FD.io VPP  v18.07-34-g55fbdb9
Vector Packet Processing
pool.h
Go to the documentation of this file.
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 #include <vppinfra/mheap.h>
50 
51 
52 typedef struct
53 {
54  /** Bitmap of indices of free objects. */
56 
57  /** Vector of free indices. One element for each set bit in bitmap. */
59 
60  /* The following fields are set for fixed-size, preallocated pools */
61 
62  /** Maximum size of the pool, in elements */
64 
65  /** mmap segment info: base + length */
68 
70 
71 /** Align pool header so that pointers are naturally aligned. */
72 #define pool_aligned_header_bytes \
73  vec_aligned_header_bytes (sizeof (pool_header_t), sizeof (void *))
74 
75 /** Get pool header from user pool pointer */
77 pool_header (void *v)
78 {
79  return vec_aligned_header (v, sizeof (pool_header_t), sizeof (void *));
80 }
81 
82 extern void _pool_init_fixed (void **, u32, u32);
83 extern void fpool_free (void *);
84 
85 /** initialize a fixed-size, preallocated pool */
86 #define pool_init_fixed(pool,max_elts) \
87 { \
88  _pool_init_fixed((void **)&(pool),sizeof(pool[0]),max_elts); \
89 }
90 
91 /** Validate a pool */
92 always_inline void
94 {
95  pool_header_t *p = pool_header (v);
96  uword i, n_free_bitmap;
97 
98  if (!v)
99  return;
100 
101  n_free_bitmap = clib_bitmap_count_set_bits (p->free_bitmap);
102  ASSERT (n_free_bitmap == vec_len (p->free_indices));
103  for (i = 0; i < vec_len (p->free_indices); i++)
104  ASSERT (clib_bitmap_get (p->free_bitmap, p->free_indices[i]) == 1);
105 }
106 
107 always_inline void
109 {
110  pool_header_t *p = pool_header (v);
111 
112  if (v)
113  vec_validate (p->free_bitmap, index / BITS (uword));
114 }
115 
116 #define pool_validate_index(v,i) \
117 do { \
118  uword __pool_validate_index = (i); \
119  vec_validate_ha ((v), __pool_validate_index, \
120  pool_aligned_header_bytes, /* align */ 0); \
121  pool_header_validate_index ((v), __pool_validate_index); \
122 } while (0)
123 
124 /** Number of active elements in a pool.
125  * @return Number of active elements in a pool
126  */
128 pool_elts (void *v)
129 {
130  uword ret = vec_len (v);
131  if (v)
132  ret -= vec_len (pool_header (v)->free_indices);
133  return ret;
134 }
135 
136 /** Number of elements in pool vector.
137 
138  @note You probably want to call pool_elts() instead.
139 */
140 #define pool_len(p) vec_len(p)
141 
142 /** Number of elements in pool vector (usable as an lvalue)
143 
144  @note You probably don't want to use this macro.
145 */
146 #define _pool_len(p) _vec_len(p)
147 
148 /** Memory usage of pool header. */
151 {
152  pool_header_t *p = pool_header (v);
153 
154  if (!v)
155  return 0;
156 
157  return vec_bytes (p->free_bitmap) + vec_bytes (p->free_indices);
158 }
159 
160 /** Memory usage of pool. */
161 #define pool_bytes(P) (vec_bytes (P) + pool_header_bytes (P))
162 
163 /** Local variable naming macro. */
164 #define _pool_var(v) _pool_##v
165 
166 /** Queries whether pool has at least N_FREE free elements. */
169 {
170  pool_header_t *p = pool_header (v);
171  uword n_free = 0;
172 
173  if (v)
174  {
175  n_free += vec_len (p->free_indices);
176 
177  /* Space left at end of vector? */
178  n_free += vec_capacity (v, sizeof (p[0])) - vec_len (v);
179  }
180 
181  return n_free;
182 }
183 
184 /** Allocate an object E from a pool P (general version).
