(SIGAR-207) Add Pdh.getDescription method

bindings/java/src/jni/win32/pdh.c

@@ -222,6 +222,38 @@ JNIEXPORT jdouble SIGAR_JNI(win32_Pdh_pdhGetValue)
     }
 }
 
+JNIEXPORT jstring SIGAR_JNI(win32_Pdh_pdhGetDescription)
+(JNIEnv *env, jclass cur, jlong counter)
+{
+    HCOUNTER h_counter = (HCOUNTER)counter;
+    PDH_COUNTER_INFO *info = NULL;
+    jstring retval = NULL;
+    DWORD size = 0;
+    PDH_STATUS status;
+
+    status = PdhGetCounterInfo(h_counter, TRUE, &size, NULL);
+    if (status != PDH_MORE_DATA) {
+        win32_throw_exception(env, get_error_message(status));
+        return NULL;
+    }
+
+    info = malloc(size);
+
+    status = PdhGetCounterInfo(h_counter, 1, &size, info);
+    if (status == ERROR_SUCCESS) {
+        if (info->szExplainText) {
+            retval = JENV->NewString(env, info->szExplainText,
+                                     lstrlen(info->szExplainText));
+        }
+    }
+    else {
+        win32_throw_exception(env, get_error_message(status));
+    }
+
+    free(info);
+    return retval;
+}
+
 JNIEXPORT jobjectArray SIGAR_JNI(win32_Pdh_pdhGetInstances)
 (JNIEnv *env, jclass cur, jstring cp)
 {

bindings/java/src/org/hyperic/sigar/win32/Pdh.java

@@ -292,6 +292,17 @@ public class Pdh extends Win32 {
         }
     }
 
+    /* PdhCounterInfo.ExplainText */
+    public String getDescription(String path) throws Win32Exception {
+        long counter =
+            pdhAddCounter(this.query, translate(path));
+        try {
+            return pdhGetDescription(counter);
+        } finally {
+            pdhRemoveCounter(counter);
+        }
+    }
+
     public static String[] getInstances(String path) throws Win32Exception {
         return pdhGetInstances(getCounterName(path));
     }
@@ -319,6 +330,8 @@ public class Pdh extends Win32 {
                                                    long counter,
                                                    boolean fmt)
         throws Win32Exception;
+    private static final native String pdhGetDescription(long counter)
+        throws Win32Exception;
     private static final native String[] pdhGetInstances(String path)
         throws Win32Exception;
     private static final native String[] pdhGetKeys(String path)

bindings/java/src/org/hyperic/sigar/win32/test/TestPdh.java

@@ -33,7 +33,7 @@ public class TestPdh extends SigarTestCase {
     private void getValue(String key) throws Exception {
         Pdh pdh = new Pdh();
 
-        traceln(key);
+        traceln(key + ": " + pdh.getDescription(key));
         assertGtEqZeroTrace("raw",
                             (long)pdh.getRawValue(key));
         assertGtEqZeroTrace("fmt",