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   /** mmap segment info: base + length */
  65   u8 *mmap_base;
  66   u64 mmap_size;
  67
  68 } pool_header_t;
  69
  70 /** Align pool header so that pointers are naturally aligned. */
  71 #define pool_aligned_header_bytes                                             \
  72   round_pow2 (sizeof (pool_header_t), sizeof (void *))
  73
  74 /** Get pool header from user pool pointer */
  75 always_inline pool_header_t *
  76 pool_header (void *v)
  77 {
  78   return vec_aligned_header (v, sizeof (pool_header_t), sizeof (void *));
  79 }
  80
  81 extern void _pool_init_fixed (void **, u32, u32);
  82 extern void fpool_free (void *);
  83
  84 /** initialize a fixed-size, preallocated pool */
  85 #define pool_init_fixed(pool,max_elts)                  \
  86 {                                                       \
  87   _pool_init_fixed((void **)&(pool),sizeof(pool[0]),max_elts);  \
  88 }
  89
  90 /** Validate a pool */
  91 always_inline void
  92 pool_validate (void *v)
  93 {
  94   pool_header_t *p = pool_header (v);
  95   uword i, n_free_bitmap;
  96
  97   if (!v)
  98     return;
  99
 100   n_free_bitmap = clib_bitmap_count_set_bits (p->free_bitmap);
 101   ASSERT (n_free_bitmap == vec_len (p->free_indices));
 102   for (i = 0; i < vec_len (p->free_indices); i++)
 103     ASSERT (clib_bitmap_get (p->free_bitmap, p->free_indices[i]) == 1);
 104 }
 105
 106 always_inline void
 107 pool_header_validate_index (void *v, uword index)
 108 {
 109   pool_header_t *p = pool_header (v);
 110
 111   if (v)
 112     vec_validate (p->free_bitmap, index / BITS (uword));
 113 }
 114
 115 #define pool_validate_index(v,i)                                \
 116 do {                                                            \
 117   uword __pool_validate_index = (i);                            \
 118   vec_validate_ha ((v), __pool_validate_index,                  \
 119                    pool_aligned_header_bytes, /* align */ 0);   \
 120   pool_header_validate_index ((v), __pool_validate_index);      \
 121 } while (0)
 122
 123 /** Number of active elements in a pool.
 124  * @return Number of active elements in a pool
 125  */
 126 always_inline uword
 127 pool_elts (void *v)
 128 {
 129   uword ret = vec_len (v);
 130   if (v)
 131     ret -= vec_len (pool_header (v)->free_indices);
 132   return ret;
 133 }
 134
 135 /** Number of elements in pool vector.
 136
 137     @note You probably want to call pool_elts() instead.
 138 */
 139 #define pool_len(p)     vec_len(p)
 140
 141 /** Number of elements in pool vector (usable as an lvalue)
 142
 143     @note You probably don't want to use this macro.
 144 */
 145 #define _pool_len(p)    _vec_len(p)
 146
 147 /** Memory usage of pool header. */
 148 always_inline uword
 149 pool_header_bytes (void *v)
 150 {
 151   pool_header_t *p = pool_header (v);
 152
 153   if (!v)
 154     return 0;
 155
 156   return vec_bytes (p->free_bitmap) + vec_bytes (p->free_indices);
 157 }
 158
 159 /** Memory usage of pool. */
 160 #define pool_bytes(P) (vec_bytes (P) + pool_header_bytes (P))
 161
 162 /** Local variable naming macro. */
 163 #define _pool_var(v) _pool_##v
 164
 165 /** Number of elements that can fit into pool with current allocation */
 166 #define pool_max_len(P) vec_max_len (P)
 167
 168 /** Number of free elements in pool */
 169 #define pool_free_elts(P)                                                     \
 170   ({                                                                          \
 171     pool_header_t *_pool_var (p) = pool_header (P);                           \
 172     uword n_free = 0;                                                         \
 173     if (P)                                                                    \
 174       {                                                                       \
 175         n_free += vec_len (_pool_var (p)->free_indices);                      \
 176         /* Fixed-size pools have max_elts set non-zero */                     \
 177         if (_pool_var (p)->max_elts == 0)                                     \
 178           n_free += pool_max_len (P) - vec_len (P);                           \
 179       }                                                                       \
 180     n_free;                                                                   \
 181   })
 182
 183 /** Allocate an object E from a pool P (general version).
