FD.io VPP  v17.07-30-g839fa73
Vector Packet Processing
pool.h
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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:
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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
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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
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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. */
60 
61 /** Align pool header so that pointers are naturally aligned. */
62 #define pool_aligned_header_bytes \
63  vec_aligned_header_bytes (sizeof (pool_header_t), sizeof (void *))
64 
65 /** Get pool header from user pool pointer */
67 pool_header (void *v)
68 {
69  return vec_aligned_header (v, sizeof (pool_header_t), sizeof (void *));
70 }
71 
72 /** Validate a pool */
73 always_inline void
75 {
76  pool_header_t *p = pool_header (v);
77  uword i, n_free_bitmap;
78 
79  if (!v)
80  return;
81 
82  n_free_bitmap = clib_bitmap_count_set_bits (p->free_bitmap);
83  ASSERT (n_free_bitmap == vec_len (p->free_indices));
84  for (i = 0; i < vec_len (p->free_indices); i++)
86 }
87 
88 always_inline void
90 {
91  pool_header_t *p = pool_header (v);
92 
93  if (v)
94  vec_validate (p->free_bitmap, index / BITS (uword));
95 }
96 
97 #define pool_validate_index(v,i) \
98 do { \
99  uword __pool_validate_index = (i); \
100  vec_validate_ha ((v), __pool_validate_index, \
101  pool_aligned_header_bytes, /* align */ 0); \
102  pool_header_validate_index ((v), __pool_validate_index); \
103 } while (0)
104 
105 /** Number of active elements in a pool.
106  * @return Number of active elements in a pool
107  */
109 pool_elts (void *v)
110 {
111  uword ret = vec_len (v);
112  if (v)
113  ret -= vec_len (pool_header (v)->free_indices);
114  return ret;
115 }
116 
117 /** Number of elements in pool vector.
118 
119  @note You probably want to call pool_elts() instead.
120 */
121 #define pool_len(p) vec_len(p)
122 
123 /** Number of elements in pool vector (usable as an lvalue)
124 
125  @note You probably don't want to use this macro.
126 */
127 #define _pool_len(p) _vec_len(p)
128 
129 /** Memory usage of pool header. */
132 {
133  pool_header_t *p = pool_header (v);
134 
135  if (!v)
136  return 0;
137 
138  return vec_bytes (p->free_bitmap) + vec_bytes (p->free_indices);
139 }
140 
141 /** Memory usage of pool. */
142 #define pool_bytes(P) (vec_bytes (P) + pool_header_bytes (P))
143 
144 /** Local variable naming macro. */
145 #define _pool_var(v) _pool_##v
146 
147 /** Queries whether pool has at least N_FREE free elements. */
150 {
151  pool_header_t *p = pool_header (v);
152  uword n_free = 0;
153 
154  if (v)
155  {
156  n_free += vec_len (p->free_indices);
157 
158  /* Space left at end of vector? */
159  n_free += vec_capacity (v, sizeof (p[0])) - vec_len (v);
160  }
161 
162  return n_free;
163 }
164 
165 /** Allocate an object E from a pool P (general version).
