/*

 * Copyright (c) 2015, 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 "gc/shared/suspendibleThreadSet.hpp"

#include "gc/z/zAddress.inline.hpp"

#include "gc/z/zCollectedHeap.hpp"

#include "gc/z/zFuture.inline.hpp"

#include "gc/z/zGlobals.hpp"

#include "gc/z/zLock.inline.hpp"

#include "gc/z/zPage.inline.hpp"

#include "gc/z/zPageAllocator.hpp"

#include "gc/z/zPageCache.inline.hpp"

#include "gc/z/zSafeDelete.inline.hpp"

#include "gc/z/zStat.hpp"

#include "gc/z/zTracer.inline.hpp"

#include "runtime/globals.hpp"

#include "runtime/init.hpp"

#include "runtime/java.hpp"

#include "utilities/debug.hpp"

static const ZStatCounter       ZCounterAllocationRate("Memory", "Allocation Rate", ZStatUnitBytesPerSecond);

static const ZStatCounter       ZCounterPageCacheFlush("Memory", "Page Cache Flush", ZStatUnitBytesPerSecond);

static const ZStatCounter       ZCounterUncommit("Memory", "Uncommit", ZStatUnitBytesPerSecond);

static const ZStatCriticalPhase ZCriticalPhaseAllocationStall("Allocation Stall");

class ZPageAllocRequest : public StackObj {

  friend class ZList<ZPageAllocRequest>;

private:

  const uint8_t                _type;

  const size_t                 _size;

  const ZAllocationFlags       _flags;

  const unsigned int           _total_collections;

  ZListNode<ZPageAllocRequest> _node;

  ZFuture<ZPage*>              _result;

public:

  ZPageAllocRequest(uint8_t type, size_t size, ZAllocationFlags flags, unsigned int total_collections) :

      _type(type),

      _size(size),

      _flags(flags),

      _total_collections(total_collections),

      _node(),

      _result() {}

  uint8_t type() const {

    return _type;

  }

  size_t size() const {

    return _size;

  }

  ZAllocationFlags flags() const {

    return _flags;

  }

  unsigned int total_collections() const {

    return _total_collections;

  }

  ZPage* peek() {

    return _result.peek();

  }

  ZPage* wait() {

    return _result.get();

  }

  void satisfy(ZPage* page) {

    _result.set(page);

  }

};

ZPage* const ZPageAllocator::gc_marker = (ZPage*)-1;

ZPageAllocator::ZPageAllocator(size_t min_capacity,

                               size_t initial_capacity,

                               size_t max_capacity,

                               size_t max_reserve) :

    _lock(),

    _virtual(max_capacity),

    _physical(),

    _cache(),

    _min_capacity(min_capacity),

    _max_capacity(max_capacity),

    _max_reserve(max_reserve),

    _current_max_capacity(max_capacity),

    _capacity(0),

    _used_high(0),

    _used_low(0),

    _used(0),

    _allocated(0),

    _reclaimed(0),

    _queue(),

    _satisfied(),

    _safe_delete(),

    _uncommit(false),

    _initialized(false) {

  if (!_virtual.is_initialized() || !_physical.is_initialized()) {

    return;

  }

  log_info(gc, init)("Min Capacity: " SIZE_FORMAT "M", min_capacity / M);

  log_info(gc, init)("Initial Capacity: " SIZE_FORMAT "M", initial_capacity / M);

  log_info(gc, init)("Max Capacity: " SIZE_FORMAT "M", max_capacity / M);

  log_info(gc, init)("Max Reserve: " SIZE_FORMAT "M", max_reserve / M);

  log_info(gc, init)("Pre-touch: %s", AlwaysPreTouch ? "Enabled" : "Disabled");

  // Warn if system limits could stop us from reaching max capacity

  _physical.warn_commit_limits(max_capacity);

  // Commit initial capacity

  _capacity = _physical.commit(initial_capacity);

  if (_capacity != initial_capacity) {

    log_error(gc)("Failed to allocate initial Java heap (" SIZE_FORMAT "M)", initial_capacity / M);

    return;

  }

  // If uncommit is not explicitly disabled, max capacity is greater than

  // min capacity, and uncommit is supported by the platform, then we will

  // try to uncommit unused memory.

  _uncommit = ZUncommit && (max_capacity > min_capacity) && _physical.supports_uncommit();

  if (_uncommit) {

    log_info(gc, init)("Uncommit: Enabled, Delay: " UINTX_FORMAT "s", ZUncommitDelay);

  } else {

    log_info(gc, init)("Uncommit: Disabled");

  }

  // Pre-map initial capacity

  prime_cache(initial_capacity);

  // Successfully initialized

  _initialized = true;

}

void ZPageAllocator::prime_cache(size_t size) {

  // Allocate physical memory

  const ZPhysicalMemory pmem = _physical.alloc(size);

  guarantee(!pmem.is_null(), "Invalid size");

  // Allocate virtual memory

  const ZVirtualMemory vmem = _virtual.alloc(size, true /* alloc_from_front */);

  guarantee(!vmem.is_null(), "Invalid size");

  // Allocate page

  ZPage* const page = new ZPage(vmem, pmem);

