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, 28 insertions, 2 deletions

diff --git a/lib/multiif.h b/lib/multiif.h
index c84b6184c..0dcdec76e 100644
--- a/lib/multiif.h
+++ b/lib/multiif.h
@@ -27,7 +27,7 @@
  */
 void Curl_expire(struct SessionHandle *data, long milli);
 
-bool Curl_multi_canPipeline(const struct Curl_multi* multi);
+bool Curl_multi_pipeline_enabled(const struct Curl_multi* multi);
 void Curl_multi_handlePipeBreak(struct SessionHandle *data);
 
 /* the write bits start at bit 16 for the *getsock() bitmap */
@@ -50,5 +50,31 @@ void Curl_multi_handlePipeBreak(struct SessionHandle *data);
 void Curl_multi_dump(const struct Curl_multi *multi_handle);
 #endif
 
-#endif /* HEADER_CURL_MULTIIF_H */
+/* Update the current connection of a One_Easy handle */
+void Curl_multi_set_easy_connection(struct SessionHandle *handle,
+                                    struct connectdata *conn);
+
+void Curl_multi_process_pending_handles(struct Curl_multi *multi);
+
+/* Return the value of the CURLMOPT_MAX_HOST_CONNECTIONS option */
+size_t Curl_multi_max_host_connections(struct Curl_multi *multi);
+
+/* Return the value of the CURLMOPT_MAX_PIPELINE_LENGTH option */
+size_t Curl_multi_max_pipeline_length(struct Curl_multi *multi);
+
+/* Return the value of the CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE option */
+curl_off_t Curl_multi_content_length_penalty_size(struct Curl_multi *multi);
 
+/* Return the value of the CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE option */
+curl_off_t Curl_multi_chunk_length_penalty_size(struct Curl_multi *multi);
+
+/* Return the value of the CURLMOPT_PIPELINING_SITE_BL option */
+struct curl_llist *Curl_multi_pipelining_site_bl(struct Curl_multi *multi);
+
+/* Return the value of the CURLMOPT_PIPELINING_SERVER_BL option */
+struct curl_llist *Curl_multi_pipelining_server_bl(struct Curl_multi *multi);
+
+/* Return the value of the CURLMOPT_MAX_TOTAL_CONNECTIONS option */
+size_t Curl_multi_max_total_connections(struct Curl_multi *multi);
+
+#endif /* HEADER_CURL_MULTIIF_H */