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/*
* Copyright (c) 2017, 2019, 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
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* 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.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
#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/zNMethodData.hpp"
#include "gc/z/zNMethodTable.hpp"
#include "gc/z/zNMethodTableEntry.hpp"
#include "gc/z/zNMethodTableIteration.hpp"
#include "gc/z/zSafeDelete.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/mutexLocker.hpp"
#include "utilities/debug.hpp"
#include "utilities/powerOfTwo.hpp"
ZNMethodTableEntry* ZNMethodTable::_table = NULL;
size_t ZNMethodTable::_size = 0;
size_t ZNMethodTable::_nregistered = 0;
size_t ZNMethodTable::_nunregistered = 0;
ZNMethodTableIteration ZNMethodTable::_iteration;
ZSafeDeleteNoLock<ZNMethodTableEntry[]> ZNMethodTable::_safe_delete;
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 "(%.0f%%->%.0f%%) registered, "
SIZE_FORMAT "(%.0f%%->%.0f%%) 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 = new ZNMethodTableEntry[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
_safe_delete(_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);
}
}
}
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");
// Grow/Shrink/Prune table if needed
rebuild_if_needed();
// 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++;
}
}
void ZNMethodTable::wait_until_iteration_done() {
assert(CodeCache_lock->owned_by_self(), "Lock must be held");
while (_iteration.in_progress()) {
CodeCache_lock->wait_without_safepoint_check();
}
}
void ZNMethodTable::unregister_nmethod(nmethod* nm) {
assert(CodeCache_lock->owned_by_self(), "Lock must be held");
// Remove entry
unregister_entry(_table, _size, nm);
_nunregistered++;
_nregistered--;
}
void ZNMethodTable::nmethods_do_begin() {
MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
// Do not allow the table to be deleted while iterating
_safe_delete.enable_deferred_delete();
// Prepare iteration
_iteration.nmethods_do_begin(_table, _size);
}
void ZNMethodTable::nmethods_do_end() {
MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
// Finish iteration
_iteration.nmethods_do_end();
// Allow the table to be deleted
_safe_delete.disable_deferred_delete();
// Notify iteration done
CodeCache_lock->notify_all();
}
void ZNMethodTable::nmethods_do(NMethodClosure* cl) {
_iteration.nmethods_do(cl);
}
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