 184
 185    First search free list.  If nothing is free extend vector of objects.
 186 */
 187 #define _pool_get_aligned_internal_numa(P,E,A,Z,N)                      \
 188 do {                                                                    \
 189   pool_header_t * _pool_var (p) = pool_header (P);                      \
 190   uword _pool_var (l);                                                  \
 191                                                                         \
 192   STATIC_ASSERT(A==0 || ((A % sizeof(P[0]))==0)                         \
 193                 || ((sizeof(P[0]) % A) == 0),                           \
 194                 "Pool aligned alloc of incorrectly sized object");      \
 195   _pool_var (l) = 0;                                                    \
 196   if (P)                                                                \
 197     _pool_var (l) = vec_len (_pool_var (p)->free_indices);              \
 198                                                                         \
 199   if (_pool_var (l) > 0)                                                \
 200     {                                                                   \
 201       /* Return free element from free list. */                         \
 202       uword _pool_var (i) =                                             \
 203         _pool_var (p)->free_indices[_pool_var (l) - 1];                 \
 204       (E) = (P) + _pool_var (i);                                        \
 205       _pool_var (p)->free_bitmap =                                      \
 206         clib_bitmap_andnoti_notrim (_pool_var (p)->free_bitmap,         \
 207                                      _pool_var (i));                    \
 208       _vec_len (_pool_var (p)->free_indices) = _pool_var (l) - 1;       \
 209       CLIB_MEM_UNPOISON((E), sizeof((E)[0]));                           \
 210     }                                                                   \
 211   else                                                                  \
 212     {                                                                   \
 213       /* fixed-size, preallocated pools cannot expand */                \
 214       if ((P) && _pool_var(p)->max_elts)                                \
 215         {                                                               \
 216           clib_warning ("can't expand fixed-size pool");                \
 217           os_out_of_memory();                                           \
 218         }                                                               \
 219       /* Nothing on free list, make a new element and return it. */     \
 220       P = _vec_resize_numa (P,                                          \
 221                        /* length_increment */ 1,                        \
 222                        /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
 223                        pool_aligned_header_bytes,                       \
 224                        /* align */ (A),                                 \
 225                        /* numa */ (N));                                 \
 226       E = vec_end (P) - 1;                                              \
 227     }                                                                   \
 228   if (Z)                                                                \
 229     memset(E, 0, sizeof(*E));                                           \
 230 } while (0)
 231
 232 #define pool_get_aligned_zero_numa(P,E,A,Z,S) \
 233   _pool_get_aligned_internal_numa(P,E,A,Z,S)
 234
 235 #define pool_get_aligned_numa(P,E,A,S) \
 236   _pool_get_aligned_internal_numa(P,E,A,0/*zero*/,S)
 237
 238 #define pool_get_numa(P,E,S) \
 239   _pool_get_aligned_internal_numa(P,E,0/*align*/,0/*zero*/,S)
 240
 241 #define _pool_get_aligned_internal(P,E,A,Z) \
 242   _pool_get_aligned_internal_numa(P,E,A,Z,VEC_NUMA_UNSPECIFIED)
 243
 244 /** Allocate an object E from a pool P with alignment A */
 245 #define pool_get_aligned(P,E,A) _pool_get_aligned_internal(P,E,A,0)
 246
 247 /** Allocate an object E from a pool P with alignment A and zero it */
 248 #define pool_get_aligned_zero(P,E,A) _pool_get_aligned_internal(P,E,A,1)
 249
 250 /** Allocate an object E from a pool P (unspecified alignment). */
 251 #define pool_get(P,E) pool_get_aligned(P,E,0)
 252
 253 /** Allocate an object E from a pool P and zero it */
 254 #define pool_get_zero(P,E) pool_get_aligned_zero(P,E,0)
 255
 256 /** See if pool_get will expand the pool or not */
 257 #define pool_get_aligned_will_expand(P,YESNO,A)                         \
 258 do {                                                                    \
 259   pool_header_t * _pool_var (p) = pool_header (P);                      \
 260   uword _pool_var (l);                                                  \
 261                                                                         \
 262   _pool_var (l) = 0;                                                    \
 263   if (P)                                                                \
 264     {                                                                   \
