pool_t *ptrans,
+                                            conn_rec *master,
+                                            apr_bucket_alloc_t *alloc)
+{
+    apr_pool_t *pool;
+    conn_config_t *conn_config;
+    conn_rec *c = (conn_rec *) apr_pmemdup(ptrans, master, sizeof(*c));
+
+    /* Got a connection structure, so initialize what fields we can
+     * (the rest are zeroed out by pcalloc).
+     */
+    apr_pool_create(&pool, ptrans);
+    apr_pool_tag(pool, "secondary_conn");
+
+    /* we copied everything, now replace what is different */
+    c->master = master;
+    c->pool = pool;
+    c->bucket_alloc = alloc;
+    c->conn_config = ap_create_conn_config(pool);
+    c->notes = apr_table_make(pool, 5);
+    c->slaves = apr_array_make(pool, 20, sizeof(conn_slave_rec *));
+    c->requests = apr_array_make(pool, 20, sizeof(request_rec *));
+    c->input_filters = NULL;
+    c->output_filters = NULL;
+    c->filter_conn_ctx = NULL;
+
+    /* prevent mpm_event from making wrong assumptions about this connection,
+     * like e.g. using its socket for an async read check. */
+    c->clogging_input_filters = 1;
+
+    c->log = NULL;
+    c->aborted = 0;
+    c->keepalives = 0;
+
+    /* FIXME: mpms (and maybe other) parts think that there is always
+     * a socket for a connection. We cannot use the master socket for
+     * secondary connections, as this gets modified (closed?) when
+     * the secondary connection terminates.
+     * There seem to be some checks for c->master necessary in other
+     * places.
+     */
+    conn_config = apr_pcalloc(pool, sizeof(*conn_config));
+    conn_config->socket = dummy_socket;
+    ap_set_core_module_config(c->conn_config, conn_config);
+
+    return c;
+}
+
 static int core_pre_connection(conn_rec *c, void *csd)
 {
     conn_config_t *conn_config;
@@ -5670,6 +5720,11 @@ static void core_child_init(apr_pool_t *pchild, server_rec *s)
      */
     proc.pid = getpid();
     apr_random_after_fork(&proc);
+
+    /* needed for secondary connections so people do not change the master
+     * connection socket. */
+    apr_socket_create(&dummy_socket, APR_INET, SOCK_STREAM,
+                      APR_PROTO_TCP, pchild);
 }
 
 static void core_optional_fn_retrieve(void)
@@ -5905,6 +5960,8 @@ static void register_hooks(apr_pool_t *p)
      */
     ap_hook_create_connection(core_create_conn, NULL, NULL,
                               APR_HOOK_REALLY_LAST);
+    ap_hook_create_secondary_connection(core_create_secondary_conn, NULL, NULL,
+                                        APR_HOOK_REALLY_LAST);
     ap_hook_pre_connection(core_pre_connection, NULL, NULL,
                            APR_HOOK_REALLY_LAST);