text: /*
   *  ircd-ratbox: A slightly useful ircd.
   *  balloc.c: A block allocator.
   *
   * Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center
   * Copyright (C) 1996-2002 Hybrid Development Team
   * Copyright (C) 2002-2012 ircd-ratbox development team
   *
   *  Below are the orignal headers from the old blalloc.c
   *
   *  File:   blalloc.c
   *  Owner:  Wohali (Joan Touzet)
   *
   *  Modified 2001/11/29 for mmap() support by Aaron Sethman <androsyn@ratbox.org>
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  This program 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 for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to the Free Software
   *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
   *  USA
   *
   */
  
  /*
   * About the block allocator
   *
   * Basically we have three ways of getting memory off of the operating
   * system. Below are this list of methods and the order of preference.
   *
   * 1. mmap() anonymous pages with the MMAP_ANON flag.
   * 2. mmap() via the /dev/zero trick.
   * 3. HeapCreate/HeapAlloc (on win32)
   * 4. malloc()
   *
   * The advantages of 1 and 2 are this.  We can munmap() the pages which will
   * return the pages back to the operating system, thus reducing the size
   * of the process as the memory is unused.  malloc() on many systems just keeps
   * a heap of memory to itself, which never gets given back to the OS, except on
   * exit.  This of course is bad, if say we have an event that causes us to allocate
   * say, 200MB of memory, while our normal memory consumption would be 15MB.  In the
   * malloc() case, the amount of memory allocated to our process never goes down, as
   * malloc() has it locked up in its heap.  With the mmap() method, we can munmap()
   * the block and return it back to the OS, thus causing our memory consumption to go
   * down after we no longer need it.
   *
   *
   *
   */
  #include <libratbox_config.h>
  #include <ratbox_lib.h>
  
  #ifndef NOBALLOC
  #ifdef HAVE_MMAP		/* We've got mmap() that is good */
  #include <sys/mman.h>
  /* HP-UX sucks */
  #ifdef MAP_ANONYMOUS
  #ifndef MAP_ANON
  #define MAP_ANON MAP_ANONYMOUS
  #endif
  #endif
  #endif
  #endif
  
  static uintptr_t offset_pad;
  
  /* status information for an allocated block in heap */
  struct rb_heap_block {
      size_t alloc_size;
      rb_dlink_node node;
      unsigned long free_count;
      void *elems;		/* Points to allocated memory */
  };
  typedef struct rb_heap_block rb_heap_block;
  
  /* information for the root node of the heap */
  struct rb_bh {
      rb_dlink_node hlist;
      size_t elemSize;	/* Size of each element to be stored */
      unsigned long elemsPerBlock;	/* Number of elements per block */
      rb_dlink_list block_list;
      rb_dlink_list free_list;
      char *desc;
  };
  
  #ifndef NOBALLOC
  static int newblock(rb_bh *bh);
  static void rb_bh_gc_event(__unused void *unused);
  #endif /* !NOBALLOC */
  static rb_dlink_list *heap_lists;
  
  #if defined(WIN32)
  static HANDLE block_heap;
  #endif
  
  #define rb_bh_fail(x) _rb_bh_fail(x, __FILE__, __LINE__)
  
  static void
  _rb_bh_fail(const char *reason, const char *file, int line)
  {
      rb_lib_log("rb_heap_blockheap failure: %s (%s:%d)", reason, file, line);
      abort();
  }
  
  #ifndef NOBALLOC
  /*
   * static inline void free_block(void *ptr, size_t size)
   *
   * Inputs: The block and its size
   * Output: None
   * Side Effects: Returns memory for the block back to the OS
   */
  static inline void
  free_block(void *ptr, size_t size)
  {
  #ifdef HAVE_MMAP
      munmap(ptr, size);
  #else
  #ifdef _WIN32
      HeapFree(block_heap, 0, ptr);
  #else
      free(ptr);
  #endif
  #endif
  }
  #endif /* !NOBALLOC */
  
  /*
   * void rb_init_bh(void)
   *
   * Inputs: None
   * Outputs: None
   * Side Effects: Initializes the block heap
   */
  
  void
  rb_init_bh(void)
  {
      heap_lists = rb_malloc(sizeof(rb_dlink_list));
      offset_pad = sizeof(void *);
      /* XXX if you get SIGBUS when trying to use a long long..here is where you need to
       * fix your shit
       */
  #ifdef __sparc__
      if((offset_pad % __alignof__(long long)) != 0) {
          offset_pad += __alignof__(long long);
          offset_pad &= ~(__alignof__(long long) - 1);
      }
  #endif
  
