Multiple pipelines and limiting the number of connections.

Introducing a number of options to the multi interface that
allows for multiple pipelines to the same host, in order to
optimize the balance between the penalty for opening new
connections and the potential pipelining latency.

Two new options for limiting the number of connections:

CURLMOPT_MAX_HOST_CONNECTIONS - Limits the number of running connections
to the same host. When adding a handle that exceeds this limit,
that handle will be put in a pending state until another handle is
finished, so we can reuse the connection.

CURLMOPT_MAX_TOTAL_CONNECTIONS - Limits the number of connections in total.
When adding a handle that exceeds this limit,
that handle will be put in a pending state until another handle is
finished. The free connection will then be reused, if possible, or
closed if the pending handle can't reuse it.

Several new options for pipelining:

CURLMOPT_MAX_PIPELINE_LENGTH - Limits the pipeling length. If a
pipeline is "full" when a connection is to be reused, a new connection
will be opened if the CURLMOPT_MAX_xxx_CONNECTIONS limits allow it.
If not, the handle will be put in a pending state until a connection is
ready (either free or a pipe got shorter).

CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE - A pipelined connection will not
be reused if it is currently processing a transfer with a content
length that is larger than this.

CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE - A pipelined connection will not
be reused if it is currently processing a chunk larger than this.

CURLMOPT_PIPELINING_SITE_BL - A blacklist of hosts that don't allow
pipelining.

CURLMOPT_PIPELINING_SERVER_BL - A blacklist of server types that don't allow
pipelining.

See the curl_multi_setopt() man page for details.

1 files changed, 50 insertions, 0 deletions

diff --git a/lib/pipeline.h b/lib/pipeline.h
new file mode 100644
index 000000000..f3a734c9a
--- /dev/null
+++ b/lib/pipeline.h
@@ -0,0 +1,50 @@
+#ifndef HEADER_CURL_PIPELINE_H
+#define HEADER_CURL_PIPELINE_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2013, 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.
+ *
+ ***************************************************************************/
+
+struct connectdata *
+Curl_bundle_find_best(struct SessionHandle *data,
+                      struct connectbundle *cb_ptr);
+
+CURLcode Curl_add_handle_to_pipeline(struct SessionHandle *handle,
+                                     struct connectdata *conn);
+void Curl_move_handle_from_send_to_recv_pipe(struct SessionHandle *handle,
+                                             struct connectdata *conn);
+bool Curl_pipeline_penalized(struct SessionHandle *data,
+                             struct connectdata *conn);
+
+bool Curl_pipeline_site_blacklisted(struct SessionHandle *handle,
+                                    struct connectdata *conn);
+
+CURLMcode Curl_pipeline_set_site_blacklist(char **sites,
+                                           struct curl_llist **list_ptr);
+
+bool Curl_pipeline_server_blacklisted(struct SessionHandle *handle,
+                                      char *server_name);
+
+CURLMcode Curl_pipeline_set_server_blacklist(char **servers,
+                                             struct curl_llist **list_ptr);
+
+void print_pipeline(struct connectdata *conn);
+
+#endif /* HEADER_CURL_PIPELINE_H */