Launch separate threads for Javascript task execution

When a policy is loaded, a separate thread is spawned for each
Javascript script executor. This allows us to precompile the Javascript
scripts and also to have a larger stack available for script execution.

Issue-ID: POLICY-2106
Change-Id: I97323aafb623ba537ac1889b3c9504b345b4f67e
Signed-off-by: liamfallon <liam.fallon@est.tech>

4 files changed, 195 insertions, 43 deletions

diff --git a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptExecutor.java b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptExecutor.java
index c80f58fbe..2394b83d3 100644
--- a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptExecutor.java
+++ b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptExecutor.java
@@ -20,19 +20,28 @@
 
 package org.onap.policy.apex.plugins.executor.javascript;
 
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.atomic.AtomicReference;
+
 import org.apache.commons.lang3.StringUtils;
 import org.mozilla.javascript.Context;
 import org.mozilla.javascript.Script;
 import org.mozilla.javascript.Scriptable;
 import org.onap.policy.apex.core.engine.executor.exception.StateMachineException;
 import org.onap.policy.apex.model.basicmodel.concepts.AxKey;
+import org.slf4j.ext.XLogger;
+import org.slf4j.ext.XLoggerFactory;
 
 /**
  * The Class JavascriptExecutor is the executor for task logic written in Javascript.
  *
  * @author Liam Fallon (liam.fallon@ericsson.com)
  */
-public class JavascriptExecutor {
+public class JavascriptExecutor implements Runnable {
+    private static final XLogger LOGGER = XLoggerFactory.getXLogger(JavascriptExecutor.class);
+
     public static final int DEFAULT_OPTIMIZATION_LEVEL = 9;
 
     // Recurring string constants
@@ -41,16 +50,28 @@ public class JavascriptExecutor {
     // The key of the subject that wants to execute Javascript code
     final AxKey subjectKey;
 
+    private String javascriptCode;
     private Context javascriptContext;
     private Script script;
 
+    private final BlockingQueue<Object> executionQueue = new LinkedBlockingQueue<>();
+    private final BlockingQueue<Boolean> resultQueue = new LinkedBlockingQueue<>();
+
+    private final Thread executorThread;
+    private CountDownLatch intializationLatch = new CountDownLatch(1);
+    private CountDownLatch shutdownLatch = new CountDownLatch(1);
+    private AtomicReference<StateMachineException> executorException = new AtomicReference<>(null);
+
     /**
-     * Initializes the Javascripe executor.
+     * Initializes the Javascript executor.
      *
      * @param subjectKey the key of the subject that is requesting Javascript execution
      */
     public JavascriptExecutor(final AxKey subjectKey) {
         this.subjectKey = subjectKey;
+
+        executorThread = new Thread(this);
+        executorThread.setName(this.getClass().getSimpleName() + ":" + subjectKey.getId());
     }
 
     /**
@@ -60,10 +81,143 @@ public class JavascriptExecutor {
      * @throws StateMachineException thrown when instantiation of the executor fails
      */
     public void init(final String javascriptCode) throws StateMachineException {
+        LOGGER.debug("JavascriptExecutor {} starting ... ", subjectKey.getId());
+
+        if (executorThread.isAlive()) {
+            throw new StateMachineException(
+                "initiation failed, executor " + subjectKey.getId() + " is already running");
+        }
+
         if (StringUtils.isEmpty(javascriptCode)) {
             throw new StateMachineException("no logic specified for " + subjectKey.getId());
         }
 
