/*

 * Copyright (c) 1997, 2010, 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 "memory/heap.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/os.hpp"

size_t CodeHeap::header_size() {

  return sizeof(HeapBlock);

}

// Implementation of Heap

CodeHeap::CodeHeap() {

  _number_of_committed_segments = 0;

  _number_of_reserved_segments  = 0;

  _segment_size                 = 0;

  _log2_segment_size            = 0;

  _next_segment                 = 0;

  _freelist                     = NULL;

  _free_segments                = 0;

}

void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {

  assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");

  assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");

  // setup _segmap pointers for faster indexing

  address p = (address)_segmap.low() + beg;

  address q = (address)_segmap.low() + end;

  // initialize interval

  while (p < q) *p++ = 0xFF;

}

void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {

  assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");

  assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");

  // setup _segmap pointers for faster indexing

  address p = (address)_segmap.low() + beg;

  address q = (address)_segmap.low() + end;

  // initialize interval

  int i = 0;

  while (p < q) {

    *p++ = i++;

    if (i == 0xFF) i = 1;

  }

}

static size_t align_to_page_size(size_t size) {

  const size_t alignment = (size_t)os::vm_page_size();

  assert(is_power_of_2(alignment), "no kidding ???");

  return (size + alignment - 1) & ~(alignment - 1);

}

static size_t align_to_allocation_size(size_t size) {

  const size_t alignment = (size_t)os::vm_allocation_granularity();

  assert(is_power_of_2(alignment), "no kidding ???");

  return (size + alignment - 1) & ~(alignment - 1);

}

void CodeHeap::on_code_mapping(char* base, size_t size) {

#ifdef LINUX

  extern void linux_wrap_code(char* base, size_t size);

  linux_wrap_code(base, size);

#endif

}

bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,

                       size_t segment_size) {

  assert(reserved_size >= committed_size, "reserved < committed");

  assert(segment_size >= sizeof(FreeBlock), "segment size is too small");

  assert(is_power_of_2(segment_size), "segment_size must be a power of 2");

  _segment_size      = segment_size;

  _log2_segment_size = exact_log2(segment_size);

  // Reserve and initialize space for _memory.

  const size_t page_size = os::can_execute_large_page_memory() ?

          os::page_size_for_region(committed_size, reserved_size, 8) :

          os::vm_page_size();

  const size_t granularity = os::vm_allocation_granularity();

  const size_t r_align = MAX2(page_size, granularity);

  const size_t r_size = align_size_up(reserved_size, r_align);

  const size_t c_size = align_size_up(committed_size, page_size);

  const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :

    MAX2(page_size, granularity);

  ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);

  os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,

                       rs.base(), rs.size());

  if (!_memory.initialize(rs, c_size)) {

    return false;

  }

  on_code_mapping(_memory.low(), _memory.committed_size());

  _number_of_committed_segments = number_of_segments(_memory.committed_size());

  _number_of_reserved_segments  = number_of_segments(_memory.reserved_size());

  assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");

  // reserve space for _segmap

  if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) {

    return false;

  }

  assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit  enough space for segment map");

  assert(_segmap.reserved_size()  >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");

  assert(_segmap.reserved_size()  >= _segmap.committed_size()     , "just checking");

  // initialize remaining instance variables

  clear();

  return true;

}

void CodeHeap::release() {

  Unimplemented();

}

bool CodeHeap::expand_by(size_t size) {

  // expand _memory space

  size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();

  if (dm > 0) {

    char* base = _memory.low() + _memory.committed_size();

    if (!_memory.expand_by(dm)) return false;

    on_code_mapping(base, dm);

    size_t i = _number_of_committed_segments;

    _number_of_committed_segments = number_of_segments(_memory.committed_size());

    assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");

    assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");

    // expand _segmap space

    size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();

    if (ds > 0) {

      if (!_segmap.expand_by(ds)) return false;

    }

    assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");

    // initialize additional segmap entries

    mark_segmap_as_free(i, _number_of_committed_segments);

  }

  return true;

}

void CodeHeap::shrink_by(size_t size) {

  Unimplemented();

}

void CodeHeap::clear() {

  _next_segment = 0;

  mark_segmap_as_free(0, _number_of_committed_segments);

}

void* CodeHeap::allocate(size_t size) {

  size_t length = number_of_segments(size + sizeof(HeapBlock));

  assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");

