src/vppinfra/pool.h

   1 /*
   2  * Copyright (c) 2015 Cisco and/or its affiliates.
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15 /*
  16   Copyright (c) 2001, 2002, 2003, 2004 Eliot Dresselhaus
  17
  18   Permission is hereby granted, free of charge, to any person obtaining
  19   a copy of this software and associated documentation files (the
  20   "Software"), to deal in the Software without restriction, including
  21   without limitation the rights to use, copy, modify, merge, publish,
  22   distribute, sublicense, and/or sell copies of the Software, and to
  23   permit persons to whom the Software is furnished to do so, subject to
  24   the following conditions:
  25
  26   The above copyright notice and this permission notice shall be
  27   included in all copies or substantial portions of the Software.
  28
  29   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  30   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  31   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  32   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  33   LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  34   OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  35   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  36 */
  37 /** @file
  38  * @brief Fixed length block allocator.
  39    Pools are built from clib vectors and bitmaps. Use pools when
  40    repeatedly allocating and freeing fixed-size data. Pools are
  41    fast, and avoid memory fragmentation.
  42  */
  43
  44 #ifndef included_pool_h
  45 #define included_pool_h
  46
  47 #include <vppinfra/bitmap.h>
  48 #include <vppinfra/error.h>
  49
  50
  51 typedef struct
  52 {
  53   /** Bitmap of indices of free objects. */
  54   uword *free_bitmap;
  55
  56   /** Vector of free indices.  One element for each set bit in bitmap. */
  57   u32 *free_indices;
  58
  59   /* The following fields are set for fixed-size, preallocated pools */
  60
  61   /** Maximum size of the pool, in elements */
  62   u32 max_elts;
  63
  64 } pool_header_t;
  65
  66 /** Align pool header so that pointers are naturally aligned. */
  67 #define pool_aligned_header_bytes                                             \
  68   round_pow2 (sizeof (pool_header_t), sizeof (void *))
  69
  70 /** Get pool header from user pool pointer */
  71 always_inline pool_header_t *
  72 pool_header (void *v)
  73 {
  74   return vec_aligned_header (v, sizeof (pool_header_t), sizeof (void *));
  75 }
  76
  77 extern void _pool_init_fixed (void **, u32, u32);
  78 extern void fpool_free (void *);
  79
  80 /** initialize a fixed-size, preallocated pool */
  81 #define pool_init_fixed(pool,max_elts)                  \
  82 {                                                       \
  83   _pool_init_fixed((void **)&(pool),sizeof(pool[0]),max_elts);  \
  84 }
  85
  86 /** Validate a pool */
  87 always_inline void
  88 pool_validate (void *v)
  89 {
  90   pool_header_t *p = pool_header (v);
  91   uword i, n_free_bitmap;
  92
  93   if (!v)
  94     return;
  95
  96   n_free_bitmap = clib_bitmap_count_set_bits (p->free_bitmap);
  97   ASSERT (n_free_bitmap == vec_len (p->free_indices));
  98   for (i = 0; i < vec_len (p->free_indices); i++)
  99     ASSERT (clib_bitmap_get (p->free_bitmap, p->free_indices[i]) == 1);
 100 }
 101
 102 always_inline void
 103 pool_header_validate_index (void *v, uword index)
 104 {
 105   pool_header_t *p = pool_header (v);
 106
 107   if (v)
 108     vec_validate (p->free_bitmap, index / BITS (uword));
 109 }
 110
 111 #define pool_validate_index(v,i)                                \
 112 do {                                                            \
 113   uword __pool_validate_index = (i);                            \
 114   vec_validate_ha ((v), __pool_validate_index,                  \
 115                    pool_aligned_header_bytes, /* align */ 0);   \
 116   pool_header_validate_index ((v), __pool_validate_index);      \
 117 } while (0)
 118
 119 /** Number of active elements in a pool.
 120  * @return Number of active elements in a pool
 121  */
 122 always_inline uword
 123 pool_elts (void *v)
 124 {
 125   uword ret = vec_len (v);
 126   if (v)
 127     ret -= vec_len (pool_header (v)->free_indices);
 128   return ret;
 129 }
 130
 131 /** Number of elements in pool vector.
 132
 133     @note You probably want to call pool_elts() instead.
 134 */
 135 #define pool_len(p)     vec_len(p)
 136
 137 /** Number of elements in pool vector (usable as an lvalue)
 138
 139     @note You probably don't want to use this macro.
