From 3777a2acca37cf3e6063df4ea780fbe729036193 Mon Sep 17 00:00:00 2001
From: Gengchen Tuo <gengchen.tuo@ibm.com>
Date: Thu, 10 Oct 2024 11:45:49 -0400
Subject: [PATCH] Add omrthread_get_self_thread_time()

This function returns the user and system cpu time of the calling
thread. This new function is needed because the only way that we're
aware of to get the user CPU time of a thread is to use
getrusage(RUSAGE_THREAD, ...) which can only be called on the current
thread.

Related: https://github.com/eclipse-openj9/openj9/pull/20186

Signed-off-by: Gengchen Tuo <gengchen.tuo@ibm.com>
---
 include_core/thread_api.h | 14 ++++++++++++++
 thread/common/thrprof.c   | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include_core/thread_api.h b/include_core/thread_api.h
index 8fd03718435..285ca031bcc 100644
--- a/include_core/thread_api.h
+++ b/include_core/thread_api.h
@@ -98,6 +98,11 @@ typedef struct omrthread_monitor_walk_state_t {
 	BOOLEAN lockTaken;
 } omrthread_monitor_walk_state_t;
 
+typedef struct omrthread_thread_time_t {
+	int64_t userTime;
+	int64_t sysTime;
+} omrthread_thread_time_t;
+
 /* ---------------- omrthreadinspect.c ---------------- */
 
 /**
@@ -1424,6 +1429,15 @@ omrthread_monitor_pin(omrthread_monitor_t monitor, omrthread_t self);
 void
 omrthread_monitor_unpin(omrthread_monitor_t monitor, omrthread_t self);
 
+/**
+ * Gets the system and user CPU time of the current thread
+ *
+ * @param[out] threadTime the pointer to the thread time structure
+ * @return 0 on success or -1 on failure
+ */
+intptr_t
+omrthread_get_self_thread_time(omrthread_thread_time_t *threadTime);
+
 /* forward struct definition */
 struct J9ThreadLibrary;
 
diff --git a/thread/common/thrprof.c b/thread/common/thrprof.c
index 023085ff616..cc2cb7bb581 100644
--- a/thread/common/thrprof.c
+++ b/thread/common/thrprof.c
@@ -28,6 +28,11 @@
  * APIs for querying per-thread statistics: CPU usage, stack usage.
  */
 
+#if defined (LINUX)
+#define _GNU_SOURCE
+#include <sys/resource.h>
+#endif /* defined (LINUX) */
+
 #include <string.h> /* for memset() */
 #include "omrcfg.h"
 
@@ -1025,3 +1030,34 @@ omrthread_get_jvm_cpu_usage_info_error_recovery(void)
 		GLOBAL_UNLOCK_SIMPLE(lib);
 	}
 }
+
+intptr_t
+omrthread_get_self_thread_time(omrthread_thread_time_t *threadTime) {
+ #if defined(LINUX)
+	struct rusage rUsage = {0};
+	int rc = getrusage(RUSAGE_THREAD, &rUsage);
+
+	if (-1 == rc) {
+		return -1;
+	}
+
+	threadTime->userTime = (SEC_TO_NANO_CONVERSION_CONSTANT * (int64_t)rUsage.ru_utime.tv_sec)
+							+ (MICRO_TO_NANO_CONVERSION_CONSTANT * (int64_t)rUsage.ru_utime.tv_usec);
+	threadTime->sysTime = (SEC_TO_NANO_CONVERSION_CONSTANT * (int64_t)rUsage.ru_stime.tv_sec)
+							+ (MICRO_TO_NANO_CONVERSION_CONSTANT * (int64_t)rUsage.ru_stime.tv_usec);
+#else /* defined(LINUX) */
+	omrthread_t self = omrthread_self();
+
+	int64_t userTime = omrthread_get_user_time(self);
+	int64_t cpuTime = omrthread_get_cpu_time(self);
+
+	if (-1 == cpuTime || -1 == userTime) {
+		return -1;
+	}
+
+	threadTime->sysTime = cpuTime - userTime;
+	threadTime->userTime = userTime;
+#endif /* defined(LINUX) */
+
+	return 0;
+}