Use MVEL for rule evaluation

Co-Authored-By: Prakhar Sapre <[email protected]>

Author: willmostly

docs/routing-rules.md

@@ -296,8 +296,8 @@ actions:
 ```
 
 This can difficult to maintain with more rules. To have better control over the
-execution of rules, we can use rule priorities and composite rules. Overall,
-priorities, composite rules, and other constructs that MVEL support allows
+execution of rules, we can use rule priorities. Overall,
+priorities and other constructs that MVEL support allows
 you to express your routing logic.
 
 #### Rule priority
@@ -328,99 +328,12 @@ that the first rule (priority 0) is fired before the second rule (priority 1).
 Thus `routingGroup` is set to `etl` and then to `etl-special`, so the
 `routingGroup` is always `etl-special` in the end.
 
-More specific rules must be set to a lesser priority so they are evaluated last
-to set a `routingGroup`. To further control the execution of rules, for example
-to have only one rule fire, you can use composite rules.
-
-##### Composite rules
-
-First, please refer to the [easy-rule composite rules documentation](https://github.com/j-easy/easy-rules/wiki/defining-rules#composite-rules).
-
-The preceding section covers how to control the order of rule execution using
-priorities. In addition, you can configure evaluation so that only the first
-rule matched fires (the highest priority one) and the rest is ignored. You can
-use `ActivationRuleGroup` to achieve this:
-
-```yaml
----
-name: "airflow rule group"
-description: "routing rules for query from airflow"
-compositeRuleType: "ActivationRuleGroup"
-composingRules:
-  - name: "airflow special"
-    description: "if query from airflow with special label, route to etl-special group"
-    priority: 0
-    condition: 'request.getHeader("X-Trino-Source") == "airflow" && request.getHeader("X-Trino-Client-Tags") contains "label=special"'
-    actions:
-      - 'result.put("routingGroup", "etl-special")'
-  - name: "airflow"
-    description: "if query from airflow, route to etl group"
-    priority: 1
-    condition: 'request.getHeader("X-Trino-Source") == "airflow"'
-    actions:
-      - 'result.put("routingGroup", "etl")'
-```
-
-Note that the priorities have switched. The more specific rule has a higher
-priority, since it should fire first. A query coming from airflow with special
-label is matched to the "airflow special" rule first, since it's higher
-priority, and the second rule is ignored. A query coming from airflow with no
-labels does not match the first rule, and is then tested and matched to the
-second rule.
-
-You can also use `ConditionalRuleGroup` and `ActivationRuleGroup` to implement
-an if/else workflow. The following logic in pseudocode:
-
-```text
-if source == "airflow":
-  if clientTags["label"] == "foo":
-    return "etl-foo"
-  else if clientTags["label"] = "bar":
-    return "etl-bar"
-  else
-    return "etl"
-```
-
-This logic can be implemented with the following rules:
-
-```yaml
-name: "airflow rule group"
-description: "routing rules for query from airflow"
-compositeRuleType: "ConditionalRuleGroup"
-composingRules:
-  - name: "main condition"
-    description: "source is airflow"
-    priority: 0 # rule with the highest priority acts as main condition
-    condition: 'request.getHeader("X-Trino-Source") == "airflow"'
-    actions:
-      - ""
-  - name: "airflow subrules"
-    compositeRuleType: "ActivationRuleGroup" # use ActivationRuleGroup to simulate if/else
-    composingRules:
-      - name: "label foo"
-        description: "label client tag is foo"
-        priority: 0
-        condition: 'request.getHeader("X-Trino-Client-Tags") contains "label=foo"'
-        actions:
-          - 'result.put("routingGroup", "etl-foo")'
-      - name: "label bar"
-        description: "label client tag is bar"
-        priority: 0
-        condition: 'request.getHeader("X-Trino-Client-Tags") contains "label=bar"'
-        actions:
-          - 'result.put("routingGroup", "etl-bar")'
-      - name: "airflow default"
-        description: "airflow queries default to etl"
-        condition: "true"
-        actions:
-          - 'result.put("routingGroup", "etl")'
-```
+More specific rules must be set to a higher priority so they are evaluated last
+to set a `routingGroup`.
 
 ##### If statements (MVEL Flow Control)
 
-In the preceding section you see how `ConditionalRuleGroup` and
-`ActivationRuleGroup` are used to implement an `if/else` workflow. You can
-use MVEL support for `if` statements and other flow control. The following logic
+You can use MVEL support for `if` statements and other flow control. The following logic
 in pseudocode:
 
 ```text

gateway-ha/pom.xml

@@ -21,7 +21,6 @@
         <frontend.pnpmRegistryURL>https://registry.npmmirror.com</frontend.pnpmRegistryURL>
 
         <!-- dependency versions -->
-        <dep.jeasy.version>4.1.0</dep.jeasy.version>
         <dep.mockito.version>5.14.2</dep.mockito.version>
         <dep.okhttp3.version>4.12.0</dep.okhttp3.version>
         <dep.trino.version>462</dep.trino.version>
@@ -253,21 +252,9 @@
         </dependency>
 
         <dependency>
-            <groupId>org.jeasy</groupId>
-            <artifactId>easy-rules-core</artifactId>
-            <version>${dep.jeasy.version}</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.jeasy</groupId>
-            <artifactId>easy-rules-mvel</artifactId>
-            <version>${dep.jeasy.version}</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.jeasy</groupId>
-            <artifactId>easy-rules-support</artifactId>
-            <version>${dep.jeasy.version}</version>
+            <groupId>org.mvel</groupId>
+            <artifactId>mvel2</artifactId>
+            <version>2.5.2.Final</version>
         </dependency>
 