+        this.javascriptCode = javascriptCode;
+
+        try {
+            executorThread.start();
+        } catch (Exception e) {
+            throw new StateMachineException("initiation failed, executor " + subjectKey.getId() + " failed to start",
+                e);
+        }
+
+        try {
+            intializationLatch.await();
+        } catch (InterruptedException e) {
+            LOGGER.debug("JavascriptExecutor {} interrupted on execution thread startup", subjectKey.getId(), e);
+            Thread.currentThread().interrupt();
+        }
+
+        if (executorException.get() != null) {
+            clearAndThrowExecutorException();
+        }
+
+        LOGGER.debug("JavascriptExecutor {} started ... ", subjectKey.getId());
+    }
+
+    /**
+     * Execute a Javascript script.
+     *
+     * @param executionContext the execution context to use for script execution
+     * @return true if execution was successful, false otherwise
+     * @throws StateMachineException on execution errors
+     */
+    public boolean execute(final Object executionContext) throws StateMachineException {
+        if (!executorThread.isAlive()) {
+            throw new StateMachineException("execution failed, executor " + subjectKey.getId() + " is not running");
+        }
+
+        executionQueue.add(executionContext);
+
+        boolean result = false;
+
+        try {
+            result = resultQueue.take();
+        } catch (final InterruptedException e) {
+            LOGGER.debug("JavascriptExecutor {} interrupted on execution result wait", subjectKey.getId(), e);
+            Thread.currentThread().interrupt();
+        }
+
+        if (executorException.get() != null) {
+            clearAndThrowExecutorException();
+        }
+
+        return result;
+    }
+
+    /**
+     * Cleans up the executor after processing.
+     *
+     * @throws StateMachineException thrown when cleanup of the executor fails
+     */
+    public void cleanUp() throws StateMachineException {
+        if (!executorThread.isAlive()) {
+            throw new StateMachineException("cleanup failed, executor " + subjectKey.getId() + " is not running");
+        }
+
+        executorThread.interrupt();
+
+        try {
+            shutdownLatch.await();
+        } catch (InterruptedException e) {
+            LOGGER.debug("JavascriptExecutor {} interrupted on execution clkeanup wait", subjectKey.getId(), e);
+            Thread.currentThread().interrupt();
+        }
+
+        if (executorException.get() != null) {
+            clearAndThrowExecutorException();
+        }
+    }
+
+    @Override
+    public void run() {
+        LOGGER.debug("JavascriptExecutor {} initializing ... ", subjectKey.getId());
+
+        try {
+            initExecutor();
+        } catch (StateMachineException sme) {
+            LOGGER.warn("JavascriptExecutor {} initialization failed", sme);
+            executorException.set(sme);
+            intializationLatch.countDown();
+            return;
+        }
+
+        intializationLatch.countDown();
+
+        LOGGER.debug("JavascriptExecutor {} executing ... ", subjectKey.getId());
+
+        // Take jobs from the execution queue of the worker and execute them
+        while (!executorThread.isInterrupted()) {
+            try {
+                Object contextObject = executionQueue.take();
+                if (contextObject == null) {
+                    break;
+                }
+
+                resultQueue.add(executeScript(contextObject));
+            } catch (final InterruptedException e) {
+                LOGGER.debug("execution was interruped for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
+                resultQueue.add(false);
+                Thread.currentThread().interrupt();
+            } catch (StateMachineException sme) {
+                executorException.set(sme);
+                resultQueue.add(false);
+            }
+        }
+
+        try {
+            Context.exit();
+        } catch (final Exception e) {
+            executorException.set(new StateMachineException(
+                "executor close failed to close for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e));
+        }
+
+        shutdownLatch.countDown();
+
+        LOGGER.debug("JavascriptExecutor {} completed processing", subjectKey.getId());
+    }
+
+    private void initExecutor() throws StateMachineException {
         try {
             // Create a Javascript context for this thread
             javascriptContext = Context.enter();
@@ -76,18 +230,11 @@ public class JavascriptExecutor {
         } catch (Exception e) {
             Context.exit();
             throw new StateMachineException(
-                    "logic failed to compile for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
+                "logic failed to compile for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
         }
     }
 
-    /**
-     * Executes the the Javascript code.
-     *
-     * @param executionContext the execution context of the subject to be passed to the Javascript context
-     * @return true if the Javascript executed properly
-     * @throws StateMachineException thrown when Javascript execution fails
-     */
-    public boolean execute(final Object executionContext) throws StateMachineException {
+    private boolean executeScript(final Object executionContext) throws StateMachineException {
         Object returnObject = null;
 
         try {
@@ -99,28 +246,25 @@ public class JavascriptExecutor {
             returnObject = script.exec(javascriptContext, javascriptScope);
         } catch (final Exception e) {
             throw new StateMachineException(
-                    "logic failed to run for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
+                "logic failed to run for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
         }
 
         if (!(returnObject instanceof Boolean)) {
             throw new StateMachineException(
-                    "execute: logic for " + subjectKey.getId() + " returned a non-boolean value " + returnObject);
+                "execute: logic for " + subjectKey.getId() + " returned a non-boolean value " + returnObject);
         }
 
         return (boolean) returnObject;
     }
 
-    /**
-     * Cleans up the executor after processing.
-     *
-     * @throws StateMachineException thrown when cleanup of the executor fails
-     */
-    public void cleanUp() throws StateMachineException {
-        try {
-            Context.exit();
-        } catch (final Exception e) {
-            throw new StateMachineException("cleanUp: executor cleanup failed to close for " + subjectKey.getId()
-                    + WITH_MESSAGE + e.getMessage(), e);
+    private void clearAndThrowExecutorException() throws StateMachineException {
+        StateMachineException exceptionToThrow = executorException.getAndSet(null);
+        if (exceptionToThrow != null) {
+            throw exceptionToThrow;
         }
     }
+
+    protected Thread getExecutorThread() {
+        return executorThread;
+    }
 }
diff --git a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptStateFinalizerExecutor.java b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptStateFinalizerExecutor.java
index 27e649fd3..63e4948dd 100644
--- a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptStateFinalizerExecutor.java
+++ b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptStateFinalizerExecutor.java
@@ -53,11 +53,12 @@ public class JavascriptStateFinalizerExecutor extends StateFinalizerExecutor {
         super.prepare();
 
         // Create the executor
-        javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
+        if (javascriptExecutor == null) {
+            javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
+        }
 
         // Initialize and cleanup the executor to check the Javascript code
         javascriptExecutor.init(getSubject().getLogic());
-        javascriptExecutor.cleanUp();
     }
 