 265       if (_pool_var (p)->max_elts)                                      \
 266         _pool_var (l) = _pool_var (p)->max_elts;                        \
 267       else                                                              \
 268         _pool_var (l) = vec_len (_pool_var (p)->free_indices);          \
 269     }                                                                   \
 270                                                                         \
 271   /* Free elements, certainly won't expand */                           \
 272   if (_pool_var (l) > 0)                                                \
 273       YESNO=0;                                                          \
 274   else                                                                  \
 275     {                                                                   \
 276       /* Nothing on free list, make a new element and return it. */     \
 277       YESNO = _vec_resize_will_expand                                   \
 278         (P,                                                             \
 279          /* length_increment */ 1,                                      \
 280          /* new size */ (vec_len (P) + 1) * sizeof (P[0]),              \
 281          pool_aligned_header_bytes,                                     \
 282          /* align */ (A));                                              \
 283     }                                                                   \
 284 } while (0)
 285
 286 /** See if pool_put will expand free_bitmap or free_indices or not */
 287 #define pool_put_will_expand(P, E, YESNO)                                     \
 288   do                                                                          \
 289     {                                                                         \
 290       pool_header_t *_pool_var (p) = pool_header (P);                         \
 291                                                                               \
 292       uword _pool_var (i) = (E) - (P);                                        \
 293       /* free_bitmap or free_indices may expand. */                           \
 294       YESNO =                                                                 \
 295         clib_bitmap_will_expand (_pool_var (p)->free_bitmap, _pool_var (i));  \
 296                                                                               \
 297       YESNO += _vec_resize_will_expand (                                      \
 298         _pool_var (p)->free_indices, 1,                                       \
 299         (vec_len (_pool_var (p)->free_indices) + 1) *                         \
 300           sizeof (_pool_var (p)->free_indices[0]),                            \
 301         0, 0);                                                                \
 302     }                                                                         \
 303   while (0)
 304
 305 /** Tell the caller if pool get will expand the pool */
 306 #define pool_get_will_expand(P,YESNO) pool_get_aligned_will_expand(P,YESNO,0)
 307
 308 /** Use free bitmap to query whether given element is free. */
 309 #define pool_is_free(P,E)                                               \
 310 ({                                                                      \
 311   pool_header_t * _pool_var (p) = pool_header (P);                      \
 312   uword _pool_var (i) = (E) - (P);                                      \
 313   (_pool_var (i) < vec_len (P)) ? clib_bitmap_get (_pool_var (p)->free_bitmap, _pool_i) : 1; \
 314 })
 315
 316 /** Use free bitmap to query whether given index is free */
 317 #define pool_is_free_index(P,I) pool_is_free((P),(P)+(I))
 318
 319 /** Free an object E in pool P. */
 320 #define pool_put(P, E)                                                        \
 321   do                                                                          \
 322     {                                                                         \
 323       typeof (P) _pool_var (p__) = (P);                                       \
 324       typeof (E) _pool_var (e__) = (E);                                       \
 325       pool_header_t *_pool_var (p) = pool_header (_pool_var (p__));           \
 326       uword _pool_var (l) = _pool_var (e__) - _pool_var (p__);                \
 327       if (_pool_var (p)->max_elts == 0)                                       \
 328         ASSERT (vec_is_member (_pool_var (p__), _pool_var (e__)));            \
 329       ASSERT (!pool_is_free (_pool_var (p__), _pool_var (e__)));              \
 330                                                                               \
 331       /* Add element to free bitmap and to free list. */                      \
 332       _pool_var (p)->free_bitmap =                                            \
 333         clib_bitmap_ori_notrim (_pool_var (p)->free_bitmap, _pool_var (l));   \
 334                                                                               \
 335       /* Preallocated pool? */                                                \
 336       if (_pool_var (p)->max_elts)                                            \
