text: /** @file
  
    A brief file description
  
    @section license License
  
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
  
        http://www.apache.org/licenses/LICENSE-2.0
  
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
   */
  
  #pragma once
  
  /***********************************************************************
  
      Generic Queue Implementation (for pointer data types only)
  
      Uses atomic memory operations to avoid blocking.
      Intended as a replacement for llqueue.
  
  
  ***********************************************************************/
  
  #include "tscore/ink_platform.h"
  #include "tscore/ink_defs.h"
  #include "tscore/ink_apidefs.h"
  
  /*
    For information on the structure of the x86_64 memory map:
  
    http://en.wikipedia.org/wiki/X86-64#Linux
  
    Essentially, in the current 48-bit implementations, the
    top bit as well as the  lower 47 bits are used, leaving
    the upper-but one 16 bits free to be used for the version.
    We will use the top-but-one 15 and sign extend when generating
    the pointer was required by the standard.
  */
  
  /*
  #if defined(POSIX_THREAD)
  #include <pthread.h>
  #include <stdlib.h>
  #endif
  */
  
  #ifdef __cplusplus
  extern "C" {
  #endif /* __cplusplus */
  
  void ink_queue_load_64(void *dst, void *src);
  
  #ifdef __x86_64__
  #define INK_QUEUE_LD64(dst, src) *((uint64_t *)&(dst)) = *((uint64_t *)&(src))
  #else
  #define INK_QUEUE_LD64(dst, src) (ink_queue_load_64((void *)&(dst), (void *)&(src)))
  #endif
  
  #if TS_HAS_128BIT_CAS
  #define INK_QUEUE_LD(dst, src)                                                       \
    do {                                                                               \
      *(__int128_t *)&(dst) = __sync_val_compare_and_swap((__int128_t *)&(src), 0, 0); \
    } while (0)
  #else
  #define INK_QUEUE_LD(dst, src) INK_QUEUE_LD64(dst, src)
  #endif
  
  /*
   * Generic Free List Manager
   */
  // Warning: head_p is read and written in multiple threads without a
  // lock, use INK_QUEUE_LD to read safely.
  union head_p {
    head_p() : data(){};
  
  #if (defined(__i386__) || defined(__arm__) || defined(__mips__)) && (SIZEOF_VOIDP == 4)
    typedef int32_t version_type;
    typedef int64_t data_type;
  #elif TS_HAS_128BIT_CAS
    typedef int64_t version_type;
    typedef __int128_t data_type;
  #else
    typedef int64_t version_type;
    typedef int64_t data_type;
  #endif
  
    struct {
      void *pointer;
      version_type version;
    } s;
  
    data_type data;
  };
  
  /*
   * Why is version required? One scenario is described below
   * Think of a list like this -> A -> C -> D
   * and you are popping from the list
   * Between the time you take the ptr(A) and swap the head pointer
   * the list could start looking like this
   * -> A -> B -> C -> D
   * If the version check is not there, the list will look like
   * -> C -> D after the pop, which will result in the loss of "B"
   *
   * For more information, see:  https://en.wikipedia.org/wiki/ABA_problem .
   * (Versioning is a case of the "tagged state reference" workaround.)
   */
  #define ZERO_HEAD_P(_x)
  
  #ifdef DEBUG
  #define FROM_PTR(_x) (void *)(((uintptr_t)_x) + 1)
  #define TO_PTR(_x) (void *)(((uintptr_t)_x) - 1)
  #else
  #define FROM_PTR(_x) ((void *)(_x))
  #define TO_PTR(_x) ((void *)(_x))
  #endif
  