  #ifndef NOBALLOC
  #ifdef _WIN32
      block_heap = HeapCreate(HEAP_NO_SERIALIZE, 0, 0);
  #endif
      rb_event_addish("rb_bh_gc_event", rb_bh_gc_event, NULL, 300);
  #endif /* !NOBALLOC */
  }
  
  #ifndef NOBALLOC
  /*
   * static inline void *get_block(size_t size)
   *
   * Input: Size of block to allocate
   * Output: Pointer to new block
   * Side Effects: None
   */
  static inline void *
  get_block(size_t size)
  {
      void *ptr;
  #ifdef HAVE_MMAP
  #ifdef MAP_ANON
      ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
  #else
      int zero_fd;
      zero_fd = open("/dev/zero", O_RDWR);
      if(zero_fd < 0)
          rb_bh_fail("Failed opening /dev/zero");
      ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, zero_fd, 0);
      close(zero_fd);
  #endif /* MAP_ANON */
      if(ptr == MAP_FAILED)
          ptr = NULL;
  #else
  #ifdef _WIN32
      ptr = HeapAlloc(block_heap, 0, size);
  #else
      ptr = malloc(size);
  #endif
  #endif
      return (ptr);
  }
  
  
  static void
  rb_bh_gc_event(__unused void *unused)
  {
      rb_dlink_node *ptr;
      RB_DLINK_FOREACH(ptr, heap_lists->head) {
          rb_bh_gc(ptr->data);
      }
  }
  
  /* ************************************************************************ */
  /* FUNCTION DOCUMENTATION:                                                  */
  /*    newblock                                                              */
  /* Description:                                                             */
  /*    Allocates a new block for addition to a blockheap                     */
  /* Parameters:                                                              */
  /*    bh (IN): Pointer to parent blockheap.                                 */
  /* Returns:                                                                 */
  /*    0 if successful, 1 if not                                             */
  /* ************************************************************************ */
  
  static int
  newblock(rb_bh *bh)
  {
      rb_heap_block *b;
      unsigned long i;
      uintptr_t offset;
      rb_dlink_node *node;
      /* Setup the initial data structure. */
      b = rb_malloc(sizeof(rb_heap_block));
  
      b->alloc_size = bh->elemsPerBlock * bh->elemSize;
  
      b->elems = get_block(b->alloc_size);
      if(rb_unlikely(b->elems == NULL)) {
          rb_free(b);
          return (1);
      }
      offset = (uintptr_t)b->elems;
      /* Setup our blocks now */
      for(i = 0; i < bh->elemsPerBlock; i++, offset += bh->elemSize) {
          *((void **)offset) = b;
          node = (void *)(offset + offset_pad);
          rb_dlinkAdd((void *)offset, node, &bh->free_list);
      }
      rb_dlinkAdd(b, &b->node, &bh->block_list);
      b->free_count = bh->elemsPerBlock;
      return (0);
  }
  #endif /* !NOBALLOC */
  
  /* ************************************************************************ */
  /* FUNCTION DOCUMENTATION:                                                  */
  /*    rb_bh_create                                                       */
  /* Description:                                                             */
  /*   Creates a new blockheap from which smaller blocks can be allocated.    */
  /*   Intended to be used instead of multiple calls to malloc() when         */
  /*   performance is an issue.                                               */
  /* Parameters:                                                              */
  /*   elemsize (IN):  Size of the basic element to be stored                 */
  /*   elemsperblock (IN):  Number of elements to be stored in a single block */
  /*         of memory.  When the blockheap runs out of free memory, it will  */
  /*         allocate elemsize * elemsperblock more.                          */
  /* Returns:                                                                 */
  /*   Pointer to new rb_bh, or NULL if unsuccessful                      */
  /* ************************************************************************ */
  rb_bh *
  rb_bh_create(size_t elemsize, int elemsperblock, const char *desc)
  {
      rb_bh *bh;
      lrb_assert(elemsize > 0 && elemsperblock > 0);
      lrb_assert(elemsize >= sizeof(rb_dlink_node));
  
      /* Catch idiotic requests up front */
      if((elemsize == 0) || (elemsperblock <= 0)) {
          rb_bh_fail("Attempting to rb_bh_create idiotic sizes");
      }
  
      if(elemsize < sizeof(rb_dlink_node))
          rb_bh_fail("Attempt to rb_bh_create smaller than sizeof(rb_dlink_node)");
  
      /* Allocate our new rb_bh */
      bh = rb_malloc(sizeof(rb_bh));
  #ifndef NOBALLOC
      elemsize += offset_pad;
      if((elemsize % sizeof(void *)) != 0) {
          /* Pad to even pointer boundary */
          elemsize += sizeof(void *);
          elemsize &= ~(sizeof(void *) - 1);
      }
  #endif
  
      bh->elemSize = elemsize;
      bh->elemsPerBlock = elemsperblock;
      if(desc != NULL)
          bh->desc = rb_strdup(desc);
  
