/*
 *	UCW Library -- Memory Pools (One-Time Allocation)
 *
 *	(c) 1997--2001 Martin Mares <mj@ucw.cz>
 *	(c) 2007 Pavel Charvat <pchar@ucw.cz>
 *
 *	This software may be freely distributed and used according to the terms
 *	of the GNU Lesser General Public License.
 */

#include <config.h>

#undef LOCAL_DEBUG

#include "common/mempool.h"
#include "common/mempattern.h"

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>

/** \todo This shouldn't be precalculated, but computed on load. */
#define CPU_PAGE_SIZE 4096
/** Align an integer @s to the nearest higher multiple of @a (which should be a power of two) **/
#define ALIGN_TO(s, a) (((s)+a-1)&~(a-1))
#define MP_CHUNK_TAIL ALIGN_TO(sizeof(struct mempool_chunk), CPU_STRUCT_ALIGN)
#define MP_SIZE_MAX (~0U - MP_CHUNK_TAIL - CPU_PAGE_SIZE)
#ifndef MAX
#define MAX(a, b) \
	({ typeof (a) _a = (a); typeof (b) _b = (b); _a > _b ? _a : _b; })
#endif
#define DBG(s...)

struct mempool_chunk {
  struct mempool_chunk *next;
  unsigned size;
};

static unsigned
mp_align_size(unsigned size)
{
#ifdef CONFIG_UCW_POOL_IS_MMAP
  return ALIGN_TO(size + MP_CHUNK_TAIL, CPU_PAGE_SIZE) - MP_CHUNK_TAIL;
#else
  return ALIGN_TO(size, CPU_STRUCT_ALIGN);
#endif
}

void
mp_init(struct mempool *pool, unsigned chunk_size)
{
  chunk_size = mp_align_size(MAX(sizeof(struct mempool), chunk_size));
  *pool = (struct mempool) {
    .chunk_size = chunk_size,
    .threshold = chunk_size >> 1,
    .last_big = &pool->last_big };
}

static void *
mp_new_big_chunk(unsigned size)
{
  struct mempool_chunk *chunk;
  chunk = xmalloc(size + MP_CHUNK_TAIL) + size;
  chunk->size = size;
  return chunk;
}

static void
mp_free_big_chunk(struct mempool_chunk *chunk)
{
  free((void *)chunk - chunk->size);
}

static void *
mp_new_chunk(unsigned size)
{
#ifdef CONFIG_UCW_POOL_IS_MMAP
  struct mempool_chunk *chunk;
  chunk = page_alloc(size + MP_CHUNK_TAIL) + size;
  chunk->size = size;
  return chunk;
#else
  return mp_new_big_chunk(size);
#endif
}

static void
mp_free_chunk(struct mempool_chunk *chunk)
{
#ifdef CONFIG_UCW_POOL_IS_MMAP
  page_free((void *)chunk - chunk->size, chunk->size + MP_CHUNK_TAIL);
#else
  mp_free_big_chunk(chunk);
#endif
}

struct mempool *
mp_new(unsigned chunk_size)
{
  chunk_size = mp_align_size(MAX(sizeof(struct mempool), chunk_size));
  struct mempool_chunk *chunk = mp_new_chunk(chunk_size);
  struct mempool *pool = (void *)chunk - chunk_size;
  DBG("Creating mempool %p with %u bytes long chunks", pool, chunk_size);
  chunk->next = NULL;
  *pool = (struct mempool) {
    .state = { .free = { chunk_size - sizeof(*pool) }, .last = { chunk } },
    .chunk_size = chunk_size,
    .threshold = chunk_size >> 1,
    .last_big = &pool->last_big };
  return pool;
}

static void
mp_free_chain(struct mempool_chunk *chunk)
{
  while (chunk)
    {
      struct mempool_chunk *next = chunk->next;
      mp_free_chunk(chunk);
      chunk = next;
    }
}

static void
mp_free_big_chain(struct mempool_chunk *chunk)
{
  while (chunk)
    {
      struct mempool_chunk *next = chunk->next;
      mp_free_big_chunk(chunk);
      chunk = next;
    }
}

void
mp_delete(struct mempool *pool)
{
  DBG("Deleting mempool %p", pool);
  mp_free_big_chain(pool->state.last[1]);
  mp_free_chain(pool->unused);
  mp_free_chain(pool->state.last[0]); // can contain the mempool structure
}

void
mp_flush(struct mempool *pool)
{
  mp_free_big_chain(pool->state.last[1]);
  struct mempool_chunk *chunk, *next;
  for (chunk = pool->state.last[0]; chunk && (void *)chunk - chunk->size != pool; chunk = next)
    {
      next = chunk->next;
      chunk->next = pool->unused;
      pool->unused = chunk;
    }
  pool->state.last[0] = chunk;
  pool->state.free[0] = chunk ? chunk->size - sizeof(*pool) : 0;
  pool->state.last[1] = NULL;
  pool->state.free[1] = 0;
  pool->state.next = NULL;
  pool->last_big = &pool->last_big;
}

