Remove thread in JavascriptExecutor

This change is basically a rollback of https://gerrit.onap.org/r/c/policy/apex-pdp/+/104230, with minor refactoring.
The problem that 104230 tried to address was supposed to be caused by https://jira.onap.org/browse/POLICY-2463.
With this rollback, apex-pdp increases performance and reduces memory usage.

Issue-ID: POLICY-2572
Signed-off-by: huaxing <huaxing.jin@est.tech>
Change-Id: I3a52d0ead0c1e530d218f9e3aba8b3eb5558abaf

4 files changed, 50 insertions, 288 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 0eecd5d4b..344f8c5ae 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
@@ -20,288 +20,88 @@
 
 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.TimeUnit;
-import java.util.concurrent.atomic.AtomicReference;
-import lombok.AccessLevel;
-import lombok.Getter;
-import lombok.NonNull;
-import lombok.Setter;
 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 implements Runnable {
-    private static final XLogger LOGGER = XLoggerFactory.getXLogger(JavascriptExecutor.class);
-
+public class JavascriptExecutor {
     public static final int DEFAULT_OPTIMIZATION_LEVEL = 9;
 
-    // Token passed to executor thread to stop execution
-    private static final Object STOP_EXECUTION_TOKEN = "*** STOP EXECUTION ***";
-
     // Recurring string constants
     private static final String WITH_MESSAGE = " with message: ";
-    private static final String JAVASCRIPT_EXECUTOR = "JavascriptExecutor ";
-    private static final String EXECUTION_FAILED_EXECUTOR = "execution failed, executor ";
-
-    @Setter(AccessLevel.PROTECTED)
-    private static TimeUnit timeunit4Latches = TimeUnit.SECONDS;
-    @Setter(AccessLevel.PROTECTED)
-    private static int intializationLatchTimeout = 60;
-    @Setter(AccessLevel.PROTECTED)
-    private static int cleanupLatchTimeout = 60;
 
     // The key of the subject that wants to execute Javascript code
-    final AxKey subjectKey;
+    private 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<>();
-
-    @Getter(AccessLevel.PROTECTED)
-    private Thread executorThread;
-    private CountDownLatch intializationLatch;
-    private CountDownLatch cleanupLatch;
-    private AtomicReference<StateMachineException> executorException = new AtomicReference<>(null);
+    private final Script script;
 
     /**
      * Initializes the Javascript executor.
      *
      * @param subjectKey the key of the subject that is requesting Javascript execution
-     */
-    public JavascriptExecutor(final AxKey subjectKey) {
-        this.subjectKey = subjectKey;
-    }
-
-    /**
-     * Prepares the executor for processing and compiles the Javascript code.
-     *
      * @param javascriptCode the Javascript code to execute
-     * @throws StateMachineException thrown when instantiation of the executor fails
      */
-    public synchronized void init(@NonNull final String javascriptCode) throws StateMachineException {
-        LOGGER.debug("JavascriptExecutor {} starting ... ", subjectKey.getId());
-
-        if (executorThread != null) {
-            throw new StateMachineException("initiation failed, executor " + subjectKey.getId()
-                + " already initialized, run cleanUp to clear executor");
-        }
-
+    public JavascriptExecutor(final AxKey subjectKey, String javascriptCode)  throws StateMachineException {
         if (StringUtils.isBlank(javascriptCode)) {
-            throw new StateMachineException("initiation failed, no logic specified for executor " + subjectKey.getId());
-        }
-
-        this.javascriptCode = javascriptCode;
-
-        executorThread = new Thread(this);
-        executorThread.setName(this.getClass().getSimpleName() + ":" + subjectKey.getId());
-        intializationLatch = new CountDownLatch(1);
-        cleanupLatch = new CountDownLatch(1);
-
-        try {
-            executorThread.start();
-        } catch (IllegalThreadStateException e) {
-            throw new StateMachineException("initiation failed, executor " + subjectKey.getId() + " failed to start",
-                e);
-        }
-
-        try {
-            if (!intializationLatch.await(intializationLatchTimeout, timeunit4Latches)) {
-                executorThread.interrupt();
-                throw new StateMachineException(JAVASCRIPT_EXECUTOR + subjectKey.getId()
-                    + " initiation timed out after " + intializationLatchTimeout + " " + timeunit4Latches);
-            }
-        } catch (InterruptedException e) {
-            LOGGER.debug("JavascriptExecutor {} interrupted on execution thread startup", subjectKey.getId(), e);
-            Thread.currentThread().interrupt();
-        }
-
-        if (executorException.get() != null) {
-            executorThread.interrupt();
-            checkAndThrowExecutorException();
-        }
-
-        checkAndThrowExecutorException();
-
-        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 synchronized boolean execute(final Object executionContext) throws StateMachineException {
-        if (executorThread == null) {
-            throw new StateMachineException(EXECUTION_FAILED_EXECUTOR + subjectKey.getId() + " is not initialized");
+            throw new StateMachineException("no logic specified for " + subjectKey.getId());
         }
-
-        if (!executorThread.isAlive() || executorThread.isInterrupted()) {
-            throw new StateMachineException(EXECUTION_FAILED_EXECUTOR + subjectKey.getId()
-                + " is not running, run cleanUp to clear executor and init to restart executor");
-        }
-
-        executionQueue.add(executionContext);
-
-        boolean result = false;
-
-        try {
-            result = resultQueue.take();
-        } catch (final InterruptedException e) {
-            executorThread.interrupt();
-            Thread.currentThread().interrupt();
-            throw new StateMachineException(
-                JAVASCRIPT_EXECUTOR + subjectKey.getId() + "interrupted on execution result wait", e);
-        }
-
-        checkAndThrowExecutorException();
-
-        return result;
+        this.subjectKey = subjectKey;
+        this.script = compile(subjectKey.getId(), javascriptCode);
     }
 
