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.h>
   6 #include <stdlib.h>
   7 #include <stdio.h>
   8 static struct htable *htable;
   9
  10 struct trace {
  11         const char *condstr;
  12         const char *file;
  13         unsigned int line;
  14         bool expect;
  15         unsigned long count, right;
  16 };
  17
  18 /* We hash the pointers, which will be identical for same call. */
  19 static unsigned long hash_trace(const struct trace *trace)
  20 {
  21         return hash_pointer(trace->condstr,
  22                             hash_pointer(trace->file,
  23                                          trace->line + trace->expect));
  24 }
  25
  26 static bool hash_cmp(const void *htelem, void *cmpdata)
  27 {
  28         const struct trace *t1 = htelem, *t2 = cmpdata;
  29         return t1->condstr == t2->condstr
  30                 && t1->file == t2->file
  31                 && t1->line == t2->line
  32                 && t1->expect == t2->expect;
  33 }
  34
  35 static size_t rehash(const void *elem, void *priv)
  36 {
  37         return hash_trace(elem);
  38 }
  39
  40 static void init_trace(struct trace *trace,
  41                        const char *condstr, const char *file, unsigned int line,
  42                        bool expect)
  43 {
  44         trace->condstr = condstr;
  45         trace->file = file;
  46         trace->line = line;
  47         trace->expect = expect;
  48         trace->count = trace->right = 0;
  49 }
  50
  51 static struct trace *add_trace(const char *condstr,
  52                                const char *file, unsigned int line, bool expect)
  53 {
  54         struct trace *trace = malloc(sizeof(*trace));
  55         init_trace(trace, condstr, file, line, expect);
  56         htable_add(htable, hash_trace(trace), trace);
  57         return trace;
  58 }
  59
  60 long _likely_trace(bool cond, bool expect,
  61                    const char *condstr,
  62                    const char *file, unsigned int line)
  63 {
  64         struct trace *p, trace;
  65
  66         if (!htable)
  67                 htable = htable_new(rehash, NULL);
  68
  69         init_trace(&trace, condstr, file, line, expect);
  70         p = htable_get(htable, hash_trace(&trace), hash_cmp, &trace);
  71         if (!p)
  72                 p = add_trace(condstr, file, line, expect);
  73
  74         p->count++;
  75         if (cond == expect)
  76                 p->right++;
  77
  78         return cond;
  79 }
  80
  81 struct get_stats_info {
  82         struct trace *worst;
  83         unsigned int min_hits;
  84         double worst_ratio;
  85 };
  86
  87 static double right_ratio(const struct trace *t)
  88 {
  89         return (double)t->right / t->count;
  90 }
  91
  92 static void get_stats(struct trace *trace, struct get_stats_info *info)
  93 {
  94         if (trace->count < info->min_hits)
  95                 return;
  96
  97         if (right_ratio(trace) < info->worst_ratio) {
  98                 info->worst = trace;
  99                 info->worst_ratio = right_ratio(trace);
 100         }
 101 }
 102
 103 const char *likely_stats(unsigned int min_hits, unsigned int percent)
 104 {
 105         struct get_stats_info info;
 106         struct htable_iter i;
 107         char *ret;
 108         struct trace *trace;
 109
 110         if (!htable)
 111                 return NULL;
 112
 113         info.min_hits = min_hits;
 114         info.worst = NULL;
 115         info.worst_ratio = 2;
 116
 117         /* This is O(n), but it's not likely called that often. */
 118         for (trace = htable_first(htable, &i);
 119              trace;
 120              trace = htable_next(htable,&i)) {
 121                 get_stats(trace, &info);
 122         }
 123
 124         if (info.worst_ratio * 100 > percent)
 125                 return NULL;
 126
 127         ret = malloc(strlen(info.worst->condstr) +
 128                      strlen(info.worst->file) +
 129                      sizeof(long int) * 8 +
 130                      sizeof("%s:%u:%slikely(%s) correct %u%% (%lu/%lu)"));
 131         sprintf(ret, "%s:%u:%slikely(%s) correct %u%% (%lu/%lu)",
 132                 info.worst->file, info.worst->line,
 133                 info.worst->expect ? "" : "un", info.worst->condstr,
 134                 (unsigned)(info.worst_ratio * 100),
 135                 info.worst->right, info.worst->count);
 136
 137         htable_del(htable, hash_trace(info.worst), info.worst);
 138         free(info.worst);
 139
 140         return ret;
 141 }
 142 #endif /*CCAN_LIKELY_DEBUG*/