 140 */
 141 #define _pool_len(p)    _vec_len(p)
 142
 143 /** Memory usage of pool header. */
 144 always_inline uword
 145 pool_header_bytes (void *v)
 146 {
 147   pool_header_t *p = pool_header (v);
 148
 149   if (!v)
 150     return 0;
 151
 152   return vec_bytes (p->free_bitmap) + vec_bytes (p->free_indices);
 153 }
 154
 155 /** Memory usage of pool. */
 156 #define pool_bytes(P) (vec_bytes (P) + pool_header_bytes (P))
 157
 158 /** Local variable naming macro. */
 159 #define _pool_var(v) _pool_##v
 160
 161 /** Number of elements that can fit into pool with current allocation */
 162 #define pool_max_len(P) vec_max_len (P)
 163
 164 /** Number of free elements in pool */
 165 #define pool_free_elts(P)                                                     \
 166   ({                                                                          \
 167     pool_header_t *_pool_var (p) = pool_header (P);                           \
 168     uword n_free = 0;                                                         \
 169     if (P)                                                                    \
 170       {                                                                       \
 171         n_free += vec_len (_pool_var (p)->free_indices);                      \
 172         /* Fixed-size pools have max_elts set non-zero */                     \
 173         if (_pool_var (p)->max_elts == 0)                                     \
 174           n_free += pool_max_len (P) - vec_len (P);                           \
 175       }                                                                       \
 176     n_free;                                                                   \
 177   })
 178
 179 /** Allocate an object E from a pool P (general version).
 180
 181    First search free list.  If nothing is free extend vector of objects.
 182 */
 183 #define _pool_get_aligned_internal_numa(P,E,A,Z,N)                      \
 184 do {                                                                    \
 185   pool_header_t * _pool_var (p) = pool_header (P);                      \
 186   uword _pool_var (l);                                                  \
 187                                                                         \
 188   STATIC_ASSERT(A==0 || ((A % sizeof(P[0]))==0)                         \
 189                 || ((sizeof(P[0]) % A) == 0),                           \
 190                 "Pool aligned alloc of incorrectly sized object");      \
 191   _pool_var (l) = 0;                                                    \
 192   if (P)                                                                \
 193     _pool_var (l) = vec_len (_pool_var (p)->free_indices);              \
 194                                                                         \
 195   if (_pool_var (l) > 0)                                                \
 196     {                                                                   \
 197       /* Return free element from free list. */                         \
 198       uword _pool_var (i) =                                             \
 199         _pool_var (p)->free_indices[_pool_var (l) - 1];                 \
 200       (E) = (P) + _pool_var (i);                                        \
 201       _pool_var (p)->free_bitmap =                                      \
 202         clib_bitmap_andnoti_notrim (_pool_var (p)->free_bitmap,         \
 203                                      _pool_var (i));                    \
 204       _vec_len (_pool_var (p)->free_indices) = _pool_var (l) - 1;       \
 205       CLIB_MEM_UNPOISON((E), sizeof((E)[0]));                           \
 206     }                                                                   \
 207   else                                                                  \
 208     {                                                                   \
 209       /* fixed-size, preallocated pools cannot expand */                \
 210       if ((P) && _pool_var(p)->max_elts)                                \
 211         {                                                               \
 212           clib_warning ("can't expand fixed-size pool");                \
 213           os_out_of_memory();                                           \
 214         }                                                               \
 215       /* Nothing on free list, make a new element and return it. */     \
 216       P = _vec_resize_numa (P,                                          \
 217                        /* length_increment */ 1,                        \
 218                        /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
 219                        pool_aligned_header_bytes,                       \
 220                        /* align */ (A),                                 \
 221                        /* numa */ (N));                                 \
 222       E = vec_end (P) - 1;                                              \
 223     }                                                                   \
 224   if (Z)                                                                \
 225     memset(E, 0, sizeof(*E));                                           \
 226 } while (0)
 227
 228 #define pool_get_aligned_zero_numa(P,E,A,Z,S) \
 229   _pool_get_aligned_internal_numa(P,E,A,Z,S)
 230
 231 #define pool_get_aligned_numa(P,E,A,S) \
 232   _pool_get_aligned_internal_numa(P,E,A,0/*zero*/,S)
