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solanum/libcharybdis/balloc.c
nenolod 212380e3f4 [svn] - the new plan: 
+ branches/release-2.1 -> 2.2 base
  + 3.0 -> branches/cxxconversion
  + backport some immediate 3.0 functionality for 2.2
  + other stuff
2007-01-24 22:40:21 -08:00

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/*
* 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) 2002-2005 ircd-ratbox development team
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
* $Id: balloc.c 388 2005-12-07 16:34:40Z nenolod $
*/
/*
* 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. 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.
*
* Of course it is up to the caller to make sure BlockHeapGarbageCollect() gets
* called periodically to do this cleanup, otherwise you'll keep the memory in the
* process.
*
*
*/
#include "stdinc.h"
#include "libcharybdis.h"
#define WE_ARE_MEMORY_C
#include "setup.h"
#include "balloc.h"
#ifndef NOBALLOC
#include "ircd_defs.h" /* DEBUG_BLOCK_ALLOCATOR */
#include "ircd.h"
#include "memory.h"
#include "irc_string.h"
#include "tools.h"
#include "s_log.h"
#include "client.h"
#include "event.h"
#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
static int newblock(BlockHeap * bh);
static int BlockHeapGarbageCollect(BlockHeap *);
static void block_heap_gc(void *unused);
static dlink_list heap_lists;
#if defined(HAVE_MMAP) && !defined(MAP_ANON)
static int zero_fd = -1;
#endif
#define blockheap_fail(x) _blockheap_fail(x, __FILE__, __LINE__)
static void
_blockheap_fail(const char *reason, const char *file, int line)
{
libcharybdis_log("Blockheap failure: %s (%s:%d)", reason, file, line);
abort();
}
/*
* 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
free(ptr);
#endif
}
#ifdef DEBUG_BALLOC
/* Check the list length the very slow way */
static unsigned long
slow_list_length(dlink_list *list)
{
dlink_node *ptr;
unsigned long count = 0;
for (ptr = list->head; ptr; ptr = ptr->next)
{
count++;
if(count > list->length * 2)
{
blockheap_fail("count > list->length * 2 - I give up");
}
}
return count;
}
static void
bh_sanity_check_block(BlockHeap *bh, Block *block)
{
unsigned long s_used, s_free;
s_used = slow_list_length(&block->used_list);
s_free = slow_list_length(&block->free_list);
if(s_used != dlink_list_length(&block->used_list))
blockheap_fail("used link count doesn't match head count");
if(s_free != dlink_list_length(&block->free_list))
blockheap_fail("free link count doesn't match head count");
if(dlink_list_length(&block->used_list) + dlink_list_length(&block->free_list) != bh->elemsPerBlock)
blockheap_fail("used_list + free_list != elemsPerBlock");
}
#if 0
/* See how confused we are */
static void
bh_sanity_check(BlockHeap *bh)
{
Block *walker;
unsigned long real_alloc = 0;
unsigned long s_used, s_free;
unsigned long blockcount = 0;
unsigned long allocated;
if(bh == NULL)
blockheap_fail("Trying to sanity check a NULL block");
allocated = bh->blocksAllocated * bh->elemsPerBlock;
for(walker = bh->base; walker != NULL; walker = walker->next)
{
blockcount++;
s_used = slow_list_length(&walker->used_list);
s_free = slow_list_length(&walker->free_list);
if(s_used != dlink_list_length(&walker->used_list))
blockheap_fail("used link count doesn't match head count");
if(s_free != dlink_list_length(&walker->free_list))
blockheap_fail("free link count doesn't match head count");
if(dlink_list_length(&walker->used_list) + dlink_list_length(&walker->free_list) != bh->elemsPerBlock)
blockheap_fail("used_list + free_list != elemsPerBlock");
real_alloc += dlink_list_length(&walker->used_list);
real_alloc += dlink_list_length(&walker->free_list);
}
if(allocated != real_alloc)
blockheap_fail("block allocations don't match heap");
if(bh->blocksAllocated != blockcount)
blockheap_fail("blocksAllocated don't match blockcount");
}
static void
bh_sanity_check_all(void *unused)
{
dlink_node *ptr;
DLINK_FOREACH(ptr, heap_lists.head)
{
bh_sanity_check(ptr->data);
}
}
#endif
#endif
/*
* void initBlockHeap(void)
*
* Inputs: None
* Outputs: None
* Side Effects: Initializes the block heap
*/
void
initBlockHeap(void)
{
#if defined(HAVE_MMAP) && !defined(MAP_ANON)
zero_fd = open("/dev/zero", O_RDWR);
if(zero_fd < 0)
blockheap_fail("Failed opening /dev/zero");