  #ifndef NOBALLOC
      /* Be sure our malloc was successful */
      if(newblock(bh)) {
          if(bh != NULL)
              free(bh);
          rb_lib_log("newblock() failed");
          rb_outofmemory();	/* die.. out of memory */
      }
  #endif /* !NOBALLOC */
  
      if(bh == NULL) {
          rb_bh_fail("bh == NULL when it shouldn't be");
      }
      rb_dlinkAdd(bh, &bh->hlist, heap_lists);
      return (bh);
  }
  
  /* ************************************************************************ */
  /* FUNCTION DOCUMENTATION:                                                  */
  /*    rb_bh_alloc                                                        */
  /* Description:                                                             */
  /*    Returns a pointer to a struct within our rb_bh that's free for    */
  /*    the taking.                                                           */
  /* Parameters:                                                              */
  /*    bh (IN):  Pointer to the Blockheap.                                   */
  /* Returns:                                                                 */
  /*    Pointer to a structure (void *), or NULL if unsuccessful.             */
  /* ************************************************************************ */
  
  void *
  rb_bh_alloc(rb_bh *bh)
  {
  #ifndef NOBALLOC
      rb_dlink_node *new_node;
      rb_heap_block **block;
      void *ptr;
  #endif
      lrb_assert(bh != NULL);
      if(rb_unlikely(bh == NULL)) {
          rb_bh_fail("Cannot allocate if bh == NULL");
      }
  
  #ifdef NOBALLOC
      return (rb_malloc(bh->elemSize));
  #else
      if(bh->free_list.head == NULL) {
          /* Allocate new block and assign */
          /* newblock returns 1 if unsuccessful, 0 if not */
  
          if(rb_unlikely(newblock(bh))) {
              rb_lib_log("newblock() failed");
              rb_outofmemory();	/* Well that didn't work either...bail */
          }
          if(bh->free_list.head == NULL) {
              rb_lib_log("out of memory after newblock()...");
              rb_outofmemory();
          }
      }
  
      new_node = bh->free_list.head;
      block = (rb_heap_block **) new_node->data;
      ptr = (void *)((uintptr_t)new_node->data + (uintptr_t)offset_pad);
      rb_dlinkDelete(new_node, &bh->free_list);
      (*block)->free_count--;
      memset(ptr, 0, bh->elemSize - offset_pad);
      return (ptr);
  #endif
  }
  
  
  /* ************************************************************************ */
  /* FUNCTION DOCUMENTATION:                                                  */
  /*    rb_bh_free                                                          */
  /* Description:                                                             */
  /*    Returns an element to the free pool, does not free()                  */
  /* Parameters:                                                              */
  /*    bh (IN): Pointer to rb_bh containing element                        */
  /*    ptr (in):  Pointer to element to be "freed"                           */
  /* Returns:                                                                 */
  /*    0 if successful, 1 if element not contained within rb_bh.           */
  /* ************************************************************************ */
  int
  rb_bh_free(rb_bh *bh, void *ptr)
  {
  #ifndef NOBALLOC
      rb_heap_block *block;
      void *data;
  #endif
      lrb_assert(bh != NULL);
      lrb_assert(ptr != NULL);
  
      if(rb_unlikely(bh == NULL)) {
          rb_lib_log("balloc.c:rb_bhFree() bh == NULL");
          return (1);
      }
  
      if(rb_unlikely(ptr == NULL)) {
          rb_lib_log("balloc.rb_bhFree() ptr == NULL");
          return (1);
      }
  
  #ifdef NOBALLOC
      rb_free(ptr);
  #else
      data = (void *)((uintptr_t)ptr - (uintptr_t)offset_pad);
      block = *(rb_heap_block **) data;
      /* XXX */
      if(rb_unlikely
         (!((uintptr_t)ptr >= (uintptr_t)block->elems
            && (uintptr_t)ptr < (uintptr_t)block->elems + (uintptr_t)block->alloc_size))) {
          rb_bh_fail("rb_bh_free() bogus pointer");
      }
      block->free_count++;
  
      rb_dlinkAdd(data, (rb_dlink_node *)ptr, &bh->free_list);
  #endif /* !NOBALLOC */
      return (0);
  }
  
  
  /* ************************************************************************ */
  /* FUNCTION DOCUMENTATION:                                                  */
  /*    rb_bhDestroy                                                      */
  /* Description:                                                             */
  /*    Completely free()s a rb_bh.  Use for cleanup.                     */
  /* Parameters:                                                              */
  /*    bh (IN):  Pointer to the rb_bh to be destroyed.                   */
  /* Returns:                                                                 */
  /*   0 if successful, 1 if bh == NULL                                       */
  /* ************************************************************************ */
  int
  rb_bh_destroy(rb_bh *bh)
  {
  #ifndef NOBALLOC
      rb_dlink_node *ptr, *next;
      rb_heap_block *b;
  #endif
      if(bh == NULL)
          return (1);
  