 233
 234 #define pool_get_numa(P,E,S) \
 235   _pool_get_aligned_internal_numa(P,E,0/*align*/,0/*zero*/,S)
 236
 237 #define _pool_get_aligned_internal(P,E,A,Z) \
 238   _pool_get_aligned_internal_numa(P,E,A,Z,VEC_NUMA_UNSPECIFIED)
 239
 240 /** Allocate an object E from a pool P with alignment A */
 241 #define pool_get_aligned(P,E,A) _pool_get_aligned_internal(P,E,A,0)
 242
 243 /** Allocate an object E from a pool P with alignment A and zero it */
 244 #define pool_get_aligned_zero(P,E,A) _pool_get_aligned_internal(P,E,A,1)
 245
 246 /** Allocate an object E from a pool P (unspecified alignment). */
 247 #define pool_get(P,E) pool_get_aligned(P,E,0)
 248
 249 /** Allocate an object E from a pool P and zero it */
 250 #define pool_get_zero(P,E) pool_get_aligned_zero(P,E,0)
 251
 252 /** See if pool_get will expand the pool or not */
 253 #define pool_get_aligned_will_expand(P,YESNO,A)                         \
 254 do {                                                                    \
 255   pool_header_t * _pool_var (p) = pool_header (P);                      \
 256   uword _pool_var (l);                                                  \
 257                                                                         \
 258   _pool_var (l) = 0;                                                    \
 259   if (P)                                                                \
 260     {                                                                   \
 261       if (_pool_var (p)->max_elts)                                      \
 262         _pool_var (l) = _pool_var (p)->max_elts;                        \
 263       else                                                              \
 264         _pool_var (l) = vec_len (_pool_var (p)->free_indices);          \
 265     }                                                                   \
 266                                                                         \
 267   /* Free elements, certainly won't expand */                           \
 268   if (_pool_var (l) > 0)                                                \
 269       YESNO=0;                                                          \
 270   else                                                                  \
 271     {                                                                   \
 272       /* Nothing on free list, make a new element and return it. */     \
 273       YESNO = _vec_resize_will_expand                                   \
 274         (P,                                                             \
 275          /* length_increment */ 1,                                      \
 276          /* new size */ (vec_len (P) + 1) * sizeof (P[0]),              \
 277          pool_aligned_header_bytes,                                     \
 278          /* align */ (A));                                              \
 279     }                                                                   \
 280 } while (0)
 281
 282 /** See if pool_put will expand free_bitmap or free_indices or not */
 283 #define pool_put_will_expand(P, E, YESNO)                                     \
 284   do                                                                          \
 285     {                                                                         \
 286       pool_header_t *_pool_var (p) = pool_header (P);                         \
 287                                                                               \
 288       uword _pool_var (i) = (E) - (P);                                        \
 289       /* free_bitmap or free_indices may expand. */                           \
 290       YESNO =                                                                 \
 291         clib_bitmap_will_expand (_pool_var (p)->free_bitmap, _pool_var (i));  \
 292                                                                               \
 293       YESNO += _vec_resize_will_expand (                                      \
 294         _pool_var (p)->free_indices, 1,                                       \
 295         (vec_len (_pool_var (p)->free_indices) + 1) *                         \
 296           sizeof (_pool_var (p)->free_indices[0]),                            \
 297         0, 0);                                                                \
 298     }                                                                         \
 299   while (0)
 300
 301 /** Tell the caller if pool get will expand the pool */
 302 #define pool_get_will_expand(P,YESNO) pool_get_aligned_will_expand(P,YESNO,0)
 303
 304 /** Use free bitmap to query whether given element is free. */
 305 #define pool_is_free(P,E)                                               \
 306 ({                                                                      \
 307   pool_header_t * _pool_var (p) = pool_header (P);                      \
 308   uword _pool_var (i) = (E) - (P);                                      \
 309   (_pool_var (i) < vec_len (P)) ? clib_bitmap_get (_pool_var (p)->free_bitmap, _pool_i) : 1; \
 310 })
 311
 312 /** Use free bitmap to query whether given index is free */
 313 #define pool_is_free_index(P,I) pool_is_free((P),(P)+(I))
 314
 315 /** Free an object E in pool P. */
 316 #define pool_put(P, E)                                                        \
 317   do                                                                          \
 318     {                                                                         \
