From fbb73eca2e052beb2492e763157051da9e9e38d2 Mon Sep 17 00:00:00 2001
From: Madhan Neethiraj <madhan@apache.org>
Date: Tue, 30 Apr 2019 09:15:08 -0700
Subject: [PATCH] ImpalaPostExecHook infra

---
 .../impala/hooks/ImpalaHookContext.java       | 30 +++++++
 .../impala/hooks/ImpalaPostExecHook.java      | 35 ++++++++
 .../hooks/ImpalaPostExecHookFactory.java      | 86 +++++++++++++++++++
 3 files changed, 151 insertions(+)
 create mode 100644 fe/src/main/java/org/apache/impala/hooks/ImpalaHookContext.java
 create mode 100644 fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHook.java
 create mode 100644 fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHookFactory.java

diff --git a/fe/src/main/java/org/apache/impala/hooks/ImpalaHookContext.java b/fe/src/main/java/org/apache/impala/hooks/ImpalaHookContext.java
new file mode 100644
index 000000000..81e6347ee
--- /dev/null
+++ b/fe/src/main/java/org/apache/impala/hooks/ImpalaHookContext.java
@@ -0,0 +1,30 @@
+/**
+ * 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.impala.hooks;
+
+public class ImpalaHookContext {
+    private final String lineageString;
+
+    public ImpalaHookContext(String lineageString) {
+        this.lineageString = lineageString;
+    }
+
+    public String getLineageString() {
+        return lineageString;
+    }
+}
diff --git a/fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHook.java b/fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHook.java
new file mode 100644
index 000000000..ab15047f0
--- /dev/null
+++ b/fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHook.java
@@ -0,0 +1,35 @@
+/**
+ * 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.impala.hooks;
+
+public abstract class ImpalaPostExecHook {
+    /**
+     * Initialization of Impala post-execution hook
+     */
+    public abstract void init();
+
+    /**
+     * Cleanup of Impala post-execution hook
+     */
+    public abstract void cleanUp();
+
+    /**
+     * Execute Impala post-hook
+     */
+    public abstract void execute(ImpalaHookContext context);
+}
diff --git a/fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHookFactory.java b/fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHookFactory.java
new file mode 100644
index 000000000..e81cc567c
--- /dev/null
+++ b/fe/src/main/java/org/apache/impala/hooks/ImpalaPostExecHookFactory.java
@@ -0,0 +1,86 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.impala.hooks;
+
+import org.apache.commons.lang.StringUtils;
+import org.apache.hadoop.conf.Configuration;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class ImpalaPostExecHookFactory {
+    public static final String CONFIG_POST_EXEC_HOOKS = "impala.post.exec.hooks";
+
+    private static final ImpalaPostExecHookFactory INSTANCE = new ImpalaPostExecHookFactory();
+
+    private List<ImpalaPostExecHook> hooks = Collections.emptyList();
+
+    private ImpalaPostExecHookFactory() {
+    }
+
+    public static ImpalaPostExecHookFactory getInstance() {
+        return INSTANCE;
+    }
+
+    // to be called once during Impala startup
+    public void init(Configuration config) throws Exception {
+		List<ImpalaPostExecHook> hooks = new ArrayList<>();
+
+		String confPostExecHooks = config.get(CONFIG_POST_EXEC_HOOKS);
+
+		if (StringUtils.isNotEmpty(confPostExecHooks)) {
+		    String[] postExecHooks = confPostExecHooks.split(",");
+
+		    for (String postExecHook : postExecHooks) {
+		        Class<ImpalaPostExecHook> clsHook = (Class<ImpalaPostExecHook>) Class.forName(postExecHook);
+
+		        ImpalaPostExecHook hook = clsHook.newInstance();
+
+		        hooks.add(hook);
+            }
+        }
+
+        for (ImpalaPostExecHook hook : hooks) {
+            hook.init();
+        }
+
+		this.hooks = Collections.unmodifiableList(hooks);
+    }
+
+    // to be called once during Impala shutdown
+    public void cleanUp() {
+        List<ImpalaPostExecHook> hooks = this.hooks;
+
+        this.hooks = Collections.emptyList();
+
+        for (ImpalaPostExecHook hook : hooks) {
+            hook.cleanUp();
+        }
+    }
+
+    public List<ImpalaPostExecHook> getHooks() {
+        return hooks;
+    }
+
+    public void executeHooks(ImpalaHookContext context) {
+        for (ImpalaPostExecHook hook : hooks) {
+            hook.execute(context);
+        }
+    }
+}
-- 
2.19.2