8219468: ZGC: Extract iteration functionality into a new ZNMethodTableIteration class
Reviewed-by: pliden
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "code/relocInfo.hpp"
#include "code/nmethod.hpp"
#include "code/icBuffer.hpp"
#include "gc/shared/barrierSet.hpp"
#include "gc/shared/barrierSetNMethod.hpp"
#include "gc/z/zGlobals.hpp"
#include "gc/z/zHash.inline.hpp"
#include "gc/z/zLock.inline.hpp"
#include "gc/z/zNMethodAllocator.hpp"
#include "gc/z/zNMethodData.hpp"
#include "gc/z/zNMethodTable.hpp"
#include "gc/z/zNMethodTableIteration.hpp"
#include "gc/z/zOopClosures.inline.hpp"
#include "gc/z/zTask.hpp"
#include "gc/z/zWorkers.hpp"
#include "logging/log.hpp"
#include "memory/allocation.hpp"
#include "memory/iterator.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/atomic.hpp"
#include "runtime/orderAccess.hpp"
#include "utilities/debug.hpp"
ZNMethodTableEntry* ZNMethodTable::_table = NULL;
size_t ZNMethodTable::_size = 0;
size_t ZNMethodTable::_nregistered = 0;
size_t ZNMethodTable::_nunregistered = 0;
ZNMethodTableIteration ZNMethodTable::_iteration;
static ZNMethodData* gc_data(const nmethod* nm) {
return nm->gc_data<ZNMethodData>();
}
static void set_gc_data(nmethod* nm, ZNMethodData* data) {
return nm->set_gc_data<ZNMethodData>(data);
}
ZNMethodTableEntry* ZNMethodTable::create(size_t size) {
void* const mem = ZNMethodAllocator::allocate(size * sizeof(ZNMethodTableEntry));
return ::new (mem) ZNMethodTableEntry[size];
}
void ZNMethodTable::destroy(ZNMethodTableEntry* table) {
ZNMethodAllocator::free(table);
}
void ZNMethodTable::attach_gc_data(nmethod* nm) {
GrowableArray<oop*> immediate_oops;
bool non_immediate_oops = false;
// Find all oops relocations
RelocIterator iter(nm);
while (iter.next()) {
if (iter.type() != relocInfo::oop_type) {
// Not an oop
continue;
}
oop_Relocation* r = iter.oop_reloc();
if (!r->oop_is_immediate()) {
// Non-immediate oop found
non_immediate_oops = true;
continue;
}
if (r->oop_value() != NULL) {
// Non-NULL immediate oop found. NULL oops can safely be
// ignored since the method will be re-registered if they
// are later patched to be non-NULL.
immediate_oops.push(r->oop_addr());
}
}
// Attach GC data to nmethod
ZNMethodData* data = gc_data(nm);
if (data == NULL) {
data = ZNMethodData::create(nm);
set_gc_data(nm, data);
}
// Attach oops in GC data
ZNMethodDataOops* const new_oops = ZNMethodDataOops::create(immediate_oops, non_immediate_oops);
ZNMethodDataOops* const old_oops = data->swap_oops(new_oops);
ZNMethodDataOops::destroy(old_oops);
}
void ZNMethodTable::detach_gc_data(nmethod* nm) {
// Destroy GC data
ZNMethodData::destroy(gc_data(nm));
set_gc_data(nm, NULL);
}
ZReentrantLock* ZNMethodTable::lock_for_nmethod(nmethod* nm) {
ZNMethodData* const data = gc_data(nm);
if (data == NULL) {
return NULL;
}
return data->lock();
}
size_t ZNMethodTable::first_index(const nmethod* nm, size_t size) {
assert(is_power_of_2(size), "Invalid size");
const size_t mask = size - 1;
const size_t hash = ZHash::address_to_uint32((uintptr_t)nm);
return hash & mask;
}
size_t ZNMethodTable::next_index(size_t prev_index, size_t size) {
assert(is_power_of_2(size), "Invalid size");
const size_t mask = size - 1;
return (prev_index + 1) & mask;
}
bool ZNMethodTable::register_entry(ZNMethodTableEntry* table, size_t size, nmethod* nm) {
const ZNMethodTableEntry entry(nm);