     /**
-     * Cleans up the executor after processing.
+     * Executes the Javascript code.
      *
-     * @throws StateMachineException thrown when cleanup of the executor fails
+     * @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 synchronized void cleanUp() throws StateMachineException {
-        if (executorThread == null) {
-            throw new StateMachineException("cleanup failed, executor " + subjectKey.getId() + " is not initialized");
-        }
-
-        if (executorThread.isAlive()) {
-            executionQueue.add(STOP_EXECUTION_TOKEN);
-
-            try {
-                if (!cleanupLatch.await(cleanupLatchTimeout, timeunit4Latches)) {
-                    executorException.set(new StateMachineException(JAVASCRIPT_EXECUTOR + subjectKey.getId()
-                        + " cleanup timed out after " + cleanupLatchTimeout + " " + timeunit4Latches));
-                }
-            } catch (InterruptedException e) {
-                LOGGER.debug("JavascriptExecutor {} interrupted on execution cleanup wait", subjectKey.getId(), e);
-                Thread.currentThread().interrupt();
-            }
-        }
-
-        executorThread = null;
-        executionQueue.clear();
-        resultQueue.clear();
-
-        checkAndThrowExecutorException();
-    }
-
-    @Override
-    public void run() {
-        LOGGER.debug("JavascriptExecutor {} initializing ... ", subjectKey.getId());
-
-        try {
-            initExecutor();
-        } catch (StateMachineException sme) {
-            LOGGER.warn("JavascriptExecutor {} initialization failed", subjectKey.getId(), sme);
-            executorException.set(sme);
-            intializationLatch.countDown();
-            cleanupLatch.countDown();
-            return;
-        }
-
-        intializationLatch.countDown();
-
-        LOGGER.debug("JavascriptExecutor {} executing ... ", subjectKey.getId());
-
-        // Take jobs from the execution queue of the worker and execute them
-        while (!Thread.currentThread().isInterrupted()) {
-            try {
-                Object contextObject = executionQueue.take();
-                if (STOP_EXECUTION_TOKEN.equals(contextObject)) {
-                    LOGGER.debug("execution close was ordered for  " + subjectKey.getId());
-                    break;
-                }
-                resultQueue.add(executeScript(contextObject));
-            } catch (final InterruptedException e) {
-                LOGGER.debug("execution was interruped for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
-                executionQueue.add(STOP_EXECUTION_TOKEN);
-                Thread.currentThread().interrupt();
-            } catch (StateMachineException sme) {
-                executorException.set(sme);
-                resultQueue.add(false);
-            }
-        }
-
-        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));
-        }
-
-        cleanupLatch.countDown();
-
-        LOGGER.debug("JavascriptExecutor {} completed processing", subjectKey.getId());
-    }
-
-    private void initExecutor() throws StateMachineException {
-        try {
-            // Create a Javascript context for this thread
-            javascriptContext = Context.enter();
-
-            // Set up the default values of the context
-            javascriptContext.setOptimizationLevel(DEFAULT_OPTIMIZATION_LEVEL);
-            javascriptContext.setLanguageVersion(Context.VERSION_1_8);
-
-            script = javascriptContext.compileString(javascriptCode, subjectKey.getId(), 1, null);
-        } catch (Exception e) {
-            Context.exit();
-            throw new StateMachineException(
-                "logic failed to compile for " + subjectKey.getId() + WITH_MESSAGE + e.getMessage(), e);
-        }
-    }
-
-    private boolean executeScript(final Object executionContext) throws StateMachineException {
+    public boolean execute(final Object executionContext) throws StateMachineException {
         Object returnObject = null;
 
