heaptracker.c

来自「一个小公司要求给写的很简单的任务管理系统。」· C语言 代码 · 共 1,014 行 · 第 1/3 页

    jlong      tag;
    
    /* Tag this object with this TraceInfo pointer */
    tag = (jlong)(ptrdiff_t)(void*)tinfo;
    error = (*jvmti)->SetTag(jvmti, object, tag);
    check_jvmti_error(jvmti, error, "Cannot tag object");
}

/* Java Native Method for Object.<init> */
static void
HEAP_TRACKER_native_newobj(JNIEnv *env, jclass klass, jthread thread, jobject o)
{
    TraceInfo *tinfo;
    
    if ( gdata->vmDead ) {
        return;
    }
    tinfo = findTraceInfo(gdata->jvmti, thread, TRACE_USER);
    tagObjectWithTraceInfo(gdata->jvmti, o, tinfo);
}

/* Java Native Method for newarray */
static void
HEAP_TRACKER_native_newarr(JNIEnv *env, jclass klass, jthread thread, jobject a)
{
    TraceInfo *tinfo;
    
    if ( gdata->vmDead ) {
        return;
    }
    tinfo = findTraceInfo(gdata->jvmti, thread, TRACE_USER);
    tagObjectWithTraceInfo(gdata->jvmti, a, tinfo);
}

/* Callback for JVMTI_EVENT_VM_START */
static void JNICALL
cbVMStart(jvmtiEnv *jvmti, JNIEnv *env)
{
    enterCriticalSection(jvmti); {
        jclass klass;
        jfieldID field;
        jint rc;

        /* Java Native Methods for class */
        static JNINativeMethod registry[2] = {
            {STRING(HEAP_TRACKER_native_newobj), "(Ljava/lang/Object;Ljava/lang/Object;)V", 
                (void*)&HEAP_TRACKER_native_newobj},
            {STRING(HEAP_TRACKER_native_newarr), "(Ljava/lang/Object;Ljava/lang/Object;)V", 
                (void*)&HEAP_TRACKER_native_newarr}
        };
        
        /* Register Natives for class whose methods we use */
        klass = (*env)->FindClass(env, STRING(HEAP_TRACKER_class));
        if ( klass == NULL ) {
            fatal_error("ERROR: JNI: Cannot find %s with FindClass\n", 
                        STRING(HEAP_TRACKER_class));
        }
        rc = (*env)->RegisterNatives(env, klass, registry, 2);
        if ( rc != 0 ) {
            fatal_error("ERROR: JNI: Cannot register natives for class %s\n", 
                        STRING(HEAP_TRACKER_class));
        }
        
        /* Engage calls. */
        field = (*env)->GetStaticFieldID(env, klass, STRING(HEAP_TRACKER_engaged), "I");
        if ( field == NULL ) {
            fatal_error("ERROR: JNI: Cannot get field from %s\n", 
                        STRING(HEAP_TRACKER_class));
        }
        (*env)->SetStaticIntField(env, klass, field, 1);

        /* Indicate VM has started */
        gdata->vmStarted = JNI_TRUE;
    
    } exitCriticalSection(jvmti);
}

/* Iterate Through Heap callback */
static jint JNICALL
cbObjectTagger(jlong class_tag, jlong size, jlong* tag_ptr, jint length, 
               void *user_data)
{
    TraceInfo *tinfo;
    
    tinfo = emptyTrace(TRACE_BEFORE_VM_INIT);
    *tag_ptr = (jlong)(ptrdiff_t)(void*)tinfo;
    return JVMTI_VISIT_OBJECTS;
}

/* Callback for JVMTI_EVENT_VM_INIT */
static void JNICALL
cbVMInit(jvmtiEnv *jvmti, JNIEnv *env, jthread thread)
{
    jvmtiHeapCallbacks heapCallbacks;
    jvmtiError         error;
    
    /* Iterate through heap, find all untagged objects allocated before this */
    (void)memset(&heapCallbacks, 0, sizeof(heapCallbacks));
    heapCallbacks.heap_iteration_callback = &cbObjectTagger;
    error = (*jvmti)->IterateThroughHeap(jvmti, JVMTI_HEAP_FILTER_TAGGED, 
                                         NULL, &heapCallbacks, NULL);
    check_jvmti_error(jvmti, error, "Cannot iterate through heap");

    enterCriticalSection(jvmti); {
        
        /* Indicate VM is initialized */
        gdata->vmInitialized = JNI_TRUE;
    
