Take into account spare sessions in load_balance

[yazpp-moved-to-github.git] / src / yaz-proxy.cpp

diff --git a/src/yaz-proxy.cpp b/src/yaz-proxy.cpp
index 95996b2..d226e7b 100644 (file)
--- a/src/yaz-proxy.cpp
+++ b/src/yaz-proxy.cpp
@@ -2,7 +2,7 @@
  * Copyright (c) 1998-2004, Index Data.
  * See the file LICENSE for details.
  * 
- * $Id: yaz-proxy.cpp,v 1.103 2004-02-24 20:55:57 adam Exp $
+ * $Id: yaz-proxy.cpp,v 1.104 2004-02-26 23:43:07 adam Exp $
  */
 
 #include <assert.h>
@@ -271,30 +271,53 @@ char *Yaz_Proxy::get_proxy(Z_OtherInformation **otherInfo)
 const char *Yaz_Proxy::load_balance(const char **url)
 {
     int zurl_in_use[MAX_ZURL_PLEX];
+    int zurl_in_spare[MAX_ZURL_PLEX];
     Yaz_ProxyClient *c;
     int i;
 
     for (i = 0; i<MAX_ZURL_PLEX; i++)
+    {
        zurl_in_use[i] = 0;
+       zurl_in_spare[i] = 0;
+    }
     for (c = m_parent->m_clientPool; c; c = c->m_next)
     {
        for (i = 0; url[i]; i++)
            if (!strcmp(url[i], c->get_hostname()))
+           {
                zurl_in_use[i]++;
+               if (c->m_cookie == 0 && c->m_server == 0 && c->m_waiting == 0)
+                   zurl_in_spare[i]++;
+           }
     }
-    int min = 100000;
-    const char *ret = 0;
+    int min_use = 100000;
+    int spare_for_min = 0;
+    int max_spare = 0;
+    const char *ret_min = 0;
+    const char *ret_spare = 0;
     for (i = 0; url[i]; i++)
     {
-       yaz_log(LOG_DEBUG, "%szurl=%s use=%d",
-               m_session_str, url[i], zurl_in_use[i]);
-       if (min > zurl_in_use[i])
+       yaz_log(LOG_DEBUG, "%szurl=%s use=%d spare=%d",
+               m_session_str, url[i], zurl_in_use[i], zurl_in_spare[i]);
+       if (min_use > zurl_in_use[i])
+       {
+           ret_min = url[i];
+           min_use = zurl_in_use[i];
+           spare_for_min = zurl_in_spare[i];
+       }
+       if (max_spare < zurl_in_spare[i]) 
        {
-           ret = url[i];
-           min = zurl_in_use[i];
+           ret_spare = url[i];
+           max_spare = zurl_in_spare[i];
        }
     }
-    return ret;
+    // use the one with minimum connections if spare is > 3
+    if (spare_for_min > 3)
+       return ret_min;
+    // use one with most spares (if any)
+    if (max_spare > 0)
+       return ret_spare;
+    return ret_min;
 }
 
 Yaz_ProxyClient *Yaz_Proxy::get_client(Z_APDU *apdu, const char *cookie,
@@ -411,8 +434,8 @@ Yaz_ProxyClient *Yaz_Proxy::get_client(Z_APDU *apdu, const char *cookie,
                !strcmp(m_proxyTarget, c->get_hostname()))
            {
                // found it in cache
-               yaz_log (LOG_LOG, "%sREUSE %s",
-                        m_session_str, c->get_hostname());
+               yaz_log (LOG_LOG, "%sREUSE %d %s",
+                        m_session_str, parent->m_seqno, c->get_hostname());
                
                c->m_seqno = parent->m_seqno;
                assert(c->m_server == 0);
@@ -477,16 +500,16 @@ Yaz_ProxyClient *Yaz_Proxy::get_client(Z_APDU *apdu, const char *cookie,
            c = c_min;
            if (c->m_waiting || strcmp(m_proxyTarget, c->get_hostname()))
            {
-               yaz_log (LOG_LOG, "%sMAXCLIENTS Destroy %d",
-                        m_session_str, c->m_seqno);
+               yaz_log (LOG_LOG, "%sMAXCLIENTS %d Destroy %d",
+                        m_session_str, parent->m_max_clients, c->m_seqno);
                if (c->m_server && c->m_server != this)
                    delete c->m_server;
                c->m_server = 0;
            }
            else
            {
-               yaz_log (LOG_LOG, "%sMAXCLIENTS Reuse %d %d %s",
-                        m_session_str,
+               yaz_log (LOG_LOG, "%sMAXCLIENTS %d Reuse %d %d %s",
+                        m_session_str, parent->m_max_clients,
                         c->m_seqno, parent->m_seqno, c->get_hostname());
                xfree (c->m_cookie);
                c->m_cookie = 0;