lib/ccan/likely/likely.c

   1 /* Licensed under LGPLv2.1+ - see LICENSE file for details */
   2 #ifdef CCAN_LIKELY_DEBUG
   3 #include <ccan/likely/likely.h>
   4 #include <ccan/hash/hash.h>
   5 #include <ccan/htable/htable_type.h>
   6 #include <stdlib.h>
   7 #include <stdio.h>
   8 struct trace {
   9         const char *condstr;
  10         const char *file;
  11         unsigned int line;
  12         bool expect;
  13         unsigned long count, right;
  14 };
  15
  16 static size_t hash_trace(const struct trace *trace)
  17 {
  18         return hash(trace->condstr, strlen(trace->condstr),
  19                     hash(trace->file, strlen(trace->file),
  20                          trace->line + trace->expect));
  21 }
  22
  23 static bool trace_eq(const struct trace *t1, const struct trace *t2)
  24 {
  25         return t1->condstr == t2->condstr
  26                 && t1->file == t2->file
  27                 && t1->line == t2->line
  28                 && t1->expect == t2->expect;
  29 }
  30
  31 /* struct thash */
  32 HTABLE_DEFINE_TYPE(struct trace, (const struct trace *), hash_trace, trace_eq,
  33                    thash);
  34
  35 static struct thash htable
  36 = { HTABLE_INITIALIZER(htable.raw, thash_hash, NULL) };
  37
  38 static void init_trace(struct trace *trace,
  39                        const char *condstr, const char *file, unsigned int line,
  40                        bool expect)
  41 {
  42         trace->condstr = condstr;
  43         trace->file = file;
  44         trace->line = line;
  45         trace->expect = expect;
  46         trace->count = trace->right = 0;
  47 }
  48
  49 static struct trace *add_trace(const struct trace *t)
  50 {
  51         struct trace *trace = malloc(sizeof(*trace));
  52         *trace = *t;
  53         thash_add(&htable, trace);
  54         return trace;
  55 }
  56
  57 long _likely_trace(bool cond, bool expect,
  58                    const char *condstr,
  59                    const char *file, unsigned int line)
  60 {
  61         struct trace *p, trace;
  62
  63         init_trace(&trace, condstr, file, line, expect);
  64         p = thash_get(&htable, &trace);
  65         if (!p)
  66                 p = add_trace(&trace);
  67
  68         p->count++;
  69         if (cond == expect)
  70                 p->right++;
  71
  72         return cond;
  73 }
  74
  75 static double right_ratio(const struct trace *t)
  76 {
  77         return (double)t->right / t->count;
  78 }
  79
  80 char *likely_stats(unsigned int min_hits, unsigned int percent)
  81 {
  82         struct trace *worst;
  83         double worst_ratio;
  84         struct thash_iter i;
  85         char *ret;
  86         struct trace *t;
  87
  88         worst = NULL;
  89         worst_ratio = 2;
  90
  91         /* This is O(n), but it's not likely called that often. */
  92         for (t = thash_first(&htable, &i); t; t = thash_next(&htable, &i)) {
  93                 if (t->count >= min_hits) {
  94                         if (right_ratio(t) < worst_ratio) {
  95                                 worst = t;
  96                                 worst_ratio = right_ratio(t);
  97                         }
  98                 }
  99         }
 100
 101         if (worst_ratio * 100 > percent)
 102                 return NULL;
 103
 104         ret = malloc(strlen(worst->condstr) +
 105                      strlen(worst->file) +
 106                      sizeof(long int) * 8 +
 107                      sizeof("%s:%u:%slikely(%s) correct %u%% (%lu/%lu)"));
 108         sprintf(ret, "%s:%u:%slikely(%s) correct %u%% (%lu/%lu)",
 109                 worst->file, worst->line,
 110                 worst->expect ? "" : "un", worst->condstr,
 111                 (unsigned)(worst_ratio * 100),
 112                 worst->right, worst->count);
 113
 114         thash_del(&htable, worst);
 115         free(worst);
 116
 117         return ret;
 118 }
 119
 120 void likely_stats_reset(void)
 121 {
 122         struct thash_iter i;
 123         struct trace *t;
 124
 125         /* This is a bit better than O(n^2), but we have to loop since
 126          * first/next during delete is unreliable. */
 127         while ((t = thash_first(&htable, &i)) != NULL) {
 128                 for (; t; t = thash_next(&htable, &i)) {
 129                         thash_del(&htable, t);
 130                         free(t);
 131                 }
 132         }
 133
 134         thash_clear(&htable);
 135 }
 136 #endif /*CCAN_LIKELY_DEBUG*/