/* Prevent garbage collection of an object */
jvmtiError
commonRef_pin(jlong id)
{
JNIEnv *env = getEnv();
jvmtiError error = JVMTI_ERROR_NONE;
RefNode *node;
if (id == NULL_OBJECT_ID) {
return JNI_FALSE;
}
debugMonitorEnter(refLock);
node = findNodeByID(env, id);
if (node == NULL) {
error = JVMTI_ERROR_INVALID_OBJECT;
} else {
jobject strongRef = strengthenNode(env, node);
if (strongRef == NULL) {
/*
* Referent has been collected, clean up now.
*/
error = JVMTI_ERROR_INVALID_OBJECT;
deleteNodeByID(env, id, ALL_REFS);
}
}
debugMonitorExit(refLock);
return error;
}
void
commonRef_releaseMultiple(JNIEnv *env, jlong id, jint refCount)
{
debugMonitorEnter(gdata->refLock); {
deleteNodeByID(env, id, refCount);
} debugMonitorExit(gdata->refLock);
}
/* Release tracking of an object by ID */
void
commonRef_release(JNIEnv *env, jlong id)
{
debugMonitorEnter(gdata->refLock); {
deleteNodeByID(env, id, 1);
} debugMonitorExit(gdata->refLock);
}
/*
* Given an object ID obtained from the debugger front end, return a
* strong, global reference to that object (or NULL if the object
* has been collected). The reference can then be used for JNI and
* JVMTI calls. Caller is resposible for deleting the returned reference.
*/
jobject
commonRef_idToRef(JNIEnv *env, jlong id)
{
jobject ref;
ref = NULL;
debugMonitorEnter(gdata->refLock); {
RefNode *node;
node = findNodeByID(env, id);
if (node != NULL) {
if (node->isStrong) {
saveGlobalRef(env, node->ref, &ref);
} else {
jobject lref;
lref = JNI_FUNC_PTR(env,NewLocalRef)(env, node->ref);
if ( lref == NULL ) {
/* Object was GC'd shortly after we found the node */
deleteNodeByID(env, node->seqNum, ALL_REFS);
} else {
saveGlobalRef(env, node->ref, &ref);
JNI_FUNC_PTR(env,DeleteLocalRef)(env, lref);
}
}
}
} debugMonitorExit(gdata->refLock);
return ref;
}
void
commonRef_releaseMultiple(jlong id, jint refCount)
{
JNIEnv *env = getEnv();
debugMonitorEnter(refLock);
deleteNodeByID(env, id, refCount);
debugMonitorExit(refLock);
}
void
commonRef_release(jlong id)
{
JNIEnv *env = getEnv();
debugMonitorEnter(refLock);
deleteNodeByID(env, id, 1);
debugMonitorExit(refLock);
}
/*
* Returns the node stored in the object hash table for the given object
* id. The id should be a value previously returned by
* commonRef_refToID.
*/
static RefNode *
findNodeByID(JNIEnv *env, jlong id)
{
jint slot = hashID(id);
RefNode *node = objectsByID[slot];
while (node != NULL) {
/*
* Use this opportunity to clean up any nodes for weak
* references that have been garbage collected.
*/
if (isSameObject(env, node->ref, NULL)) {
jlong collectedID = OBJECT_ID(node);
node = node->nextByID;
deleteNodeByID(env, collectedID, ALL_REFS);
} else if (id == OBJECT_ID(node)) {
break; /* found it */
} else {
node = node->nextByID;
}
}
return node;
}