166 
167  First search free list. If nothing is free extend vector of objects.
168 */
169 #define pool_get_aligned(P,E,A) \
170 do { \
171  pool_header_t * _pool_var (p) = pool_header (P); \
172  uword _pool_var (l); \
173  \
174  _pool_var (l) = 0; \
175  if (P) \
176  _pool_var (l) = vec_len (_pool_var (p)->free_indices); \
177  \
178  if (_pool_var (l) > 0) \
179  { \
180  /* Return free element from free list. */ \
181  uword _pool_var (i) = _pool_var (p)->free_indices[_pool_var (l) - 1]; \
182  (E) = (P) + _pool_var (i); \
183  _pool_var (p)->free_bitmap = \
184  clib_bitmap_andnoti (_pool_var (p)->free_bitmap, _pool_var (i)); \
185  _vec_len (_pool_var (p)->free_indices) = _pool_var (l) - 1; \
186  } \
187  else \
188  { \
189  /* Nothing on free list, make a new element and return it. */ \
190  P = _vec_resize (P, \
191  /* length_increment */ 1, \
192  /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
193  pool_aligned_header_bytes, \
194  /* align */ (A)); \
195  E = vec_end (P) - 1; \
196  } \
197 } while (0)
198 
199 /** Allocate an object E from a pool P (unspecified alignment). */
200 #define pool_get(P,E) pool_get_aligned(P,E,0)
201 
202 /** See if pool_get will expand the pool or not */
203 #define pool_get_aligned_will_expand (P,YESNO,A) \
204 do { \
205  pool_header_t * _pool_var (p) = pool_header (P); \
206  uword _pool_var (l); \
207  \
208  _pool_var (l) = 0; \
209  if (P) \
210  _pool_var (l) = vec_len (_pool_var (p)->free_indices); \
211  \
212  /* Free elements, certainly won't expand */ \
213  if (_pool_var (l) > 0) \
214  YESNO=0; \
215  else \
216  { \
217  /* Nothing on free list, make a new element and return it. */ \
218  YESNO = _vec_resize_will_expand \
219  (P, \
220  /* length_increment */ 1, \
221  /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
222  pool_aligned_header_bytes, \
223  /* align */ (A)); \
224  } \
225 } while (0)
226 
227 #define pool_get_will_expand(P,YESNO) pool_get_aligned_will_expand(P,YESNO,0)
228 
229 /** Use free bitmap to query whether given element is free. */
230 #define pool_is_free(P,E) \
231 ({ \
232  pool_header_t * _pool_var (p) = pool_header (P); \
233  uword _pool_var (i) = (E) - (P); \
234  (_pool_var (i) < vec_len (P)) ? clib_bitmap_get (_pool_var (p)->free_bitmap, _pool_i) : 1; \
235 })
236 
237 /** Use free bitmap to query whether given index is free */
238 #define pool_is_free_index(P,I) pool_is_free((P),(P)+(I))
239 
240 /** Free an object E in pool P. */
241 #define pool_put(P,E) \
242 do { \
243  pool_header_t * _pool_var (p) = pool_header (P); \
244  uword _pool_var (l) = (E) - (P); \
245  ASSERT (vec_is_member (P, E)); \
246  ASSERT (! pool_is_free (P, E)); \
247  \
248  /* Add element to free bitmap and to free list. */ \
249  _pool_var (p)->free_bitmap = \
250  clib_bitmap_ori (_pool_var (p)->free_bitmap, _pool_var (l)); \
251  vec_add1 (_pool_var (p)->free_indices, _pool_var (l)); \
252 } while (0)
253 
254 /** Free pool element with given index. */
255 #define pool_put_index(p,i) \
256 do { \
257  typeof (p) _e = (p) + (i); \
258  pool_put (p, _e); \
259 } while (0)
260 
261 /** Allocate N more free elements to pool (general version). */
262 #define pool_alloc_aligned(P,N,A) \
263 do { \
264  pool_header_t * _p; \
265  (P) = _vec_resize ((P), 0, (vec_len (P) + (N)) * sizeof (P[0]), \
266  pool_aligned_header_bytes, \
267  (A)); \
268  _p = pool_header (P); \
269  vec_resize (_p->free_indices, (N)); \
270  _vec_len (_p->free_indices) -= (N); \
271 } while (0)
272 
273 /** Allocate N more free elements to pool (unspecified alignment). */
274 #define pool_alloc(P,N) pool_alloc_aligned(P,N,0)
275 
276 /** Low-level free pool operator (do not call directly). */
277 always_inline void *
278 _pool_free (void *v)
279 {
280  pool_header_t *p = pool_header (v);
281  if (!v)
282  return v;
284  vec_free (p->free_indices);
286  return 0;
287 }
288 
289 /** Free a pool. */
290 #define pool_free(p) (p) = _pool_free(p)
291 
292 /** Optimized iteration through pool.
