/*
*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;
}
/*
* 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: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;
}
/*
* Remove "obj" from "pRef". We extract the table offset bits from "iref"
* and zap the corresponding entry, leaving a hole if it's not at the top.
*
* If the entry is not between the current top index and the bottom index
* specified by the cookie, we don't remove anything. This is the behavior
* required by JNI's DeleteLocalRef function.
*
* Note this is NOT called when a local frame is popped. This is only used
* for explicit single removals.
*
* Returns "false" if nothing was removed.
*/
bool IndirectRefTable::remove(u4 cookie, IndirectRef iref)
{
IRTSegmentState prevState;
prevState.all = cookie;
int topIndex = segmentState.parts.topIndex;
int bottomIndex = prevState.parts.topIndex;
assert(table_ != NULL);
assert(alloc_entries_ <= max_entries_);
assert(segmentState.parts.numHoles >= prevState.parts.numHoles);
int idx = extractIndex(iref);
bool workAroundAppJniBugs = false;
if (indirectRefKind(iref) == kIndirectKindInvalid && gDvmJni.workAroundAppJniBugs) {
idx = linearScan(iref, bottomIndex, topIndex, table_);
workAroundAppJniBugs = true;
if (idx == -1) {
LOGW("trying to work around app JNI bugs, but didn't find %p in table!", iref);
return false;
}
}
if (idx < bottomIndex) {
/* wrong segment */
LOGV("Attempt to remove index outside index area (%d vs %d-%d)",
idx, bottomIndex, topIndex);
return false;
}
if (idx >= topIndex) {
/* bad -- stale reference? */
LOGD("Attempt to remove invalid index %d (bottom=%d top=%d)",
idx, bottomIndex, topIndex);
return false;
}
if (idx == topIndex-1) {
// Top-most entry. Scan up and consume holes.
if (workAroundAppJniBugs == false && !checkEntry("remove", iref, idx)) {
return false;
}
table_[idx] = NULL;
int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
if (numHoles != 0) {
while (--topIndex > bottomIndex && numHoles != 0) {
LOGV("+++ checking for hole at %d (cookie=0x%08x) val=%p",
topIndex-1, cookie, table_[topIndex-1]);
if (table_[topIndex-1] != NULL) {
break;
}
LOGV("+++ ate hole at %d", topIndex-1);
numHoles--;
}
segmentState.parts.numHoles = numHoles + prevState.parts.numHoles;
segmentState.parts.topIndex = topIndex;
} else {
segmentState.parts.topIndex = topIndex-1;
LOGV("+++ 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.
*/
if (table_[idx] == NULL) {
LOGV("--- WEIRD: removing null entry %d", idx);
return false;
}
if (workAroundAppJniBugs == false && !checkEntry("remove", iref, idx)) {
return false;
}
table_[idx] = NULL;
segmentState.parts.numHoles++;
LOGV("+++ left hole at %d, holes=%d", idx, segmentState.parts.numHoles);
}
return true;
}
