1 files changed, 141 insertions, 0 deletions
diff --git a/lib/ccan/likely/likely.c b/lib/ccan/likely/likely.c
new file mode 100644
index 00000000000..8893d0b6d24
--- /dev/null
+++ b/lib/ccan/likely/likely.c
@@ -0,0 +1,141 @@
+#ifdef CCAN_LIKELY_DEBUG
+#include <ccan/likely/likely.h>
+#include <ccan/hash/hash.h>
+#include <ccan/htable/htable.h>
+#include <stdlib.h>
+#include <stdio.h>
+static struct htable *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 size_t 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);
+	htable_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 = htable_new(rehash, NULL);
+
+	init_trace(&trace, condstr, file, line, expect);
+	p = htable_get(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 void get_stats(struct trace *trace, struct get_stats_info *info)
+{
+	if (trace->count < info->min_hits)
+		return;
+
+	if (right_ratio(trace) < info->worst_ratio) {
+		info->worst = trace;
+		info->worst_ratio = right_ratio(trace);
+	}
+}
+
+const char *likely_stats(unsigned int min_hits, unsigned int percent)
+{
+	struct get_stats_info info;
+	struct htable_iter i;
+	char *ret;
+	struct trace *trace;
+
+	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. */
+	for (trace = htable_first(htable, &i);
+	     trace;
+	     trace = htable_next(htable,&i)) {
+		get_stats(trace, &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);
+
+	htable_del(htable, hash_trace(info.worst), info.worst);
+	free(info.worst);
+
+	return ret;
+}
+#endif /*CCAN_LIKELY_DEBUG*/