libcounter/counter-api.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2020 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng Counters API, requiring counter/config.h
   7  */
   8
   9 #ifndef _LTTNG_COUNTER_API_H
  10 #define _LTTNG_COUNTER_API_H
  11
  12 #include <stdint.h>
  13 #include <limits.h>
  14 #include "counter.h"
  15 #include "counter-internal.h"
  16 #include <urcu/compiler.h>
  17 #include <urcu/uatomic.h>
  18 #include <lttng/bitmap.h>
  19 #include "../libringbuffer/getcpu.h"
  20
  21 /*
  22  * Using unsigned arithmetic because overflow is defined.
  23  */
  24 static inline int __lttng_counter_add(const struct lib_counter_config *config,
  25                                       enum lib_counter_config_alloc alloc,
  26                                       enum lib_counter_config_sync sync,
  27                                       struct lib_counter *counter,
  28                                       const size_t *dimension_indexes, int64_t v,
  29                                       int64_t *remainder)
  30 {
  31         size_t index;
  32         bool overflow = false, underflow = false;
  33         struct lib_counter_layout *layout;
  34         int64_t move_sum = 0;
  35
  36         if (caa_unlikely(lttng_counter_validate_indexes(config, counter, dimension_indexes)))
  37                 return -EOVERFLOW;
  38         index = lttng_counter_get_index(config, counter, dimension_indexes);
  39
  40         switch (alloc) {
  41         case COUNTER_ALLOC_PER_CPU:
  42                 layout = &counter->percpu_counters[lttng_ust_get_cpu()];
  43                 break;
  44         case COUNTER_ALLOC_GLOBAL:
  45                 layout = &counter->global_counters;
  46                 break;
  47         default:
  48                 return -EINVAL;
  49         }
  50         if (caa_unlikely(!layout->counters))
  51                 return -ENODEV;
  52
  53         switch (config->counter_size) {
  54         case COUNTER_SIZE_8_BIT:
  55         {
  56                 int8_t *int_p = (int8_t *) layout->counters + index;
  57                 int8_t old, n, res;
  58                 int8_t global_sum_step = counter->global_sum_step.s8;
  59
  60                 res = *int_p;
  61                 switch (sync) {
  62                 case COUNTER_SYNC_PER_CPU:
  63                 {
  64                         do {
  65                                 move_sum = 0;
  66                                 old = res;
  67                                 n = (int8_t) ((uint8_t) old + (uint8_t) v);
  68                                 if (caa_unlikely(n > (int8_t) global_sum_step))
  69                                         move_sum = (int8_t) global_sum_step / 2;
  70                                 else if (caa_unlikely(n < -(int8_t) global_sum_step))
  71                                         move_sum = -((int8_t) global_sum_step / 2);
  72                                 n -= move_sum;
  73                                 res = uatomic_cmpxchg(int_p, old, n);
  74                         } while (old != res);
  75                         break;
  76                 }
  77                 case COUNTER_SYNC_GLOBAL:
  78                 {
  79                         do {
  80                                 old = res;
  81                                 n = (int8_t) ((uint8_t) old + (uint8_t) v);
  82                                 res = uatomic_cmpxchg(int_p, old, n);
  83                         } while (old != res);
  84                         break;
  85                 }
  86                 default:
  87                         return -EINVAL;
  88                 }
  89                 if (v > 0 && (v >= UINT8_MAX || n < old))
  90                         overflow = true;
  91                 else if (v < 0 && (v <= -(int64_t) UINT8_MAX || n > old))
  92                         underflow = true;
  93                 break;
  94         }
  95         case COUNTER_SIZE_16_BIT:
  96         {
  97                 int16_t *int_p = (int16_t *) layout->counters + index;
  98                 int16_t old, n, res;
  99                 int16_t global_sum_step = counter->global_sum_step.s16;
 100
 101                 res = *int_p;
 102                 switch (sync) {
 103                 case COUNTER_SYNC_PER_CPU:
 104                 {
 105                         do {
