feat: add function_metadata() datasource function

asterixdb/asterix-app/src/main/java/org/apache/asterix/app/function/FunctionMetadataDatasource.java

@@ -0,0 +1,53 @@
+/*
+ * 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.
+ */
+package org.apache.asterix.app.function;
+
+import java.util.Objects;
+
+import org.apache.asterix.metadata.api.IDatasourceFunction;
+import org.apache.asterix.metadata.declared.DataSourceId;
+import org.apache.asterix.metadata.declared.FunctionDataSource;
+import org.apache.asterix.metadata.declared.MetadataProvider;
+import org.apache.hyracks.algebricks.common.constraints.AlgebricksAbsolutePartitionConstraint;
+import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
+import org.apache.hyracks.algebricks.core.algebra.properties.INodeDomain;
+
+public class FunctionMetadataDatasource extends FunctionDataSource {
+
+    private static final DataSourceId FUNCTION_METADATA_DATASOURCE_ID =
+            createDataSourceId(FunctionMetadataRewriter.FUNCTION_METADATA);
+
+    public FunctionMetadataDatasource(INodeDomain domain) throws AlgebricksException {
+        super(FUNCTION_METADATA_DATASOURCE_ID, FunctionMetadataRewriter.FUNCTION_METADATA, domain);
+    }
+
+    @Override
+    protected IDatasourceFunction createFunction(MetadataProvider metadataProvider,
+            AlgebricksAbsolutePartitionConstraint locations) {
+        // The builtin function registry is identical on every node, so run on a single
+        // location to avoid emitting duplicate rows.
+        return new FunctionMetadataFunction(
+                AlgebricksAbsolutePartitionConstraint.randomLocation(locations.getLocations()));
+    }
+
+    @Override
+    protected boolean sameFunctionDatasource(FunctionDataSource other) {
+        return Objects.equals(this.functionId, other.getFunctionId());
+    }
+}

asterixdb/asterix-app/src/main/java/org/apache/asterix/app/function/FunctionMetadataFunction.java

@@ -0,0 +1,93 @@
+/*
+ * 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.
+ */
+package org.apache.asterix.app.function;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.asterix.external.api.IRecordReader;
+import org.apache.asterix.metadata.declared.AbstractDatasourceFunction;
+import org.apache.asterix.om.functions.BuiltinFunctionInfo;
+import org.apache.asterix.om.functions.BuiltinFunctions;
+import org.apache.hyracks.algebricks.common.constraints.AlgebricksAbsolutePartitionConstraint;
+import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+import org.apache.hyracks.api.context.IHyracksTaskContext;
+import org.apache.hyracks.api.exceptions.HyracksDataException;
+
+public class FunctionMetadataFunction extends AbstractDatasourceFunction {
+
+    private static final long serialVersionUID = 1L;
+
+    public FunctionMetadataFunction(AlgebricksAbsolutePartitionConstraint locations) {
+        super(locations);
+    }
+
+    @Override
+    public IRecordReader<char[]> createRecordReader(IHyracksTaskContext ctx, int partition)
+            throws HyracksDataException {
+        List<String> records = new ArrayList<>();
+        for (FunctionIdentifier fi : BuiltinFunctions.getBuiltinFunctionIdentifiers()) {
+            records.add(toRecord(fi));
+        }
+        return new FunctionMetadataReader(records.toArray(new String[0]));
+    }
+
+    private static String toRecord(FunctionIdentifier fi) {
+        BuiltinFunctionInfo info = BuiltinFunctions.getBuiltinFunctionInfo(fi);
+        boolean isPrivate = info != null && info.isPrivate();
+        return "{\"name\":\"" + escape(fi.getName()) + "\",\"arity\":" + fi.getArity() + ",\"category\":\""
+                + category(fi) + "\",\"private\":" + isPrivate + "}";
+    }
+
+    private static String category(FunctionIdentifier fi) {
+        if (BuiltinFunctions.isWindowFunction(fi) || BuiltinFunctions.getWindowFunction(fi) != null) {
+            // isWindowFunction matches the internal *-impl ids; getWindowFunction matches the
+            // user-facing names (row_number, rank, ...) that map to those impls.
+            return "window";
+        }
+        if (BuiltinFunctions.isBuiltinAggregateFunction(fi)) {
+            return "aggregate";
+        }
+        if (BuiltinFunctions.isBuiltinScalarAggregateFunction(fi)) {
+            return "aggregate-scalar";
+        }
+        if (BuiltinFunctions.isBuiltinUnnestingFunction(fi)) {
+            return "unnest";
+        }
+        if (BuiltinFunctions.getDatasourceTransformer(fi) != null) {
+            return "datasource";
+        }
+        return "scalar";
+    }
+
+    private static String escape(String s) {
+        StringBuilder sb = new StringBuilder(s.length());
+        for (int i = 0; i < s.length(); i++) {
+            char c = s.charAt(i);
+            if (c == '"' || c == '\\') {
+                sb.append('\\').append(c);
+            } else if (c < 0x20) {
+                sb.append(String.format("\\u%04x", (int) c));
+            } else {
+                sb.append(c);
+            }
+        }
+        return sb.toString();
+    }
+}

asterixdb/asterix-app/src/main/java/org/apache/asterix/app/function/FunctionMetadataReader.java

