/*
* Copyright (c) 2011, 2016, 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 "gc/g1/g1CollectedHeap.inline.hpp"
#include "gc/g1/heapRegionRemSet.hpp"
#include "gc/g1/heapRegionSet.inline.hpp"
uint FreeRegionList::_unrealistically_long_length = 0;
#ifndef PRODUCT
void HeapRegionSetBase::verify_region(HeapRegion* hr) {
assert(hr->containing_set() == this, "Inconsistent containing set for %u", hr->hrm_index());
assert(!hr->is_young(), "Adding young region %u", hr->hrm_index()); // currently we don't use these sets for young regions
assert(hr->is_humongous() == regions_humongous(), "Wrong humongous state for region %u and set %s", hr->hrm_index(), name());
assert(hr->is_free() == regions_free(), "Wrong free state for region %u and set %s", hr->hrm_index(), name());
assert(!hr->is_free() || hr->is_empty(), "Free region %u is not empty for set %s", hr->hrm_index(), name());
assert(!hr->is_empty() || hr->is_free() || hr->is_archive(),
"Empty region %u is not free or archive for set %s", hr->hrm_index(), name());
}
#endif
void HeapRegionSetBase::verify() {
// It's important that we also observe the MT safety protocol even
// for the verification calls. If we do verification without the
// appropriate locks and the set changes underneath our feet
// verification might fail and send us on a wild goose chase.
check_mt_safety();
guarantee_heap_region_set(( is_empty() && length() == 0) ||
(!is_empty() && length() > 0),
"invariant");
}
void HeapRegionSetBase::verify_start() {
// See comment in verify() about MT safety and verification.
check_mt_safety();
assert_heap_region_set(!_verify_in_progress, "verification should not be in progress");
// Do the basic verification first before we do the checks over the regions.
HeapRegionSetBase::verify();
_verify_in_progress = true;
}
void HeapRegionSetBase::verify_end() {
// See comment in verify() about MT safety and verification.
check_mt_safety();
assert_heap_region_set(_verify_in_progress, "verification should be in progress");
_verify_in_progress = false;
}
void HeapRegionSetBase::print_on(outputStream* out, bool print_contents) {
out->cr();
out->print_cr("Set: %s (" PTR_FORMAT ")", name(), p2i(this));
out->print_cr(" Region Assumptions");
out->print_cr(" humongous : %s", BOOL_TO_STR(regions_humongous()));
out->print_cr(" free : %s", BOOL_TO_STR(regions_free()));
out->print_cr(" Attributes");
out->print_cr(" length : %14u", length());
}
HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker)
: _name(name), _verify_in_progress(false),
_is_humongous(humongous), _is_free(free), _mt_safety_checker(mt_safety_checker),
_length(0)
{ }
void FreeRegionList::set_unrealistically_long_length(uint len) {
guarantee(_unrealistically_long_length == 0, "should only be set once");
_unrealistically_long_length = len;
}
void FreeRegionList::remove_all() {
check_mt_safety();
verify_optional();
HeapRegion* curr = _head;
while (curr != NULL) {
verify_region(curr);
HeapRegion* next = curr->next();
curr->set_next(NULL);
curr->set_prev(NULL);
curr->set_containing_set(NULL);
curr = next;
}
clear();
verify_optional();
}
void FreeRegionList::add_ordered(FreeRegionList* from_list) {
check_mt_safety();
from_list->check_mt_safety();
verify_optional();
from_list->verify_optional();
if (from_list->is_empty()) {
return;
}
#ifdef ASSERT
FreeRegionListIterator iter(from_list);
while (iter.more_available()) {
HeapRegion* hr = iter.get_next();
// In set_containing_set() we check that we either set the value
// from NULL to non-NULL or vice versa to catch bugs. So, we have
// to NULL it first before setting it to the value.
hr->set_containing_set(NULL);
hr->set_containing_set(this);
}
#endif // ASSERT
if (is_empty()) {
assert_free_region_list(length() == 0 && _tail == NULL, "invariant");
_head = from_list->_head;
_tail = from_list->_tail;
} else {
HeapRegion* curr_to = _head;
HeapRegion* curr_from = from_list->_head;
while (curr_from != NULL) {
while (curr_to != NULL && curr_to->hrm_index() < curr_from->hrm_index()) {
curr_to = curr_to->next();
}
if (curr_to == NULL) {
// The rest of the from list should be added as tail
_tail->set_next(curr_from);
curr_from->set_prev(_tail);
curr_from = NULL;
} else {
HeapRegion* next_from = curr_from->next();
curr_from->set_next(curr_to);
curr_from->set_prev(curr_to->prev());
if (curr_to->prev() == NULL) {
_head = curr_from;
} else {
curr_to->prev()->set_next(curr_from);
}
curr_to->set_prev(curr_from);
curr_from = next_from;
}
}
if (_tail->hrm_index() < from_list->_tail->hrm_index()) {
_tail = from_list->_tail;
}
}
_length += from_list->length();
from_list->clear();
verify_optional();
from_list->verify_optional();
}
void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) {
check_mt_safety();
assert_free_region_list(num_regions >= 1, "pre-condition");
assert_free_region_list(!is_empty(), "pre-condition");
verify_optional();
DEBUG_ONLY(uint old_length = length();)
HeapRegion* curr = first;
uint count = 0;
while (count < num_regions) {
verify_region(curr);
HeapRegion* next = curr->next();
HeapRegion* prev = curr->prev();
assert(count < num_regions,
"[%s] should not come across more regions "
"pending for removal than num_regions: %u",
name(), num_regions);
if (prev == NULL) {
assert_free_region_list(_head == curr, "invariant");
_head = next;
} else {
assert_free_region_list(_head != curr, "invariant");
prev->set_next(next);
}
if (next == NULL) {
assert_free_region_list(_tail == curr, "invariant");
_tail = prev;
} else {
assert_free_region_list(_tail != curr, "invariant");
next->set_prev(prev);
}
if (_last == curr) {
_last = NULL;
}
curr->set_next(NULL);
curr->set_prev(NULL);
remove(curr);
count++;
curr = next;
}
assert(count == num_regions,
"[%s] count: %u should be == num_regions: %u",
name(), count, num_regions);
assert(length() + num_regions == old_length,
"[%s] new length should be consistent "
"new length: %u old length: %u num_regions: %u",
name(), length(), old_length, num_regions);
verify_optional();
}
void FreeRegionList::verify() {
// See comment in HeapRegionSetBase::verify() about MT safety and
// verification.