    } exitCriticalSection(jvmti);
}

/* Iterate Through Heap callback */
static jint JNICALL
cbObjectSpaceCounter(jlong class_tag, jlong size, jlong* tag_ptr, jint length,
                     void *user_data)
{
    TraceInfo *tinfo;
    
    tinfo = (TraceInfo*)(ptrdiff_t)(*tag_ptr);
    if ( tinfo == NULL ) {
        tinfo = emptyTrace(TRACE_MYSTERY);
        *tag_ptr = (jlong)(ptrdiff_t)(void*)tinfo;
    }
    tinfo->totalSpace += size;
    return JVMTI_VISIT_OBJECTS;
}

/* Qsort compare function */
static int
compareInfo(const void *p1, const void *p2)
{
    TraceInfo *tinfo1, *tinfo2;
    
    tinfo1 = *((TraceInfo**)p1);
    tinfo2 = *((TraceInfo**)p2);
    return (int)(tinfo2->totalSpace - tinfo1->totalSpace);
}

/* Frame to text */
static void
frameToString(jvmtiEnv *jvmti, char *buf, int buflen, jvmtiFrameInfo *finfo)
{
    jvmtiError           error;
    jclass               klass;
    char                *signature;
    char                *methodname;
    char                *methodsig;
    jboolean             isNative;
    char                *filename;
    int                  lineCount;
    jvmtiLineNumberEntry*lineTable;
    int                  lineNumber;
   
    /* Initialize defaults */
    buf[0]     = 0;
    klass      = NULL;
    signature  = NULL;
    methodname = NULL;
    methodsig  = NULL;
    isNative   = JNI_FALSE;
    filename   = NULL;
    lineCount  = 0;
    lineTable  = NULL;
    lineNumber = 0;
   
    /* Get jclass object for the jmethodID */
    error = (*jvmti)->GetMethodDeclaringClass(jvmti, finfo->method, &klass);
    check_jvmti_error(jvmti, error, "Cannot get method's class");

    /* Get the class signature */
    error = (*jvmti)->GetClassSignature(jvmti, klass, &signature, NULL);
    check_jvmti_error(jvmti, error, "Cannot get class signature");

    /* Skip all this if it's our own Tracker method */
    if ( strcmp(signature, "L" STRING(HEAP_TRACKER_class) ";" ) == 0 ) {
        deallocate(jvmti, signature);
        return;
    }

    /* Get the name and signature for the method */
    error = (*jvmti)->GetMethodName(jvmti, finfo->method, 
                &methodname, &methodsig, NULL);
    check_jvmti_error(jvmti, error, "Cannot method name");
   
    /* Check to see if it's a native method, which means no lineNumber */
    error = (*jvmti)->IsMethodNative(jvmti, finfo->method, &isNative);
    check_jvmti_error(jvmti, error, "Cannot get method native status");
  
    /* Get source file name */
    error = (*jvmti)->GetSourceFileName(jvmti, klass, &filename);
    if ( error != JVMTI_ERROR_NONE && error != JVMTI_ERROR_ABSENT_INFORMATION ) {
        check_jvmti_error(jvmti, error, "Cannot get source filename");
    }
        
    /* Get lineNumber if we can */
    if ( !isNative ) {
        int i;

        /* Get method line table */
        error = (*jvmti)->GetLineNumberTable(jvmti, finfo->method, &lineCount, &lineTable);
        if ( error == JVMTI_ERROR_NONE ) {
            /* Search for line */
            lineNumber = lineTable[0].line_number;
            for ( i = 1 ; i < lineCount ; i++ ) {
                if ( finfo->location < lineTable[i].start_location ) {
                    break;
                }
                lineNumber = lineTable[i].line_number;
            }
        } else if ( error != JVMTI_ERROR_ABSENT_INFORMATION ) {
            check_jvmti_error(jvmti, error, "Cannot get method line table");
        }
    }

    /* Create string for this frame location.
     *    NOTE: These char* quantities are mUTF (Modified UTF-8) bytes
     *          and should actually be converted to the default system
     *          character encoding. Sending them to things like
     *          printf() without converting them is actually an I18n
     *          (Internationalization) error.
     */
    (void)sprintf(buf, "%s.%s@%d[%s:%d]", 
            (signature==NULL?"UnknownClass":signature), 
            (methodname==NULL?"UnknownMethod":methodname), 
            (int)finfo->location, 
            (filename==NULL?"UnknownFile":filename), 
            lineNumber);