 337         {                                                                     \
 338           ASSERT (_pool_var (l) < _pool_var (p)->max_elts);                   \
 339           _pool_var (p)                                                       \
 340             ->free_indices[_vec_len (_pool_var (p)->free_indices)] =          \
 341             _pool_var (l);                                                    \
 342           _vec_len (_pool_var (p)->free_indices) += 1;                        \
 343         }                                                                     \
 344       else                                                                    \
 345         vec_add1 (_pool_var (p)->free_indices, _pool_var (l));                \
 346                                                                               \
 347       CLIB_MEM_POISON (_pool_var (e__), sizeof (_pool_var (e__)[0]));         \
 348     }                                                                         \
 349   while (0)
 350
 351 /** Free pool element with given index. */
 352 #define pool_put_index(p,i)                     \
 353 do {                                            \
 354   typeof (p) _e = (p) + (i);                    \
 355   pool_put (p, _e);                             \
 356 } while (0)
 357
 358 /** Allocate N more free elements to pool (general version). */
 359 #define pool_alloc_aligned(P,N,A)                                       \
 360 do {                                                                    \
 361   pool_header_t * _p;                                                   \
 362                                                                         \
 363   if ((P))                                                              \
 364     {                                                                   \
 365       _p = pool_header (P);                                             \
 366       if (_p->max_elts)                                                 \
 367         {                                                               \
 368            clib_warning ("Can't expand fixed-size pool");               \
 369            os_out_of_memory();                                          \
 370         }                                                               \
 371     }                                                                   \
 372                                                                         \
 373   (P) = _vec_resize ((P), 0, (vec_len (P) + (N)) * sizeof (P[0]),       \
 374                      pool_aligned_header_bytes,                         \
 375                      (A));                                              \
 376   _p = pool_header (P);                                                 \
 377   vec_resize (_p->free_indices, (N));                                   \
 378   _vec_len (_p->free_indices) -= (N);                                   \
 379 } while (0)
 380
 381 /** Allocate N more free elements to pool (unspecified alignment). */
 382 #define pool_alloc(P,N) pool_alloc_aligned(P,N,0)
 383
 384 /**
 385  * Return copy of pool with alignment
 386  *
 387  * @param P pool to copy
 388  * @param A alignment (may be zero)
 389  * @return copy of pool
 390  */
 391 #define pool_dup_aligned(P, A)                                                \
 392   ({                                                                          \
 393     typeof (P) _pool_var (new) = 0;                                           \
 394     pool_header_t *_pool_var (ph), *_pool_var (new_ph);                       \
 395     u32 _pool_var (n) = pool_len (P);                                         \
 396     if ((P))                                                                  \
 397       {                                                                       \
 398         _pool_var (new) = _vec_resize (_pool_var (new), _pool_var (n),        \
 399                                        _pool_var (n) * sizeof ((P)[0]),       \
 400                                        pool_aligned_header_bytes, (A));       \
 401         CLIB_MEM_OVERFLOW_PUSH ((P), _pool_var (n) * sizeof ((P)[0]));        \
 402         clib_memcpy_fast (_pool_var (new), (P),                               \
 403                           _pool_var (n) * sizeof ((P)[0]));                   \
 404         CLIB_MEM_OVERFLOW_POP ();                                             \
 405         _pool_var (ph) = pool_header (P);                                     \
 406         _pool_var (new_ph) = pool_header (_pool_var (new));                   \
 407         _pool_var (new_ph)->free_bitmap =                                     \
 408           clib_bitmap_dup (_pool_var (ph)->free_bitmap);                      \
 409         _pool_var (new_ph)->free_indices =                                    \
 410           vec_dup (_pool_var (ph)->free_indices);                             \
 411         _pool_var (new_ph)->max_elts = _pool_var (ph)->max_elts;              \
 412       }                                                                       \