  // First check if we can satify request from freelist

  debug_only(verify());

  HeapBlock* block = search_freelist(length);

  debug_only(if (VerifyCodeCacheOften) verify());

  if (block != NULL) {

    assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check");

    assert(!block->free(), "must be marked free");

#ifdef ASSERT

    memset((void *)block->allocated_space(), badCodeHeapNewVal, size);

#endif

    return block->allocated_space();

  }

  if (length < CodeCacheMinBlockLength) {

    length = CodeCacheMinBlockLength;

  }

  if (_next_segment + length <= _number_of_committed_segments) {

    mark_segmap_as_used(_next_segment, _next_segment + length);

    HeapBlock* b =  block_at(_next_segment);

    b->initialize(length);

    _next_segment += length;

#ifdef ASSERT

    memset((void *)b->allocated_space(), badCodeHeapNewVal, size);

#endif

    return b->allocated_space();

  } else {

    return NULL;

  }

}

void CodeHeap::deallocate(void* p) {

  assert(p == find_start(p), "illegal deallocation");

  // Find start of HeapBlock

  HeapBlock* b = (((HeapBlock *)p) - 1);

  assert(b->allocated_space() == p, "sanity check");

#ifdef ASSERT

  memset((void *)b->allocated_space(),

         badCodeHeapFreeVal,

         size(b->length()) - sizeof(HeapBlock));

#endif

  add_to_freelist(b);

  debug_only(if (VerifyCodeCacheOften) verify());

}

void* CodeHeap::find_start(void* p) const {

  if (!contains(p)) {

    return NULL;

  }

  size_t i = segment_for(p);

  address b = (address)_segmap.low();

  if (b[i] == 0xFF) {

    return NULL;

  }

  while (b[i] > 0) i -= (int)b[i];

  HeapBlock* h = block_at(i);

  if (h->free()) {

    return NULL;

  }

  return h->allocated_space();

}

size_t CodeHeap::alignment_unit() const {

  // this will be a power of two

  return _segment_size;

}

size_t CodeHeap::alignment_offset() const {

  // The lowest address in any allocated block will be

  // equal to alignment_offset (mod alignment_unit).

  return sizeof(HeapBlock) & (_segment_size - 1);

}

// Finds the next free heapblock. If the current one is free, that it returned

void* CodeHeap::next_free(HeapBlock *b) const {

  // Since free blocks are merged, there is max. on free block

  // between two used ones

  if (b != NULL && b->free()) b = next_block(b);

  assert(b == NULL || !b->free(), "must be in use or at end of heap");

  return (b == NULL) ? NULL : b->allocated_space();

}

// Returns the first used HeapBlock

HeapBlock* CodeHeap::first_block() const {

  if (_next_segment > 0)

    return block_at(0);

  return NULL;

}

HeapBlock *CodeHeap::block_start(void *q) const {

  HeapBlock* b = (HeapBlock*)find_start(q);

  if (b == NULL) return NULL;

  return b - 1;

}

// Returns the next Heap block an offset into one

HeapBlock* CodeHeap::next_block(HeapBlock *b) const {

  if (b == NULL) return NULL;

  size_t i = segment_for(b) + b->length();

  if (i < _next_segment)

    return block_at(i);

  return NULL;

}

// Returns current capacity

size_t CodeHeap::capacity() const {

  return _memory.committed_size();

}

size_t CodeHeap::max_capacity() const {

  return _memory.reserved_size();

}

size_t CodeHeap::allocated_capacity() const {

  // Start with the committed size in _memory;

  size_t l = _memory.committed_size();

  // Subtract the committed, but unused, segments

  l -= size(_number_of_committed_segments - _next_segment);

  // Subtract the size of the freelist

  l -= size(_free_segments);

  return l;

}

size_t CodeHeap::largest_free_block() const {

  size_t len = 0;

  for (FreeBlock* b = _freelist; b != NULL; b = b->link()) {

    if (b->length() > len)

      len = b->length();

  }

}

// Free list management

FreeBlock *CodeHeap::following_block(FreeBlock *b) {

  return (FreeBlock*)(((address)b) + _segment_size * b->length());

}

// Inserts block b after a

void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {

  assert(a != NULL && b != NULL, "must be real pointers");