 319       typeof (P) _pool_var (p__) = (P);                                       \
 320       typeof (E) _pool_var (e__) = (E);                                       \
 321       pool_header_t *_pool_var (p) = pool_header (_pool_var (p__));           \
 322       uword _pool_var (l) = _pool_var (e__) - _pool_var (p__);                \
 323       if (_pool_var (p)->max_elts == 0)                                       \
 324         ASSERT (vec_is_member (_pool_var (p__), _pool_var (e__)));            \
 325       ASSERT (!pool_is_free (_pool_var (p__), _pool_var (e__)));              \
 326                                                                               \
 327       /* Add element to free bitmap and to free list. */                      \
 328       _pool_var (p)->free_bitmap =                                            \
 329         clib_bitmap_ori_notrim (_pool_var (p)->free_bitmap, _pool_var (l));   \
 330                                                                               \
 331       /* Preallocated pool? */                                                \
 332       if (_pool_var (p)->max_elts)                                            \
 333         {                                                                     \
 334           ASSERT (_pool_var (l) < _pool_var (p)->max_elts);                   \
 335           _pool_var (p)                                                       \
 336             ->free_indices[_vec_len (_pool_var (p)->free_indices)] =          \
 337             _pool_var (l);                                                    \
 338           _vec_len (_pool_var (p)->free_indices) += 1;                        \
 339         }                                                                     \
 340       else                                                                    \
 341         vec_add1 (_pool_var (p)->free_indices, _pool_var (l));                \
 342                                                                               \
 343       CLIB_MEM_POISON (_pool_var (e__), sizeof (_pool_var (e__)[0]));         \
 344     }                                                                         \
 345   while (0)
 346
 347 /** Free pool element with given index. */
 348 #define pool_put_index(p,i)                     \
 349 do {                                            \
 350   typeof (p) _e = (p) + (i);                    \
 351   pool_put (p, _e);                             \
 352 } while (0)
 353
 354 /** Allocate N more free elements to pool (general version). */
 355 #define pool_alloc_aligned(P,N,A)                                       \
 356 do {                                                                    \
 357   pool_header_t * _p;                                                   \
 358                                                                         \
 359   if ((P))                                                              \
 360     {                                                                   \
 361       _p = pool_header (P);                                             \
 362       if (_p->max_elts)                                                 \
 363         {                                                               \
 364            clib_warning ("Can't expand fixed-size pool");               \
 365            os_out_of_memory();                                          \
 366         }                                                               \
 367     }                                                                   \
 368                                                                         \
 369   (P) = _vec_resize ((P), 0, (vec_len (P) + (N)) * sizeof (P[0]),       \
 370                      pool_aligned_header_bytes,                         \
 371                      (A));                                              \
 372   _p = pool_header (P);                                                 \
 373   vec_resize (_p->free_indices, (N));                                   \
 374   _vec_len (_p->free_indices) -= (N);                                   \
 375 } while (0)
 376
 377 /** Allocate N more free elements to pool (unspecified alignment). */
 378 #define pool_alloc(P,N) pool_alloc_aligned(P,N,0)
 379
 380 /**
 381  * Return copy of pool with alignment
 382  *
 383  * @param P pool to copy
 384  * @param A alignment (may be zero)
 385  * @return copy of pool
 386  */
 387 #define pool_dup_aligned(P, A)                                                \
 388   ({                                                                          \
 389     typeof (P) _pool_var (new) = 0;                                           \
 390     pool_header_t *_pool_var (ph), *_pool_var (new_ph);                       \
 391     u32 _pool_var (n) = pool_len (P);                                         \
 392     if ((P))                                                                  \
 393       {                                                                       \
 394         _pool_var (new) = _vec_resize (_pool_var (new), _pool_var (n),        \
 395                                        _pool_var (n) * sizeof ((P)[0]),       \
 396                                        pool_aligned_header_bytes, (A));       \
 397         CLIB_MEM_OVERFLOW_PUSH ((P), _pool_var (n) * sizeof ((P)[0]));        \