  // Map page

  map_page(page);

  page->set_pre_mapped();

  // Add page to cache

  page->set_last_used();

  _cache.free_page(page);

}

bool ZPageAllocator::is_initialized() const {

  return _initialized;

}

size_t ZPageAllocator::min_capacity() const {

  return _min_capacity;

}

size_t ZPageAllocator::max_capacity() const {

  return _max_capacity;

}

size_t ZPageAllocator::soft_max_capacity() const {

  // Note that SoftMaxHeapSize is a manageable flag

  return MIN2(SoftMaxHeapSize, _current_max_capacity);

}

size_t ZPageAllocator::capacity() const {

  return _capacity;

}

size_t ZPageAllocator::max_reserve() const {

  return _max_reserve;

}

size_t ZPageAllocator::used_high() const {

  return _used_high;

}

size_t ZPageAllocator::used_low() const {

  return _used_low;

}

size_t ZPageAllocator::used() const {

  return _used;

}

size_t ZPageAllocator::unused() const {

  const ssize_t unused = (ssize_t)_capacity - (ssize_t)_used - (ssize_t)_max_reserve;

  return unused > 0 ? (size_t)unused : 0;

}

size_t ZPageAllocator::allocated() const {

  return _allocated;

}

size_t ZPageAllocator::reclaimed() const {

  return _reclaimed > 0 ? (size_t)_reclaimed : 0;

}

void ZPageAllocator::reset_statistics() {

  assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");

  _allocated = 0;

  _reclaimed = 0;

  _used_high = _used_low = _used;

}

void ZPageAllocator::increase_used(size_t size, bool relocation) {

  if (relocation) {

    // Allocating a page for the purpose of relocation has a

    // negative contribution to the number of reclaimed bytes.

    _reclaimed -= size;

  }

  _allocated += size;

  _used += size;

  if (_used > _used_high) {

    _used_high = _used;

  }

}

void ZPageAllocator::decrease_used(size_t size, bool reclaimed) {

  if (reclaimed) {

    // Only pages explicitly released with the reclaimed flag set

    // counts as reclaimed bytes. This flag is typically true when

    // a worker releases a page after relocation, and is typically

    // false when we release a page to undo an allocation.

    _reclaimed += size;

  }

  _used -= size;

  if (_used < _used_low) {

    _used_low = _used;

  }

}

ZPage* ZPageAllocator::create_page(uint8_t type, size_t size) {

  // Allocate virtual memory

  const ZVirtualMemory vmem = _virtual.alloc(size);

  if (vmem.is_null()) {

    // Out of address space

    return NULL;

  }

  // Allocate physical memory

  const ZPhysicalMemory pmem = _physical.alloc(size);

  assert(!pmem.is_null(), "Invalid size");

  // Allocate page

  return new ZPage(type, vmem, pmem);

}

void ZPageAllocator::destroy_page(ZPage* page) {

  const ZVirtualMemory& vmem = page->virtual_memory();

  const ZPhysicalMemory& pmem = page->physical_memory();

  // Unmap memory

  _physical.unmap(pmem, vmem.start());

  // Free physical memory

  _physical.free(pmem);

  // Free virtual memory

  _virtual.free(vmem);

  // Delete page safely

  _safe_delete(page);

}

void ZPageAllocator::map_page(const ZPage* page) const {

  // Map physical memory

  _physical.map(page->physical_memory(), page->start());

}

size_t ZPageAllocator::max_available(bool no_reserve) const {

  size_t available = _current_max_capacity - _used;

  if (no_reserve) {

    // The reserve should not be considered available

    available -= MIN2(available, _max_reserve);

  }

  return available;

}

bool ZPageAllocator::ensure_available(size_t size, bool no_reserve) {

  if (max_available(no_reserve) < size) {

    // Not enough free memory

    return false;

  }

  // We add the max_reserve to the requested size to avoid losing

  // the reserve because of failure to increase capacity before

  // reaching max capacity.

  size += _max_reserve;

  // Don't try to increase capacity if enough unused capacity

  // is available or if current max capacity has been reached.

  const size_t available = _capacity - _used;

  if (available < size && _capacity < _current_max_capacity) {

    // Try to increase capacity

    const size_t commit = MIN2(size - available, _current_max_capacity - _capacity);

    const size_t committed = _physical.commit(commit);

    _capacity += committed;

    log_trace(gc, heap)("Make Available: Size: " SIZE_FORMAT "M, NoReserve: %s, "

                        "Available: " SIZE_FORMAT "M, Commit: " SIZE_FORMAT "M, "

                        "Committed: " SIZE_FORMAT "M, Capacity: " SIZE_FORMAT "M",

                        size / M, no_reserve ? "True" : "False", available / M,

                        commit / M, committed / M, _capacity / M);

    if (committed != commit) {

      // Failed, or partly failed, to increase capacity. Adjust current

      // max capacity to avoid further attempts to increase capacity.

      log_error(gc)("Forced to lower max Java heap size from "