185 
186  First search free list. If nothing is free extend vector of objects.
187 */
188 #define pool_get_aligned(P,E,A) \
189 do { \
190  pool_header_t * _pool_var (p) = pool_header (P); \
191  uword _pool_var (l); \
192  \
193  STATIC_ASSERT(A==0 || ((A % sizeof(P[0]))==0) || ((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) = _pool_var (p)->free_indices[_pool_var (l) - 1]; \
203  (E) = (P) + _pool_var (i); \
204  _pool_var (p)->free_bitmap = \
205  clib_bitmap_andnoti_notrim (_pool_var (p)->free_bitmap, \
206  _pool_var (i)); \
207  _vec_len (_pool_var (p)->free_indices) = _pool_var (l) - 1; \
208  } \
209  else \
210  { \
211  /* fixed-size, preallocated pools cannot expand */ \
212  if ((P) && _pool_var(p)->max_elts) \
213  { \
214  clib_warning ("can't expand fixed-size pool"); \
215  os_out_of_memory(); \
216  } \
217  /* Nothing on free list, make a new element and return it. */ \
218  P = _vec_resize (P, \
219  /* length_increment */ 1, \
220  /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
221  pool_aligned_header_bytes, \
222  /* align */ (A)); \
223  E = vec_end (P) - 1; \
224  } \
225 } while (0)
226 
227 /** Allocate an object E from a pool P (unspecified alignment). */
228 #define pool_get(P,E) pool_get_aligned(P,E,0)
229 
230 /** See if pool_get will expand the pool or not */
231 #define pool_get_aligned_will_expand(P,YESNO,A) \
232 do { \
233  pool_header_t * _pool_var (p) = pool_header (P); \
234  uword _pool_var (l); \
235  \
236  _pool_var (l) = 0; \
237  if (P) \
238  { \
239  if (_pool_var (p)->max_elts) \
240  _pool_var (l) = _pool_var (p)->max_elts; \
241  else \
242  _pool_var (l) = vec_len (_pool_var (p)->free_indices); \
243  } \
244  \
245  /* Free elements, certainly won't expand */ \
246  if (_pool_var (l) > 0) \
247  YESNO=0; \
248  else \
249  { \
250  /* Nothing on free list, make a new element and return it. */ \
251  YESNO = _vec_resize_will_expand \
252  (P, \
253  /* length_increment */ 1, \
254  /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
255  pool_aligned_header_bytes, \
256  /* align */ (A)); \
257  } \
258 } while (0)
259 
260 #define pool_get_will_expand(P,YESNO) pool_get_aligned_will_expand(P,YESNO,0)
261 
262 /** Use free bitmap to query whether given element is free. */
263 #define pool_is_free(P,E) \
264 ({ \
265  pool_header_t * _pool_var (p) = pool_header (P); \
266  uword _pool_var (i) = (E) - (P); \
267  (_pool_var (i) < vec_len (P)) ? clib_bitmap_get (_pool_var (p)->free_bitmap, _pool_i) : 1; \
268 })
269 
270 /** Use free bitmap to query whether given index is free */
271 #define pool_is_free_index(P,I) pool_is_free((P),(P)+(I))
272 
273 /** Free an object E in pool P. */
274 #define pool_put(P,E) \
275 do { \
276  pool_header_t * _pool_var (p) = pool_header (P); \
277  uword _pool_var (l) = (E) - (P); \
278  ASSERT (vec_is_member (P, E)); \
279  ASSERT (! pool_is_free (P, E)); \
280  \
281  /* Add element to free bitmap and to free list. */ \
282  _pool_var (p)->free_bitmap = \
283  clib_bitmap_ori_notrim (_pool_var (p)->free_bitmap, \
284  _pool_var (l)); \
285  \
286  /* Preallocated pool? */ \
287  if (_pool_var (p)->max_elts) \
288  { \
289  ASSERT(_pool_var(l) < _pool_var (p)->max_elts); \
290  _pool_var(p)->free_indices[_vec_len(_pool_var(p)->free_indices)] = \
291  _pool_var(l); \
292  _vec_len(_pool_var(p)->free_indices) += 1; \
293  } \
294  else \
295  vec_add1 (_pool_var (p)->free_indices, _pool_var (l)); \
296 } while (0)
297 
298 /** Free pool element with given index. */
299 #define pool_put_index(p,i) \
300 do { \
301  typeof (p) _e = (p) + (i); \
302  pool_put (p, _e); \
303 } while (0)
304 
305 /** Allocate N more free elements to pool (general version). */
306 #define pool_alloc_aligned(P,N,A) \
307 do { \
308  pool_header_t * _p; \
309  \
310  if ((P)) \
311  { \
312  _p = pool_header (P); \
313  if (_p->max_elts) \
314  { \
315  clib_warning ("Can't expand fixed-size pool"); \
316  os_out_of_memory(); \
317  } \
318  } \
319  \
320  (P) = _vec_resize ((P), 0, (vec_len (P) + (N)) * sizeof (P[0]), \
321  pool_aligned_header_bytes, \
322  (A)); \
323  _p = pool_header (P); \
324  vec_resize (_p->free_indices, (N)); \
325  _vec_len (_p->free_indices) -= (N); \
326 } while (0)
327 
328 /** Allocate N more free elements to pool (unspecified alignment). */
329 #define pool_alloc(P,N) pool_alloc_aligned(P,N,0)
330 
331 /** Low-level free pool operator (do not call directly). */
332 always_inline void *
333 _pool_free (void *v)
334 {
335  pool_header_t *p = pool_header (v);
336  if (!v)
337  return v;
339 
340  if (p->max_elts)
341  {
342  int rv;
343 
344  rv = munmap (p->mmap_base, p->mmap_size);
345  if (rv)
346  clib_unix_warning ("munmap");
347  }
348  else
349  {
350  vec_free (p->free_indices);
352  }
353  return 0;
354 }
355 
356 /** Free a pool. */
357 #define pool_free(p) (p) = _pool_free(p)
358 
359 /** Optimized iteration through pool.
