/// \copyright SPDX-License-Identifier: Apache-2.0
/// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2015-2024

#include "internals.h"

static inline size_t txl_size2bytes(const size_t size) {
  assert(size > 0 && size <= txl_max * 2);
  size_t bytes =
      ceil_powerof2(MDBX_ASSUME_MALLOC_OVERHEAD + sizeof(txnid_t) * (size + 2), txl_granulate * sizeof(txnid_t)) -
      MDBX_ASSUME_MALLOC_OVERHEAD;
  return bytes;
}

static inline size_t txl_bytes2size(const size_t bytes) {
  size_t size = bytes / sizeof(txnid_t);
  assert(size > 2 && size <= txl_max * 2);
  return size - 2;
}

MDBX_INTERNAL txl_t txl_alloc(void) {
  size_t bytes = txl_size2bytes(txl_initial);
  txl_t txl = osal_malloc(bytes);
  if (likely(txl)) {
#if __GLIBC_PREREQ(2, 12) || defined(__FreeBSD__) || defined(malloc_usable_size)
    bytes = malloc_usable_size(txl);
#endif /* malloc_usable_size */
    txl[0] = txl_bytes2size(bytes);
    assert(txl[0] >= txl_initial);
    txl += 1;
    *txl = 0;
  }
  return txl;
}

MDBX_INTERNAL void txl_free(txl_t txl) {
  if (likely(txl))
    osal_free(txl - 1);
}

MDBX_INTERNAL int txl_reserve(txl_t __restrict *__restrict ptxl, const size_t wanna) {
  const size_t allocated = (size_t)MDBX_PNL_ALLOCLEN(*ptxl);
  assert(MDBX_PNL_GETSIZE(*ptxl) <= txl_max && MDBX_PNL_ALLOCLEN(*ptxl) >= MDBX_PNL_GETSIZE(*ptxl));
  if (likely(allocated >= wanna))
    return MDBX_SUCCESS;

  if (unlikely(wanna > /* paranoia */ txl_max)) {
    ERROR("TXL too long (%zu > %zu)", wanna, (size_t)txl_max);
    return MDBX_TXN_FULL;
  }

  const size_t size = (wanna + wanna - allocated < txl_max) ? wanna + wanna - allocated : txl_max;
  size_t bytes = txl_size2bytes(size);
  txl_t txl = osal_realloc(*ptxl - 1, bytes);
  if (likely(txl)) {
#if __GLIBC_PREREQ(2, 12) || defined(__FreeBSD__) || defined(malloc_usable_size)
    bytes = malloc_usable_size(txl);
#endif /* malloc_usable_size */
    *txl = txl_bytes2size(bytes);
    assert(*txl >= wanna);
    *ptxl = txl + 1;
    return MDBX_SUCCESS;
  }
  return MDBX_ENOMEM;
}

static __always_inline int __must_check_result txl_need(txl_t __restrict *__restrict ptxl, size_t num) {
  assert(MDBX_PNL_GETSIZE(*ptxl) <= txl_max && MDBX_PNL_ALLOCLEN(*ptxl) >= MDBX_PNL_GETSIZE(*ptxl));
  assert(num <= PAGELIST_LIMIT);
  const size_t wanna = (size_t)MDBX_PNL_GETSIZE(*ptxl) + num;
  return likely(MDBX_PNL_ALLOCLEN(*ptxl) >= wanna) ? MDBX_SUCCESS : txl_reserve(ptxl, wanna);
}

static __always_inline void txl_xappend(txl_t __restrict txl, txnid_t id) {
  assert(MDBX_PNL_GETSIZE(txl) < MDBX_PNL_ALLOCLEN(txl));
  txl[0] += 1;
  MDBX_PNL_LAST(txl) = id;
}

#define TXNID_SORT_CMP(first, last) ((first) > (last))
SORT_IMPL(txnid_sort, false, txnid_t, TXNID_SORT_CMP)
MDBX_INTERNAL void txl_sort(txl_t txl) { txnid_sort(MDBX_PNL_BEGIN(txl), MDBX_PNL_END(txl)); }

MDBX_INTERNAL int __must_check_result txl_append(txl_t __restrict *ptxl, txnid_t id) {
  if (unlikely(MDBX_PNL_GETSIZE(*ptxl) == MDBX_PNL_ALLOCLEN(*ptxl))) {
    int rc = txl_need(ptxl, txl_granulate);
    if (unlikely(rc != MDBX_SUCCESS))
      return rc;
  }
  txl_xappend(*ptxl, id);
  return MDBX_SUCCESS;
}