size_t index = first_index(nm, size);
for (;;) {
const ZNMethodTableEntry table_entry = table[index];
if (!table_entry.registered() && !table_entry.unregistered()) {
// Insert new entry
table[index] = entry;
return true;
}
if (table_entry.registered() && table_entry.method() == nm) {
// Replace existing entry
table[index] = entry;
return false;
}
index = next_index(index, size);
}
}
void ZNMethodTable::unregister_entry(ZNMethodTableEntry* table, size_t size, nmethod* nm) {
size_t index = first_index(nm, size);
for (;;) {
const ZNMethodTableEntry table_entry = table[index];
assert(table_entry.registered() || table_entry.unregistered(), "Entry not found");
if (table_entry.registered() && table_entry.method() == nm) {
// Remove entry
table[index] = ZNMethodTableEntry(true /* unregistered */);
return;
}
index = next_index(index, size);
}
}
void ZNMethodTable::rebuild(size_t new_size) {
assert(CodeCache_lock->owned_by_self(), "Lock must be held");
assert(is_power_of_2(new_size), "Invalid size");
log_debug(gc, nmethod)("Rebuilding NMethod Table: "
SIZE_FORMAT "->" SIZE_FORMAT " entries, "
SIZE_FORMAT "(%.0lf%%->%.0lf%%) registered, "
SIZE_FORMAT "(%.0lf%%->%.0lf%%) unregistered",
_size, new_size,
_nregistered, percent_of(_nregistered, _size), percent_of(_nregistered, new_size),
_nunregistered, percent_of(_nunregistered, _size), 0.0);
// Allocate new table
ZNMethodTableEntry* const new_table = ZNMethodTable::create(new_size);
// Transfer all registered entries
for (size_t i = 0; i < _size; i++) {
const ZNMethodTableEntry entry = _table[i];
if (entry.registered()) {
register_entry(new_table, new_size, entry.method());
}
}
// Free old table
ZNMethodTable::destroy(_table);
// Install new table
_table = new_table;
_size = new_size;
_nunregistered = 0;
}
void ZNMethodTable::rebuild_if_needed() {
// The hash table uses linear probing. To avoid wasting memory while
// at the same time maintaining good hash collision behavior we want
// to keep the table occupancy between 30% and 70%. The table always
// grows/shrinks by doubling/halving its size. Pruning of unregistered
// entries is done by rebuilding the table with or without resizing it.
const size_t min_size = 1024;
const size_t shrink_threshold = _size * 0.30;
const size_t prune_threshold = _size * 0.65;
const size_t grow_threshold = _size * 0.70;
if (_size == 0) {
// Initialize table
rebuild(min_size);
} else if (_nregistered < shrink_threshold && _size > min_size) {
// Shrink table
rebuild(_size / 2);
} else if (_nregistered + _nunregistered > grow_threshold) {
// Prune or grow table
if (_nregistered < prune_threshold) {
// Prune table
rebuild(_size);
} else {
// Grow table
rebuild(_size * 2);
}
}
}
void ZNMethodTable::log_register(const nmethod* nm) {
LogTarget(Trace, gc, nmethod) log;
if (!log.is_enabled()) {
return;
}
const ZNMethodDataOops* const oops = gc_data(nm)->oops();
log.print("Register NMethod: %s.%s (" PTR_FORMAT "), "
"Compiler: %s, Oops: %d, ImmediateOops: " SIZE_FORMAT ", NonImmediateOops: %s",
nm->method()->method_holder()->external_name(),
nm->method()->name()->as_C_string(),
p2i(nm),
nm->compiler_name(),
nm->oops_count() - 1,
oops->immediates_count(),
oops->has_non_immediates() ? "Yes" : "No");
LogTarget(Trace, gc, nmethod, oops) log_oops;
if (!log_oops.is_enabled()) {
return;
}
// Print nmethod oops table
{
oop* const begin = nm->oops_begin();