check_mt_safety();
// This will also do the basic verification too.
verify_start();
verify_list();
verify_end();
}
void FreeRegionList::clear() {
_length = 0;
_head = NULL;
_tail = NULL;
_last = NULL;
}
void FreeRegionList::verify_list() {
HeapRegion* curr = _head;
HeapRegion* prev1 = NULL;
HeapRegion* prev0 = NULL;
uint count = 0;
size_t capacity = 0;
uint last_index = 0;
guarantee(_head == NULL || _head->prev() == NULL, "_head should not have a prev");
while (curr != NULL) {
verify_region(curr);
count++;
guarantee(count < _unrealistically_long_length,
"[%s] the calculated length: %u seems very long, is there maybe a cycle? curr: " PTR_FORMAT " prev0: " PTR_FORMAT " " "prev1: " PTR_FORMAT " length: %u",
name(), count, p2i(curr), p2i(prev0), p2i(prev1), length());
if (curr->next() != NULL) {
guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up");
}
guarantee(curr->hrm_index() == 0 || curr->hrm_index() > last_index, "List should be sorted");
last_index = curr->hrm_index();
capacity += curr->capacity();
prev1 = prev0;
prev0 = curr;
curr = curr->next();
}
guarantee(_tail == prev0, "Expected %s to end with %u but it ended with %u.", name(), _tail->hrm_index(), prev0->hrm_index());
guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");
guarantee(length() == count, "%s count mismatch. Expected %u, actual %u.", name(), length(), count);
}
// Note on the check_mt_safety() methods below:
//
// Verification of the "master" heap region sets / lists that are
// maintained by G1CollectedHeap is always done during a STW pause and
// by the VM thread at the start / end of the pause. The standard
// verification methods all assert check_mt_safety(). This is
// important as it ensures that verification is done without
// concurrent updates taking place at the same time. It follows, that,
// for the "master" heap region sets / lists, the check_mt_safety()
// method should include the VM thread / STW case.
void MasterFreeRegionListMtSafeChecker::check() {
// Master Free List MT safety protocol:
// (a) If we're at a safepoint, operations on the master free list
// should be invoked by either the VM thread (which will serialize
// them) or by the GC workers while holding the
// FreeList_lock.
// (b) If we're not at a safepoint, operations on the master free
// list should be invoked while holding the Heap_lock.
if (SafepointSynchronize::is_at_safepoint()) {
guarantee(Thread::current()->is_VM_thread() ||
FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
} else {
guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
}
}
void SecondaryFreeRegionListMtSafeChecker::check() {
// Secondary Free List MT safety protocol:
// Operations on the secondary free list should always be invoked
// while holding the SecondaryFreeList_lock.
guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol");
}
void OldRegionSetMtSafeChecker::check() {
// Master Old Set MT safety protocol:
// (a) If we're at a safepoint, operations on the master old set
// should be invoked:
// - by the VM thread (which will serialize them), or
// - by the GC workers while holding the FreeList_lock, if we're
// at a safepoint for an evacuation pause (this lock is taken
// anyway when an GC alloc region is retired so that a new one
// is allocated from the free list), or
// - by the GC workers while holding the OldSets_lock, if we're at a
// safepoint for a cleanup pause.
// (b) If we're not at a safepoint, operations on the master old set
// should be invoked while holding the Heap_lock.
if (SafepointSynchronize::is_at_safepoint()) {
guarantee(Thread::current()->is_VM_thread()
|| FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
"master old set MT safety protocol at a safepoint");
} else {
guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
}
}
void HumongousRegionSetMtSafeChecker::check() {
// Humongous Set MT safety protocol:
// (a) If we're at a safepoint, operations on the master humongous
// set should be invoked by either the VM thread (which will
// serialize them) or by the GC workers while holding the
// OldSets_lock.
// (b) If we're not at a safepoint, operations on the master
// humongous set should be invoked while holding the Heap_lock.
if (SafepointSynchronize::is_at_safepoint()) {
guarantee(Thread::current()->is_VM_thread() ||
OldSets_lock->owned_by_self(),
"master humongous set MT safety protocol at a safepoint");
} else {
guarantee(Heap_lock->owned_by_self(),
"master humongous set MT safety protocol outside a safepoint");
}
}