1 #include <jni.h>
2
3 #include <pthread.h>
4 #include <stdlib.h>
5 #include <time.h>
6 #include <string>
7
8 #define noinline __attribute__((__noinline__))
9
10 extern "C"
11 JNIEXPORT jstring JNICALL
Java_com_example_simpleperf_simpleperfexamplewithnative_MainActivity_stringFromJNI(JNIEnv * env,jobject)12 Java_com_example_simpleperf_simpleperfexamplewithnative_MainActivity_stringFromJNI(
13 JNIEnv *env,
14 jobject /* this */) {
15 std::string hello = "Hello from C++";
16 return env->NewStringUTF(hello.c_str());
17 }
18
ThrowErrnoException(JNIEnv * env,const char * function_name,int err)19 static void ThrowErrnoException(JNIEnv* env, const char* function_name, int err) {
20 jclass cls = env->FindClass("android/system/ErrnoException");
21 if (cls == nullptr) {
22 return;
23 }
24 jmethodID cid = env->GetMethodID(cls, "<init>", "(Ljava/lang/String;I)V");
25 if (cid == nullptr) {
26 return;
27 }
28 jstring msg = env->NewStringUTF(function_name);
29 if (msg == nullptr) {
30 return;
31 }
32 jthrowable obj = (jthrowable)env->NewObject(cls, cid, msg, err);
33 if (obj == nullptr) {
34 return;
35 }
36 env->Throw(obj);
37 }
38
CallFunction(int a)39 int CallFunction(int a) {
40 return a + atoi("1");
41 }
42
BusyLoopThread(void *)43 static void* BusyLoopThread(void*) {
44 volatile int i = 0;
45 while (true) {
46 i = CallFunction(i);
47 }
48 return nullptr;
49 }
50
51 extern "C"
52 JNIEXPORT void JNICALL
Java_com_example_simpleperf_simpleperfexamplewithnative_MainActivity_createBusyThreadFromJNI(JNIEnv * env,jobject)53 Java_com_example_simpleperf_simpleperfexamplewithnative_MainActivity_createBusyThreadFromJNI(
54 JNIEnv *env,
55 jobject /* this */) {
56 pthread_t thread;
57 int ret = pthread_create(&thread, nullptr, BusyLoopThread, nullptr);
58 if (ret) {
59 ThrowErrnoException(env, "pthread_create", ret);
60 return;
61 }
62 }
63
GetSystemClock()64 static inline uint64_t GetSystemClock() {
65 timespec ts;
66 clock_gettime(CLOCK_MONOTONIC, &ts);
67 return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
68 }
69
70 constexpr int LOOP_COUNT = 100000000;
RunFunction()71 static uint64_t noinline RunFunction() {
72 uint64_t start_time_in_ns = GetSystemClock();
73 for (volatile int i = 0; i < LOOP_COUNT; ++i) {
74 }
75 return GetSystemClock() - start_time_in_ns;
76 }
77
SleepFunction(unsigned long long sleep_time_in_ns)78 static uint64_t noinline SleepFunction(unsigned long long sleep_time_in_ns) {
79 uint64_t start_time_in_ns = GetSystemClock();
80 struct timespec req;
81 req.tv_sec = sleep_time_in_ns / 1000000000;
82 req.tv_nsec = sleep_time_in_ns % 1000000000;
83 nanosleep(&req, nullptr);
84 return GetSystemClock() - start_time_in_ns;
85 }
86
SleepThread(void *)87 static void* SleepThread(void*) {
88 pthread_setname_np(pthread_self(), "SleepThread");
89 uint64_t total_sleep_time_in_ns = 0;
90 uint64_t total_run_time_in_ns = 0;
91 while (true) {
92 total_run_time_in_ns += RunFunction();
93 if (total_sleep_time_in_ns < total_run_time_in_ns) {
94 total_sleep_time_in_ns += SleepFunction(total_run_time_in_ns - total_sleep_time_in_ns);
95 }
96 }
97 }
98
99 extern "C"
100 JNIEXPORT void JNICALL
Java_com_example_simpleperf_simpleperfexamplewithnative_SleepActivity_createSleepThreadFromJNI(JNIEnv * env,jobject)101 Java_com_example_simpleperf_simpleperfexamplewithnative_SleepActivity_createSleepThreadFromJNI(
102 JNIEnv *env,
103 jobject /* this */) {
104 pthread_t thread;
105 int ret = pthread_create(&thread, nullptr, SleepThread, nullptr);
106 if (ret) {
107 ThrowErrnoException(env, "pthread_create", ret);
108 return;
109 }
110 }
111
112 extern "C"
113 JNIEXPORT int JNICALL
Java_com_example_simpleperf_simpleperfexamplewithnative_MixActivity_callFunction(JNIEnv * env,jobject,int a)114 Java_com_example_simpleperf_simpleperfexamplewithnative_MixActivity_callFunction(
115 JNIEnv *env,
116 jobject /* this */,
117 int a) {
118 return CallFunction(a);
119 }