Added getTracesExist support

zipkin-server/src/main/scala/com/twitter/zipkin/query/QueryService.scala

@@ -144,6 +144,15 @@ class QueryService(storage: Storage, index: Index, aggregates: Aggregates, adjus
     }
   }
 
+  def tracesExist(traceIds: Seq[Long]): Future[Set[Long]] = {
+    log.debug("tracesExist. " + traceIds)
+    call("tracesExist") {
+      FTrace.recordBinary("numIds", traceIds.length)
+
+      storage.tracesExist(traceIds)
+    }
+  }
+
   def getTracesByIds(traceIds: Seq[Long], adjust: Seq[gen.Adjust]): Future[Seq[gen.Trace]] = {
     log.debug("getTracesByIds. " + traceIds + " adjust " + adjust)
     call("getTracesByIds") {

zipkin-server/src/main/scala/com/twitter/zipkin/storage/Storage.scala

@@ -44,6 +44,8 @@ trait Storage {
    */
   def getTimeToLive(traceId: Long): Future[Duration]
 
+  def tracesExist(traceIds: Seq[Long]): Future[Set[Long]]
+
   /**
    * Get the available trace information from the storage system.
    * Spans in trace should be sorted by the first annotation timestamp

zipkin-server/src/main/scala/com/twitter/zipkin/storage/cassandra/CassandraStorage.scala

@@ -40,6 +40,9 @@ trait CassandraStorage extends Storage with Cassandra {
   // read the trace
   private val CASSANDRA_GET_TRACE = Stats.getCounter("cassandra_gettrace")
 
+  // trace exist call
+  private val CASSANDRA_TRACE_EXISTS = Stats.getCounter("cassandra_traceexists")
+
   // trace is too big!
   private val CASSANDRA_GET_TRACE_TOO_BIG = Stats.getCounter("cassandra_gettrace_too_big")
 
@@ -89,6 +92,35 @@ trait CassandraStorage extends Storage with Cassandra {
     }
   }
 
+  /**
+   * Finds traces that have been stored from a list of trace IDs
+   *
+   * @param traceIds a List of trace IDs
+   * @return a Set of those trace IDs from the list which are stored
+   */
+
+  def tracesExist(traceIds: Seq[Long]): Future[Set[Long]] = {
+    CASSANDRA_TRACE_EXISTS.incr
+    Future.collect {
+      traceIds.grouped(storageConfig.traceFetchBatchSize).toSeq.map { ids =>
+        traces.multigetRows(ids.toSet.asJava, None, None, Order.Normal, 1).map { rowSet =>
+          ids.flatMap { id =>
+            val spans = rowSet.asScala(id).asScala.map {
+              case (colName, col) => ThriftAdapter(col.value)
+            }
+            if (spans.isEmpty) {
+              None
+            } else {
+              Some(spans.head.traceId)
+            }
+          }.toSet
+        }
+      }
+    }.map {
+      _.reduce { (left, right) => left ++ right }
+    }
+  }
+
   /**
    * Fetches traces from the underlying storage. Note that there might be multiple
    * entries per span.

zipkin-test/src/test/scala/com/twitter/zipkin/ZipkinSpec.scala

@@ -130,10 +130,14 @@ class ZipkinSpec extends Specification with JMocker with ClassMocker {
       // let's check that the trace we just sent has been stored and indexed properly
       val queryClient = new gen.ZipkinQuery.FinagledClient(queryTransport, protocol)
       val traces = queryClient.getTracesByIds(Seq(123), Seq())()
+      val existSet = queryClient.tracesExist(Seq(123, 5))()
 
       traces.isEmpty mustEqual false
       traces(0).spans.isEmpty mustEqual false
       traces(0).spans(0).traceId mustEqual 123
+
+      existSet.contains(123) mustEqual true
+      existSet.contains(5) mustEqual false
     }
 
   }

zipkin-thrift/src/main/thrift/zipkinQuery.thrift

@@ -120,6 +120,12 @@ service ZipkinQuery {
 
     //************** Fetch traces from id **************
 
+    /**
+     * Get the traces that are in the database from the given list of trace ids.
+     */
+
+    set<i64> tracesExist(1: list<i64> trace_ids) throws (1: QueryException qe);
+
     /**
      * Get the full traces associated with the given trace ids.
      *