 413     _pool_var (new);                                                          \
 414   })
 415
 416 /**
 417  * Return copy of pool without alignment
 418  *
 419  * @param P pool to copy
 420  * @return copy of pool
 421  */
 422 #define pool_dup(P) pool_dup_aligned(P,0)
 423
 424 /** Low-level free pool operator (do not call directly). */
 425 always_inline void *
 426 _pool_free (void *v)
 427 {
 428   pool_header_t *p = pool_header (v);
 429   if (!v)
 430     return v;
 431   clib_bitmap_free (p->free_bitmap);
 432
 433   if (p->max_elts)
 434     {
 435       int rv;
 436
 437       rv = munmap (p->mmap_base, p->mmap_size);
 438       if (rv)
 439         clib_unix_warning ("munmap");
 440     }
 441   else
 442     {
 443       vec_free (p->free_indices);
 444       vec_free_h (v, pool_aligned_header_bytes);
 445     }
 446   return 0;
 447 }
 448
 449 static_always_inline uword
 450 pool_get_first_index (void *pool)
 451 {
 452   pool_header_t *h = pool_header (pool);
 453   return clib_bitmap_first_clear (h->free_bitmap);
 454 }
 455
 456 static_always_inline uword
 457 pool_get_next_index (void *pool, uword last)
 458 {
 459   pool_header_t *h = pool_header (pool);
 460   return clib_bitmap_next_clear (h->free_bitmap, last + 1);
 461 }
 462
 463 /** Free a pool. */
 464 #define pool_free(p) (p) = _pool_free(p)
 465
 466 /** Optimized iteration through pool.
 467
 468     @param LO pointer to first element in chunk
 469     @param HI pointer to last element in chunk
 470     @param POOL pool to iterate across
 471     @param BODY operation to perform
 472
 473     Optimized version which assumes that BODY is smart enough to
 474     process multiple (LOW,HI) chunks. See also pool_foreach().
 475  */
 476 #define pool_foreach_region(LO,HI,POOL,BODY)                            \
 477 do {                                                                    \
 478   uword _pool_var (i), _pool_var (lo), _pool_var (hi), _pool_var (len); \
 479   uword _pool_var (bl), * _pool_var (b);                                \
 480   pool_header_t * _pool_var (p);                                        \
 481                                                                         \
 482   _pool_var (p) = pool_header (POOL);                                   \
 483   _pool_var (b) = (POOL) ? _pool_var (p)->free_bitmap : 0;              \
 484   _pool_var (bl) = vec_len (_pool_var (b));                             \
 485   _pool_var (len) = vec_len (POOL);                                     \
 486   _pool_var (lo) = 0;                                                   \
 487                                                                         \
 488   for (_pool_var (i) = 0;                                               \
 489        _pool_var (i) <= _pool_var (bl);                                 \
 490        _pool_var (i)++)                                                 \
 491     {                                                                   \
 492       uword _pool_var (m), _pool_var (f);                               \
 493       _pool_var (m) = (_pool_var (i) < _pool_var (bl)                   \
 494                        ? _pool_var (b) [_pool_var (i)]                  \
 495                        : 1);                                            \
 496       while (_pool_var (m) != 0)                                        \
 497         {                                                               \
 498           _pool_var (f) = first_set (_pool_var (m));                    \
 499           _pool_var (hi) = (_pool_var (i) * BITS (_pool_var (b)[0])     \
 500                             + min_log2 (_pool_var (f)));                \
 501           _pool_var (hi) = (_pool_var (i) < _pool_var (bl)              \
 502                             ? _pool_var (hi) : _pool_var (len));        \
 503           _pool_var (m) ^= _pool_var (f);                               \
 504           if (_pool_var (hi) > _pool_var (lo))                          \
 505             {                                                           \
 506               (LO) = _pool_var (lo);                                    \
 507               (HI) = _pool_var (hi);                                    \
 508               do { BODY; } while (0);                                   \
 509             }                                                           \
 510           _pool_var (lo) = _pool_var (hi) + 1;                          \
 511         }                                                               \
 512     }                                                                   \
 513 } while (0)
 514
 515 /** Iterate through pool.
 516
 517     @param VAR A variable of same type as pool vector to be used as an
 518                iterator.
 519     @param POOL The pool to iterate across.
 520     @param BODY The operation to perform, typically a code block. See
 521                 the example below.
 522
 523     This macro will call @c BODY with each active pool element.
 524
 525     It is a bad idea to allocate or free pool element from within
 526     @c pool_foreach. Build a vector of indices and dispose of them later.
