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8269542: JDWP: EnableCollection support is no longer spec compliant after JDK-8255987

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8258071: Fix for JDK-8255987 can be subverted with ObjectReference.EnableCollection

Reviewed-by: dholmes, pliden
This commit is contained in:
Chris Plummer 2022-01-25 19:26:11 +00:00
parent 76fe03fe01
commit 841eae6f52
2 changed files with 50 additions and 32 deletions
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77
src/jdk.jdwp.agent/share/native/libjdwp/commonRef.c
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1998, 2020, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -82,6 +82,14 @@ newSeqNum(void)
return gdata->nextSeqNum++;
}
/* Returns true if this is a strong reference, meaning that either or both of
isPinAll and isCommonPin are true. */
static jboolean
isStrong(RefNode* node)
{
return node->isPinAll || node->isCommonPin;
}
/* Create a fresh RefNode structure, create a weak ref and tag the object */
static RefNode *
createNode(JNIEnv *env, jobject ref)
@ -89,7 +97,7 @@ createNode(JNIEnv *env, jobject ref)
RefNode *node;
jobject strongOrWeakRef;
jvmtiError error;
jboolean pin = gdata->pinAllCount != 0;
jboolean pinAll = gdata->pinAllCount != 0;
/* Could allocate RefNode's in blocks, not sure it would help much */
node = (RefNode*)jvmtiAllocate((int)sizeof(RefNode));
@ -97,7 +105,7 @@ createNode(JNIEnv *env, jobject ref)
return NULL;
}
if (pin) {
if (pinAll) {
/* Create strong reference to make sure we have a reference */
strongOrWeakRef = JNI_FUNC_PTR(env,NewGlobalRef)(env, ref);
} else {
@ -116,7 +124,7 @@ createNode(JNIEnv *env, jobject ref)
error = JVMTI_FUNC_PTR(gdata->jvmti, SetTag)
(gdata->jvmti, strongOrWeakRef, ptr_to_jlong(node));
if ( error != JVMTI_ERROR_NONE ) {
if (pin) {
if (pinAll) {
JNI_FUNC_PTR(env,DeleteGlobalRef)(env, strongOrWeakRef);
} else {
JNI_FUNC_PTR(env,DeleteWeakGlobalRef)(env, strongOrWeakRef);
@ -128,7 +136,8 @@ createNode(JNIEnv *env, jobject ref)
/* Fill in RefNode */
node->ref = strongOrWeakRef;
node->count = 1;
node->strongCount = pin ? 1 : 0;
node->isPinAll = pinAll;
node->isCommonPin = JNI_FALSE;
node->seqNum = newSeqNum();
/* Count RefNode's created */
@ -146,7 +155,7 @@ deleteNode(JNIEnv *env, RefNode *node)
/* Clear tag */
(void)JVMTI_FUNC_PTR(gdata->jvmti,SetTag)
(gdata->jvmti, node->ref, NULL_OBJECT_ID);
if (node->strongCount != 0) {
if (isStrong(node)) {
JNI_FUNC_PTR(env,DeleteGlobalRef)(env, node->ref);
} else {
JNI_FUNC_PTR(env,DeleteWeakGlobalRef)(env, node->ref);
@ -158,9 +167,9 @@ deleteNode(JNIEnv *env, RefNode *node)
/* Change a RefNode to have a strong reference */
static jobject
strengthenNode(JNIEnv *env, RefNode *node)
strengthenNode(JNIEnv *env, RefNode *node, jboolean isPinAll)
{
if (node->strongCount == 0) {
if (!isStrong(node)) {
jobject strongRef;
strongRef = JNI_FUNC_PTR(env,NewGlobalRef)(env, node->ref);
@ -176,20 +185,27 @@ strengthenNode(JNIEnv *env, RefNode *node)
if (strongRef != NULL) {
JNI_FUNC_PTR(env,DeleteWeakGlobalRef)(env, node->ref);
node->ref = strongRef;
node->strongCount = 1;
} else {
return NULL;
}
return strongRef;
} else {
node->strongCount++;
return node->ref;