293 
294  @param LO pointer to first element in chunk
295  @param HI pointer to last element in chunk
296  @param POOL pool to iterate across
297  @param BODY operation to perform
298 
299  Optimized version which assumes that BODY is smart enough to
300  process multiple (LOW,HI) chunks. See also pool_foreach().
301  */
302 #define pool_foreach_region(LO,HI,POOL,BODY) \
303 do { \
304  uword _pool_var (i), _pool_var (lo), _pool_var (hi), _pool_var (len); \
305  uword _pool_var (bl), * _pool_var (b); \
306  pool_header_t * _pool_var (p); \
307  \
308  _pool_var (p) = pool_header (POOL); \
309  _pool_var (b) = (POOL) ? _pool_var (p)->free_bitmap : 0; \
310  _pool_var (bl) = vec_len (_pool_var (b)); \
311  _pool_var (len) = vec_len (POOL); \
312  _pool_var (lo) = 0; \
313  \
314  for (_pool_var (i) = 0; \
315  _pool_var (i) <= _pool_var (bl); \
316  _pool_var (i)++) \
317  { \
318  uword _pool_var (m), _pool_var (f); \
319  _pool_var (m) = (_pool_var (i) < _pool_var (bl) \
320  ? _pool_var (b) [_pool_var (i)] \
321  : 1); \
322  while (_pool_var (m) != 0) \
323  { \
324  _pool_var (f) = first_set (_pool_var (m)); \
325  _pool_var (hi) = (_pool_var (i) * BITS (_pool_var (b)[0]) \
326  + min_log2 (_pool_var (f))); \
327  _pool_var (hi) = (_pool_var (i) < _pool_var (bl) \
328  ? _pool_var (hi) : _pool_var (len)); \
329  _pool_var (m) ^= _pool_var (f); \
330  if (_pool_var (hi) > _pool_var (lo)) \
331  { \
332  (LO) = _pool_var (lo); \
333  (HI) = _pool_var (hi); \
334  do { BODY; } while (0); \
335  } \
336  _pool_var (lo) = _pool_var (hi) + 1; \
337  } \
338  } \
339 } while (0)
340 
341 /** Iterate through pool.
342 
343  @param VAR A variable of same type as pool vector to be used as an
344  iterator.
345  @param POOL The pool to iterate across.
346  @param BODY The operation to perform, typically a code block. See
347  the example below.
348 
349  This macro will call @c BODY with each active pool element.
350 
351  It is a bad idea to allocate or free pool element from within
352  @c pool_foreach. Build a vector of indices and dispose of them later.
353  Or call pool_flush.
354 
355 
356  @par Example
357  @code{.c}
358  proc_t *procs; // a pool of processes.
359  proc_t *proc; // pointer to one process; used as the iterator.
360 
361  pool_foreach (proc, procs, ({
362  if (proc->state != PROC_STATE_RUNNING)
363  continue;
364 
365  // check a running proc in some way
366  ...
367  }));
368  @endcode
369 
370  @warning Because @c pool_foreach is a macro, syntax errors can be
371  difficult to find inside @c BODY, let alone actual code bugs. One
372  can temporarily split a complex @c pool_foreach into a trivial
373  @c pool_foreach which builds a vector of active indices, and a
374  vec_foreach() (or plain for-loop) to walk the active index vector.
375  */
376 #define pool_foreach(VAR,POOL,BODY) \
377 do { \
378  uword _pool_foreach_lo, _pool_foreach_hi; \
379  pool_foreach_region (_pool_foreach_lo, _pool_foreach_hi, (POOL), \
380  ({ \
381  for ((VAR) = (POOL) + _pool_foreach_lo; \
382  (VAR) < (POOL) + _pool_foreach_hi; \
383  (VAR)++) \
384  do { BODY; } while (0); \
385  })); \
386 } while (0)
387 
388 /** Returns pointer to element at given index.
