FD.io VPP  v16.09
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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7  * http://www.apache.org/licenses/LICENSE-2.0
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12  * See the License for the specific language governing permissions and
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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
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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
74 pool_validate (void *v)
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. */
149 pool_free_elts (void *v)
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 /** Use free bitmap to query whether given element is free. */
203 #define pool_is_free(P,E) \
204 ({ \
205  pool_header_t * _pool_var (p) = pool_header (P); \
206  uword _pool_var (i) = (E) - (P); \
207  (_pool_var (i) < vec_len (P)) ? clib_bitmap_get (_pool_var (p)->free_bitmap, _pool_i) : 1; \
208 })
209 
210 /** Use free bitmap to query whether given index is free */
211 #define pool_is_free_index(P,I) pool_is_free((P),(P)+(I))
212 
213 /** Free an object E in pool P. */
214 #define pool_put(P,E) \
215 do { \
216  pool_header_t * _pool_var (p) = pool_header (P); \
217  uword _pool_var (l) = (E) - (P); \
218  ASSERT (vec_is_member (P, E)); \
219  ASSERT (! pool_is_free (P, E)); \
220  \
221  /* Add element to free bitmap and to free list. */ \
222  _pool_var (p)->free_bitmap = \
223  clib_bitmap_ori (_pool_var (p)->free_bitmap, _pool_var (l)); \
224  vec_add1 (_pool_var (p)->free_indices, _pool_var (l)); \
225 } while (0)
226 
227 /** Free pool element with given index. */
228 #define pool_put_index(p,i) \
229 do { \
230  typeof (p) _e = (p) + (i); \
231  pool_put (p, _e); \
232 } while (0)
233 
234 /** Allocate N more free elements to pool (general version). */
235 #define pool_alloc_aligned(P,N,A) \
236 do { \
237  pool_header_t * _p; \
238  (P) = _vec_resize ((P), 0, (vec_len (P) + (N)) * sizeof (P[0]), \
239  pool_aligned_header_bytes, \
240  (A)); \
241  _p = pool_header (P); \
242  vec_resize (_p->free_indices, (N)); \
243  _vec_len (_p->free_indices) -= (N); \
244 } while (0)
245 
246 /** Allocate N more free elements to pool (unspecified alignment). */
247 #define pool_alloc(P,N) pool_alloc_aligned(P,N,0)
248 
249 /** Low-level free pool operator (do not call directly). */
250 always_inline void *
251 _pool_free (void *v)
252 {
253  pool_header_t *p = pool_header (v);
254  if (!v)
255  return v;
257  vec_free (p->free_indices);
259  return 0;
260 }
261 
262 /** Free a pool. */
263 #define pool_free(p) (p) = _pool_free(p)
264 
265 /** Optimized iteration through pool.
266 
267  @param LO pointer to first element in chunk
268  @param HI pointer to last element in chunk
269  @param POOL pool to iterate across
270  @param BODY operation to perform
271 
272  Optimized version which assumes that BODY is smart enough to
273  process multiple (LOW,HI) chunks. See also pool_foreach().
274  */
275 #define pool_foreach_region(LO,HI,POOL,BODY) \
276 do { \
277  uword _pool_var (i), _pool_var (lo), _pool_var (hi), _pool_var (len); \
278  uword _pool_var (bl), * _pool_var (b); \
279  pool_header_t * _pool_var (p); \
280  \
281  _pool_var (p) = pool_header (POOL); \
282  _pool_var (b) = (POOL) ? _pool_var (p)->free_bitmap : 0; \
283  _pool_var (bl) = vec_len (_pool_var (b)); \
284  _pool_var (len) = vec_len (POOL); \
285  _pool_var (lo) = 0; \
286  \
287  for (_pool_var (i) = 0; \
288  _pool_var (i) <= _pool_var (bl); \
289  _pool_var (i)++) \
290  { \
291  uword _pool_var (m), _pool_var (f); \
292  _pool_var (m) = (_pool_var (i) < _pool_var (bl) \
293  ? _pool_var (b) [_pool_var (i)] \
294  : 1); \
295  while (_pool_var (m) != 0) \
296  { \
297  _pool_var (f) = first_set (_pool_var (m)); \
298  _pool_var (hi) = (_pool_var (i) * BITS (_pool_var (b)[0]) \
299  + min_log2 (_pool_var (f))); \
300  _pool_var (hi) = (_pool_var (i) < _pool_var (bl) \
301  ? _pool_var (hi) : _pool_var (len)); \
302  _pool_var (m) ^= _pool_var (f); \
303  if (_pool_var (hi) > _pool_var (lo)) \
304  { \
305  (LO) = _pool_var (lo); \
306  (HI) = _pool_var (hi); \
307  do { BODY; } while (0); \
308  } \
309  _pool_var (lo) = _pool_var (hi) + 1; \
310  } \
311  } \
312 } while (0)
313 
314 /** Iterate through pool.