         <dependency>
@@ -290,13 +277,6 @@
             <scope>runtime</scope>
         </dependency>
 
-        <dependency>
-            <groupId>org.mvel</groupId>
-            <artifactId>mvel2</artifactId>
-            <version>2.5.2.Final</version>
-            <scope>runtime</scope>
-        </dependency>
-
         <dependency>
             <groupId>org.postgresql</groupId>
             <artifactId>postgresql</artifactId>

gateway-ha/src/main/java/io/trino/gateway/ha/router/MVELFileRoutingGroupSelector.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed 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 io.trino.gateway.ha.router;
+
+import io.trino.gateway.ha.config.RequestAnalyzerConfig;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.List;
+
+public class MVELFileRoutingGroupSelector
+        extends RulesRoutingGroupSelector
+{
+    Path rulesPath;
+
+    MVELFileRoutingGroupSelector(String rulesPath, RequestAnalyzerConfig requestAnalyzerConfig)
+    {
+        super(requestAnalyzerConfig);
+        this.rulesPath = Paths.get(rulesPath);
+
+        List<RoutingRule> ruleList = readRulesFromPath(this.rulesPath, MVELRoutingRule.class);
+        setRules(ruleList);
+    }
+
+    @Override
+    void reloadRules(long lastUpdatedTimeMillis)
+    {
+        try {
+            BasicFileAttributes attr = Files.readAttributes(this.rulesPath, BasicFileAttributes.class);
+            if (attr.lastModifiedTime().toMillis() > lastUpdatedTimeMillis) {
+                synchronized (this) {
+                    if (attr.lastModifiedTime().toMillis() > lastUpdatedTimeMillis) {
+                        List<RoutingRule> ruleList = readRulesFromPath(this.rulesPath, MVELRoutingRule.class);
+                        setRules(ruleList);
+                    }
+                }
+            }
+        }
+        catch (IOException e) {
+            throw new RuntimeException("Could not access rules file", e);
+        }
+    }
+}

gateway-ha/src/main/java/io/trino/gateway/ha/router/MVELRoutingRule.java

@@ -0,0 +1,60 @@
+/*
+ * Licensed 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 io.trino.gateway.ha.router;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.io.Serializable;
+import java.util.List;
+import java.util.Map;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static org.mvel2.MVEL.compileExpression;
+import static org.mvel2.MVEL.executeExpression;
+
+public class MVELRoutingRule
+        extends RoutingRule
+{
+    @JsonCreator
+    public MVELRoutingRule(
+            @JsonProperty("name") String name,
+            @JsonProperty("description") String description,
+            @JsonProperty("priority") Integer priority,
+            @JsonProperty("condition") Serializable condition,
+            @JsonProperty("actions") List<Serializable> actions)
+    {
+        super(
+                name,
+                description,
+                priority,
+                condition instanceof String stringCondition ? compileExpression(stringCondition) : condition,
+                actions.stream().map(action -> {
+                    if (action instanceof String stringAction) {
+                        return compileExpression(stringAction);
+                    }
+                    else {
+                        return action;
+                    }
+                }).collect(toImmutableList()));
+    }
+
+    @Override
+    public void evaluate(Map<String, Object> variables)
+    {
+        if ((boolean) executeExpression(condition, variables)) {
+            actions.forEach(action -> executeExpression(action, variables));
+        }
+    }
+}

gateway-ha/src/main/java/io/trino/gateway/ha/router/RoutingGroupSelector.java

@@ -39,7 +39,7 @@ static RoutingGroupSelector byRoutingGroupHeader()
      */
     static RoutingGroupSelector byRoutingRulesEngine(String rulesConfigPath, RequestAnalyzerConfig requestAnalyzerConfig)
     {
-        return new RuleReloadingRoutingGroupSelector(rulesConfigPath, requestAnalyzerConfig);
+        return new MVELFileRoutingGroupSelector(rulesConfigPath, requestAnalyzerConfig);
     }
 
     /**

gateway-ha/src/main/java/io/trino/gateway/ha/router/RoutingRule.java

@@ -0,0 +1,60 @@
+/*
+ * Licensed 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 io.trino.gateway.ha.router;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.io.Serializable;
+import java.util.List;
+import java.util.Map;
+
+import static java.util.Objects.requireNonNull;
+import static java.util.Objects.requireNonNullElse;
+
+public abstract class RoutingRule
+        implements Comparable<RoutingRule>
+{
+    String name;
+    String description;
+    Integer priority;
+    Serializable condition;
+    List<Serializable> actions;
+
+    @JsonCreator
+    public RoutingRule(
+            @JsonProperty("name") String name,
+            @JsonProperty("description") String description,
+            @JsonProperty("priority") Integer priority,
+            @JsonProperty("condition") Serializable condition,
+            @JsonProperty("actions") List<Serializable> actions)
+    {
+        this.name = requireNonNull(name, "name is null");
+        this.description = requireNonNullElse(description, "");
+        this.priority = requireNonNullElse(priority, 0);
+        this.condition = requireNonNull(condition, "condition is null");
+        this.actions = requireNonNull(actions, "actions is null");
+    }
+
+    public abstract void evaluate(Map<String, Object> variables);
+
+    @Override
+    public int compareTo(RoutingRule o)
+    {
+        if (o == null) {
+            return 1;
+        }
+        return priority.compareTo(o.priority);
+    }
+}