360 
361  @param LO pointer to first element in chunk
362  @param HI pointer to last element in chunk
363  @param POOL pool to iterate across
364  @param BODY operation to perform
365 
366  Optimized version which assumes that BODY is smart enough to
367  process multiple (LOW,HI) chunks. See also pool_foreach().
368  */
369 #define pool_foreach_region(LO,HI,POOL,BODY) \
370 do { \
371  uword _pool_var (i), _pool_var (lo), _pool_var (hi), _pool_var (len); \
372  uword _pool_var (bl), * _pool_var (b); \
373  pool_header_t * _pool_var (p); \
374  \
375  _pool_var (p) = pool_header (POOL); \
376  _pool_var (b) = (POOL) ? _pool_var (p)->free_bitmap : 0; \
377  _pool_var (bl) = vec_len (_pool_var (b)); \
378  _pool_var (len) = vec_len (POOL); \
379  _pool_var (lo) = 0; \
380  \
381  for (_pool_var (i) = 0; \
382  _pool_var (i) <= _pool_var (bl); \
383  _pool_var (i)++) \
384  { \
385  uword _pool_var (m), _pool_var (f); \
386  _pool_var (m) = (_pool_var (i) < _pool_var (bl) \
387  ? _pool_var (b) [_pool_var (i)] \
388  : 1); \
389  while (_pool_var (m) != 0) \
390  { \
391  _pool_var (f) = first_set (_pool_var (m)); \
392  _pool_var (hi) = (_pool_var (i) * BITS (_pool_var (b)[0]) \
393  + min_log2 (_pool_var (f))); \
394  _pool_var (hi) = (_pool_var (i) < _pool_var (bl) \
395  ? _pool_var (hi) : _pool_var (len)); \
396  _pool_var (m) ^= _pool_var (f); \
397  if (_pool_var (hi) > _pool_var (lo)) \
398  { \
399  (LO) = _pool_var (lo); \
400  (HI) = _pool_var (hi); \
401  do { BODY; } while (0); \
402  } \
403  _pool_var (lo) = _pool_var (hi) + 1; \
404  } \
405  } \
406 } while (0)
407 
408 /** Iterate through pool.
409 
410  @param VAR A variable of same type as pool vector to be used as an
411  iterator.
412  @param POOL The pool to iterate across.
413  @param BODY The operation to perform, typically a code block. See
414  the example below.
415 
416  This macro will call @c BODY with each active pool element.
417 
418  It is a bad idea to allocate or free pool element from within
419  @c pool_foreach. Build a vector of indices and dispose of them later.
420  Or call pool_flush.
421 
422 
423  @par Example
424  @code{.c}
425  proc_t *procs; // a pool of processes.
426  proc_t *proc; // pointer to one process; used as the iterator.
427 
428  pool_foreach (proc, procs, ({
429  if (proc->state != PROC_STATE_RUNNING)
430  continue;
431 
432  // check a running proc in some way
433  ...
434  }));
435  @endcode
436 
437  @warning Because @c pool_foreach is a macro, syntax errors can be
438  difficult to find inside @c BODY, let alone actual code bugs. One
439  can temporarily split a complex @c pool_foreach into a trivial
440  @c pool_foreach which builds a vector of active indices, and a
441  vec_foreach() (or plain for-loop) to walk the active index vector.
442  */
443 #define pool_foreach(VAR,POOL,BODY) \
444 do { \
445  uword _pool_foreach_lo, _pool_foreach_hi; \
446  pool_foreach_region (_pool_foreach_lo, _pool_foreach_hi, (POOL), \
447  ({ \
448  for ((VAR) = (POOL) + _pool_foreach_lo; \
449  (VAR) < (POOL) + _pool_foreach_hi; \
450  (VAR)++) \
451  do { BODY; } while (0); \
452  })); \
453 } while (0)
454 
455 /** Returns pointer to element at given index.
456 
457  ASSERTs that the supplied index is valid.
458  Even though one can write correct code of the form
459  @code
460  p = pool_base + index;
461  @endcode
462  use of @c pool_elt_at_index is strongly suggested.