315 
316  @param VAR A variable of same type as pool vector to be used as an
317  iterator.
318  @param POOL The pool to iterate across.
319  @param BODY The operation to perform, typically a code block. See
320  the example below.
321 
322  This macro will call @c BODY with each active pool element.
323 
324  It is a bad idea to allocate or free pool element from within
325  @c pool_foreach. Build a vector of indices and dispose of them later.
326 
327 
328  @par Example
329  @code{.c}
330  proc_t *procs; // a pool of processes.
331  proc_t *proc; // pointer to one process; used as the iterator.
332 
333  pool_foreach (proc, procs, ({
334  if (proc->state != PROC_STATE_RUNNING)
335  continue;
336 
337  // check a running proc in some way
338  ...
339  }));
340  @endcode
341 
342  @warning Because @c pool_foreach is a macro, syntax errors can be
343  difficult to find inside @c BODY, let alone actual code bugs. One
344  can temporarily split a complex @c pool_foreach into a trivial
345  @c pool_foreach which builds a vector of active indices, and a
346  vec_foreach() (or plain for-loop) to walk the active index vector.
347  */
348 #define pool_foreach(VAR,POOL,BODY) \
349 do { \
350  uword _pool_foreach_lo, _pool_foreach_hi; \
351  pool_foreach_region (_pool_foreach_lo, _pool_foreach_hi, (POOL), \
352  ({ \
353  for ((VAR) = (POOL) + _pool_foreach_lo; \
354  (VAR) < (POOL) + _pool_foreach_hi; \
355  (VAR)++) \
356  do { BODY; } while (0); \
357  })); \
358 } while (0)
359 
360 /** Returns pointer to element at given index.
361 
362  ASSERTs that the supplied index is valid.
363  Even though one can write correct code of the form
364  @code
365  p = pool_base + index;
366  @endcode
367  use of @c pool_elt_at_index is strongly suggested.
368  */
369 #define pool_elt_at_index(p,i) \
370 ({ \
371  typeof (p) _e = (p) + (i); \
372  ASSERT (! pool_is_free (p, _e)); \
373  _e; \
374 })
375 
376 /** Return next occupied pool index after @c i, useful for safe iteration. */
377 #define pool_next_index(P,I) \
378 ({ \
379  pool_header_t * _pool_var (p) = pool_header (P); \
380  uword _pool_var (rv) = (I) + 1; \
381  \
382  _pool_var(rv) = \
383  (_pool_var (rv) < vec_len (P) ? \
384  clib_bitmap_next_clear (_pool_var (p)->free_bitmap, _pool_var(rv)) \
385  : ~0); \
386  _pool_var(rv); \
387 })
388 
389 /** Iterate pool by index. */
390 #define pool_foreach_index(i,v,body) \
391  for ((i) = 0; (i) < vec_len (v); (i)++) \
392  { \
393  if (! pool_is_free_index ((v), (i))) \
394  do { body; } while (0); \
395  }
396 
397 #endif /* included_pool_h */
398 
399 /*
400  * fd.io coding-style-patch-verification: ON
401  *
402  * Local Variables:
403  * eval: (c-set-style "gnu")
404  * End:
405  */
#define vec_validate(V, I)
Make sure vector is long enough for given index (no header, unspecified alignment) ...
Definition: vec.h:396
sll srl srl sll sra u16x4 i
Definition: vector_sse2.h:343
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 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:300
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:287
#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