Added CURLMOPT_MAXCONNECTS which is a curl_multi_setopt() option for setting

the maximum size of the connection cache maximum size of the multi handle.

CHANGES

@@ -5,6 +5,10 @@
                              \___|\___/|_| \_\_____|
 
                                   Changelog
+Daniel S (30 May 2007)
+- Added CURLMOPT_MAXCONNECTS which is a curl_multi_setopt() option for setting
+  the maximum size of the connection cache maximum size of the multi handle.
+
 Daniel S (27 May 2007)
 - When working with a problem Stefan Becker had, I found an off-by-one buffer
   overwrite in Curl_select(). While fixing it, I also improved its performance

RELEASE-NOTES

@@ -17,6 +17,7 @@ This release includes the following changes:
  o CURLOPT_HTTP200ALIASES matched transfers assume HTTP 1.0 compliance
  o more than one test harness can run at the same time without conflict
  o SFTP now supports quote commands before a transfer
+ o CURLMOPT_MAXCONNECTS added to curl_multi_setopt()
 
 This release includes the following bugfixes:
 

docs/libcurl/curl_easy_setopt.3

@@ -1129,10 +1129,10 @@ speed. (Added in 7.15.5)
 .IP CURLOPT_MAXCONNECTS
 Pass a long. The set number will be the persistent connection cache size. The
 set amount will be the maximum amount of simultaneously open connections that
-libcurl may cache. Default is 5, and there isn't much point in changing this
-value unless you are perfectly aware of how this work and changes libcurl's
-behaviour. This concerns connection using any of the protocols that support
-persistent connections.
+libcurl may cache in this easy handle. Default is 5, and there isn't much
+point in changing this value unless you are perfectly aware of how this work
+and changes libcurl's behaviour. This concerns connection using any of the
+protocols that support persistent connections.
 
 When reaching the maximum limit, curl closes the oldest one in the cache to
 prevent the number of open connections to increase.
@@ -1140,6 +1140,10 @@ prevent the number of open connections to increase.
 If you already have performed transfers with this curl handle, setting a
 smaller MAXCONNECTS than before may cause open connections to get closed
 unnecessarily.
+
+Note that if you add this easy handle to a multi handle, this setting is not
+being acknowledged, but you must instead use \fIcurl_multi_setopt(3)\fP and
+the \fICURLMOPT_MAXCONNECTS\fP option.
 .IP CURLOPT_CLOSEPOLICY
 (Obsolete) This option does nothing.
 .IP CURLOPT_FRESH_CONNECT

docs/libcurl/curl_multi_setopt.3

@@ -56,6 +56,22 @@ Pass a pointer to whatever you want passed to the
 \fBcurl_multi_timer_callback\fP's third argument, the userp pointer.  This is
 not used by libcurl but only passed-thru as-is. Set the callback pointer with
 \fICURLMOPT_TIMERFUNCTION\fP. (Added in 7.16.0)
+.IP CURLMOPT_MAXCONNECTS
+Pass a long. The set number will be used as the maximum amount of
+simultaneously open connections that libcurl may cache. Default is 10, and
+libcurl will enlarge the size for each added easy handle to make it fit 4
+times the number of added easy handles.
+
+By setting this option, you can prevent the cache size to grow beyond the
+limit set by you.
+
+When the cache is full, curl closes the oldest one in the cache to prevent the
+number of open connections to increase.
+
+This option is for the multi handle's use only, when using the easy interface
+you should instead use the \fICURLOPT_MAXCONNECTS\fP option.
+
+(Added in 7.16.3)
 .SH RETURNS
 The standard CURLMcode for multi interface error codes. Note that it returns a
 CURLM_UNKNOWN_OPTION if you try setting an option that this version of libcurl

include/curl/multi.h

@@ -309,6 +309,9 @@ typedef enum {
   /* This is the argument passed to the timer callback */
   CINIT(TIMERDATA, OBJECTPOINT, 5),
 
+  /* maximum number of entries in the connection cache */
+  CINIT(MAXCONNECTS, LONG, 6),
+
   CURLMOPT_LASTENTRY /* the last unused */
 } CURLMoption;
 

lib/multi.c

@@ -160,6 +160,8 @@ struct Curl_multi {
 
   /* shared connection cache */
   struct conncache *connc;
+  long maxconnects; /* if >0, a fixed limit of the maximum number of entries
+                       we're allowed to grow the connection cache to */
 
   /* list of easy handles kept around for doing nice connection closures */
   struct closure *closure;
@@ -484,12 +486,20 @@ CURLMcode curl_multi_add_handle(CURLM *multi_handle,
     /* We want the connection cache to have plenty room. Before we supported
        the shared cache every single easy handle had 5 entries in their cache
        by default. */
-    CURLcode res = Curl_ch_connc(easy_handle, multi->connc,
-                                 multi->num_easy * 4);
+    int newmax = multi->num_easy * 4;
+
+    if(multi->maxconnects && (multi->maxconnects < newmax))
+      /* don't grow beyond the allowed size */
+      newmax = multi->maxconnects;
+
+    if(newmax > multi->connc->num) {
+      /* we only do this is we can in fact grow the cache */
+      CURLcode res = Curl_ch_connc(easy_handle, multi->connc, newmax);
       if(res != CURLE_OK)
         /* TODO: we need to do some cleaning up here! */
         return CURLM_OUT_OF_MEMORY;
     }
+  }
 
   /* increase the alive-counter */
   multi->num_alive++;
@@ -1810,6 +1820,9 @@ CURLMcode curl_multi_setopt(CURLM *multi_handle,
   case CURLMOPT_TIMERDATA:
     multi->timer_userp = va_arg(param, void *);
     break;
+  case CURLMOPT_MAXCONNECTS:
+    multi->maxconnects = va_arg(param, long);
+    break;
   default:
     res = CURLM_UNKNOWN_OPTION;
     break;