static void
mp_stats_chain(struct mempool_chunk *chunk, struct mempool_stats *stats, unsigned idx)
{
  while (chunk)
    {
      stats->chain_size[idx] += chunk->size + sizeof(*chunk);
      stats->chain_count[idx]++;
      chunk = chunk->next;
    }
  stats->total_size += stats->chain_size[idx];
}

void
mp_stats(struct mempool *pool, struct mempool_stats *stats)
{
  bzero(stats, sizeof(*stats));
  mp_stats_chain(pool->state.last[0], stats, 0);
  mp_stats_chain(pool->state.last[1], stats, 1);
  mp_stats_chain(pool->unused, stats, 2);
}

uint64_t
mp_total_size(struct mempool *pool)
{
  struct mempool_stats stats;
  mp_stats(pool, &stats);
  return stats.total_size;
}

void *
mp_alloc_internal(struct mempool *pool, unsigned size)
{
  struct mempool_chunk *chunk;
  if (size <= pool->threshold)
    {
      pool->idx = 0;
      if (pool->unused)
        {
	  chunk = pool->unused;
	  pool->unused = chunk->next;
	}
      else
	chunk = mp_new_chunk(pool->chunk_size);
      chunk->next = pool->state.last[0];
      pool->state.last[0] = chunk;
      pool->state.free[0] = pool->chunk_size - size;
      return (void *)chunk - pool->chunk_size;
    }
  else if (size <= MP_SIZE_MAX)
    {
      pool->idx = 1;
      unsigned aligned = ALIGN_TO(size, CPU_STRUCT_ALIGN);
      chunk = mp_new_big_chunk(aligned);
      chunk->next = pool->state.last[1];
      pool->state.last[1] = chunk;
      pool->state.free[1] = aligned - size;
      return pool->last_big = (void *)chunk - aligned;
    }
  else {
    fprintf(stderr, "Cannot allocate %u bytes from a mempool", size);
    assert(0);
    return NULL;
  }
}

void *
mp_alloc(struct mempool *pool, unsigned size)
{
  return mp_alloc_fast(pool, size);
}

void *
mp_alloc_noalign(struct mempool *pool, unsigned size)
{
  return mp_alloc_fast_noalign(pool, size);
}

void *
mp_alloc_zero(struct mempool *pool, unsigned size)
{
  void *ptr = mp_alloc_fast(pool, size);
  bzero(ptr, size);
  return ptr;
}

void *
mp_start_internal(struct mempool *pool, unsigned size)
{
  void *ptr = mp_alloc_internal(pool, size);
  pool->state.free[pool->idx] += size;
  return ptr;
}

void *
mp_start(struct mempool *pool, unsigned size)
{
  return mp_start_fast(pool, size);
}

void *
mp_start_noalign(struct mempool *pool, unsigned size)
{
  return mp_start_fast_noalign(pool, size);
}

void *
mp_grow_internal(struct mempool *pool, unsigned size)
{
  if (size > MP_SIZE_MAX) {
    fprintf(stderr, "Cannot allocate %u bytes of memory", size);
    assert(0);
  }
  unsigned avail = mp_avail(pool);
  void *ptr = mp_ptr(pool);
  if (pool->idx)
    {
      unsigned amortized = (avail <= MP_SIZE_MAX / 2) ? avail * 2 : MP_SIZE_MAX;
      amortized = MAX(amortized, size);
      amortized = ALIGN_TO(amortized, CPU_STRUCT_ALIGN);
      struct mempool_chunk *chunk = pool->state.last[1], *next = chunk->next;
      ptr = xrealloc(ptr, amortized + MP_CHUNK_TAIL);
      chunk = ptr + amortized;
      chunk->next = next;
      chunk->size = amortized;
      pool->state.last[1] = chunk;
      pool->state.free[1] = amortized;
      pool->last_big = ptr;
      return ptr;
    }
  else
    {
      void *p = mp_start_internal(pool, size);
      memcpy(p, ptr, avail);
      return p;
    }
}

unsigned
mp_open(struct mempool *pool, void *ptr)
{
  return mp_open_fast(pool, ptr);
}

void *
mp_realloc(struct mempool *pool, void *ptr, unsigned size)
{
  return mp_realloc_fast(pool, ptr, size);
}

void *
mp_realloc_zero(struct mempool *pool, void *ptr, unsigned size)
{
  unsigned old_size = mp_open_fast(pool, ptr);
  ptr = mp_grow(pool, size);
  if (size > old_size)
    bzero(ptr + old_size, size - old_size);
  mp_end(pool, ptr + size);
  return ptr;
}

void *
mp_spread_internal(struct mempool *pool, void *p, unsigned size)
{
  void *old = mp_ptr(pool);
  void *new = mp_grow_internal(pool, p-old+size);
  return p-old+new;
}