/*

 * Copyright (c) 1997, 2015, 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"

#include "services/memTracker.hpp"

size_t CodeHeap::header_size() {

  return sizeof(HeapBlock);

}

// Implementation of Heap

CodeHeap::CodeHeap(const char* name, const int code_blob_type)

  : _code_blob_type(code_blob_type) {

  _name                         = name;

  _number_of_committed_segments = 0;

  _number_of_reserved_segments  = 0;

  _segment_size                 = 0;

  _log2_segment_size            = 0;

  _next_segment                 = 0;

  _freelist                     = NULL;

  _freelist_segments            = 0;

  _freelist_length              = 0;

  _max_allocated_capacity       = 0;

  _was_full                     = false;

}

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

  assert(              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++ = free_sentinel;

}

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

  assert(              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 == free_sentinel) 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);

}

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(ReservedSpace rs, size_t committed_size, size_t segment_size) {

  assert(rs.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.

  size_t page_size = os::vm_page_size();

  if (os::can_execute_large_page_memory()) {

    const size_t min_pages = 8;

    page_size = MIN2(os::page_size_for_region_aligned(committed_size, min_pages),

                     os::page_size_for_region_aligned(rs.size(), min_pages));

  }

  const size_t granularity = os::vm_allocation_granularity();

  const size_t c_size = align_size_up(committed_size, page_size);

  os::trace_page_sizes(_name, committed_size, rs.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 = size_to_segments(_memory.committed_size());

  _number_of_reserved_segments  = size_to_segments(_memory.reserved_size());

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

  const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity);

  const size_t reserved_segments_size = align_size_up(_number_of_reserved_segments, reserved_segments_alignment);

  const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments);

  // reserve space for _segmap

  if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) {

    return false;

  }

  MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode);

  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;

}

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 = size_to_segments(_memory.committed_size());

    assert(_number_of_reserved_segments == size_to_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) && !_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::clear() {

  _next_segment = 0;

  mark_segmap_as_free(0, _number_of_committed_segments);

}

void* CodeHeap::allocate(size_t instance_size) {

  size_t number_of_segments = size_to_segments(instance_size + header_size());

  assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList");

  // First check if we can satisfy request from freelist

  NOT_PRODUCT(verify());

  HeapBlock* block = search_freelist(number_of_segments);

  NOT_PRODUCT(verify());

  if (block != NULL) {

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

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

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

    _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());

    return block->allocated_space();

  }

  // Ensure minimum size for allocation to the heap.

  number_of_segments = MAX2((int)CodeCacheMinBlockLength, (int)number_of_segments);

  if (_next_segment + number_of_segments <= _number_of_committed_segments) {

    mark_segmap_as_used(_next_segment, _next_segment + number_of_segments);

    HeapBlock* b =  block_at(_next_segment);

    b->initialize(number_of_segments);

    _next_segment += number_of_segments;

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

    _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());

    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");

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

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

  add_to_freelist(b);

  NOT_PRODUCT(verify());

}

/**

 * Uses segment map to find the the start (header) of a nmethod. This works as follows:

 * The memory of the code cache is divided into 'segments'. The size of a segment is

 * determined by -XX:CodeCacheSegmentSize=XX. Allocation in the code cache can only

 * happen at segment boundaries. A pointer in the code cache can be mapped to a segment

 * by calling segment_for(addr). Each time memory is requested from the code cache,

 * the segmap is updated accordingly. See the following example, which illustrates the

 * state of code cache and the segment map: (seg -> segment, nm ->nmethod)

 *

 *          code cache          segmap

 *         -----------        ---------

 * seg 1   | nm 1    |   ->   | 0     |

 * seg 2   | nm 1    |   ->   | 1     |

 * ...     | nm 1    |   ->   | ..    |

 * seg m   | nm 2    |   ->   | 0     |

 * seg m+1 | nm 2    |   ->   | 1     |

 * ...     | nm 2    |   ->   | 2     |

 * ...     | nm 2    |   ->   | ..    |

 * ...     | nm 2    |   ->   | 0xFE  |

 * seg m+n | nm 2    |   ->   | 1     |

 * ...     | nm 2    |   ->   |       |

 *

 * A value of '0' in the segmap indicates that this segment contains the beginning of

 * an nmethod. Let's walk through a simple example: If we want to find the start of

 * an nmethod that falls into seg 2, we read the value of the segmap[2]. The value

 * is an offset that points to the segment that contains the start of the nmethod.