}
if (isPinAll) {
node->isPinAll = JNI_TRUE;
} else {
node->isCommonPin = JNI_TRUE;
}
return node->ref;
}
/* Change a RefNode to have a weak reference */
static jweak
weakenNode(JNIEnv *env, RefNode *node)
weakenNode(JNIEnv *env, RefNode *node, jboolean isUnpinAll)
{
if (node->strongCount == 1) {
jboolean willStillBeStrong = (node->isPinAll && !isUnpinAll) || (node->isCommonPin && isUnpinAll);
// If the node is strong, but the reason(s) for it being strong
// will no longer exist, then weaken it.
if (isStrong(node) && !willStillBeStrong) {
jweak weakRef;
weakRef = JNI_FUNC_PTR(env,NewWeakGlobalRef)(env, node->ref);
@ -200,16 +216,18 @@ weakenNode(JNIEnv *env, RefNode *node)
if (weakRef != NULL) {
JNI_FUNC_PTR(env,DeleteGlobalRef)(env, node->ref);
node->ref = weakRef;
node->strongCount = 0;
node->ref = weakRef;
} else {
return NULL;
}
return weakRef;
} else {
if (node->strongCount > 0) {
node->strongCount--;
}
return node->ref;
}
if (isUnpinAll) {
node->isPinAll = JNI_FALSE;
} else {
node->isCommonPin = JNI_FALSE;
}
return node->ref;
}
/*
@ -470,7 +488,7 @@ commonRef_idToRef(JNIEnv *env, jlong id)
node = findNodeByID(env, id);
if (node != NULL) {
if (node->strongCount != 0) {
if (isStrong(node)) {
saveGlobalRef(env, node->ref, &ref);
} else {
jobject lref;
@ -522,7 +540,7 @@ commonRef_pin(jlong id)
} else {
jobject strongRef;
strongRef = strengthenNode(env, node);
strongRef = strengthenNode(env, node, JNI_FALSE /* isPinAll */);
if (strongRef == NULL) {
/*
* Referent has been collected, clean up now.
@ -551,7 +569,7 @@ commonRef_unpin(jlong id)
if (node != NULL) {
jweak weakRef;
weakRef = weakenNode(env, node);
weakRef = weakenNode(env, node, JNI_FALSE /* isUnpinAll */);
if (weakRef == NULL) {
error = AGENT_ERROR_OUT_OF_MEMORY;
}
@ -585,7 +603,7 @@ commonRef_pinAll()
while (node != NULL) {
jobject strongRef;
strongRef = strengthenNode(env, node);
strongRef = strengthenNode(env, node, JNI_TRUE /* isPinAll */);
/* Has the object been collected? */
if (strongRef == NULL) {
@ -628,7 +646,7 @@ commonRef_unpinAll()
for (node = gdata->objectsByID[i]; node != NULL; node = node->next) {
jweak weakRef;
weakRef = weakenNode(env, node);
weakRef = weakenNode(env, node, JNI_TRUE /* isUnpinAll */);
if (weakRef == NULL) {
EXIT_ERROR(AGENT_ERROR_NULL_POINTER,"NewWeakGlobalRef");
}
@ -676,8 +694,7 @@ commonRef_compact(void)
prev = NULL;
while (node != NULL) {
/* Has the object been collected? */
if ( (node->strongCount == 0) &&
isSameObject(env, node->ref, NULL)) {
if (!isStrong(node) && isSameObject(env, node->ref, NULL)) {
RefNode *freed;
/* Detach from the ID list */

5
src/jdk.jdwp.agent/share/native/libjdwp/util.h
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1998, 2021, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -65,7 +65,8 @@ typedef struct RefNode {
jobject ref; /* could be strong or weak */
struct RefNode *next; /* next RefNode* in bucket chain */
jint count; /* count of references */
unsigned strongCount; /* count of strong reference */
jboolean isPinAll; /* true if this is a strong reference due to a commonRef_pinAll() */
jboolean isCommonPin; /* true if this is a strong reference due to a commonRef_pin() */
} RefNode;
/* Value of a NULL ID */