Introducing a new persistent connection caching system using "bundles".

A bundle is a list of all persistent connections to the same host.
The connection cache consists of a hash of bundles, with the
hostname as the key.
The benefits may not be obvious, but they are two:

1) Faster search for connections to reuse, since the hash
   lookup only finds connections to the host in question.
2) It lays out the groundworks for an upcoming patch,
   which will introduce multiple HTTP pipelines.

This patch also removes the awkward list of "closure handles",
which were needed to send QUIT commands to the FTP server
when closing a connection.
Now we allocate a separate closure handle and use that
one to close all connections.

This has been tested in a live system for a few weeks, and of
course passes the test suite.

1 files changed, 101 insertions, 0 deletions

diff --git a/lib/bundles.c b/lib/bundles.c
new file mode 100644
index 000000000..046e3bb3b
--- /dev/null
+++ b/lib/bundles.c
@@ -0,0 +1,101 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2012, Linus Nielsen Feltzing, <linus@haxx.se>
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "setup.h"
+
+#include <curl/curl.h>
+
+#include "urldata.h"
+#include "url.h"
+#include "progress.h"
+#include "multiif.h"
+#include "bundles.h"
+#include "sendf.h"
+#include "rawstr.h"
+
+#include "curl_memory.h"
+/* The last #include file should be: */
+#include "memdebug.h"
+
+static void conn_llist_dtor(void *user, void *element)
+{
+  struct connectdata *data = element;
+  (void)user;
+
+  data->bundle = NULL;
+}
+
+CURLcode Curl_bundle_create(struct SessionHandle *data,
+                            struct connectbundle **cb_ptr)
+{
+  (void)data;
+  *cb_ptr = malloc(sizeof(struct connectbundle));
+  if(!*cb_ptr)
+    return CURLE_OUT_OF_MEMORY;
+
+  (*cb_ptr)->num_connections = 0;
+  (*cb_ptr)->server_supports_pipelining = FALSE;
+
+  (*cb_ptr)->conn_list = Curl_llist_alloc((curl_llist_dtor) conn_llist_dtor);
+  if(!(*cb_ptr)->conn_list)
+    return CURLE_OUT_OF_MEMORY;
+  return CURLE_OK;
+}
+
+void Curl_bundle_destroy(struct connectbundle *cb_ptr)
+{
+  if(cb_ptr->conn_list)
+    Curl_llist_destroy(cb_ptr->conn_list, NULL);
+  Curl_safefree(cb_ptr);
+}
+
+/* Add a connection to a bundle */
+CURLcode Curl_bundle_add_conn(struct connectbundle *cb_ptr,
+                              struct connectdata *conn)
+{
+  if(!Curl_llist_insert_next(cb_ptr->conn_list, cb_ptr->conn_list->tail, conn))
+    return CURLE_OUT_OF_MEMORY;
+
+  conn->bundle = cb_ptr;
+
+  cb_ptr->num_connections++;
+  return CURLE_OK;
+}
+
+/* Remove a connection from a bundle */
+int Curl_bundle_remove_conn(struct connectbundle *cb_ptr,
+                            struct connectdata *conn)
+{
+  struct curl_llist_element *curr;
+
+  curr = cb_ptr->conn_list->head;
+  while(curr) {
+    if(curr->ptr == conn) {
+      Curl_llist_remove(cb_ptr->conn_list, curr, NULL);
+      cb_ptr->num_connections--;
+      conn->bundle = NULL;
+      return 1; /* we removed a handle */
+    }
+    curr = curr->next;
+  }
+  return 0;
+}