force sampling when debug flag is set

Author: flier

examples/simple_proxy/main.c

@@ -291,6 +291,10 @@ void reply_json_response(struct mg_connection *nc, struct http_message *hm)
     {
       zipkin_span_set_sampled(span, strtoul(hv->p, NULL, 10));
     }
+    else if (0 == mg_vcmp(hn, ZIPKIN_X_FLAGS))
+    {
+      zipkin_span_set_debug(span, strtoul(hv->p, NULL, 10) & ZIPKIN_X_FLAG_DEBUG);
+    }
 
     mg_printf(nc, "%s\"%.*s\": \"%.*s\"", (i != 0 ? "," : ""), (int)hn->len, hn->p, (int)hv->len, hv->p);
   }

include/zipkin.h

@@ -60,6 +60,8 @@
 #define ZIPKIN_X_SAMPLED "X-B3-Sampled"             ///< Boolean (either “1” or “0”, can be absent)
 #define ZIPKIN_X_FLAGS "X-B3-Flags"                 ///< “1” means debug (can be absent)
 
+#define ZIPKIN_X_FLAG_DEBUG (1 << 0)
+
 typedef uint64_t zipkin_span_id_t;
 typedef uint64_t zipkin_trace_id_t;
 typedef void *zipkin_userdata_t;
@@ -113,6 +115,7 @@ zipkin_span_t zipkin_span_set_trace_id_high(zipkin_span_t span, zipkin_trace_id_
 zipkin_span_t zipkin_span_parse_trace_id(zipkin_span_t span, const char *str, size_t len);
 
 int zipkin_span_debug(zipkin_span_t span);
+zipkin_span_t zipkin_span_set_debug(zipkin_span_t span, int debug);
 
 int zipkin_span_sampled(zipkin_span_t span);
 zipkin_span_t zipkin_span_set_sampled(zipkin_span_t span, int sampled);

src/CApi.cpp

@@ -142,6 +142,13 @@ int zipkin_span_debug(zipkin_span_t span)
 {
     return span ? static_cast<zipkin::Span *>(span)->debug() : false;
 }
+zipkin_span_t zipkin_span_set_debug(zipkin_span_t span, int debug)
+{
+    if (span)
+        static_cast<zipkin::Span *>(span)->with_debug(debug);
+
+    return span;
+}
 int zipkin_span_sampled(zipkin_span_t span)
 {
     return span ? static_cast<zipkin::Span *>(span)->sampled() : false;

src/Tracer.cpp

@@ -35,7 +35,7 @@ Span *CachedTracer::span(const std::string &name, span_id_t parent_id, void *use
 
 void CachedTracer::submit(Span *span)
 {
-    if (m_collector && span->sampled())
+    if (m_collector && (span->sampled() || span->debug()))
     {
         VLOG(2) << "Span @ " << span << " submited to collector @ " << m_collector << ", id=" << span->id();