zbxpcp: add derived metrics support

[Marko Myllynen <myllynen@xxxxxxxxxx>]

Hi,

Turns out adding derived metrics support to zbxpcp is trivial.

Based on comments from Ken yesterday I think we can ignore errors from
pmLoadDerivedMetrics, if the configuration file is malformed then
messages will be logged into the zabbix-agent log file.

Update the man page accordingly. The file name is quite a name monster,
please feel free to adjust if you can come up with something better.

A small CodingStyle fixlet included as a bonus as well.

---
 src/zabbix-agent/src/zbxpcp.3 | 10 +++++++++-
 src/zabbix-agent/src/zbxpcp.c | 15 ++++++++++-----
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/zabbix-agent/src/zbxpcp.3 b/src/zabbix-agent/src/zbxpcp.3
index 3a03d19..557ac4a 100644
--- a/src/zabbix-agent/src/zbxpcp.3
+++ b/src/zabbix-agent/src/zbxpcp.3
@@ -117,6 +117,13 @@ the system.
 .BI /etc/zabbix/zabbix_agentd.conf
 Typical Zabbix agent configuration file location.
 .TP 10
+.BI /etc/zabbix/zbxpcp-derived-metrics.conf
+Optional PCP derived metrics configuration file for
+.BR zbxpcp .
+See
+.BR pmLoadDerivedConfig (3)
+for more info on derived metrics.
+.TP 10
 .BI $(PCP_LIB_DIR)/zabbix/agent/zbxpcp.so
 Zabbix agent loadable PCP module.
 .PD
@@ -124,6 +131,7 @@ Zabbix agent loadable PCP module.
 .BR PCPIntro (1),
 .BR pminfo (1),
 .BR pmrep (1),
-.BR zabbix_get (1)
+.BR zabbix_get (1),
+.BR pmLoadDerivedConfig (3)
 and
 .BR zabbix_agentd (8).
diff --git a/src/zabbix-agent/src/zbxpcp.c b/src/zabbix-agent/src/zbxpcp.c
index fef75f3..5e20d4f 100644
--- a/src/zabbix-agent/src/zbxpcp.c
+++ b/src/zabbix-agent/src/zbxpcp.c
@@ -19,7 +19,6 @@
 
 /*
  * TODO
- * - derived metrics support
  * - config file support
  *   - conn type
  *   - conn target
@@ -36,6 +35,10 @@
 #define ZBX_PCP_METRIC_PREFIX "pcp."
 #endif
 
+#ifndef ZBX_PCP_DERIVED_CONFIG
+#define ZBX_PCP_DERIVED_CONFIG "/etc/zabbix/zbxpcp-derived-metrics.conf"
+#endif
+
 /* PCP includes.  */
 #include "pmapi.h"
 #include "impl.h"
@@ -50,6 +53,10 @@ static int ctx = -1;
 
 int zbx_module_pcp_connect()
 {
+    /* Load possible derived metric definitions.  */
+    if (access(ZBX_PCP_DERIVED_CONFIG, F_OK ) != -1)
+        pmLoadDerivedConfig(ZBX_PCP_DERIVED_CONFIG);
+
     ctx = pmNewContext(PM_CONTEXT_HOST, "localhost");
     return ctx;
 }
@@ -228,11 +235,9 @@ int zbx_module_pcp_fetch_metric(AGENT_REQUEST *request, 
AGENT_RESULT *result)
     }
 
     /* Locate the correct instance.  */
-    for (i = 0; desc[0].indom != PM_INDOM_NULL && i < rp->vset[0]->numval; 
i++) {
-        if (rp->vset[0]->vlist[i].inst == iid) {
+    for (i = 0; desc[0].indom != PM_INDOM_NULL && i < rp->vset[0]->numval; i++)
+        if (rp->vset[0]->vlist[i].inst == iid)
             break;
-        }
-    }
     if (i == rp->vset[0]->numval) {
         pmFreeResult(rp);
         return SYSINFO_RET_FAIL;

Thanks,

-- 
Marko Myllynen