[libvirt] [java] [PATCH 1/2] GetNodeCpuStat binding

[Pasquale.phate867 at gmail.com]

From: Pasquale Di Rienzo <phate867 at gmail.com>

-Added the getNodeCpuStat binding to Libvirt class
-Added virNodeCPUStats and CPUStat classes to support this binding
-Added the method getCPUStats to Connect class
---
 AUTHORS                                            |  1 +
 src/main/java/org/libvirt/CPUStat.java             | 57 ++++++++++++++++++++++
 src/main/java/org/libvirt/Connect.java             | 53 ++++++++++++++++++++
 src/main/java/org/libvirt/jna/Libvirt.java         |  5 ++
 src/main/java/org/libvirt/jna/virNodeCPUStats.java | 19 ++++++++
 5 files changed, 135 insertions(+)
 create mode 100644 src/main/java/org/libvirt/CPUStat.java
 create mode 100644 src/main/java/org/libvirt/jna/virNodeCPUStats.java

diff --git a/AUTHORS b/AUTHORS
index 07809bf..77139e5 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -16,3 +16,4 @@ Andrea Sansottera <andrea.sansottera at gmail.com>
 Stefan Majer <stefan.majer at gmail.com>
 Wido den Hollander <wido at widodh.nl>
 Eric Blake <eblake at redhat.com>
+Pasquale Di Rienzo <phate867 at gmail.com>
diff --git a/src/main/java/org/libvirt/CPUStat.java b/src/main/java/org/libvirt/CPUStat.java
new file mode 100644
index 0000000..527049c
--- /dev/null
+++ b/src/main/java/org/libvirt/CPUStat.java
@@ -0,0 +1,57 @@
+package org.libvirt;
+
+import java.nio.charset.Charset;
+import org.libvirt.jna.virNodeCPUStats;
+import org.libvirt.jna.virTypedParameter;
+
+/**
+ * This class holds a cpu time.
+ * The tag attribute is a string of either "kernel","user","idle","iowait"
+ * while the value attribute is the actual time value
+ * @author Pasquale Di Rienzo
+ *
+ */
+public class CPUStat {
+	public String tag;
+    public long value;
+    
+    private String createStringFromBytes(byte[] b){
+    	Charset ch = Charset.forName("UTF-8");
+    	int i = 0;
+    	while ((i<b.length) && (b[i]!=0))	
+    		i++;
+    	
+    	return new String(b,0,i,ch);
+    }
+    
+    public CPUStat(virNodeCPUStats stat){
+    	tag = createStringFromBytes(stat.field);
+    	value = stat.value.longValue();
+    }
+    
+    public CPUStat(virTypedParameter stat){
+    	tag = createStringFromBytes(stat.field);
+		value = stat.value.l;
+    }
+
+    public String getTag() {
+        return tag;
+    }
+
+    public long getValue() {
+        return value;
+    }
+
+    public void setTag(String tag) {
+        this.tag = tag;
+    }
+
+    public void setValue(long val) {
+        this.value = val;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("tag:%s%nval:%d%n", tag, value);
+    }
+}
diff --git a/src/main/java/org/libvirt/Connect.java b/src/main/java/org/libvirt/Connect.java
index fedc60e..d8a4ce2 100644
--- a/src/main/java/org/libvirt/Connect.java
+++ b/src/main/java/org/libvirt/Connect.java
@@ -2,6 +2,8 @@ package org.libvirt;
 
 import java.util.UUID;
 
+import org.libvirt.CPUStat;
+import org.libvirt.LibvirtException;
 import org.libvirt.jna.ConnectionPointer;
 import org.libvirt.jna.DevicePointer;
 import org.libvirt.jna.DomainPointer;
@@ -14,6 +16,7 @@ import org.libvirt.jna.StoragePoolPointer;
 import org.libvirt.jna.StorageVolPointer;
 import org.libvirt.jna.StreamPointer;
 import org.libvirt.jna.virConnectAuth;
+import org.libvirt.jna.virNodeCPUStats;
 import org.libvirt.jna.virNodeInfo;
 
 import static org.libvirt.Library.libvirt;
@@ -23,6 +26,7 @@ import static org.libvirt.ErrorHandler.processErrorIfZero;
 import com.sun.jna.Memory;
 import com.sun.jna.NativeLong;
 import com.sun.jna.Pointer;
+import com.sun.jna.ptr.IntByReference;
 import com.sun.jna.ptr.LongByReference;
 