                    SIZE_FORMAT "M(%.0f%%) to " SIZE_FORMAT "M(%.0f%%)",

                    _current_max_capacity / M, percent_of(_current_max_capacity, _max_capacity),

                    _capacity / M, percent_of(_capacity, _max_capacity));

      _current_max_capacity = _capacity;

    }

  }

  if (!no_reserve) {

    size -= _max_reserve;

  }

  const size_t new_available = _capacity - _used;

  return new_available >= size;

}

void ZPageAllocator::ensure_uncached_available(size_t size) {

  assert(_capacity - _used >= size, "Invalid size");

  const size_t uncached_available = _capacity - _used - _cache.available();

  if (size > uncached_available) {

    flush_cache_for_allocation(size - uncached_available);

  }

}

ZPage* ZPageAllocator::alloc_page_common_inner(uint8_t type, size_t size, bool no_reserve) {

  if (!ensure_available(size, no_reserve)) {

    // Not enough free memory

    return NULL;

  }

  // Try allocate page from the cache

  ZPage* const page = _cache.alloc_page(type, size);

  if (page != NULL) {

    return page;

  }

  // Try flush pages from the cache

  ensure_uncached_available(size);

  // Create new page

  return create_page(type, size);

}

ZPage* ZPageAllocator::alloc_page_common(uint8_t type, size_t size, ZAllocationFlags flags) {

  ZPage* const page = alloc_page_common_inner(type, size, flags.no_reserve());

  if (page == NULL) {

    // Out of memory

    return NULL;

  }

  // Update used statistics

  increase_used(size, flags.relocation());

  // Send trace event

  ZTracer::tracer()->report_page_alloc(size, _used, max_available(flags.no_reserve()), _cache.available(), flags);

  return page;

}

void ZPageAllocator::check_out_of_memory_during_initialization() {

  if (!is_init_completed()) {

    vm_exit_during_initialization("java.lang.OutOfMemoryError", "Java heap too small");

  }

}

ZPage* ZPageAllocator::alloc_page_blocking(uint8_t type, size_t size, ZAllocationFlags flags) {

  // Prepare to block

  ZPageAllocRequest request(type, size, flags, ZCollectedHeap::heap()->total_collections());

  _lock.lock();

  // Try non-blocking allocation

  ZPage* page = alloc_page_common(type, size, flags);

  if (page == NULL) {

    // Allocation failed, enqueue request

    _queue.insert_last(&request);

  }

  _lock.unlock();

  if (page == NULL) {

    // Allocation failed

    ZStatTimer timer(ZCriticalPhaseAllocationStall);

    // We can only block if VM is fully initialized

    check_out_of_memory_during_initialization();

    do {

      // Start asynchronous GC

      ZCollectedHeap::heap()->collect(GCCause::_z_allocation_stall);

      // Wait for allocation to complete or fail

      page = request.wait();

    } while (page == gc_marker);

    {

      //

      // We grab the lock here for two different reasons:

      //

      // 1) Guard deletion of underlying semaphore. This is a workaround for

      // a bug in sem_post() in glibc < 2.21, where it's not safe to destroy

      // the semaphore immediately after returning from sem_wait(). The

      // reason is that sem_post() can touch the semaphore after a waiting

      // thread have returned from sem_wait(). To avoid this race we are

      // forcing the waiting thread to acquire/release the lock held by the

      // posting thread. https://sourceware.org/bugzilla/show_bug.cgi?id=12674

      //

      // 2) Guard the list of satisfied pages.

      //

      ZLocker<ZLock> locker(&_lock);

      _satisfied.remove(&request);

    }

  }

  return page;

}

ZPage* ZPageAllocator::alloc_page_nonblocking(uint8_t type, size_t size, ZAllocationFlags flags) {

  ZLocker<ZLock> locker(&_lock);

  return alloc_page_common(type, size, flags);

}

ZPage* ZPageAllocator::alloc_page(uint8_t type, size_t size, ZAllocationFlags flags) {

  ZPage* const page = flags.non_blocking()

                      ? alloc_page_nonblocking(type, size, flags)

                      : alloc_page_blocking(type, size, flags);

  if (page == NULL) {

    // Out of memory

    return NULL;

  }

  // Map page if needed

  if (!page->is_mapped()) {

    map_page(page);

  }

  // Reset page. This updates the page's sequence number and must

  // be done after page allocation, which potentially blocked in

  // a safepoint where the global sequence number was updated.

  page->reset();

  // Update allocation statistics. Exclude worker threads to avoid

  // artificial inflation of the allocation rate due to relocation.

  if (!flags.worker_thread()) {

    // Note that there are two allocation rate counters, which have

    // different purposes and are sampled at different frequencies.

    const size_t bytes = page->size();

    ZStatInc(ZCounterAllocationRate, bytes);

    ZStatInc(ZStatAllocRate::counter(), bytes);

  }

  return page;

}

void ZPageAllocator::satisfy_alloc_queue() {

  for (;;) {

    ZPageAllocRequest* const request = _queue.first();

    if (request == NULL) {

      // Allocation queue is empty

      return;

    }

    ZPage* const page = alloc_page_common(request->type(), request->size(), request->flags());

    if (page == NULL) {

      // Allocation could not be satisfied, give up