comm_socket(zero_fd, FD_FILE, "Anonymous mmap()");
#endif
eventAddIsh("block_heap_gc", block_heap_gc, NULL, 30);
}
/*
* 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
ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, zero_fd, 0);
#endif
if(ptr == MAP_FAILED)
{
ptr = NULL;
}
#else
ptr = malloc(size);
#endif
return (ptr);
}
static void
block_heap_gc(void *unused)
{
dlink_node *ptr;
DLINK_FOREACH(ptr, heap_lists.head)
{
BlockHeapGarbageCollect(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(BlockHeap * bh)
{
MemBlock *newblk;
Block *b;
unsigned long i;
void *offset;
/* Setup the initial data structure. */
b = (Block *) calloc(1, sizeof(Block));
if(b == NULL)
{
return (1);
}
b->free_list.head = b->free_list.tail = NULL;
b->used_list.head = b->used_list.tail = NULL;
b->next = bh->base;
b->alloc_size = (bh->elemsPerBlock + 1) * (bh->elemSize + sizeof(MemBlock));
b->elems = get_block(b->alloc_size);
if(b->elems == NULL)
{
return (1);
}
offset = b->elems;
/* Setup our blocks now */
for (i = 0; i < bh->elemsPerBlock; i++)
{
void *data;
newblk = (void *) offset;
newblk->block = b;
#ifdef DEBUG_BALLOC
newblk->magic = BALLOC_MAGIC;
#endif
data = (void *) ((size_t) offset + sizeof(MemBlock));
newblk->block = b;
dlinkAdd(data, &newblk->self, &b->free_list);
offset = (unsigned char *) ((unsigned char *) offset +
bh->elemSize + sizeof(MemBlock));
}
++bh->blocksAllocated;
bh->freeElems += bh->elemsPerBlock;
bh->base = b;
return (0);
}
/* ************************************************************************ */
/* FUNCTION DOCUMENTATION: */
/* BlockHeapCreate */
/* 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 BlockHeap, or NULL if unsuccessful */
/* ************************************************************************ */
BlockHeap *
BlockHeapCreate(size_t elemsize, int elemsperblock)
{
BlockHeap *bh;
s_assert(elemsize > 0 && elemsperblock > 0);
/* Catch idiotic requests up front */
if((elemsize <= 0) || (elemsperblock <= 0))
{
blockheap_fail("Attempting to BlockHeapCreate idiotic sizes");
}
/* Allocate our new BlockHeap */
bh = (BlockHeap *) calloc(1, sizeof(BlockHeap));
if(bh == NULL)
{
blockheap_fail("Attempt to calloc() failed");
outofmemory(); /* die.. out of memory */
}
if((elemsize % sizeof(void *)) != 0)
{
/* Pad to even pointer boundary */
elemsize += sizeof(void *);
elemsize &= ~(sizeof(void *) - 1);
}
bh->elemSize = elemsize;
bh->elemsPerBlock = elemsperblock;
bh->blocksAllocated = 0;
bh->freeElems = 0;
bh->base = NULL;
/* Be sure our malloc was successful */
if(newblock(bh))
{
if(bh != NULL)
free(bh);
libcharybdis_restart("Aiee! -- newblock() failed!!!");
}
if(bh == NULL)
{
blockheap_fail("bh == NULL when it shouldn't be");
}
dlinkAdd(bh, &bh->hlist, &heap_lists);
return (bh);
}
/* ************************************************************************ */
/* FUNCTION DOCUMENTATION: */
/* BlockHeapAlloc */
/* Description: */
/* Returns a pointer to a struct within our BlockHeap that's free for */
/* the taking. */
/* Parameters: */
/* bh (IN): Pointer to the Blockheap. */
/* Returns: */
/* Pointer to a structure (void *), or NULL if unsuccessful. */
/* ************************************************************************ */
void *
BlockHeapAlloc(BlockHeap * bh)
{
Block *walker;
dlink_node *new_node;
s_assert(bh != NULL);
if(bh == NULL)
{
blockheap_fail("Cannot allocate if bh == NULL");
}
if(bh->freeElems == 0)
{
/* Allocate new block and assign */
/* newblock returns 1 if unsuccessful, 0 if not */
if(newblock(bh))
{
/* That didn't work..try to garbage collect */
BlockHeapGarbageCollect(bh);
if(bh->freeElems == 0)
{
libcharybdis_restart("newblock() failed and garbage collection didn't help");
}
}
}
for (walker = bh->base; walker != NULL; walker = walker->next)
{
if(dlink_list_length(&walker->free_list) > 0)
{
#ifdef DEBUG_BALLOC
bh_sanity_check_block(bh, walker);
#endif
bh->freeElems--;
new_node = walker->free_list.head;
dlinkMoveNode(new_node, &walker->free_list, &walker->used_list);
s_assert(new_node->data != NULL);
if(new_node->data == NULL)
blockheap_fail("new_node->data is NULL and that shouldn't happen!!!");
memset(new_node->data, 0, bh->elemSize);
#ifdef DEBUG_BALLOC
do
{
struct MemBlock *memblock = (void *) ((size_t) new_node->data - sizeof(MemBlock));
