/*
*breif:获取表的间接引用对象.
*param[iref]:间接引用表.
*/
Object* IndirectRefTable::get(IndirectRef iref) const {
IndirectRefKind kind = indirectRefKind(iref);
if (kind != kind_) {
if (iref == NULL) {
ALOGW("Attempt to look up NULL %s reference", indirectRefKindToString(kind_));
return kInvalidIndirectRefObject;
}
if (kind == kIndirectKindInvalid) {
ALOGE("JNI ERROR (app bug): invalid %s reference %p",
indirectRefKindToString(kind_), iref);
abortMaybe();
return kInvalidIndirectRefObject;
}
// References of the requested kind cannot appear within this table.
return kInvalidIndirectRefObject;
}
u4 topIndex = segmentState.parts.topIndex;
u4 index = extractIndex(iref);
if (index >= topIndex) {
/* bad -- stale reference? */
ALOGE("JNI ERROR (app bug): accessed stale %s reference %p (index %d in a table of size %d)",
indirectRefKindToString(kind_), iref, index, topIndex);
abortMaybe();
return kInvalidIndirectRefObject;
}
Object* obj = table_[index].obj;
if (obj == NULL) {
ALOGI("JNI ERROR (app bug): accessed deleted %s reference %p",
indirectRefKindToString(kind_), iref);
abortMaybe();
return kInvalidIndirectRefObject;
}
u4 serial = extractSerial(iref);
if (serial != table_[index].serial) {
ALOGE("JNI ERROR (app bug): attempt to use stale %s reference %p",
indirectRefKindToString(kind_), iref);
abortMaybe();
return kInvalidIndirectRefObject;
}
return obj;
}
/*
* Make sure that the entry at "idx" is correctly paired with "iref".
*/
bool IndirectRefTable::checkEntry(const char* what, IndirectRef iref, int idx) const
{
Object* obj = table_[idx];
IndirectRef checkRef = toIndirectRef(obj, idx);
if (checkRef != iref) {
LOGE("JNI ERROR (app bug): attempt to %s stale %s reference %p (should be %p)",
what, indirectRefKindToString(kind_), iref, checkRef);
abortMaybe();
return false;
}
return true;
}
/*
* Verify that the indirect table lookup is valid.
*
* Returns "false" if something looks bad.
*/
bool IndirectRefTable::getChecked(IndirectRef iref) const
{
if (iref == NULL) {
LOGW("Attempt to look up NULL %s reference", indirectRefKindToString(kind_));
return false;
}
if (indirectRefKind(iref) == kIndirectKindInvalid) {
LOGE("JNI ERROR (app bug): invalid %s reference %p",
indirectRefKindToString(kind_), iref);
abortMaybe();
return false;
}
int topIndex = segmentState.parts.topIndex;
int idx = extractIndex(iref);
if (idx >= topIndex) {
/* bad -- stale reference? */
LOGE("JNI ERROR (app bug): accessed stale %s reference %p (index %d in a table of size %d)",
indirectRefKindToString(kind_), iref, idx, topIndex);
abortMaybe();
return false;
}
if (table_[idx] == NULL) {
LOGI("JNI ERROR (app bug): accessed deleted %s reference %p",
indirectRefKindToString(kind_), iref);
abortMaybe();
return false;
}
if (!checkEntry("use", iref, idx)) {
return false;
}
return true;
}
/*
*breif:添加一个新的条目.重新调整表大小.
*param[cookie]:
*param[obj]:要添加的条目.
*/
IndirectRef IndirectRefTable::add(u4 cookie, Object* obj)
{
IRTSegmentState prevState;
prevState.all = cookie;
size_t topIndex = segmentState.parts.topIndex;
assert(obj != NULL);
assert(dvmIsHeapAddress(obj));
assert(table_ != NULL);
assert(alloc_entries_ <= max_entries_);
assert(segmentState.parts.numHoles >= prevState.parts.numHoles);
/*
* We know there's enough room in the table. Now we just need to find
* the right spot. If there's a hole, find it and fill it; otherwise,
* add to the end of the list.
*/
IndirectRef result;
IndirectRefSlot* slot;
int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
if (numHoles > 0) {
assert(topIndex > 1);
/* find the first hole; likely to be near the end of the list,
* we know the item at the topIndex is not a hole */
slot = &table_[topIndex - 1];
assert(slot->obj != NULL);
while ((--slot)->obj != NULL) {
assert(slot >= table_ + prevState.parts.topIndex);
}
segmentState.parts.numHoles--;
} else {
/* add to the end, grow if needed */
if (topIndex == alloc_entries_) {
/* reached end of allocated space; did we hit buffer max? */
if (topIndex == max_entries_) {
ALOGE("JNI ERROR (app bug): %s reference table overflow (max=%d)",
indirectRefKindToString(kind_), max_entries_);
return NULL;
}
size_t newSize = alloc_entries_ * 2;
if (newSize > max_entries_) {
newSize = max_entries_;
}
assert(newSize > alloc_entries_);
IndirectRefSlot* newTable =
(IndirectRefSlot*) realloc(table_, newSize * sizeof(IndirectRefSlot));
if (table_ == NULL) {
ALOGE("JNI ERROR (app bug): unable to expand %s reference table "
"(from %d to %d, max=%d)",
indirectRefKindToString(kind_),
alloc_entries_, newSize, max_entries_);
return NULL;
}
memset(newTable + alloc_entries_, 0xd1,
(newSize - alloc_entries_) * sizeof(IndirectRefSlot));
alloc_entries_ = newSize;
table_ = newTable;
}
slot = &table_[topIndex++];
segmentState.parts.topIndex = topIndex;
}
slot->obj = obj;
slot->serial = nextSerial(slot->serial);
result = toIndirectRef(slot - table_, slot->serial, kind_);
assert(result != NULL);
return result;
}
/*
*breif:从"pRef"删除 "obj".