 527     Or call pool_flush.
 528
 529
 530     @par Example
 531     @code{.c}
 532     proc_t *procs;   // a pool of processes.
 533     proc_t *proc;    // pointer to one process; used as the iterator.
 534
 535     pool_foreach (proc, procs, ({
 536         if (proc->state != PROC_STATE_RUNNING)
 537             continue;
 538
 539         // check a running proc in some way
 540         ...
 541     }));
 542     @endcode
 543
 544     @warning Because @c pool_foreach is a macro, syntax errors can be
 545     difficult to find inside @c BODY, let alone actual code bugs. One
 546     can temporarily split a complex @c pool_foreach into a trivial
 547     @c pool_foreach which builds a vector of active indices, and a
 548     vec_foreach() (or plain for-loop) to walk the active index vector.
 549  */
 550
 551 #define pool_foreach(VAR,POOL)                                          \
 552   if (POOL)                                                             \
 553     for (VAR = POOL + pool_get_first_index (POOL);                      \
 554          VAR < vec_end (POOL);                                          \
 555          VAR = POOL + pool_get_next_index (POOL, VAR - POOL))
 556
 557 /** Returns pointer to element at given index.
 558
 559     ASSERTs that the supplied index is valid.
 560     Even though one can write correct code of the form
 561     @code
 562         p = pool_base + index;
 563     @endcode
 564     use of @c pool_elt_at_index is strongly suggested.
 565  */
 566 #define pool_elt_at_index(p,i)                  \
 567 ({                                              \
 568   typeof (p) _e = (p) + (i);                    \
 569   ASSERT (! pool_is_free (p, _e));              \
 570   _e;                                           \
 571 })
 572
 573 /** Return next occupied pool index after @c i, useful for safe iteration. */
 574 #define pool_next_index(P,I)                                            \
 575 ({                                                                      \
 576   pool_header_t * _pool_var (p) = pool_header (P);                      \
 577   uword _pool_var (rv) = (I) + 1;                                       \
 578                                                                         \
 579   _pool_var(rv) =                                                       \
 580     (_pool_var (rv) < vec_len (P) ?                                     \
 581      clib_bitmap_next_clear (_pool_var (p)->free_bitmap, _pool_var(rv)) \
 582      : ~0);                                                             \
 583   _pool_var(rv) =                                                       \
 584     (_pool_var (rv) < vec_len (P) ?                                     \
 585      _pool_var (rv) : ~0);                                              \
 586   _pool_var(rv);                                                        \
 587 })
 588
 589 #define pool_foreach_index(i,v)         \
 590   if (v)                                        \
 591     for (i = pool_get_first_index (v);          \
 592          i < vec_len (v);                       \
 593          i = pool_get_next_index (v, i))        \
 594
 595 /**
 596  * @brief Remove all elements from a pool in a safe way
 597  *
 598  * @param VAR each element in the pool
 599  * @param POOL The pool to flush
 600  * @param BODY The actions to perform on each element before it is returned to
 601  *        the pool. i.e. before it is 'freed'
 602  */
 603 #define pool_flush(VAR, POOL, BODY)                     \
 604 {                                                       \
 605   uword *_pool_var(ii), *_pool_var(dv) = NULL;          \
 606                                                         \
 607   pool_foreach((VAR), (POOL))                          \
 608   {                                                     \
 609     vec_add1(_pool_var(dv), (VAR) - (POOL));            \
 610   }                                                     \
 611   vec_foreach(_pool_var(ii), _pool_var(dv))             \
 612   {                                                     \
 613     (VAR) = pool_elt_at_index((POOL), *_pool_var(ii));  \
 614     do { BODY; } while (0);                             \
 615     pool_put((POOL), (VAR));                            \
 616   }                                                     \
 617   vec_free(_pool_var(dv));                              \
 618 }
 619
 620 #endif /* included_pool_h */
 621
 622 /*
 623  * fd.io coding-style-patch-verification: ON
 624  *
 625  * Local Variables:
 626  * eval: (c-set-style "gnu")
 627  * End:
 628  */