 106                                 move_sum = 0;
 107                                 old = res;
 108                                 n = (int16_t) ((uint16_t) old + (uint16_t) v);
 109                                 if (caa_unlikely(n > (int16_t) global_sum_step))
 110                                         move_sum = (int16_t) global_sum_step / 2;
 111                                 else if (caa_unlikely(n < -(int16_t) global_sum_step))
 112                                         move_sum = -((int16_t) global_sum_step / 2);
 113                                 n -= move_sum;
 114                                 res = uatomic_cmpxchg(int_p, old, n);
 115                         } while (old != res);
 116                         break;
 117                 }
 118                 case COUNTER_SYNC_GLOBAL:
 119                 {
 120                         do {
 121                                 old = res;
 122                                 n = (int16_t) ((uint16_t) old + (uint16_t) v);
 123                                 res = uatomic_cmpxchg(int_p, old, n);
 124                         } while (old != res);
 125                         break;
 126                 }
 127                 default:
 128                         return -EINVAL;
 129                 }
 130                 if (v > 0 && (v >= UINT16_MAX || n < old))
 131                         overflow = true;
 132                 else if (v < 0 && (v <= -(int64_t) UINT16_MAX || n > old))
 133                         underflow = true;
 134                 break;
 135         }
 136         case COUNTER_SIZE_32_BIT:
 137         {
 138                 int32_t *int_p = (int32_t *) layout->counters + index;
 139                 int32_t old, n, res;
 140                 int32_t global_sum_step = counter->global_sum_step.s32;
 141
 142                 res = *int_p;
 143                 switch (sync) {
 144                 case COUNTER_SYNC_PER_CPU:
 145                 {
 146                         do {
 147                                 move_sum = 0;
 148                                 old = res;
 149                                 n = (int32_t) ((uint32_t) old + (uint32_t) v);
 150                                 if (caa_unlikely(n > (int32_t) global_sum_step))
 151                                         move_sum = (int32_t) global_sum_step / 2;
 152                                 else if (caa_unlikely(n < -(int32_t) global_sum_step))
 153                                         move_sum = -((int32_t) global_sum_step / 2);
 154                                 n -= move_sum;
 155                                 res = uatomic_cmpxchg(int_p, old, n);
 156                         } while (old != res);
 157                         break;
 158                 }
 159                 case COUNTER_SYNC_GLOBAL:
 160                 {
 161                         do {
 162                                 old = res;
 163                                 n = (int32_t) ((uint32_t) old + (uint32_t) v);
 164                                 res = uatomic_cmpxchg(int_p, old, n);
 165                         } while (old != res);
 166                         break;
 167                 }
 168                 default:
 169                         return -EINVAL;
 170                 }
 171                 if (v > 0 && (v >= UINT32_MAX || n < old))
 172                         overflow = true;
 173                 else if (v < 0 && (v <= -(int64_t) UINT32_MAX || n > old))
 174                         underflow = true;
 175                 break;
 176         }
 177 #if CAA_BITS_PER_LONG == 64
 178         case COUNTER_SIZE_64_BIT:
 179         {
 180                 int64_t *int_p = (int64_t *) layout->counters + index;
 181                 int64_t old, n, res;
 182                 int64_t global_sum_step = counter->global_sum_step.s64;
 183
 184                 res = *int_p;
 185                 switch (sync) {
 186                 case COUNTER_SYNC_PER_CPU:
 187                 {
 188                         do {
 189                                 move_sum = 0;
 190                                 old = res;
 191                                 n = (int64_t) ((uint64_t) old + (uint64_t) v);
 192                                 if (caa_unlikely(n > (int64_t) global_sum_step))
 193                                         move_sum = (int64_t) global_sum_step / 2;
