share: add support for sharing the connection cache

debug/shared-conn.c

@@ -0,0 +1,68 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * 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 https://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.
+ *
+ ***************************************************************************/
+/* <DESC>
+ * Two HTTP GET using connection sharing with the share inteface
+ * </DESC>
+ */
+#include <stdio.h>
+#include <curl/curl.h>
+
+int main(void)
+{
+  CURL *curl;
+  CURLcode res;
+  CURLSH *share;
+  int i;
+
+  share = curl_share_init();
+  curl_share_setopt(share, CURLSHOPT_SHARE, CURL_LOCK_DATA_CONNECT);
+
+  /* Loop the transfer and cleanup the handle properly every lap. This will
+     still reuse connections since the pool is in the shared object! */
+
+  for(i = 0; i < 3; i++) {
+    curl = curl_easy_init();
+    if(curl) {
+      curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
+      /* example.com is redirected, so we tell libcurl to follow redirection */
+      curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
+
+      /* use the connection pool in the share object */
+      curl_easy_setopt(curl, CURLOPT_SHARE, share);
+
+      curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+
+      /* Perform the request, res will get the return code */
+      res = curl_easy_perform(curl);
+      /* Check for errors */
+      if(res != CURLE_OK)
+        fprintf(stderr, "curl_easy_perform() failed: %s\n",
+                curl_easy_strerror(res));
+
+      /* always cleanup */
+      curl_easy_cleanup(curl);
+    }
+  }
+
+  curl_share_cleanup(share);
+  return 0;
+}