Add is_present function in MQE for check if the list metrics has value or not

docs/en/api/metrics-query-expression.md

@@ -293,6 +293,21 @@ The following example would return the content of the **service_cpm** metric.
 view_as_seq(not_existing, service_cpm)
 ```
 
+### IsPresent Operation
+IsPresent operation represents that in a list of metrics, if any expression has a value, it would return `1` in the result; otherwise, it would return `0`.
+
+Expression:
+```text
+is_present([<expression_1>, <expression_2>, ...])
+```
+
+For example:
+When the meter does not exist or the metrics has no value, it would return `0`. 
+However, if the metrics list contains meter with values, it would return `1`.
+```text
+is_present(not_existing, existing_without_value, exiting_with_value)
+```
+
 #### Result Type
 The result type is determined by the type of selected not-null metric expression.
 

docs/en/changes/changes.md

@@ -5,6 +5,7 @@
 
 #### OAP Server
 * Add `layer` parameter to the global topology graphQL query.
+* Add `is_present` function in MQE for check if the list metrics has a value or not.
 
 #### UI
 

oap-server/mqe-grammar/src/main/antlr4/org/apache/skywalking/mqe/rt/grammar/MQELexer.g4

@@ -68,6 +68,9 @@ TOP_N:        'top_n';
 // ViewAsSeq
 VIEW_AS_SEQ: 'view_as_seq';
 
+// IsPresent
+IS_PRESENT: 'is_present';
+
 // Relabels
 RELABELS:     'relabels';
 

oap-server/mqe-grammar/src/main/antlr4/org/apache/skywalking/mqe/rt/grammar/MQEParser.g4

@@ -76,7 +76,7 @@ trend:
 topN: TOP_N;
 
 logical_operator:
-    VIEW_AS_SEQ;
+    VIEW_AS_SEQ | IS_PRESENT;
 
 relabels: RELABELS;
 

oap-server/mqe-rt/src/main/java/org/apache/skywalking/mqe/rt/operation/LogicalFunctionOp.java

@@ -22,15 +22,23 @@
 import org.apache.skywalking.mqe.rt.grammar.MQEParser;
 import org.apache.skywalking.mqe.rt.grammar.MQEParserBaseVisitor;
 import org.apache.skywalking.mqe.rt.type.ExpressionResult;
+import org.apache.skywalking.mqe.rt.type.ExpressionResultType;
+import org.apache.skywalking.mqe.rt.type.MQEValue;
+import org.apache.skywalking.mqe.rt.type.MQEValues;
+import org.apache.skywalking.mqe.rt.type.Metadata;
 import org.apache.skywalking.oap.server.library.util.CollectionUtils;
 
+import java.util.Objects;
+
 public class LogicalFunctionOp {
 
     public static ExpressionResult doOP(int opType, MQEParser.ExpressionListContext expressionListContext,
                                                        MQEParserBaseVisitor<ExpressionResult> visitor) throws IllegalExpressionException {
         switch (opType) {
             case MQEParser.VIEW_AS_SEQ:
                 return viewAsSeq(expressionListContext, visitor);
+            case MQEParser.IS_PRESENT:
+                return isPresent(expressionListContext, visitor);
         }
 
         throw new IllegalExpressionException("Unsupported function.");
@@ -57,4 +65,31 @@ private static ExpressionResult viewAsSeq(MQEParser.ExpressionListContext expres
         return firstResult;
     }
 
+    private static ExpressionResult isPresent(MQEParser.ExpressionListContext expressionListContext,
+                                              MQEParserBaseVisitor<ExpressionResult> visitor) {
+        boolean present = false;
+        for (MQEParser.ExpressionContext expContext : expressionListContext.expression()) {
+            final ExpressionResult result = visitor.visit(expContext);
+            // the expression data exist and contains not empty value
+            if (result != null) {
+                present = result.getResults().stream().filter(Objects::nonNull).anyMatch(r ->
+                    r.getValues().stream().anyMatch(v -> !v.isEmptyValue()));
+            }
+            if (present) {
+                break;
+            }
+        }
+
+        final ExpressionResult result = new ExpressionResult();
+        result.setType(ExpressionResultType.SINGLE_VALUE);
+
+        MQEValue mqeValue = new MQEValue();
+        MQEValues mqeValues = new MQEValues();
+        mqeValues.setMetric(new Metadata());
+        mqeValues.getValues().add(mqeValue);
+        result.getResults().add(mqeValues);
+        mqeValue.setDoubleValue(present ? 1 : 0);
+        mqeValue.setEmptyValue(false);
+        return result;
+    }
 }

test/e2e-v2/cases/mqe/expected/isPresent-OP-false.yml

@@ -0,0 +1,24 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+type: SINGLE_VALUE
+results:
+  - metric:
+      labels: []
+    values:
+      - id: null
+        value: "0"
+        traceid: null
+error: null

test/e2e-v2/cases/mqe/expected/isPresent-OP-true.yml

@@ -0,0 +1,24 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+type: SINGLE_VALUE
+results:
+  - metric:
+      labels: []
+    values:
+      - id: null
+        value: "1"
+        traceid: null
+error: null

test/e2e-v2/cases/mqe/mqe-cases.yaml

@@ -68,6 +68,12 @@ cases:
   - query: swctl --display yaml --base-url=http://${oap_host}:${oap_12800}/graphql metrics exec --expression="view_as_seq(mq_service_consume_sla,service_sla)" --service-name=e2e-service-provider
     expected: expected/viewAsSeq-OP.yml
 
+  # isPresent-OP
+  - query: swctl --display yaml --base-url=http://${oap_host}:${oap_12800}/graphql metrics exec --expression="is_present(service_sla)" --service-name=e2e-service-provider
+    expected: expected/isPresent-OP-true.yml
+  - query: swctl --display yaml --base-url=http://${oap_host}:${oap_12800}/graphql metrics exec --expression="is_present(not_exist_meter,mq_service_consume_cpm)" --service-name=e2e-service-provider
+    expected: expected/isPresent-OP-false.yml
+
   # trend-OP
   - query: swctl --display yaml --base-url=http://${oap_host}:${oap_12800}/graphql metrics exec --expression="increase(service_resp_time,2)" --service-name=e2e-service-provider
     expected: expected/trend-OP.yml