oop* const end = nm->oops_end();
for (oop* p = begin; p < end; p++) {
log_oops.print(" Oop[" SIZE_FORMAT "] " PTR_FORMAT " (%s)",
(p - begin), p2i(*p), (*p)->klass()->external_name());
}
}
// Print nmethod immediate oops
{
oop** const begin = oops->immediates_begin();
oop** const end = oops->immediates_end();
for (oop** p = begin; p < end; p++) {
log_oops.print(" ImmediateOop[" SIZE_FORMAT "] " PTR_FORMAT " @ " PTR_FORMAT " (%s)",
(p - begin), p2i(**p), p2i(*p), (**p)->klass()->external_name());
}
}
}
void ZNMethodTable::log_unregister(const nmethod* nm) {
LogTarget(Debug, gc, nmethod) log;
if (!log.is_enabled()) {
return;
}
log.print("Unregister NMethod: %s.%s (" PTR_FORMAT ")",
nm->method()->method_holder()->external_name(),
nm->method()->name()->as_C_string(),
p2i(nm));
}
size_t ZNMethodTable::registered_nmethods() {
return _nregistered;
}
size_t ZNMethodTable::unregistered_nmethods() {
return _nunregistered;
}
void ZNMethodTable::register_nmethod(nmethod* nm) {
assert(CodeCache_lock->owned_by_self(), "Lock must be held");
ResourceMark rm;
// Grow/Shrink/Prune table if needed
rebuild_if_needed();
// Create and attach gc data
attach_gc_data(nm);
log_register(nm);
// Insert new entry
if (register_entry(_table, _size, nm)) {
// New entry registered. When register_entry() instead returns
// false the nmethod was already in the table so we do not want
// to increase number of registered entries in that case.
_nregistered++;
}
// Disarm nmethod entry barrier
disarm_nmethod(nm);
}
void ZNMethodTable::wait_until_iteration_done() {
assert(CodeCache_lock->owned_by_self(), "Lock must be held");
while (_iteration.in_progress()) {
CodeCache_lock->wait(Monitor::_no_safepoint_check_flag);
}
}
void ZNMethodTable::unregister_nmethod(nmethod* nm) {
assert(CodeCache_lock->owned_by_self(), "Lock must be held");
if (Thread::current()->is_Code_cache_sweeper_thread()) {
// The sweeper must wait for any ongoing iteration to complete
// before it can unregister an nmethod.
ZNMethodTable::wait_until_iteration_done();
}
ResourceMark rm;
log_unregister(nm);
// Remove entry
unregister_entry(_table, _size, nm);
_nunregistered++;
_nregistered--;
detach_gc_data(nm);
}
void ZNMethodTable::disarm_nmethod(nmethod* nm) {
BarrierSetNMethod* const bs = BarrierSet::barrier_set()->barrier_set_nmethod();
if (bs != NULL) {
bs->disarm(nm);
}
}
void ZNMethodTable::nmethods_do_begin() {
MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
// Make sure we don't free data while iterating
ZNMethodAllocator::activate_deferred_frees();
// Prepare iteration
_iteration.nmethods_do_begin(_table, _size);
}
void ZNMethodTable::nmethods_do_end() {
MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
// Finish iteration
_iteration.nmethods_do_end();
// Process deferred frees
ZNMethodAllocator::deactivate_and_process_deferred_frees();
// Notify iteration done
CodeCache_lock->notify_all();
}
void ZNMethodTable::oops_do(nmethod* nm, OopClosure* cl) {
// Process oops table
{
oop* const begin = nm->oops_begin();
oop* const end = nm->oops_end();
for (oop* p = begin; p < end; p++) {
if (*p != Universe::non_oop_word()) {
cl->do_oop(p);
}
}
}
ZNMethodDataOops* const oops = gc_data(nm)->oops();
// Process immediate oops
{
oop** const begin = oops->immediates_begin();
oop** const end = oops->immediates_end();
for (oop** p = begin; p < end; p++) {
if (**p != Universe::non_oop_word()) {