  #if (defined(__i386__) || defined(__arm__) || defined(__mips__)) && (SIZEOF_VOIDP == 4)
  #define FREELIST_POINTER(_x) (_x).s.pointer
  #define FREELIST_VERSION(_x) (_x).s.version
  #define SET_FREELIST_POINTER_VERSION(_x, _p, _v) \
    (_x).s.pointer = _p;                           \
    (_x).s.version = _v
  #elif TS_HAS_128BIT_CAS
  #define FREELIST_POINTER(_x) (_x).s.pointer
  #define FREELIST_VERSION(_x) (_x).s.version
  #define SET_FREELIST_POINTER_VERSION(_x, _p, _v) \
    (_x).s.pointer = _p;                           \
    (_x).s.version = _v
  #elif defined(__x86_64__) || defined(__ia64__) || defined(__powerpc64__) || defined(__aarch64__) || defined(__mips64)
  /* Layout of FREELIST_POINTER
   *
   *  0 ~ 47 bits : 48 bits, Virtual Address (47 bits for AMD64 and 48 bits for AArch64)
   * 48 ~ 62 bits : 15 bits, Freelist Version
   *      63 bits :  1 bits, The type of Virtual Address (0 = user space, 1 = kernel space)
   */
  /* Detect which shift is implemented by the simple expression ((~0 >> 1) < 0):
   *
   * If the shift is 'logical' the highest order bit of the left side of the comparison is 0 so the result is positive.
   * If the shift is 'arithmetic' the highest order bit of the left side is 1 so the result is negative.
   */
  #if ((~0 >> 1) < 0)
  /* the shift is `arithmetic' */
  #define FREELIST_POINTER(_x) \
    ((void *)((((intptr_t)(_x).data) & 0x0000FFFFFFFFFFFFLL) | ((((intptr_t)(_x).data) >> 63) << 48))) // sign extend
  #else
  /* the shift is `logical' */
  #define FREELIST_POINTER(_x) \
    ((void *)((((intptr_t)(_x).data) & 0x0000FFFFFFFFFFFFLL) | (((~((((intptr_t)(_x).data) >> 63) - 1)) >> 48) << 48)))
  #endif
  
  #define FREELIST_VERSION(_x) ((((intptr_t)(_x).data) & 0x7FFF000000000000LL) >> 48)
  #define SET_FREELIST_POINTER_VERSION(_x, _p, _v) (_x).data = ((((intptr_t)(_p)) & 0x8000FFFFFFFFFFFFLL) | (((_v)&0x7FFFLL) << 48))
  #else
  #error "unsupported processor"
  #endif
  
  struct _InkFreeList {
    head_p head;
    const char *name;
    uint32_t type_size, chunk_size, used, allocated, alignment;
    uint32_t allocated_base, used_base;
    int advice;
  };
  
  typedef struct ink_freelist_ops InkFreeListOps;
  typedef struct _InkFreeList InkFreeList;
  
  const InkFreeListOps *ink_freelist_malloc_ops();
  const InkFreeListOps *ink_freelist_freelist_ops();
  void ink_freelist_init_ops(int nofl_class, int nofl_proxy);
  
  /*
   * alignment must be a power of 2
   */
  InkFreeList *ink_freelist_create(const char *name, uint32_t type_size, uint32_t chunk_size, uint32_t alignment);
  
  inkcoreapi void ink_freelist_init(InkFreeList **fl, const char *name, uint32_t type_size, uint32_t chunk_size, uint32_t alignment);
  inkcoreapi void ink_freelist_madvise_init(InkFreeList **fl, const char *name, uint32_t type_size, uint32_t chunk_size,
                                            uint32_t alignment, int advice);
  inkcoreapi void *ink_freelist_new(InkFreeList *f);
  inkcoreapi void ink_freelist_free(InkFreeList *f, void *item);
  inkcoreapi void ink_freelist_free_bulk(InkFreeList *f, void *head, void *tail, size_t num_item);
  void ink_freelists_dump(FILE *f);
  void ink_freelists_dump_baselinerel(FILE *f);
  void ink_freelists_snap_baseline();
  
  struct InkAtomicList {
    InkAtomicList() {}
    head_p head{};
    const char *name = nullptr;
    uint32_t offset  = 0;
  };
  
  #if !defined(INK_QUEUE_NT)
  #define INK_ATOMICLIST_EMPTY(_x) (!(TO_PTR(FREELIST_POINTER((_x.head)))))
  #else
  /* ink_queue_nt.c doesn't do the FROM/TO pointer swizzling */
  #define INK_ATOMICLIST_EMPTY(_x) (!((FREELIST_POINTER((_x.head)))))
  #endif
  
  inkcoreapi void ink_atomiclist_init(InkAtomicList *l, const char *name, uint32_t offset_to_next);
  inkcoreapi void *ink_atomiclist_push(InkAtomicList *l, void *item);
  void *ink_atomiclist_pop(InkAtomicList *l);
  inkcoreapi void *ink_atomiclist_popall(InkAtomicList *l);
  /*
   * WARNING WARNING WARNING WARNING WARNING WARNING WARNING
   * only if only one thread is doing pops it is possible to have a "remove"
   * which only that thread can use as well.
   * WARNING WARNING WARNING WARNING WARNING WARNING WARNING
   */
  void *ink_atomiclist_remove(InkAtomicList *l, void *item);
  
  #ifdef __cplusplus
  }
  #endif /* __cplusplus */
  