1 #include <assert.h>

     2 #include <jni.h>

     3 #include <alloca.h>

     4 

     5 #include <pthread.h>

     6 

     7 union env_union

     8 {

     9   void *void_env;

    10   JNIEnv *jni_env;

    11 };

    12 

    13 union env_union tmp;

    14 JNIEnv* env;

    15 JavaVM* jvm;

    16 JavaVMInitArgs vm_args;

    17 JavaVMOption options[1];

    18 jclass class_id;

    19 jmethodID method_id;

    20 jint result;

    21 

    22 long product(unsigned long n, unsigned long m) {

    23     if (m == 1) {

    24       return n;

    25     } else {

    26       int *p = alloca(sizeof (int));

    27       *p = n;

    28       return product (n, m-1) + *p;

    29     }

    30 }

    31 

    32 void *

    33 floobydust (void *p)

    34 {

    35   (*jvm)->AttachCurrentThread(jvm, &tmp.void_env, NULL);

    36   env = tmp.jni_env;

    37 

    38   class_id = (*env)->FindClass (env, "T");

    39   assert (class_id);

    40 

    41   method_id = (*env)->GetStaticMethodID (env, class_id, "printIt", "()V");

    42   assert (method_id);

    43 

    44   (*env)->CallStaticVoidMethod (env, class_id, method_id, NULL);

    45 

    46   (*jvm)->DetachCurrentThread(jvm);

    47 

    48   printf("%ld\n", product(5000,5000));

    49 

    50   (*jvm)->AttachCurrentThread(jvm, &tmp.void_env, NULL);

    51   env = tmp.jni_env;

    52 

    53   class_id = (*env)->FindClass (env, "T");

    54   assert (class_id);

    55 

    56   method_id = (*env)->GetStaticMethodID (env, class_id, "printIt", "()V");

    57   assert (method_id);

    58 

    59   (*env)->CallStaticVoidMethod (env, class_id, method_id, NULL);

    60 

    61   (*jvm)->DetachCurrentThread(jvm);

    62 

    63   printf("%ld\n", product(5000,5000));

    64 

    65   return NULL;

    66 }

    67 

    68 int

    69 main (int argc, const char** argv)

    70 {

    71   options[0].optionString = "-Xss320k";

    72 

    73   vm_args.version = JNI_VERSION_1_2;

    74   vm_args.ignoreUnrecognized = JNI_TRUE;

    75   vm_args.options = options;

    76   vm_args.nOptions = 1;

    77 

    78   result = JNI_CreateJavaVM (&jvm, &tmp.void_env, &vm_args);

    79   assert (result >= 0);

    80 

    81   env = tmp.jni_env;

    82 

    83   floobydust (NULL);

    84 

    85   pthread_t thr;

    86   pthread_create (&thr, NULL, floobydust, NULL);

    87   pthread_join (thr, NULL);

    88 

    89   return 0;

    90 }