/*

 * 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/z/zList.inline.hpp"

#include "gc/z/zNUMA.hpp"

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

#include "gc/z/zPageCache.hpp"

#include "gc/z/zStat.hpp"

#include "logging/log.hpp"

static const ZStatCounter ZCounterPageCacheHitL1("Memory", "Page Cache Hit L1", ZStatUnitOpsPerSecond);

static const ZStatCounter ZCounterPageCacheHitL2("Memory", "Page Cache Hit L2", ZStatUnitOpsPerSecond);

static const ZStatCounter ZCounterPageCacheMiss("Memory", "Page Cache Miss", ZStatUnitOpsPerSecond);

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

ZPageCache::ZPageCache() :

    _available(0),

    _small(),

    _medium(),

    _large() {}

ZPage* ZPageCache::alloc_small_page() {

  const uint32_t numa_id = ZNUMA::id();

  const uint32_t numa_count = ZNUMA::count();

  // Try NUMA local page cache

  ZPage* const l1_page = _small.get(numa_id).remove_first();

  if (l1_page != NULL) {

    ZStatInc(ZCounterPageCacheHitL1);

    return l1_page;

  }

  // Try NUMA remote page cache(s)

  uint32_t remote_numa_id = numa_id + 1;

  const uint32_t remote_numa_count = numa_count - 1;

  for (uint32_t i = 0; i < remote_numa_count; i++) {

    if (remote_numa_id == numa_count) {

      remote_numa_id = 0;

    }

    ZPage* const l2_page = _small.get(remote_numa_id).remove_first();

    if (l2_page != NULL) {

      ZStatInc(ZCounterPageCacheHitL2);

      return l2_page;

    }

    remote_numa_id++;

  }

  ZStatInc(ZCounterPageCacheMiss);

  return NULL;

}

ZPage* ZPageCache::alloc_medium_page() {

  ZPage* const l1_page = _medium.remove_first();

  if (l1_page != NULL) {

    ZStatInc(ZCounterPageCacheHitL1);

    return l1_page;

  }

  ZStatInc(ZCounterPageCacheMiss);

  return NULL;

}

ZPage* ZPageCache::alloc_large_page(size_t size) {

  // Find a page with the right size

  ZListIterator<ZPage> iter(&_large);

  for (ZPage* l1_page; iter.next(&l1_page);) {

    if (l1_page->size() == size) {

      // Page found

      _large.remove(l1_page);

      ZStatInc(ZCounterPageCacheHitL1);

      return l1_page;

    }

  }

  ZStatInc(ZCounterPageCacheMiss);

  return NULL;

}

ZPage* ZPageCache::alloc_page(uint8_t type, size_t size) {

  ZPage* page;

  if (type == ZPageTypeSmall) {

    page = alloc_small_page();

  } else if (type == ZPageTypeMedium) {

    page = alloc_medium_page();

  } else {

    page = alloc_large_page(size);

  }

  if (page != NULL) {

    _available -= page->size();

  }

  return page;

}

void ZPageCache::free_page(ZPage* page) {

  const uint8_t type = page->type();

  if (type == ZPageTypeSmall) {

    _small.get(page->numa_id()).insert_first(page);

  } else if (type == ZPageTypeMedium) {

    _medium.insert_first(page);

  } else {

    _large.insert_first(page);

  }

  _available += page->size();

}

void ZPageCache::flush_list(ZList<ZPage>* from, size_t requested, ZList<ZPage>* to, size_t* flushed) {

  while (*flushed < requested) {

    // Flush least recently used

    ZPage* const page = from->remove_last();

    if (page == NULL) {

      break;

    }

    *flushed += page->size();

    to->insert_last(page);

  }

}

void ZPageCache::flush_per_numa_lists(ZPerNUMA<ZList<ZPage> >* from, size_t requested, ZList<ZPage>* to, size_t* flushed) {

  const uint32_t numa_count = ZNUMA::count();

  uint32_t numa_empty = 0;

  uint32_t numa_next = 0;

  // Flush lists round-robin

  while (*flushed < requested) {

    ZPage* const page = from->get(numa_next).remove_last();

    if (++numa_next == numa_count) {

      numa_next = 0;

    }

    if (page == NULL) {

      // List is empty

      if (++numa_empty == numa_count) {

        // All lists are empty

        break;

      }

      // Try next list

      continue;

    }

    // Flush page

    numa_empty = 0;

    *flushed += page->size();

    to->insert_last(page);

  }

}

void ZPageCache::flush(ZList<ZPage>* to, size_t requested) {

  size_t flushed = 0;

  // Prefer flushing large, then medium and last small pages

  flush_list(&_large, requested, to, &flushed);

  flush_list(&_medium, requested, to, &flushed);

  flush_per_numa_lists(&_small, requested, to, &flushed);

  ZStatInc(ZCounterPageCacheFlush, flushed);

  log_info(gc, heap)("Page Cache Flushed: "

                     SIZE_FORMAT "M requested, "

                     SIZE_FORMAT "M(" SIZE_FORMAT "M->" SIZE_FORMAT "M) flushed",

                     requested / M, flushed / M , _available / M, (_available - flushed) / M);

  _available -= flushed;

}