Add stats serializer.

stats.c

@@ -0,0 +1,43 @@
+#include <assert.h>
+#include <time.h>
+#include <jansson.h>
+
+#include "common.h"
+#include "backend.h"
+#include "json.h"
+#include "stats.h"
+
+
+static struct stats_state {
+	uint64_t total_count;
+	uint64_t type_count[NUM_TYPES];
+	struct timespec start;
+} stats_state = { 0 };
+
+
+void stats_init() {
+	assert(clock_gettime(CLOCK_MONOTONIC, &stats_state.start) == 0);
+}
+
+
+void stats_serialize(struct packet *packet, struct buf *buf) {
+	if (packet) {
+		stats_state.total_count++;
+		stats_state.type_count[packet->type]++;
+	}
+	if (stats_state.total_count % 1000 != 0) {
+		return;
+	}
+	json_t *counts = json_object();
+	for (int i = 0; i < NUM_TYPES; i++) {
+		json_object_set_new(counts, packet_type_names[i], json_integer(stats_state.type_count[i]));
+	}
+	struct timespec now;
+	assert(clock_gettime(CLOCK_MONOTONIC, &now) == 0);
+	json_t *out = json_pack("{sIso}",
+			"uptime_seconds", (json_int_t) (now.tv_sec - stats_state.start.tv_sec),
+			"packet_counts", counts);
+	assert(json_dump_callback(out, json_buf_append_callback, buf, 0) == 0);
+	json_decref(out);
+	buf_chr(buf, buf->length++) = '\n';
+}