389 
390  ASSERTs that the supplied index is valid.
391  Even though one can write correct code of the form
392  @code
393  p = pool_base + index;
394  @endcode
395  use of @c pool_elt_at_index is strongly suggested.
396  */
397 #define pool_elt_at_index(p,i) \
398 ({ \
399  typeof (p) _e = (p) + (i); \
400  ASSERT (! pool_is_free (p, _e)); \
401  _e; \
402 })
403 
404 /** Return next occupied pool index after @c i, useful for safe iteration. */
405 #define pool_next_index(P,I) \
406 ({ \
407  pool_header_t * _pool_var (p) = pool_header (P); \
408  uword _pool_var (rv) = (I) + 1; \
409  \
410  _pool_var(rv) = \
411  (_pool_var (rv) < vec_len (P) ? \
412  clib_bitmap_next_clear (_pool_var (p)->free_bitmap, _pool_var(rv)) \
413  : ~0); \
414  _pool_var(rv); \
415 })
416 
417 /** Iterate pool by index. */
418 #define pool_foreach_index(i,v,body) \
419  for ((i) = 0; (i) < vec_len (v); (i)++) \
420  { \
421  if (! pool_is_free_index ((v), (i))) \
422  do { body; } while (0); \
423  }
424 
425 /**
426  * @brief Remove all elemenets from a pool in a safe way
427  *
428  * @param VAR each element in the pool
429  * @param POOL The pool to flush
430  * @param BODY The actions to perform on each element before it is returned to
431  * the pool. i.e. before it is 'freed'
432  */
433 #define pool_flush(VAR, POOL, BODY) \
434 { \
435  uword *_pool_var(ii), *_pool_var(dv) = NULL; \
436  \
437  pool_foreach((VAR), (POOL), \
438  ({ \
439  vec_add1(_pool_var(dv), (VAR) - (POOL)); \
440  })); \
441  vec_foreach(_pool_var(ii), _pool_var(dv)) \
442  { \
443  (VAR) = pool_elt_at_index((POOL), *_pool_var(ii)); \
444  do { BODY; } while (0); \
445  pool_put((POOL), (VAR)); \
446  } \
447  vec_free(_pool_var(dv)); \
448 }
449 
450 #endif /* included_pool_h */
451 
452 /*
453  * fd.io coding-style-patch-verification: ON
454  *
455  * Local Variables:
456  * eval: (c-set-style "gnu")
457  * End:
458  */
#define vec_validate(V, I)
Make sure vector is long enough for given index (no header, unspecified alignment) ...
Definition: vec.h:436
sll srl srl sll sra u16x4 i
Definition: vector_sse2.h:337
static void pool_header_validate_index(void *v, uword index)
Definition: pool.h:89
u32 * free_indices
Vector of free indices.
Definition: pool.h:58
#define vec_bytes(v)
Number of data bytes in vector.
#define always_inline
Definition: clib.h:84
static pool_header_t * pool_header(void *v)
Get pool header from user pool pointer.
Definition: pool.h:67
#define v
Definition: acl.c:320
#define pool_aligned_header_bytes
Align pool header so that pointers are naturally aligned.
Definition: pool.h:62
static uword pool_header_bytes(void *v)
Memory usage of pool header.
Definition: pool.h:131
static void pool_validate(void *v)
Validate a pool.
Definition: pool.h:74
#define vec_free(V)
Free vector&#39;s memory (no header).
Definition: vec.h:340
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)
unsigned int u32
Definition: types.h:88
Bitmaps built as vectors of machine words.
#define clib_bitmap_free(v)
Free a bitmap.
Definition: bitmap.h:92
u64 uword
Definition: types.h:112
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:441
#define vec_free_h(V, H)
Free vector&#39;s memory (general version)
Definition: vec.h:327
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
#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:149
static uword pool_elts(void *v)
Number of active elements in a pool.
Definition: pool.h:109