Return another error if only one data point has been recorded

This is to determine if a call to omrsysinfo_get_CPU_load has onlyone
data point recorded.

Also fixed a mistake in the description saying that the first two
invocations return OMRPORT_ERROR_OPFAILED and fix the time unit in the
description to "ms".

Related: eclipse-openj9/openj9#18451

Signed-off-by: Gengchen Tuo <gengchen.tuo@ibm.com>

fvtest/porttest/si.cpp

@@ -1690,19 +1690,17 @@ TEST(PortSysinfoTest, sysinfo_test_get_CPU_load)
 {
 	OMRPORT_ACCESS_FROM_OMRPORT(portTestEnv->getPortLibrary());
 
-	/* As per the API specification the first two calls to this API will return a negative portable error code. However
-	 * for the purposes of this test we will not be testing this. This is because the test infrastructure is setup such
-	 * that we cannot guarantee that no other test has called omrsysinfo_get_CPU_utlization or omrsysinfo_get_CPU_load
-	 * up to this point. If some other test did call these APIs then the internal buffers would have been populated and
-	 * as such the omrsysinfo_get_CPU_load could return a zero return code on the very first invocation within this
-	 * test.
+	/* As per the API specification if only one data point has been recorded this API will return a negative portable
+	 * error code. However for the purposes of this test we will not be testing this. This is because the test infrastructure
+	 * is setup such that we cannot guarantee that no other test has called omrsysinfo_get_CPU_load up to this point. If
+	 * some other test calls this API then the internal buffers would have been populated and as such the omrsysinfo_get_CPU_load
+	 * could return a zero return code on the very first invocation within this test.
 	 *
-	 * To avoid inter-test dependencies we do not assert on the return value of the first two calls here, and only test
+	 * To avoid inter-test dependencies we do not assert on the return value of the first call here, and only test
 	 * that the API returns valid numbers within the range outlined in the API specification.
 	 */
 	double cpuLoad;
 	omrsysinfo_get_CPU_load(&cpuLoad);
-	omrsysinfo_get_CPU_load(&cpuLoad);
 
 	/* Sleep for 100ms before re-sampling processor usage stats. This allows other processes and the operating system to
 	 * use the CPU and drive up the user and kernel utilization. The call to cpuBurner probably won't be optimized out,

include_core/omrporterror.h

@@ -67,6 +67,7 @@
 #define OMRPORT_ERROR_INVALID_HANDLE (OMRPORT_ERROR_BASE-17)
 #define OMRPORT_ERROR_NOT_SUPPORTED_ON_THIS_PLATFORM (OMRPORT_ERROR_BASE-18)
 #define OMRPORT_ERROR_INVALID_ARGUMENTS (OMRPORT_ERROR_BASE-19)
+#define OMRPORT_ERROR_INSUFFICIENT_DATA (OMRPORT_ERROR_BASE-20)
 /** @} */
 
 /**

port/common/omrsysinfo.c

@@ -651,10 +651,10 @@ omrsysinfo_get_CPU_utilization(struct OMRPortLibrary *portLibrary, struct J9Sysi
  * @param[out] cpuLoad the cumulative CPU utilization of all CPUs on the system
  *
  * @return
- * 	- 0 on success
- *		- \arg OMRPORT_ERROR_OPFAILED on the first two invocations of this API
- *		- \arg OMRPORT_ERROR_OPFAILED if less than 10ns have passed since the second call to this API
- *		- negative portable error code on other failures
+ *  \arg 0 on success
+ *  \arg OMRPORT_ERROR_INSUFFICIENT_DATA if only one data point has been recorded
+ *  \arg OMRPORT_ERROR_OPFAILED if less than 10 ms have passed since the last call to this API
+ *  \arg negative portable error code on other failures
  */
 intptr_t
 omrsysinfo_get_CPU_load(struct OMRPortLibrary *portLibrary, double *cpuLoad)

port/unix/omrsysinfo.c

@@ -4642,7 +4642,7 @@ omrsysinfo_get_CPU_load(struct OMRPortLibrary *portLibrary, double *cpuLoad)
 	if (oldestCPUTime->timestamp == 0) {
 		*oldestCPUTime = currentCPUTime;
 		*latestCPUTime = currentCPUTime;
-		return OMRPORT_ERROR_OPFAILED;
+		return OMRPORT_ERROR_INSUFFICIENT_DATA;
 	}
 
 	/* Calculate using the most recent value in the history */
@@ -4674,7 +4674,7 @@ omrsysinfo_get_CPU_load(struct OMRPortLibrary *portLibrary, double *cpuLoad)
 	if (oldestCPUTime->timestamp == 0) {
 		*oldestCPUTime = currentCPUTime;
 		*latestCPUTime = currentCPUTime;
-		return OMRPORT_ERROR_OPFAILED;
+		return OMRPORT_ERROR_INSUFFICIENT_DATA;
 	}
 
 	/* Calculate using the most recent value in the history */

port/win32/omrsysinfo.c

@@ -1271,7 +1271,7 @@ omrsysinfo_get_CPU_load(struct OMRPortLibrary *portLibrary, double *cpuLoad)
 	if (oldestCPUTime->timestamp == 0) {
 		*oldestCPUTime = currentCPUTime;
 		*latestCPUTime = currentCPUTime;
-		return OMRPORT_ERROR_OPFAILED;
+		return OMRPORT_ERROR_INSUFFICIENT_DATA;
 	}
 
 	/* Calculate using the most recent value in the history */