    /* Free up JVMTI space allocated by the above calls */
    deallocate(jvmti, signature);
    deallocate(jvmti, methodname);
    deallocate(jvmti, methodsig);
    deallocate(jvmti, filename);
    deallocate(jvmti, lineTable);
}

/* Print the information */
static void
printTraceInfo(jvmtiEnv *jvmti, int index, TraceInfo* tinfo)
{
    if ( tinfo == NULL ) {
        fatal_error("%d: NULL ENTRY ERROR\n", index);
        return;
    }
    
    stdout_message("%2d: %7d bytes %5d objects %5d live %s",
                index, (int)tinfo->totalSpace, tinfo->totalCount, 
                tinfo->useCount, flavorDesc[tinfo->trace.flavor]);
    
    if (  tinfo->trace.nframes > 0 ) {
        int i;
        int fcount;

        fcount = 0;
        stdout_message(" stack=(");
        for ( i = 0 ; i < tinfo->trace.nframes ; i++ ) {
            char buf[4096];

            frameToString(jvmti, buf, (int)sizeof(buf), tinfo->trace.frames+i);
            if ( buf[0] == 0 ) {
                continue; /* Skip the ones that are from Tracker class */
            }
            fcount++;
            stdout_message("%s", buf);
            if ( i < (tinfo->trace.nframes-1) ) {
                stdout_message(",");
            }
        }
        stdout_message(") nframes=%d\n", fcount);
    } else {
        stdout_message(" stack=<empty>\n");
    }
}

/* Callback for JVMTI_EVENT_VM_DEATH */
static void JNICALL
cbVMDeath(jvmtiEnv *jvmti, JNIEnv *env)
{
    jvmtiHeapCallbacks heapCallbacks;
    jvmtiError         error;

    /* These are purposely done outside the critical section */

    /* Force garbage collection now so we get our ObjectFree calls */
    error = (*jvmti)->ForceGarbageCollection(jvmti);
    check_jvmti_error(jvmti, error, "Cannot force garbage collection");
    
    /* Iterate through heap and find all objects */
    (void)memset(&heapCallbacks, 0, sizeof(heapCallbacks));
    heapCallbacks.heap_iteration_callback = &cbObjectSpaceCounter;
    error = (*jvmti)->IterateThroughHeap(jvmti, 0, NULL, &heapCallbacks, NULL);
    check_jvmti_error(jvmti, error, "Cannot iterate through heap");

    /* Process VM Death */
    enterCriticalSection(jvmti); {
        jclass              klass;
        jfieldID            field;
        jvmtiEventCallbacks callbacks;

        /* Disengage calls in HEAP_TRACKER_class. */
        klass = (*env)->FindClass(env, STRING(HEAP_TRACKER_class));
        if ( klass == NULL ) {
            fatal_error("ERROR: JNI: Cannot find %s with FindClass\n", 
                        STRING(HEAP_TRACKER_class));
        }
        field = (*env)->GetStaticFieldID(env, klass, STRING(HEAP_TRACKER_engaged), "I");
        if ( field == NULL ) {
            fatal_error("ERROR: JNI: Cannot get field from %s\n", 
                        STRING(HEAP_TRACKER_class));
        }
        (*env)->SetStaticIntField(env, klass, field, 0);

        /* The critical section here is important to hold back the VM death
         *    until all other callbacks have completed.
         */

        /* Clear out all callbacks. */
        (void)memset(&callbacks,0, sizeof(callbacks));
        error = (*jvmti)->SetEventCallbacks(jvmti, &callbacks, 
                                            (jint)sizeof(callbacks));
        check_jvmti_error(jvmti, error, "Cannot set jvmti callbacks");
        
        /* Since this critical section could be holding up other threads
         *   in other event callbacks, we need to indicate that the VM is
         *   dead so that the other callbacks can short circuit their work.
         *   We don't expect an further events after VmDeath but we do need
         *   to be careful that existing threads might be in our own agent
         *   callback code.
         */
        gdata->vmDead = JNI_TRUE;

        /* Dump all objects */
        if ( gdata->traceInfoCount > 0 ) {
            TraceInfo **list;
            int         count;
            int         i;
           
            stdout_message("Dumping heap trace information\n");