 398         clib_memcpy_fast (_pool_var (new), (P),                               \
 399                           _pool_var (n) * sizeof ((P)[0]));                   \
 400         CLIB_MEM_OVERFLOW_POP ();                                             \
 401         _pool_var (ph) = pool_header (P);                                     \
 402         _pool_var (new_ph) = pool_header (_pool_var (new));                   \
 403         _pool_var (new_ph)->free_bitmap =                                     \
 404           clib_bitmap_dup (_pool_var (ph)->free_bitmap);                      \
 405         _pool_var (new_ph)->free_indices =                                    \
 406           vec_dup (_pool_var (ph)->free_indices);                             \
 407         _pool_var (new_ph)->max_elts = _pool_var (ph)->max_elts;              \
 408       }                                                                       \
 409     _pool_var (new);                                                          \
 410   })
 411
 412 /**
 413  * Return copy of pool without alignment
 414  *
 415  * @param P pool to copy
 416  * @return copy of pool
 417  */
 418 #define pool_dup(P) pool_dup_aligned(P,0)
 419
 420 /** Low-level free pool operator (do not call directly). */
 421 always_inline void *
 422 _pool_free (void *v)
 423 {
 424   pool_header_t *p = pool_header (v);
 425   if (!v)
 426     return v;
 427   clib_bitmap_free (p->free_bitmap);
 428
 429   vec_free (p->free_indices);
 430   vec_free_h (v, pool_aligned_header_bytes);
 431   return 0;
 432 }
 433
 434 static_always_inline uword
 435 pool_get_first_index (void *pool)
 436 {
 437   pool_header_t *h = pool_header (pool);
 438   return clib_bitmap_first_clear (h->free_bitmap);
 439 }
 440
 441 static_always_inline uword
 442 pool_get_next_index (void *pool, uword last)
 443 {
 444   pool_header_t *h = pool_header (pool);
 445   return clib_bitmap_next_clear (h->free_bitmap, last + 1);
 446 }
 447
 448 /** Free a pool. */
 449 #define pool_free(p) (p) = _pool_free(p)
 450
 451 /** Optimized iteration through pool.
 452
 453     @param LO pointer to first element in chunk
 454     @param HI pointer to last element in chunk
 455     @param POOL pool to iterate across
 456     @param BODY operation to perform
 457
 458     Optimized version which assumes that BODY is smart enough to
 459     process multiple (LOW,HI) chunks. See also pool_foreach().
 460  */
 461 #define pool_foreach_region(LO,HI,POOL,BODY)                            \
 462 do {                                                                    \
 463   uword _pool_var (i), _pool_var (lo), _pool_var (hi), _pool_var (len); \
 464   uword _pool_var (bl), * _pool_var (b);                                \
 465   pool_header_t * _pool_var (p);                                        \
 466                                                                         \
 467   _pool_var (p) = pool_header (POOL);                                   \
 468   _pool_var (b) = (POOL) ? _pool_var (p)->free_bitmap : 0;              \
 469   _pool_var (bl) = vec_len (_pool_var (b));                             \
 470   _pool_var (len) = vec_len (POOL);                                     \
 471   _pool_var (lo) = 0;                                                   \
 472                                                                         \
 473   for (_pool_var (i) = 0;                                               \
 474        _pool_var (i) <= _pool_var (bl);                                 \
 475        _pool_var (i)++)                                                 \
 476     {                                                                   \
 477       uword _pool_var (m), _pool_var (f);                               \
 478       _pool_var (m) = (_pool_var (i) < _pool_var (bl)                   \
 479                        ? _pool_var (b) [_pool_var (i)]                  \
 480                        : 1);                                            \
 481       while (_pool_var (m) != 0)                                        \
 482         {                                                               \
 483           _pool_var (f) = first_set (_pool_var (m));                    \
 484           _pool_var (hi) = (_pool_var (i) * BITS (_pool_var (b)[0])     \
 485                             + min_log2 (_pool_var (f)));                \
 486           _pool_var (hi) = (_pool_var (i) < _pool_var (bl)              \
 487                             ? _pool_var (hi) : _pool_var (len));        \
 488           _pool_var (m) ^= _pool_var (f);                               \
 489           if (_pool_var (hi) > _pool_var (lo))                          \
 490             {                                                           \
 491               (LO) = _pool_var (lo);                                    \
 492               (HI) = _pool_var (hi);                                    \
 493               do { BODY; } while (0);                                   \
 494             }                                                           \
 495           _pool_var (lo) = _pool_var (hi) + 1;                          \
 496         }                                                               \
 497     }                                                                   \
 498 } while (0)
 499
 500 /** Iterate through pool.
 501
 502     @param VAR A variable of same type as pool vector to be used as an
 503                iterator.