*/
bool IndirectRefTable::remove(u4 cookie, IndirectRef iref)
{
IRTSegmentState prevState;
prevState.all = cookie;
u4 topIndex = segmentState.parts.topIndex;
u4 bottomIndex = prevState.parts.topIndex;
assert(table_ != NULL);
assert(alloc_entries_ <= max_entries_);
assert(segmentState.parts.numHoles >= prevState.parts.numHoles);
IndirectRefKind kind = indirectRefKind(iref);
u4 index;
if (kind == kind_) {
index = extractIndex(iref);
if (index < bottomIndex) {
/* wrong segment */
ALOGV("Attempt to remove index outside index area (%ud vs %ud-%ud)",
index, bottomIndex, topIndex);
return false;
}
if (index >= topIndex) {
/* bad -- stale reference? */
ALOGD("Attempt to remove invalid index %ud (bottom=%ud top=%ud)",
index, bottomIndex, topIndex);
return false;
}
if (table_[index].obj == NULL) {
ALOGD("Attempt to remove cleared %s reference %p",
indirectRefKindToString(kind_), iref);
return false;
}
u4 serial = extractSerial(iref);
if (table_[index].serial != serial) {
ALOGD("Attempt to remove stale %s reference %p",
indirectRefKindToString(kind_), iref);
return false;
}
} else if (kind == kIndirectKindInvalid && gDvmJni.workAroundAppJniBugs) {
// reference looks like a pointer, scan the table to find the index
int i = findObject(reinterpret_cast<Object*>(iref), bottomIndex, topIndex, table_);
if (i < 0) {
ALOGW("trying to work around app JNI bugs, but didn't find %p in table!", iref);
return false;
}
index = i;
} else {
// References of the requested kind cannot appear within this table.
return false;
}
if (index == topIndex - 1) {
// Top-most entry. Scan up and consume holes.
int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
if (numHoles != 0) {
while (--topIndex > bottomIndex && numHoles != 0) {
ALOGV("+++ checking for hole at %d (cookie=0x%08x) val=%p",
topIndex-1, cookie, table_[topIndex-1].obj);
if (table_[topIndex-1].obj != NULL) {
break;
}
ALOGV("+++ ate hole at %d", topIndex-1);
numHoles--;
}
segmentState.parts.numHoles = numHoles + prevState.parts.numHoles;
segmentState.parts.topIndex = topIndex;
} else {
segmentState.parts.topIndex = topIndex-1;
ALOGV("+++ ate last entry %d", topIndex-1);
}
} else {
/*
* Not the top-most entry. This creates a hole. We NULL out the
* entry to prevent somebody from deleting it twice and screwing up
* the hole count.
*/
table_[index].obj = NULL;
segmentState.parts.numHoles++;
ALOGV("+++ left hole at %d, holes=%d", index, segmentState.parts.numHoles);
}
return true;
}
IndirectRef IndirectRefTable::add(u4 cookie, Object* obj)
{
IRTSegmentState prevState;
prevState.all = cookie;
size_t topIndex = segmentState.parts.topIndex;
assert(obj != NULL);
assert(dvmIsHeapAddress(obj));
assert(table_ != NULL);
assert(alloc_entries_ <= max_entries_);
assert(segmentState.parts.numHoles >= prevState.parts.numHoles);
if (topIndex == alloc_entries_) {
/* reached end of allocated space; did we hit buffer max? */
if (topIndex == max_entries_) {
LOGE("JNI ERROR (app bug): %s reference table overflow (max=%d)",
indirectRefKindToString(kind_), max_entries_);
dump(indirectRefKindToString(kind_));
dvmAbort();
}
size_t newSize = alloc_entries_ * 2;
if (newSize > max_entries_) {
newSize = max_entries_;
}
assert(newSize > alloc_entries_);
table_ = (Object**) realloc(table_, newSize * sizeof(Object*));
slot_data_ = (IndirectRefSlot*) realloc(slot_data_, newSize * sizeof(IndirectRefSlot));
if (table_ == NULL || slot_data_ == NULL) {
LOGE("JNI ERROR (app bug): unable to expand %s reference table (from %d to %d, max=%d)",
indirectRefKindToString(kind_),
alloc_entries_, newSize, max_entries_);
dump(indirectRefKindToString(kind_));
dvmAbort();
}
// Clear the newly-allocated slot_data_ elements.
memset(slot_data_ + alloc_entries_, 0, (newSize - alloc_entries_) * sizeof(IndirectRefSlot));
alloc_entries_ = newSize;
}
/*
* We know there's enough room in the table. Now we just need to find
* the right spot. If there's a hole, find it and fill it; otherwise,
* add to the end of the list.
*/
IndirectRef result;
int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
if (numHoles > 0) {
assert(topIndex > 1);
/* find the first hole; likely to be near the end of the list */
Object** pScan = &table_[topIndex - 1];
assert(*pScan != NULL);
while (*--pScan != NULL) {
assert(pScan >= table_ + prevState.parts.topIndex);
}
updateSlotAdd(obj, pScan - table_);
result = toIndirectRef(obj, pScan - table_);
*pScan = obj;
segmentState.parts.numHoles--;
} else {
/* add to the end */
updateSlotAdd(obj, topIndex);
result = toIndirectRef(obj, topIndex);
table_[topIndex++] = obj;
segmentState.parts.topIndex = topIndex;
}
assert(result != NULL);
return result;
}
