change spanId toolkit api type (#6216)

apm-application-toolkit/apm-toolkit-trace/src/main/java/org/apache/skywalking/apm/toolkit/trace/TraceContext.java

@@ -46,12 +46,13 @@ public class TraceContext {
     }
 
     /**
-     * Try to get the spanId of current trace context.
+     * Try to get the spanId of current trace context. The spanId is a negative number when the trace context is
+     * missing.
      *
      * @return spanId, if it exists, or empty {@link String}.
      */
-    public static String spanId() {
-        return "";
+    public static int spanId() {
+        return -1;
     }
 
     /**

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/AbstractTracerContext.java

@@ -74,7 +74,7 @@ public interface AbstractTracerContext {
      *
      * @return the string represents the id.
      */
-    String getSpanId();
+    int getSpanId();
 
     /**
      * Create an entry span

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/ContextManager.java

@@ -70,7 +70,7 @@ public class ContextManager implements BootService {
     }
 
     /**
-     * @return the first global trace id if needEnhance. Otherwise, "N/A".
+     * @return the first global trace id when tracing. Otherwise, "N/A".
      */
     public static String getGlobalTraceId() {
         AbstractTracerContext context = CONTEXT.get();
@@ -78,7 +78,7 @@ public class ContextManager implements BootService {
     }
 
     /**
-     * @return the current segment id if needEnhance. Otherwise, "N/A".
+     * @return the current segment id when tracing. Otherwise, "N/A".
      */
     public static String getSegmentId() {
         AbstractTracerContext context = CONTEXT.get();
@@ -86,11 +86,11 @@ public class ContextManager implements BootService {
     }
 
     /**
-     * @return the current span id if needEnhance. Otherwise, "N/A".
+     * @return the current span id when tracing. Otherwise, the value is -1.
      */
-    public static String getSpanId() {
+    public static int getSpanId() {
         AbstractTracerContext context = CONTEXT.get();
-        return Objects.nonNull(context) ? context.getSpanId() : EMPTY_TRACE_CONTEXT_ID;
+        return Objects.nonNull(context) ? context.getSpanId() : -1;
     }
 
     public static AbstractSpan createEntrySpan(String operationName, ContextCarrier carrier) {

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/IgnoredTracerContext.java

@@ -75,8 +75,8 @@ public class IgnoredTracerContext implements AbstractTracerContext {
     }
 
     @Override
-    public String getSpanId() {
-        return IGNORE_TRACE;
+    public int getSpanId() {
+        return -1;
     }
 
     @Override

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/TracingContext.java

@@ -249,8 +249,8 @@ public class TracingContext implements AbstractTracerContext {
     }
 
     @Override
-    public String getSpanId() {
-        return String.valueOf(activeSpan().getSpanId());
+    public int getSpanId() {
+        return activeSpan().getSpanId();
     }
 
     /**

test/plugin/scenarios/apm-toolkit-trace-scenario/src/main/java/org/apache/skywalking/apm/toolkit/trace/TraceContext.java

@@ -46,12 +46,13 @@ public class TraceContext {
     }
 
     /**
-     * Try to get the spanId of current trace context.
+     * Try to get the spanId of current trace context. The spanId is a negative number when the trace context is
+     * missing.
      *
      * @return spanId, if it exists, or empty {@link String}.
      */
-    public static String spanId() {
-        return "";
+    public static int spanId() {
+        return -1;
     }
 
     /**

test/plugin/scenarios/apm-toolkit-trace-scenario/src/main/java/test/apache/skywalking/apm/testcase/toolkit/controller/TestController.java

@@ -61,7 +61,9 @@ public class TestController {
         TraceContext.putCorrelation(CORRELATION_CONTEXT_KEY, CORRELATION_CONTEXT_VALUE);
         ActiveSpan.tag("traceID", TraceContext.traceId());
         ActiveSpan.tag("segmentID", TraceContext.segmentId());
-        ActiveSpan.tag("spanID", TraceContext.spanId());
+        if (TraceContext.spanId() > -1) {
+            ActiveSpan.tag("spanID", String.valueOf(TraceContext.spanId()));
+        }
         testService.asyncCallable(() -> {
             visit("http://localhost:8080/apm-toolkit-trace-scenario/case/asyncVisit/callable");
             return true;