Add a new API call which returns the total memory in use

This will be expanded upon later so we can return more of the
particulars of where memory is used

REST Request:
-------------------------------
PUT /sysadm/systeminfo
{
   "action" : "memorypercentage"
}

REST Response:
-------------------------------
{
    "args": {
        "memorypercentage": {
            "memoryused": 42
        }
    }
}

WebSocket Request:
-------------------------------
{
   "id" : "fooid",
   "args" : {
      "action" : "memorypercentage"
   },
   "namespace" : "sysadm",
   "name" : "systeminfo"
}

WebSocket Response:
-------------------------------
{
  "args": {
    "memorypercentage": {
      "memoryused": 42
    }
  },
  "id": "fooid",
  "name": "response",
  "namespace": "sysadm"
}

src/library/sysadm-systeminfo.cpp

@@ -160,3 +160,17 @@ QJsonObject SysInfo::externalDevicePaths() {
   // Return the devices / mounts
   return retObject;
 }
+
+// KPM 1-21-2016
+// This needs to beefed up as well, so we return more stats on arc, wired, etc
+QJsonObject SysInfo::memoryPercentage() {
+  QJsonObject retObject;
+  //SYSCTL: vm.stats.vm.v_<something>_count
+  QStringList info = General::RunCommand("sysctl -n vm.stats.vm.v_page_count vm.stats.vm.v_wire_count vm.stats.vm.v_active_count").split("\n");
+  if(info.length()<3){ return retObject; } //error in fetching information
+     //List output: [total, wired, active]
+  double perc = 100.0* (info[1].toLong()+info[2].toLong())/(info[0].toDouble());
+  retObject.insert("memoryused", qRound(perc));
+  return retObject;
+}
+

src/library/sysadm-systeminfo.h

@@ -18,6 +18,7 @@ public:
 	static QJsonObject cpuPercentage();
 	static QJsonObject cpuTemps();
 	static QJsonObject externalDevicePaths();
+	static QJsonObject memoryPercentage();
 };
 	
 } //end of pcbsd namespace

src/server/WebBackend.cpp

@@ -271,6 +271,10 @@ RestOutputStruct::ExitCode WebSocket::EvaluateSysadmSystemInfoRequest(const QJso
 	ok = true;
         out->insert("externalmounts", sysadm::SysInfo::externalDevicePaths());
       }
+      if(act=="memorypercentage"){
+	ok = true;
+        out->insert("memorypercentage", sysadm::SysInfo::memoryPercentage());
+      }
 
     } //end of "action" key usage