     /**
@@ -72,14 +73,12 @@ public class JavascriptStateFinalizerExecutor extends StateFinalizerExecutor {
      */
     @Override
     public String execute(final long executionId, final Properties executionProperties,
-            final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
+        final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
         // Do execution pre work
         executePre(executionId, executionProperties, incomingFields);
 
         // Execute the Javascript executor
-        javascriptExecutor.init(getSubject().getLogic());
         boolean result = javascriptExecutor.execute(getExecutionContext());
-        javascriptExecutor.cleanUp();
 
         // Execute the Javascript
         executePost(result);
@@ -95,6 +94,8 @@ public class JavascriptStateFinalizerExecutor extends StateFinalizerExecutor {
     @Override
     public void cleanUp() throws StateMachineException {
         LOGGER.debug("cleanUp:" + getSubject().getKey().getId() + "," + getSubject().getLogicFlavour() + ","
-                + getSubject().getLogic());
+            + getSubject().getLogic());
+
+        javascriptExecutor.cleanUp();
     }
 }
diff --git a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskExecutor.java b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskExecutor.java
index bec5670c5..a9dba27f2 100644
--- a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskExecutor.java
+++ b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskExecutor.java
@@ -53,11 +53,12 @@ public class JavascriptTaskExecutor extends TaskExecutor {
         super.prepare();
 
         // Create the executor
-        javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
+        if (javascriptExecutor == null) {
+            javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
+        }
 
         // Initialize and cleanup the executor to check the Javascript code
         javascriptExecutor.init(getSubject().getTaskLogic().getLogic());
-        javascriptExecutor.cleanUp();
     }
 
     /**
@@ -72,15 +73,13 @@ public class JavascriptTaskExecutor extends TaskExecutor {
      */
     @Override
     public Map<String, Object> execute(final long executionId, final Properties executionProperties,
-            final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
+        final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
 
         // Do execution pre work
         executePre(executionId, executionProperties, incomingFields);
 
         // Execute the Javascript executor
-        javascriptExecutor.init(getSubject().getTaskLogic().getLogic());
         boolean result = javascriptExecutor.execute(getExecutionContext());
-        javascriptExecutor.cleanUp();
 
         // Execute the Javascript
         executePost(result);
@@ -96,6 +95,12 @@ public class JavascriptTaskExecutor extends TaskExecutor {
     @Override
     public void cleanUp() throws StateMachineException {
         LOGGER.debug("cleanUp:" + getSubject().getKey().getId() + "," + getSubject().getTaskLogic().getLogicFlavour()
-                + "," + getSubject().getTaskLogic().getLogic());
+            + "," + getSubject().getTaskLogic().getLogic());
+
+        if (javascriptExecutor != null) {
+            javascriptExecutor.cleanUp();
+        }
+
+        javascriptExecutor = null;
     }
 }
diff --git a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskSelectExecutor.java b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskSelectExecutor.java
index c32b70991..93384c129 100644
--- a/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskSelectExecutor.java
+++ b/plugins/plugins-executor/plugins-executor-javascript/src/main/java/org/onap/policy/apex/plugins/executor/javascript/JavascriptTaskSelectExecutor.java
@@ -54,7 +54,9 @@ public class JavascriptTaskSelectExecutor extends TaskSelectExecutor {
         super.prepare();
 
         // Create the executor
-        javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
+        if (javascriptExecutor == null) {
+            javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
+        }
 
         // Initialize and cleanup the executor to check the Javascript code
         javascriptExecutor.init(getSubject().getTaskSelectionLogic().getLogic());
@@ -72,14 +74,12 @@ public class JavascriptTaskSelectExecutor extends TaskSelectExecutor {
      */
     @Override
     public AxArtifactKey execute(final long executionId, final Properties executionProperties,
-            final EnEvent incomingEvent) throws StateMachineException, ContextException {
+        final EnEvent incomingEvent) throws StateMachineException, ContextException {
         // Do execution pre work
         executePre(executionId, executionProperties, incomingEvent);
 
         // Execute the Javascript executor
-        javascriptExecutor.init(getSubject().getTaskSelectionLogic().getLogic());
         boolean result = javascriptExecutor.execute(getExecutionContext());
-        javascriptExecutor.cleanUp();
 
         // Execute the Javascript
         executePost(result);
@@ -94,8 +94,10 @@ public class JavascriptTaskSelectExecutor extends TaskSelectExecutor {
      */
     @Override
     public void cleanUp() throws StateMachineException {
-        LOGGER.debug("cleanUp:" + getSubject().getKey().getId() + ","
-                + getSubject().getTaskSelectionLogic().getLogicFlavour() + ","
-                + getSubject().getTaskSelectionLogic().getLogic());
+        LOGGER.debug(
+            "cleanUp:" + getSubject().getKey().getId() + "," + getSubject().getTaskSelectionLogic().getLogicFlavour()
+                + "," + getSubject().getTaskSelectionLogic().getLogic());
+
+        javascriptExecutor.cleanUp();
     }
 }