  // Link b into the list after a

  b->set_link(a->link());

  a->set_link(b);

  // See if we can merge blocks

  merge_right(b); // Try to make b bigger

  merge_right(a); // Try to make a include b

}

// Try to merge this block with the following block

void CodeHeap::merge_right(FreeBlock *a) {

  assert(a->free(), "must be a free block");

  if (following_block(a) == a->link()) {

    assert(a->link() != NULL && a->link()->free(), "must be free too");

    // Update block a to include the following block

    a->set_length(a->length() + a->link()->length());

    a->set_link(a->link()->link());

    // Update find_start map

    size_t beg = segment_for(a);

    mark_segmap_as_used(beg, beg + a->length());

  }

}

void CodeHeap::add_to_freelist(HeapBlock *a) {

  FreeBlock* b = (FreeBlock*)a;

  assert(b != _freelist, "cannot be removed twice");

  // Mark as free and update free space count

  _free_segments += b->length();

  b->set_free();

  // First element in list?

  if (_freelist == NULL) {

    _freelist = b;

    b->set_link(NULL);

    return;

  }

  // Scan for right place to put into list. List

  // is sorted by increasing addresseses

  FreeBlock* prev = NULL;

  FreeBlock* cur  = _freelist;

  while(cur != NULL && cur < b) {

    assert(prev == NULL || prev < cur, "must be ordered");

    prev = cur;

    cur  = cur->link();

  }

  assert( (prev == NULL && b < _freelist) ||

          (prev < b && (cur == NULL || b < cur)), "list must be ordered");

  if (prev == NULL) {

    // Insert first in list

    b->set_link(_freelist);

    _freelist = b;

    merge_right(_freelist);

  } else {

    insert_after(prev, b);

  }

}

// Search freelist for an entry on the list with the best fit

// Return NULL if no one was found

FreeBlock* CodeHeap::search_freelist(size_t length) {

  FreeBlock *best_block = NULL;

  FreeBlock *best_prev  = NULL;

  size_t best_length = 0;

  // Search for smallest block which is bigger than length

  FreeBlock *prev = NULL;

  FreeBlock *cur = _freelist;

  while(cur != NULL) {

    size_t l = cur->length();

    if (l >= length && (best_block == NULL || best_length > l)) {

      // Remember best block, its previous element, and its length

      best_block = cur;

      best_prev  = prev;

      best_length = best_block->length();

    }

    // Next element in list

    prev = cur;

    cur  = cur->link();

  }

  if (best_block == NULL) {

    // None found

    return NULL;

  }

  assert((best_prev == NULL && _freelist == best_block ) ||

         (best_prev != NULL && best_prev->link() == best_block), "sanity check");

  // Exact (or at least good enough) fit. Remove from list.

  // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.

  if (best_length < length + CodeCacheMinBlockLength) {

    length = best_length;

    if (best_prev == NULL) {

      assert(_freelist == best_block, "sanity check");

      _freelist = _freelist->link();

    } else {

      // Unmap element

      best_prev->set_link(best_block->link());

    }

  } else {

    // Truncate block and return a pointer to the following block

    best_block->set_length(best_length - length);

    best_block = following_block(best_block);

    // Set used bit and length on new block

    size_t beg = segment_for(best_block);

    mark_segmap_as_used(beg, beg + length);

    best_block->set_length(length);

  }

  best_block->set_used();

  _free_segments -= length;

  return best_block;

}

//----------------------------------------------------------------------------

// Non-product code

#ifndef PRODUCT

void CodeHeap::print() {

  tty->print_cr("The Heap");

}

#endif

void CodeHeap::verify() {

  // Count the number of blocks on the freelist, and the amount of space

  // represented.

  int count = 0;

  size_t len = 0;

  for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {

    len += b->length();

    count++;

  }

  // Verify that freelist contains the right amount of free space

  //  guarantee(len == _free_segments, "wrong freelist");

  // Verify that the number of free blocks is not out of hand.

  static int free_block_threshold = 10000;

  if (count > free_block_threshold) {

    warning("CodeHeap: # of free blocks > %d", free_block_threshold);

    // Double the warning limit

    free_block_threshold *= 2;

  }

  // Verify that the freelist contains the same number of free blocks that is

  // found on the full list.

  for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {

    if (h->free()) count--;

  }

  //  guarantee(count == 0, "missing free blocks");

}