 504     @param POOL The pool to iterate across.
 505     @param BODY The operation to perform, typically a code block. See
 506                 the example below.
 507
 508     This macro will call @c BODY with each active pool element.
 509
 510     It is a bad idea to allocate or free pool element from within
 511     @c pool_foreach. Build a vector of indices and dispose of them later.
 512     Or call pool_flush.
 513
 514
 515     @par Example
 516     @code{.c}
 517     proc_t *procs;   // a pool of processes.
 518     proc_t *proc;    // pointer to one process; used as the iterator.
 519
 520     pool_foreach (proc, procs, ({
 521         if (proc->state != PROC_STATE_RUNNING)
 522             continue;
 523
 524         // check a running proc in some way
 525         ...
 526     }));
 527     @endcode
 528
 529     @warning Because @c pool_foreach is a macro, syntax errors can be
 530     difficult to find inside @c BODY, let alone actual code bugs. One
 531     can temporarily split a complex @c pool_foreach into a trivial
 532     @c pool_foreach which builds a vector of active indices, and a
 533     vec_foreach() (or plain for-loop) to walk the active index vector.
 534  */
 535
 536 #define pool_foreach(VAR,POOL)                                          \
 537   if (POOL)                                                             \
 538     for (VAR = POOL + pool_get_first_index (POOL);                      \
 539          VAR < vec_end (POOL);                                          \
 540          VAR = POOL + pool_get_next_index (POOL, VAR - POOL))
 541
 542 /** Returns pointer to element at given index.
 543
 544     ASSERTs that the supplied index is valid.
 545     Even though one can write correct code of the form
 546     @code
 547         p = pool_base + index;
 548     @endcode
 549     use of @c pool_elt_at_index is strongly suggested.
 550  */
 551 #define pool_elt_at_index(p,i)                  \
 552 ({                                              \
 553   typeof (p) _e = (p) + (i);                    \
 554   ASSERT (! pool_is_free (p, _e));              \
 555   _e;                                           \
 556 })
 557
 558 /** Return next occupied pool index after @c i, useful for safe iteration. */
 559 #define pool_next_index(P,I)                                            \
 560 ({                                                                      \
 561   pool_header_t * _pool_var (p) = pool_header (P);                      \
 562   uword _pool_var (rv) = (I) + 1;                                       \
 563                                                                         \
 564   _pool_var(rv) =                                                       \
 565     (_pool_var (rv) < vec_len (P) ?                                     \
 566      clib_bitmap_next_clear (_pool_var (p)->free_bitmap, _pool_var(rv)) \
 567      : ~0);                                                             \
 568   _pool_var(rv) =                                                       \
 569     (_pool_var (rv) < vec_len (P) ?                                     \
 570      _pool_var (rv) : ~0);                                              \
 571   _pool_var(rv);                                                        \
 572 })
 573
 574 #define pool_foreach_index(i,v)         \
 575   if (v)                                        \
 576     for (i = pool_get_first_index (v);          \
 577          i < vec_len (v);                       \
 578          i = pool_get_next_index (v, i))        \
 579
 580 /**
 581  * @brief Remove all elements from a pool in a safe way
 582  *
 583  * @param VAR each element in the pool
 584  * @param POOL The pool to flush
 585  * @param BODY The actions to perform on each element before it is returned to
 586  *        the pool. i.e. before it is 'freed'
 587  */
 588 #define pool_flush(VAR, POOL, BODY)                     \
 589 {                                                       \
 590   uword *_pool_var(ii), *_pool_var(dv) = NULL;          \
 591                                                         \
 592   pool_foreach((VAR), (POOL))                          \
 593   {                                                     \
 594     vec_add1(_pool_var(dv), (VAR) - (POOL));            \
 595   }                                                     \
 596   vec_foreach(_pool_var(ii), _pool_var(dv))             \
 597   {                                                     \
 598     (VAR) = pool_elt_at_index((POOL), *_pool_var(ii));  \
 599     do { BODY; } while (0);                             \
 600     pool_put((POOL), (VAR));                            \
 601   }                                                     \
 602   vec_free(_pool_var(dv));                              \
 603 }
 604
 605 #endif /* included_pool_h */
 606
 607 /*
 608  * fd.io coding-style-patch-verification: ON
 609  *
 610  * Local Variables:
 611  * eval: (c-set-style "gnu")
 612  * End:
 613  */