  #ifndef NOBALLOC
      RB_DLINK_FOREACH_SAFE(ptr, next, bh->block_list.head) {
          b = ptr->data;
          free_block(b->elems, b->alloc_size);
          rb_free(b);
      }
  #endif /* !NOBALLOC */
  
      rb_dlinkDelete(&bh->hlist, heap_lists);
      rb_free(bh->desc);
      rb_free(bh);
  
      return (0);
  }
  
  void
  rb_bh_usage(rb_bh *bh, size_t *bused, size_t *bfree, size_t *bmemusage, const char **desc)
  {
  #ifndef NOBALLOC
      size_t used, freem, memusage;
  
      if(bh == NULL) {
          return;
      }
  
      freem = rb_dlink_list_length(&bh->free_list);
      used = (rb_dlink_list_length(&bh->block_list) * bh->elemsPerBlock) - freem;
      memusage = used * bh->elemSize;
      if(bused != NULL)
          *bused = used;
      if(bfree != NULL)
          *bfree = freem;
      if(bmemusage != NULL)
          *bmemusage = memusage;
      if(desc != NULL)
          *desc = bh->desc;
  #else
      if(bused != NULL)
          *bused = 0;
      if(bfree != NULL)
          *bfree = 0;
      if(bmemusage != NULL)
          *bmemusage = 0;
      if(desc != NULL)
          *desc = "no blockheap";
  #endif
  }
  
  void
  rb_bh_usage_all(rb_bh_usage_cb *cb, void *data)
  {
      rb_dlink_node *ptr;
      rb_bh *bh;
      size_t used, freem, memusage, heapalloc;
      static const char *unnamed = "(unnamed_heap)";
      const char *desc = unnamed;
  
      if(cb == NULL)
          return;
  
      RB_DLINK_FOREACH(ptr, heap_lists->head) {
          bh = (rb_bh *)ptr->data;
          freem = rb_dlink_list_length(&bh->free_list);
          used = (rb_dlink_list_length(&bh->block_list) * bh->elemsPerBlock) - freem;
          memusage = used * bh->elemSize;
          heapalloc = (freem + used) * bh->elemSize;
          if(bh->desc != NULL)
              desc = bh->desc;
          cb(used, freem, memusage, heapalloc, desc, data);
      }
      return;
  }
  
  void
  rb_bh_total_usage(size_t *total_alloc, size_t *total_used)
  {
      rb_dlink_node *ptr;
      size_t total_memory = 0, used_memory = 0, used, freem;
      rb_bh *bh;
  
      RB_DLINK_FOREACH(ptr, heap_lists->head) {
          bh = (rb_bh *)ptr->data;
          freem = rb_dlink_list_length(&bh->free_list);
          used = (rb_dlink_list_length(&bh->block_list) * bh->elemsPerBlock) - freem;
          used_memory += used * bh->elemSize;
          total_memory += (freem + used) * bh->elemSize;
      }
  
      if(total_alloc != NULL)
          *total_alloc = total_memory;
      if(total_used != NULL)
          *total_used = used_memory;
  }
  
  #ifndef NOBALLOC
  int
  rb_bh_gc(rb_bh *bh)
  {
      rb_heap_block *b;
      rb_dlink_node *ptr, *next;
      unsigned long i;
      uintptr_t offset;
  
      if(bh == NULL) {
          /* somebody is smoking some craq..(probably lee, but don't tell him that) */
          return (1);
      }
  
      if((rb_dlink_list_length(&bh->free_list) < bh->elemsPerBlock)
         || rb_dlink_list_length(&bh->block_list) == 1) {
          /* There couldn't possibly be an entire free block.  Return. */
          return (0);
      }
  
      RB_DLINK_FOREACH_SAFE(ptr, next, bh->block_list.head) {
          b = ptr->data;
          if(rb_dlink_list_length(&bh->block_list) == 1)
              return (0);
  
          if(b->free_count == bh->elemsPerBlock) {
              /* i'm seriously going to hell for this.. */
  
              offset = (uintptr_t)b->elems;
              for(i = 0; i < bh->elemsPerBlock; i++, offset += (uintptr_t)bh->elemSize) {
                  rb_dlinkDelete((rb_dlink_node *)(offset + offset_pad),
                                 &bh->free_list);
              }
              rb_dlinkDelete(&b->node, &bh->block_list);
              free_block(b->elems, b->alloc_size);
              rb_free(b);
          }
  
      }
      return (0);
  }
  #endif /* !NOBALLOC */
  