likely: new module

[ccan] / ccan / likely / likely.c

diff --git a/ccan/likely/likely.c b/ccan/likely/likely.c
new file mode 100644 (file)
index 0000000..e4bee71
--- /dev/null
+++ b/ccan/likely/likely.c
@@ -0,0 +1,139 @@
+#ifdef DEBUG
+#include <ccan/likely/likely.h>
+#include <ccan/hash/hash.h>
+#include <ccan/hashtable/hashtable.h>
+#include <stdlib.h>
+#include <stdio.h>
+static struct hashtable *htable;
+
+struct trace {
+       const char *condstr;
+       const char *file;
+       unsigned int line;
+       bool expect;
+       unsigned long count, right;
+};
+
+/* We hash the pointers, which will be identical for same call. */
+static unsigned long hash_trace(const struct trace *trace)
+{
+       return hash_pointer(trace->condstr,
+                           hash_pointer(trace->file,
+                                        trace->line + trace->expect));
+}
+
+static bool hash_cmp(const void *htelem, void *cmpdata)
+{
+       const struct trace *t1 = htelem, *t2 = cmpdata;
+       return t1->condstr == t2->condstr
+               && t1->file == t2->file
+               && t1->line == t2->line
+               && t1->expect == t2->expect;
+}
+
+static unsigned long rehash(const void *elem, void *priv)
+{
+       return hash_trace(elem);
+}
+
+static void init_trace(struct trace *trace,
+                      const char *condstr, const char *file, unsigned int line,
+                      bool expect)
+{
+       trace->condstr = condstr;
+       trace->file = file;
+       trace->line = line;
+       trace->expect = expect;
+       trace->count = trace->right = 0;
+}
+
+static struct trace *add_trace(const char *condstr,
+                              const char *file, unsigned int line, bool expect)
+{
+       struct trace *trace = malloc(sizeof(*trace));
+       init_trace(trace, condstr, file, line, expect);
+       hashtable_add(htable, hash_trace(trace), trace);
+       return trace;
+}
+
+long _likely_trace(bool cond, bool expect,
+                  const char *condstr,
+                  const char *file, unsigned int line)
+{
+       struct trace *p, trace;
+
+       if (!htable)
+               htable = hashtable_new(rehash, NULL);
+
+       init_trace(&trace, condstr, file, line, expect);
+       p = hashtable_find(htable, hash_trace(&trace), hash_cmp, &trace);
+       if (!p)
+               p = add_trace(condstr, file, line, expect);
+
+       p->count++;
+       if (cond == expect)
+               p->right++;
+
+       return cond;
+}
+
+struct get_stats_info {
+       struct trace *worst;
+       unsigned int min_hits;
+       double worst_ratio;
+};
+
+static double right_ratio(const struct trace *t)
+{
+       return (double)t->right / t->count;
+}
+
+static bool get_stats(void *elem, void *vinfo)
+{
+       struct trace *trace = elem;
+       struct get_stats_info *info = vinfo;
+
+       if (trace->count < info->min_hits)
+               return false;
+
+       if (right_ratio(trace) < info->worst_ratio) {
+               info->worst = trace;
+               info->worst_ratio = right_ratio(trace);
+       }
+       return false;
+}
+
+const char *likely_stats(unsigned int min_hits, unsigned int percent)
+{
+       struct get_stats_info info;
+       char *ret;
+
+       if (!htable)
+               return NULL;
+
+       info.min_hits = min_hits;
+       info.worst = NULL;
+       info.worst_ratio = 2;
+
+       /* This is O(n), but it's not likely called that often. */
+       hashtable_traverse(htable, get_stats, &info);
+
+       if (info.worst_ratio * 100 > percent)
+               return NULL;
+
+       ret = malloc(strlen(info.worst->condstr) +
+                    strlen(info.worst->file) +
+                    sizeof(long int) * 8 +
+                    sizeof("%s:%u:%slikely(%s) correct %u%% (%lu/%lu)"));
+       sprintf(ret, "%s:%u:%slikely(%s) correct %u%% (%lu/%lu)",
+               info.worst->file, info.worst->line,
+               info.worst->expect ? "" : "un", info.worst->condstr,
+               (unsigned)(info.worst_ratio * 100),
+               info.worst->right, info.worst->count);
+
+       hashtable_del(htable, hash_trace(info.worst), info.worst);
+       free(info.worst);
+
+       return ret;
+}
+#endif /*DEBUG*/