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ */
+package org.apache.asterix.app.function;
+
+import java.io.IOException;
+
+import org.apache.asterix.external.api.IRawRecord;
+import org.apache.asterix.external.input.record.CharArrayRecord;
+
+public class FunctionMetadataReader extends FunctionReader {
+
+    private final String[] functions;
+    private int pos = 0;
+
+    public FunctionMetadataReader(String[] functions) {
+        this.functions = functions;
+    }
+
+    @Override
+    public boolean hasNext() throws Exception {
+        return pos < functions.length;
+    }
+
+    @Override
+    public IRawRecord<char[]> next() throws IOException, InterruptedException {
+        CharArrayRecord record = new CharArrayRecord();
+        record.set(functions[pos++]);
+        record.endRecord();
+        return record;
+    }
+}

asterixdb/asterix-app/src/main/java/org/apache/asterix/app/function/FunctionMetadataRewriter.java

@@ -0,0 +1,42 @@
+/*
+ * 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.
+ */
+package org.apache.asterix.app.function;
+
+import org.apache.asterix.common.functions.FunctionConstants;
+import org.apache.asterix.metadata.declared.FunctionDataSource;
+import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
+import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+
+public class FunctionMetadataRewriter extends FunctionRewriter {
+
+    public static final FunctionIdentifier FUNCTION_METADATA = FunctionConstants.newAsterix("function-metadata", 0);
+    public static final FunctionMetadataRewriter INSTANCE = new FunctionMetadataRewriter(FUNCTION_METADATA);
+
+    private FunctionMetadataRewriter(FunctionIdentifier functionId) {
+        super(functionId);
+    }
+
+    @Override
+    protected FunctionDataSource toDatasource(IOptimizationContext context, AbstractFunctionCallExpression f)
+            throws AlgebricksException {
+        return new FunctionMetadataDatasource(context.getComputationNodeDomain());
+    }
+}

asterixdb/asterix-app/src/main/java/org/apache/asterix/util/MetadataBuiltinFunctions.java

@@ -24,6 +24,7 @@
 import org.apache.asterix.app.function.DatasetRewriter;
 import org.apache.asterix.app.function.DumpIndexRewriter;
 import org.apache.asterix.app.function.FeedRewriter;
+import org.apache.asterix.app.function.FunctionMetadataRewriter;
 import org.apache.asterix.app.function.JobSummariesRewriter;
 import org.apache.asterix.app.function.PingRewriter;
 import org.apache.asterix.app.function.QueryIndexRewriter;
@@ -119,6 +120,12 @@ public class MetadataBuiltinFunctions {
         BuiltinFunctions.addUnnestFun(CollectionEstimateColumnCountRewriter.ESTIMATED_COLLECTION_COLUMN_COUNT, true);
         BuiltinFunctions.addDatasourceFunction(CollectionEstimateColumnCountRewriter.ESTIMATED_COLLECTION_COLUMN_COUNT,
                 CollectionEstimateColumnCountRewriter.INSTANCE);
+        // Function metadata function
+        BuiltinFunctions.addFunction(FunctionMetadataRewriter.FUNCTION_METADATA,
+                (expression, env, mp) -> RecordUtil.FULLY_OPEN_RECORD_TYPE, true);
+        BuiltinFunctions.addUnnestFun(FunctionMetadataRewriter.FUNCTION_METADATA, true);
+        BuiltinFunctions.addDatasourceFunction(FunctionMetadataRewriter.FUNCTION_METADATA,
+                FunctionMetadataRewriter.INSTANCE, BuiltinFunctions.DataSourceFunctionProperty.MIN_MEMORY_BUDGET);
     }
 
     private MetadataBuiltinFunctions() {

asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/function_metadata/function_metadata.1.query.sqlpp

@@ -0,0 +1,23 @@
+/*
+ * 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.
+ */
+
+select value f
+from function_metadata() f
+where f.name in ["rank", "row_number"]
+order by f.name;

asterixdb/asterix-app/src/test/resources/runtimets/results/misc/function_metadata/function_metadata.1.adm

@@ -0,0 +1,2 @@
+{ "name": "rank", "arity": 0, "category": "window", "private": false }
+{ "name": "row_number", "arity": 0, "category": "window", "private": false }

asterixdb/asterix-app/src/test/resources/runtimets/sqlpp_queries.xml

@@ -7548,6 +7548,11 @@
         <output-dir compare="Text">jobs</output-dir>
       </compilation-unit>
     </test-case>
+    <test-case FilePath="misc">
+      <compilation-unit name="function_metadata">
+        <output-dir compare="Text">function_metadata</output-dir>
+      </compilation-unit>
+    </test-case>
     <test-case FilePath="misc">
       <compilation-unit name="completed_requests">
         <output-dir compare="Text">completed_requests</output-dir>

asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java

@@ -3079,6 +3079,10 @@ public static BuiltinFunctionInfo getBuiltinFunctionInfo(FunctionIdentifier fi)
         return registeredFunctions.get(fi);
     }
 
+    public static Set<FunctionIdentifier> getBuiltinFunctionIdentifiers() {
+        return Collections.unmodifiableSet(registeredFunctions.keySet());
+    }
+
     public static BuiltinFunctionInfo resolveBuiltinFunction(String name, int arity) {
         //TODO:optimize
         BuiltinFunctionInfo finfo;