/* Lookup or create a new TraceInfo */
static TraceInfo *
lookupOrEnter(jvmtiEnv *jvmti, Trace *trace, TraceFlavor flavor)
{
TraceInfo *tinfo;
jlong hashCode;
/* Calculate hash code (outside critical section to lessen contention) */
hashCode = hashTrace(trace);
/* Do a lookup in the hash table */
enterCriticalSection(jvmti);
{
TraceInfo *prev;
int hashIndex;
/* Start with first item in hash buck chain */
prev = NULL;
hashIndex = (int)(hashCode & HASH_INDEX_MASK);
tinfo = gdata->hashBuckets[hashIndex];
while ( tinfo != NULL ) {
if ( tinfo->hashCode == hashCode &&
memcmp(trace, &(tinfo->trace), sizeof(Trace))==0 ) {
/* We found one that matches, move to head of bucket chain */
if ( prev != NULL ) {
/* Remove from list and add to head of list */
prev->next = tinfo->next;
tinfo->next = gdata->hashBuckets[hashIndex];
gdata->hashBuckets[hashIndex] = tinfo;
}
/* Break out */
break;
}
prev = tinfo;
tinfo = tinfo->next;
}
/* If we didn't find anything we need to enter a new entry */
if ( tinfo == NULL ) {
/* Create new hash table element */
tinfo = newTraceInfo(trace, hashCode, flavor);
}
/* Update stats */
(void)updateStats(tinfo);
}
exitCriticalSection(jvmti);
return tinfo;
}
/* Agent_OnLoad: This is called immediately after the shared library is
* loaded. This is the first code executed.
*/
JNIEXPORT jint JNICALL
Agent_OnLoad(JavaVM *vm, char *options, void *reserved)
{
static GlobalAgentData data;
jvmtiEnv *jvmti;
jvmtiError error;
jint res;
TraceFlavor flavor;
jvmtiCapabilities capabilities;
jvmtiEventCallbacks callbacks;
static Trace empty;
/* Setup initial global agent data area
* Use of static/extern data should be handled carefully here.
* We need to make sure that we are able to cleanup after ourselves
* so anything allocated in this library needs to be freed in
* the Agent_OnUnload() function.
*/
(void)memset((void*)&data, 0, sizeof(data));
gdata = &data;
/* First thing we need to do is get the jvmtiEnv* or JVMTI environment */
res = (*vm)->GetEnv(vm, (void **)&jvmti, JVMTI_VERSION_1);
if (res != JNI_OK) {
/* This means that the VM was unable to obtain this version of the
* JVMTI interface, this is a fatal error.
*/
fatal_error("ERROR: Unable to access JVMTI Version 1 (0x%x),"
" is your JDK a 5.0 or newer version?"
" JNIEnv's GetEnv() returned %d\n",
JVMTI_VERSION_1, res);
}
/* Here we save the jvmtiEnv* for Agent_OnUnload(). */
gdata->jvmti = jvmti;
/* Parse any options supplied on java command line */
parse_agent_options(options);
/* Immediately after getting the jvmtiEnv* we need to ask for the
* capabilities this agent will need.
*/
(void)memset(&capabilities,0, sizeof(capabilities));
capabilities.can_generate_all_class_hook_events = 1;
capabilities.can_tag_objects = 1;
capabilities.can_generate_object_free_events = 1;
capabilities.can_get_source_file_name = 1;
capabilities.can_get_line_numbers = 1;
capabilities.can_generate_vm_object_alloc_events = 1;
error = (*jvmti)->AddCapabilities(jvmti, &capabilities);
check_jvmti_error(jvmti, error, "Unable to get necessary JVMTI capabilities.");
/* Next we need to provide the pointers to the callback functions to
* to this jvmtiEnv*
*/
(void)memset(&callbacks,0, sizeof(callbacks));
/* JVMTI_EVENT_VM_START */
callbacks.VMStart = &cbVMStart;
/* JVMTI_EVENT_VM_INIT */
callbacks.VMInit = &cbVMInit;
/* JVMTI_EVENT_VM_DEATH */
callbacks.VMDeath = &cbVMDeath;
/* JVMTI_EVENT_OBJECT_FREE */
callbacks.ObjectFree = &cbObjectFree;
/* JVMTI_EVENT_VM_OBJECT_ALLOC */
callbacks.VMObjectAlloc = &cbVMObjectAlloc;
/* JVMTI_EVENT_CLASS_FILE_LOAD_HOOK */
callbacks.ClassFileLoadHook = &cbClassFileLoadHook;
error = (*jvmti)->SetEventCallbacks(jvmti, &callbacks, (jint)sizeof(callbacks));
check_jvmti_error(jvmti, error, "Cannot set jvmti callbacks");
/* At first the only initial events we are interested in are VM
* initialization, VM death, and Class File Loads.
* Once the VM is initialized we will request more events.
*/
error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_VM_START, (jthread)NULL);
check_jvmti_error(jvmti, error, "Cannot set event notification");
error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_VM_INIT, (jthread)NULL);
check_jvmti_error(jvmti, error, "Cannot set event notification");
error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_VM_DEATH, (jthread)NULL);
check_jvmti_error(jvmti, error, "Cannot set event notification");
error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_OBJECT_FREE, (jthread)NULL);
check_jvmti_error(jvmti, error, "Cannot set event notification");
error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_VM_OBJECT_ALLOC, (jthread)NULL);
check_jvmti_error(jvmti, error, "Cannot set event notification");
error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, (jthread)NULL);
check_jvmti_error(jvmti, error, "Cannot set event notification");
/* Here we create a raw monitor for our use in this agent to
* protect critical sections of code.
*/
error = (*jvmti)->CreateRawMonitor(jvmti, "agent data", &(gdata->lock));
check_jvmti_error(jvmti, error, "Cannot create raw monitor");
/* Create the TraceInfo for various flavors of empty traces */
for ( flavor = TRACE_FIRST ; flavor <= TRACE_LAST ; flavor++ ) {
gdata->emptyTrace[flavor] =
newTraceInfo(&empty, hashTrace(&empty), flavor);
}
/* Add jar file to boot classpath */
add_demo_jar_to_bootclasspath(jvmti, "heapTracker");
/* We return JNI_OK to signify success */
return JNI_OK;
}