if(memblock->magic == BALLOC_FREE_MAGIC)
memblock->magic = BALLOC_MAGIC;
} while(0);
bh_sanity_check_block(bh, walker);
#endif
return (new_node->data);
}
}
blockheap_fail("BlockHeapAlloc failed, giving up");
return NULL;
}
/* ************************************************************************ */
/* FUNCTION DOCUMENTATION: */
/* BlockHeapFree */
/* Description: */
/* Returns an element to the free pool, does not free() */
/* Parameters: */
/* bh (IN): Pointer to BlockHeap containing element */
/* ptr (in): Pointer to element to be "freed" */
/* Returns: */
/* 0 if successful, 1 if element not contained within BlockHeap. */
/* ************************************************************************ */
int
BlockHeapFree(BlockHeap * bh, void *ptr)
{
Block *block;
struct MemBlock *memblock;
s_assert(bh != NULL);
s_assert(ptr != NULL);
if(bh == NULL)
{
libcharybdis_restart("balloc.c:BlockHeapFree() bh == NULL");
return (1);
}
if(ptr == NULL)
{
libcharybdis_restart("balloc.BlockHeapFree() ptr == NULL");
return (1);
}
memblock = (void *) ((size_t) ptr - sizeof(MemBlock));
#ifdef DEBUG_BALLOC
if(memblock->magic == BALLOC_FREE_MAGIC)
{
blockheap_fail("double free of a block");
outofmemory();
} else
if(memblock->magic != BALLOC_MAGIC)
{
blockheap_fail("memblock->magic != BALLOC_MAGIC");
outofmemory();
}
#endif
s_assert(memblock->block != NULL);
if(memblock->block == NULL)
{
blockheap_fail("memblock->block == NULL, not a valid block?");
outofmemory();
}
block = memblock->block;
#ifdef DEBUG_BALLOC
bh_sanity_check_block(bh, block);
#endif
bh->freeElems++;
mem_frob(ptr, bh->elemSize);
dlinkMoveNode(&memblock->self, &block->used_list, &block->free_list);
#ifdef DEBUG_BALLOC
bh_sanity_check_block(bh, block);
#endif
return (0);
}
/* ************************************************************************ */
/* FUNCTION DOCUMENTATION: */
/* BlockHeapGarbageCollect */
/* Description: */
/* Performs garbage collection on the block heap. Any blocks that are */
/* completely unallocated are removed from the heap. Garbage collection */
/* will never remove the root node of the heap. */
/* Parameters: */
/* bh (IN): Pointer to the BlockHeap to be cleaned up */
/* Returns: */
/* 0 if successful, 1 if bh == NULL */
/* ************************************************************************ */
static int
BlockHeapGarbageCollect(BlockHeap * bh)
{
Block *walker, *last;
if(bh == NULL)
{
return (1);
}
if(bh->freeElems < bh->elemsPerBlock || bh->blocksAllocated == 1)
{
/* There couldn't possibly be an entire free block. Return. */
return (0);
}
last = NULL;
walker = bh->base;
while (walker != NULL)
{
if((dlink_list_length(&walker->free_list) == bh->elemsPerBlock) != 0)
{
free_block(walker->elems, walker->alloc_size);
if(last != NULL)
{
last->next = walker->next;
if(walker != NULL)
free(walker);
walker = last->next;
}
else
{
bh->base = walker->next;
if(walker != NULL)
free(walker);
walker = bh->base;
}
bh->blocksAllocated--;
bh->freeElems -= bh->elemsPerBlock;
}
else
{
last = walker;
walker = walker->next;
}
}
return (0);
}
/* ************************************************************************ */
/* FUNCTION DOCUMENTATION: */
/* BlockHeapDestroy */
/* Description: */
/* Completely free()s a BlockHeap. Use for cleanup. */
/* Parameters: */
/* bh (IN): Pointer to the BlockHeap to be destroyed. */
/* Returns: */
/* 0 if successful, 1 if bh == NULL */
/* ************************************************************************ */
int
BlockHeapDestroy(BlockHeap * bh)
{
Block *walker, *next;
if(bh == NULL)
{
return (1);
}
for (walker = bh->base; walker != NULL; walker = next)
{
next = walker->next;
free_block(walker->elems, walker->alloc_size);
if(walker != NULL)
free(walker);
}
dlinkDelete(&bh->hlist, &heap_lists);
free(bh);
return (0);
}
void
BlockHeapUsage(BlockHeap * bh, size_t * bused, size_t * bfree, size_t * bmemusage)
{
size_t used;
size_t freem;
size_t memusage;
if(bh == NULL)
{
return;
}
freem = bh->freeElems;
used = (bh->blocksAllocated * bh->elemsPerBlock) - bh->freeElems;
memusage = used * (bh->elemSize + sizeof(MemBlock));
if(bused != NULL)
*bused = used;
if(bfree != NULL)
*bfree = freem;
if(bmemusage != NULL)
*bmemusage = memusage;
}
#endif /* NOBALLOC */
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