 194                                 else if (caa_unlikely(n < -(int64_t) global_sum_step))
 195                                         move_sum = -((int64_t) global_sum_step / 2);
 196                                 n -= move_sum;
 197                                 res = uatomic_cmpxchg(int_p, old, n);
 198                         } while (old != res);
 199                         break;
 200                 }
 201                 case COUNTER_SYNC_GLOBAL:
 202                 {
 203                         do {
 204                                 old = res;
 205                                 n = (int64_t) ((uint64_t) old + (uint64_t) v);
 206                                 res = uatomic_cmpxchg(int_p, old, n);
 207                         } while (old != res);
 208                         break;
 209                 }
 210                 default:
 211                         return -EINVAL;
 212                 }
 213                 if (v > 0 && n < old)
 214                         overflow = true;
 215                 else if (v < 0 && n > old)
 216                         underflow = true;
 217                 break;
 218         }
 219 #endif
 220         default:
 221                 return -EINVAL;
 222         }
 223         if (caa_unlikely(overflow && !lttng_bitmap_test_bit(index, layout->overflow_bitmap)))
 224                 lttng_bitmap_set_bit(index, layout->overflow_bitmap);
 225         else if (caa_unlikely(underflow && !lttng_bitmap_test_bit(index, layout->underflow_bitmap)))
 226                 lttng_bitmap_set_bit(index, layout->underflow_bitmap);
 227         if (remainder)
 228                 *remainder = move_sum;
 229         return 0;
 230 }
 231
 232 static inline int __lttng_counter_add_percpu(const struct lib_counter_config *config,
 233                                              struct lib_counter *counter,
 234                                              const size_t *dimension_indexes, int64_t v)
 235 {
 236         int64_t move_sum;
 237         int ret;
 238
 239         ret = __lttng_counter_add(config, COUNTER_ALLOC_PER_CPU, config->sync,
 240                                        counter, dimension_indexes, v, &move_sum);
 241         if (caa_unlikely(ret))
 242                 return ret;
 243         if (caa_unlikely(move_sum))
 244                 return __lttng_counter_add(config, COUNTER_ALLOC_GLOBAL, COUNTER_SYNC_GLOBAL,
 245                                            counter, dimension_indexes, move_sum, NULL);
 246         return 0;
 247 }
 248
 249 static inline int __lttng_counter_add_global(const struct lib_counter_config *config,
 250                                              struct lib_counter *counter,
 251                                              const size_t *dimension_indexes, int64_t v)
 252 {
 253         return __lttng_counter_add(config, COUNTER_ALLOC_GLOBAL, config->sync, counter,
 254                                    dimension_indexes, v, NULL);
 255 }
 256
 257 static inline int lttng_counter_add(const struct lib_counter_config *config,
 258                                     struct lib_counter *counter,
 259                                     const size_t *dimension_indexes, int64_t v)
 260 {
 261         switch (config->alloc) {
 262         case COUNTER_ALLOC_PER_CPU:     /* Fallthrough */
 263         case COUNTER_ALLOC_PER_CPU | COUNTER_ALLOC_GLOBAL:
 264                 return __lttng_counter_add_percpu(config, counter, dimension_indexes, v);
 265         case COUNTER_ALLOC_GLOBAL:
 266                 return __lttng_counter_add_global(config, counter, dimension_indexes, v);
 267         default:
 268                 return -EINVAL;
 269         }
 270 }
 271
 272 static inline int lttng_counter_inc(const struct lib_counter_config *config,
 273                                     struct lib_counter *counter,
 274                                     const size_t *dimension_indexes)
 275 {
 276         return lttng_counter_add(config, counter, dimension_indexes, 1);
 277 }
 278
 279 static inline int lttng_counter_dec(const struct lib_counter_config *config,
 280                                     struct lib_counter *counter,
 281                                     const size_t *dimension_indexes)
 282 {
 283         return lttng_counter_add(config, counter, dimension_indexes, -1);
 284 }
 285
 286 #endif /* _LTTNG_COUNTER_API_H */