JdbcTracingUtils.decorate can set empty tag values which can break tracers

[randallt]

I am using the Java SpecialAgent 1.3.2 with a Wavefront Tracer. The Wavefront Tracer does not support empty tag values (an empty String) and throws an exception when processing the span. The OpenTracing spec seems to imply that empty tag values should not be used, but doesn't specifically say they are disallowed:

From https://opentracing.io/specification/ :

Set a Span tag
Required parameters

The tag key, which must be a string
The tag value, which must be either a string, a boolean value, or a numeric type
Note that the OpenTracing project documents certain “standard tags” that have prescribed semantic meanings.

The code checks for null, but allows the empty String. This should be fixed:

private static void decorate(Span span,
      String sql,
      ConnectionInfo connectionInfo) {
    Tags.COMPONENT.set(span, COMPONENT_NAME);
    Tags.DB_STATEMENT.set(span, sql);
    if (connectionInfo.getDbType() != null) {
      Tags.DB_TYPE.set(span, connectionInfo.getDbType());
    }
    if (connectionInfo.getDbPeer() != null) {
      PEER_ADDRESS.set(span, connectionInfo.getDbPeer());
    }
    if (connectionInfo.getDbInstance() != null) {
      Tags.DB_INSTANCE.set(span, connectionInfo.getDbInstance());
    }
    if (connectionInfo.getDbUser() != null) {
      Tags.DB_USER.set(span, connectionInfo.getDbUser());
    }
  }

[randallt]

It looks like it is the 'db.statement' tag that is empty in my case. Somehow the sql parameter is empty or null here. This code should handle that.

[randallt]

Possible solution here:

private static boolean isNotEmpty(CharSequence s) {
      return s != null && !"".contentEquals(s);
  }

  private static void decorate(Span span,
      String sql,
      ConnectionInfo connectionInfo) {

      Tags.COMPONENT.set(span, COMPONENT_NAME);
      if (isNotEmpty(sql)) {
          Tags.DB_STATEMENT.set(span, sql);
      }
      if (isNotEmpty(connectionInfo.getDbType())) {
          Tags.DB_TYPE.set(span, connectionInfo.getDbType());
      }
      if (isNotEmpty(connectionInfo.getDbPeer())) {
          PEER_ADDRESS.set(span, connectionInfo.getDbPeer());
      }
      if (isNotEmpty(connectionInfo.getDbInstance())) {
          Tags.DB_INSTANCE.set(span, connectionInfo.getDbInstance());
      }
      if (isNotEmpty(connectionInfo.getDbUser())) {
          Tags.DB_USER.set(span, connectionInfo.getDbUser());
      }
  }

[malafeev]

@randallt would you like to submit a PR?

[malafeev]

fixed in #46

[randallt]

Looks good. Thanks.