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8269125: Klass enqueue element size calculation wrong when traceid va…
…lue cross compress limit

Reviewed-by: jbachorik, egahlin
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Markus Grönlund committed Jun 23, 2021
1 parent bf70620 commit 1b2147a23f1bdc2ed4a91ddbb4ac70b26e5cfb2d
Showing 2 changed files with 16 additions and 10 deletions.
@@ -67,7 +67,7 @@ static const size_t ELEMENT_SIZE = sizeof(JfrEpochQueueKlassElement);
static const size_t NARROW_ELEMENT_SIZE = sizeof(JfrEpochQueueNarrowKlassElement);
static const size_t THRESHOLD_SHIFT = 30;

// If the upshifted traceid value is less than this threshold (1 073 741 824),
// If the traceid value is less than this threshold (1 073 741 824),
// compress the element for more effective queue storage.
static const traceid uncompressed_threshold = ((traceid)1) << THRESHOLD_SHIFT;

@@ -121,30 +121,36 @@ static traceid read_element(const u1* pos, const Klass** klass, bool compressed)
return compressed ? read_compressed_element(pos, klass) : read_uncompressed_element(pos, klass);
}

template <typename T>
static inline void store_traceid(T* element, traceid id, bool uncompressed) {
#ifdef VM_LITTLE_ENDIAN
id <<= METADATA_SHIFT;
#endif
element->id = uncompressed ? id | UNCOMPRESSED : id;
}

static void store_compressed_element(traceid id, const Klass* klass, u1* pos) {
assert(can_compress_element(id), "invariant");
JfrEpochQueueNarrowKlassElement* const element = new (pos) JfrEpochQueueNarrowKlassElement();
element->id = id;
store_traceid(element, id, false);
element->compressed_klass = encode(klass);
}

static void store_uncompressed_element(traceid id, const Klass* klass, u1* pos) {
JfrEpochQueueKlassElement* const element = new (pos) JfrEpochQueueKlassElement();
element->id = id | UNCOMPRESSED;
store_traceid(element, id, true);
element->klass = klass;
}

static void store_element(const Klass* klass, u1* pos) {
assert(pos != NULL, "invariant");
assert(klass != NULL, "invariant");
traceid id = JfrTraceId::load_raw(klass);
#ifdef VM_LITTLE_ENDIAN
id <<= METADATA_SHIFT;
#endif
const traceid id = JfrTraceId::load_raw(klass);
if (can_compress_element(id)) {
store_compressed_element(id, klass, pos);
} else {
store_uncompressed_element(id, klass, pos);
return;
}
store_uncompressed_element(id, klass, pos);
}

static void set_unloaded(const u1* pos) {
@@ -68,7 +68,7 @@ JfrEpochQueue<ElementPolicy>::storage_for_element(JfrEpochQueue<ElementPolicy>::
template <template <typename> class ElementPolicy>
void JfrEpochQueue<ElementPolicy>::enqueue(JfrEpochQueue<ElementPolicy>::TypePtr t) {
assert(t != NULL, "invariant");
static size_t element_size = _policy.element_size(t);
size_t element_size = _policy.element_size(t);
BufferPtr buffer = storage_for_element(t, element_size);
assert(buffer != NULL, "invariant");
_policy.store_element(t, buffer);

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