 * Another example: If we want to get the start of nm 2, and we happen to get a pointer

 * that points to seg m+n, we first read seg[n+m], which returns '1'. So we have to

 * do one more read of the segmap[m+n-1] to finally get the segment header.

 */

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

  if (!contains(p)) {

    return NULL;

  }

  size_t seg_idx = segment_for(p);

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

  if (is_segment_unused(seg_map[seg_idx])) {

    return NULL;

  }

  while (seg_map[seg_idx] > 0) {

    seg_idx -= (int)seg_map[seg_idx];

  }

  HeapBlock* h = block_at(seg_idx);

  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);

}

// Returns the current block if available and used.

// If not, it returns the subsequent block (if available), NULL otherwise.

// Free blocks are merged, therefore there is at most one free block

// between two used ones. As a result, the subsequent block (if available) is

// guaranteed to be used.

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

  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();

}

int CodeHeap::allocated_segments() const {

  return (int)_next_segment;

}

size_t CodeHeap::allocated_capacity() const {

  // size of used heap - size on freelist

  return segments_to_size(_next_segment - _freelist_segments);

}

// Returns size of the unallocated heap block

size_t CodeHeap::heap_unallocated_capacity() const {

  // Total number of segments - number currently used

  return segments_to_size(_number_of_reserved_segments - _next_segment);

}

// 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

bool 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());

    _freelist_length--;

    return true;

  }

  return false;

}

void CodeHeap::add_to_freelist(HeapBlock* a) {

  FreeBlock* b = (FreeBlock*)a;

  _freelist_length++;

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

  // Mark as free and update free space count

  _freelist_segments += b->length();

  b->set_free();

  // First element in list?

  if (_freelist == NULL) {

    _freelist = b;

    b->set_link(NULL);

    return;

  }

  // Since the freelist is ordered (smaller addresses -> larger addresses) and the

  // element we want to insert into the freelist has a smaller address than the first

  // element, we can simply add 'b' as the first element and we are done.

  if (b < _freelist) {

    // Insert first in list

    b->set_link(_freelist);

    _freelist = b;

    merge_right(_freelist);

    return;

  }

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

  // is sorted by increasing addresses

  FreeBlock* prev = _freelist;

  FreeBlock* cur  = _freelist->link();

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

    assert(prev < cur, "Freelist must be ordered");

    prev = cur;

    cur  = cur->link();

  }

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

  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* found_block = NULL;

  FreeBlock* found_prev  = NULL;

  size_t     found_length = 0;

  FreeBlock* prev = NULL;

  FreeBlock* cur = _freelist;

  // Search for first block that fits

  while(cur != NULL) {

    if (cur->length() >= length) {

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

      found_block = cur;

      found_prev  = prev;

      found_length = found_block->length();

      break;

    }

    // Next element in list

    prev = cur;

    cur  = cur->link();

  }

  if (found_block == NULL) {

    // None found

    return NULL;

  }

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

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

  if (found_length - length < CodeCacheMinBlockLength) {

    _freelist_length--;

    length = found_length;

    if (found_prev == NULL) {

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

      _freelist = _freelist->link();

    } else {

      assert((found_prev->link() == found_block), "sanity check");

      // Unmap element

      found_prev->set_link(found_block->link());

    }

  } else {

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

    // Set used bit and length on new block

    found_block->set_length(found_length - length);

    found_block = following_block(found_block);

    size_t beg = segment_for(found_block);

    mark_segmap_as_used(beg, beg + length);

    found_block->set_length(length);

  }

  found_block->set_used();

  _freelist_segments -= length;

  return found_block;

}

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

// Non-product code

#ifndef PRODUCT

void CodeHeap::print() {

  tty->print_cr("The Heap");

}

void CodeHeap::verify() {

  if (VerifyCodeCache) {

    size_t len = 0;

    int count = 0;

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

      len += b->length();

      count++;

      // Check if we have merged all free blocks

      assert(merge_right(b) == false, "Missed merging opportunity");

    }

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

    assert(len == _freelist_segments, "wrong freelist");

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

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

    }

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

    // than free blocks found on the full list.