cl->do_oop(*p);
}
}
}
// Process non-immediate oops
if (oops->has_non_immediates()) {
nm->fix_oop_relocations();
}
}
class ZNMethodToOopsDoClosure : public NMethodClosure {
private:
OopClosure* _cl;
public:
ZNMethodToOopsDoClosure(OopClosure* cl) :
_cl(cl) {}
virtual void do_nmethod(nmethod* nm) {
ZNMethodTable::oops_do(nm, _cl);
}
};
void ZNMethodTable::oops_do(OopClosure* cl) {
ZNMethodToOopsDoClosure nm_cl(cl);
nmethods_do(&nm_cl);
}
void ZNMethodTable::nmethods_do(NMethodClosure* cl) {
_iteration.nmethods_do(cl);
}
class ZNMethodTableUnlinkClosure : public NMethodClosure {
private:
bool _unloading_occurred;
volatile bool _failed;
void set_failed() {
Atomic::store(true, &_failed);
}
public:
ZNMethodTableUnlinkClosure(bool unloading_occurred) :
_unloading_occurred(unloading_occurred),
_failed(false) {}
virtual void do_nmethod(nmethod* nm) {
if (failed()) {
return;
}
if (!nm->is_alive()) {
return;
}
ZLocker<ZReentrantLock> locker(ZNMethodTable::lock_for_nmethod(nm));
if (nm->is_unloading()) {
// Unlinking of the dependencies must happen before the
// handshake separating unlink and purge.
nm->flush_dependencies(false /* delete_immediately */);
// We don't need to take the lock when unlinking nmethods from
// the Method, because it is only concurrently unlinked by
// the entry barrier, which acquires the per nmethod lock.
nm->unlink_from_method(false /* acquire_lock */);
return;
}
// Heal oops and disarm
ZNMethodOopClosure cl;
ZNMethodTable::oops_do(nm, &cl);
ZNMethodTable::disarm_nmethod(nm);
// Clear compiled ICs and exception caches
if (!nm->unload_nmethod_caches(_unloading_occurred)) {
set_failed();
}
}
bool failed() const {
return Atomic::load(&_failed);
}
};
class ZNMethodTableUnlinkTask : public ZTask {
private:
ZNMethodTableUnlinkClosure _cl;
ICRefillVerifier* _verifier;
public:
ZNMethodTableUnlinkTask(bool unloading_occurred, ICRefillVerifier* verifier) :
ZTask("ZNMethodTableUnlinkTask"),
_cl(unloading_occurred),
_verifier(verifier) {
ZNMethodTable::nmethods_do_begin();
}
~ZNMethodTableUnlinkTask() {
ZNMethodTable::nmethods_do_end();
}
virtual void work() {
ICRefillVerifierMark mark(_verifier);
ZNMethodTable::nmethods_do(&_cl);
}
bool success() const {
return !_cl.failed();
}
};
void ZNMethodTable::unlink(ZWorkers* workers, bool unloading_occurred) {
for (;;) {
ICRefillVerifier verifier;
{
ZNMethodTableUnlinkTask task(unloading_occurred, &verifier);
workers->run_concurrent(&task);
if (task.success()) {
return;
}
}
// Cleaning failed because we ran out of transitional IC stubs,
// so we have to refill and try again. Refilling requires taking
// a safepoint, so we temporarily leave the suspendible thread set.
SuspendibleThreadSetLeaver sts;
InlineCacheBuffer::refill_ic_stubs();
}
}
class ZNMethodTablePurgeClosure : public NMethodClosure {
public:
virtual void do_nmethod(nmethod* nm) {
if (nm->is_alive() && nm->is_unloading()) {
nm->make_unloaded();
}
}
};
class ZNMethodTablePurgeTask : public ZTask {
private:
ZNMethodTablePurgeClosure _cl;
public:
ZNMethodTablePurgeTask() :
ZTask("ZNMethodTablePurgeTask"),
_cl() {
ZNMethodTable::nmethods_do_begin();
}
~ZNMethodTablePurgeTask() {
ZNMethodTable::nmethods_do_end();
}
virtual void work() {
ZNMethodTable::nmethods_do(&_cl);
}
};
void ZNMethodTable::purge(ZWorkers* workers) {
ZNMethodTablePurgeTask task;
workers->run_concurrent(&task);
}