463  */
464 #define pool_elt_at_index(p,i) \
465 ({ \
466  typeof (p) _e = (p) + (i); \
467  ASSERT (! pool_is_free (p, _e)); \
468  _e; \
469 })
470 
471 /** Return next occupied pool index after @c i, useful for safe iteration. */
472 #define pool_next_index(P,I) \
473 ({ \
474  pool_header_t * _pool_var (p) = pool_header (P); \
475  uword _pool_var (rv) = (I) + 1; \
476  \
477  _pool_var(rv) = \
478  (_pool_var (rv) < vec_len (P) ? \
479  clib_bitmap_next_clear (_pool_var (p)->free_bitmap, _pool_var(rv)) \
480  : ~0); \
481  _pool_var(rv) = \
482  (_pool_var (rv) < vec_len (P) ? \
483  _pool_var (rv) : ~0); \
484  _pool_var(rv); \
485 })
486 
487 /** Iterate pool by index. */
488 #define pool_foreach_index(i,v,body) \
489  for ((i) = 0; (i) < vec_len (v); (i)++) \
490  { \
491  if (! pool_is_free_index ((v), (i))) \
492  do { body; } while (0); \
493  }
494 
495 /**
496  * @brief Remove all elemenets from a pool in a safe way
497  *
498  * @param VAR each element in the pool
499  * @param POOL The pool to flush
500  * @param BODY The actions to perform on each element before it is returned to
501  * the pool. i.e. before it is 'freed'
502  */
503 #define pool_flush(VAR, POOL, BODY) \
504 { \
505  uword *_pool_var(ii), *_pool_var(dv) = NULL; \
506  \
507  pool_foreach((VAR), (POOL), \
508  ({ \
509  vec_add1(_pool_var(dv), (VAR) - (POOL)); \
510  })); \
511  vec_foreach(_pool_var(ii), _pool_var(dv)) \
512  { \
513  (VAR) = pool_elt_at_index((POOL), *_pool_var(ii)); \
514  do { BODY; } while (0); \
515  pool_put((POOL), (VAR)); \
516  } \
517  vec_free(_pool_var(dv)); \
518 }
519 
520 #endif /* included_pool_h */
521 
522 /*
523  * fd.io coding-style-patch-verification: ON
524  *
525  * Local Variables:
526  * eval: (c-set-style "gnu")
527  * End:
528  */
#define vec_validate(V, I)
Make sure vector is long enough for given index (no header, unspecified alignment) ...
Definition: vec.h:437
u64 mmap_size
Definition: pool.h:67
unsigned long u64
Definition: types.h:89
static void pool_header_validate_index(void *v, uword index)
Definition: pool.h:108
u32 * free_indices
Vector of free indices.
Definition: pool.h:58
int i
#define vec_bytes(v)
Number of data bytes in vector.
unsigned char u8
Definition: types.h:56
#define always_inline
Definition: clib.h:92
unsigned int u32
Definition: types.h:88
void fpool_free(void *)
static pool_header_t * pool_header(void *v)
Get pool header from user pool pointer.
Definition: pool.h:77
#define v
Definition: acl.c:491
#define pool_aligned_header_bytes
Align pool header so that pointers are naturally aligned.
Definition: pool.h:72
static uword pool_header_bytes(void *v)
Memory usage of pool header.
Definition: pool.h:150
static void pool_validate(void *v)
Validate a pool.
Definition: pool.h:93
#define vec_free(V)
Free vector&#39;s memory (no header).
Definition: vec.h:339
static void * vec_aligned_header(void *v, uword header_bytes, uword align)
#define vec_capacity(v, b)
Total number of bytes that can fit in vector with current allocation.
static uword clib_bitmap_get(uword *ai, uword i)
Gets the ith bit value from a bitmap.
Definition: bitmap.h:197
#define ASSERT(truth)
Bitmaps built as vectors of machine words.
#define clib_bitmap_free(v)
Free a bitmap.
Definition: bitmap.h:92
uword * free_bitmap
Bitmap of indices of free objects.
Definition: pool.h:55
static uword clib_bitmap_count_set_bits(uword *ai)
Return the number of set bits in a bitmap.
Definition: bitmap.h:462
#define vec_free_h(V, H)
Free vector&#39;s memory (general version)
Definition: vec.h:326
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
u64 uword
Definition: types.h:112
#define clib_unix_warning(format, args...)
Definition: error.h:68
u32 max_elts
Maximum size of the pool, in elements.
Definition: pool.h:63
#define BITS(x)
Definition: clib.h:58
static uword pool_free_elts(void *v)
Queries whether pool has at least N_FREE free elements.
Definition: pool.h:168
u8 * mmap_base
mmap segment info: base + length
Definition: pool.h:66
static uword pool_elts(void *v)
Number of active elements in a pool.
Definition: pool.h:128