nserver: Add Stats_stringify.

* nserver/src/stats.c (Stats_stringify): New function definition.
* nserver/src/stats.h (Stats_stringify): New function declaration.
* nserver/tests/stats_tests.c (test_tests_stringify): Test for
Stats_stringify.

3 files changed, 69 insertions, 0 deletions

diff --git a/nserver/src/stats.c b/nserver/src/stats.c
index 0b793f8..6edf458 100644
--- a/nserver/src/stats.c
+++ b/nserver/src/stats.c
@@ -65,3 +65,25 @@ char *Stats_dump(Stats *st)
  error:
     return NULL;
 }
+
+char *Stats_stringify(Stats *st)
+{
+    size_t stats_str_len = 80;
+
+    // allocate space for stringified stats.
+    char *stats_str = calloc(stats_str_len, sizeof(char));
+    check_mem(stats_str);
+
+    // stringify the stats
+    int rc = snprintf(stats_str, stats_str_len,
+                      "%.2f::%.2f::%ld::%.2f::%.2f",
+                      st->sum, st->sumsq, st->n, st->min, st->max);
+    check(rc > 0, "stringify stats failed");
+
+    return stats_str;
+ error:
+    if (stats_str) {
+        free(stats_str);
+    }
+    return NULL;
+}
diff --git a/nserver/src/stats.h b/nserver/src/stats.h
index 776eb21..8fc971e 100644
--- a/nserver/src/stats.h
+++ b/nserver/src/stats.h
@@ -19,6 +19,8 @@ void Stats_sample(Stats *st, double s);
 
 char *Stats_dump(Stats *st);
 
+char *Stats_stringify(Stats *st);
+
 static inline double Stats_mean(Stats *st)
 {
     return st->sum / st->n;
diff --git a/nserver/tests/stats_tests.c b/nserver/tests/stats_tests.c
new file mode 100644
index 0000000..6553ea5
--- /dev/null
+++ b/nserver/tests/stats_tests.c
@@ -0,0 +1,45 @@
+#include "minunit.h"
+#include <stats.h>
+#include <string.h>
+
+/**
+ * tests for other stats functions are in
+ * ../../liblcthw/tests/stats_tests.c
+ */
+
+char *test_stats_stringify()
+{
+    Stats *st = Stats_create();
+    mu_assert(st != NULL, "stats create failed");
+
+    // fill with dummy data.
+    st->sum = 8238.33892;
+    st->sumsq = 4260238.8292;
+    st->n = 28;
+    st->min =  28.3921;
+    st->max = 238.27;
+
+    char *st_str = Stats_stringify(st);
+    mu_assert(st_str != NULL, "stats stringify failed");
+
+    char *expected_st_str = "8238.34::4260238.83::28::28.39::238.27";
+    mu_assert(strncmp(st_str, expected_st_str, strlen(expected_st_str)) == 0,
+              "stringified str invalid");
+
+    // cleanup
+    free(st_str);
+    free(st);
+
+    return NULL;
+}
+
+char *all_tests()
+{
+    mu_suite_start();
+
+    mu_run_test(test_stats_stringify);
+
+    return NULL;
+}
+
+RUN_TESTS(all_tests);