 /**
@@ -207,6 +211,55 @@ public class Connect {
         }
         return processError(success);
     }
+    
+    /**
+     * This function returns statistics about the cpu, that is the time
+     * each cpu is spending in kernel time, user time, io time and idle time.
+     * Each CPUStat object refers to a particular time.
+     * 
+     * Note that not all these stats are granted to be retrieved.
+     *  
+     * @param the number of the cpu you want to retrieve stats from.
+     * passing -1 will make this function retrieve a mean value
+     * from all cpus the system has. 
+     * 
+     * @param some flags
+     * @return a cpustat object for each cpu
+     * @throws LibvirtException
+     */
+    public CPUStat[] getCPUStats(int cpuNumber,long flags) throws LibvirtException{
+    	CPUStat[] stats = null;
+    	
+    	IntByReference nParams = new IntByReference();
+    	
+    	//according to libvirt reference you call this function once passing
+    	//null as param paramether to get the actual stats (kernel,user,io,idle) number into the 
+    	//nParams reference. Generally this number would be 4, but some systems
+    	//may not give all 4 times, so it is always good to call it.
+    	int result = libvirt.virNodeGetCPUStats(
+    			VCP, cpuNumber, null, nParams, flags);
+    	
+    	processError(result);
+    	
+    	if(result == 0){//dunno if this check is actually needed
+    		
+    		//this time we create an array to fit the number of paramethers
+    		virNodeCPUStats[] params = new virNodeCPUStats[nParams.getValue()];
+    		//and we pass it to the function
+    		result = libvirt.virNodeGetCPUStats(VCP, cpuNumber , params, nParams, flags);
+    		processError(result);
+    		
+    		//finally we parse the result in an user friendly class which does
+    		//not expose libvirt's internal paramethers
+    		if(result >= 0){
+    			stats = new CPUStat[params.length];
+    			for(int i=0;i<params.length;i++)
+					stats[i] = new CPUStat(params[i]);
+    		}	
+    	}
+    	
+    	return stats;	
+    }
 
     /**
      * Compares the given CPU description with the host CPU
diff --git a/src/main/java/org/libvirt/jna/Libvirt.java b/src/main/java/org/libvirt/jna/Libvirt.java
index 0e4c9fc..658299f 100644
--- a/src/main/java/org/libvirt/jna/Libvirt.java
+++ b/src/main/java/org/libvirt/jna/Libvirt.java
@@ -1,5 +1,8 @@
 package org.libvirt.jna;
 
+import org.libvirt.jna.ConnectionPointer;
+import org.libvirt.jna.virNodeCPUStats;
+
 import com.sun.jna.Callback;
 import com.sun.jna.Library;
 import com.sun.jna.Native;
@@ -267,6 +270,8 @@ public interface Libvirt extends Library {
     int virNetworkUndefine(NetworkPointer virConnectPtr);
 
     // Node functions
+    int virNodeGetCPUStats(ConnectionPointer virConnectPtr, int cpuNum,
+    		virNodeCPUStats[] stats,IntByReference nparams, long flags);
     int virNodeGetInfo(ConnectionPointer virConnectPtr, virNodeInfo virNodeInfo);
     int virNodeGetCellsFreeMemory(ConnectionPointer virConnectPtr, LongByReference freeMems, int startCell,
             int maxCells);
diff --git a/src/main/java/org/libvirt/jna/virNodeCPUStats.java b/src/main/java/org/libvirt/jna/virNodeCPUStats.java
new file mode 100644
index 0000000..a8f2dca
--- /dev/null
+++ b/src/main/java/org/libvirt/jna/virNodeCPUStats.java
@@ -0,0 +1,19 @@
+package org.libvirt.jna;
+
+import java.util.Arrays;
+import java.util.List;
+
+import com.sun.jna.NativeLong;
+import com.sun.jna.Structure;
+
+public class virNodeCPUStats extends Structure{
+	public byte[] field = new byte[80];
+    public NativeLong value ;
+
+    private static final List fields = Arrays.asList( "field", "value");
+
+    @Override
+    protected List getFieldOrder() {
+        return fields;
+    }
+}
-- 
1.8.3.2