+        Context context = Context.enter();
         try {
             // Pass the subject context to the Javascript engine
-            Scriptable javascriptScope = javascriptContext.initStandardObjects();
+            Scriptable javascriptScope = context.initStandardObjects();
             javascriptScope.put("executor", javascriptScope, executionContext);
 
             // Run the script
-            returnObject = script.exec(javascriptContext, javascriptScope);
+            returnObject = script.exec(context, 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);
+        } finally {
+            Context.exit();
         }
 
         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;
     }
 
-    private void checkAndThrowExecutorException() throws StateMachineException {
-        StateMachineException exceptionToThrow = executorException.getAndSet(null);
-        if (exceptionToThrow != null) {
-            throw exceptionToThrow;
+    private Script compile(String id, String javascriptCode) throws StateMachineException {
+        Context context = Context.enter();
+        try {
+            // Set up the default values of the context
+            context.setOptimizationLevel(DEFAULT_OPTIMIZATION_LEVEL);
+            context.setLanguageVersion(Context.VERSION_1_8);
+            return context.compileString(javascriptCode, id, 1, null);
+        } catch (Exception e) {
+            throw new StateMachineException(
+                "logic failed to compile for " + id + WITH_MESSAGE + e.getMessage(), e);
+        } finally {
+            Context.exit();
         }
     }
 }
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 ffd09259b..24c6b768a 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
@@ -52,12 +52,7 @@ public class JavascriptStateFinalizerExecutor extends StateFinalizerExecutor {
         super.prepare();
 
         // Create the executor
-        if (javascriptExecutor == null) {
-            javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
-        }
-
-        // Initialize and cleanup the executor to check the Javascript code
-        javascriptExecutor.init(getSubject().getLogic());
+        javascriptExecutor = new JavascriptExecutor(getSubject().getKey(), getSubject().getLogic());
     }
 
     /**
@@ -72,16 +67,10 @@ public class JavascriptStateFinalizerExecutor extends StateFinalizerExecutor {
      */
     @Override
     public String execute(final long executionId, final Properties executionProperties,
-        final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
-        // Do execution pre work
+            final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
         executePre(executionId, executionProperties, incomingFields);
-
-        // Execute the Javascript executor
         boolean result = javascriptExecutor.execute(getExecutionContext());
-
-        // Execute the Javascript
         executePost(result);
-
         return getOutgoing();
     }
 
@@ -92,9 +81,9 @@ public class JavascriptStateFinalizerExecutor extends StateFinalizerExecutor {
      */
     @Override
     public void cleanUp() throws StateMachineException {
-        LOGGER.debug("cleanUp:" + getSubject().getKey().getId() + "," + getSubject().getLogicFlavour() + ","
-            + getSubject().getLogic());
-
-        javascriptExecutor.cleanUp();
+        LOGGER.debug("cleanUp:{},{},{}",
+            getSubject().getKey().getId(),
+            getSubject().getLogicFlavour(),
+            getSubject().getLogic());
     }
 }
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 9f30f839f..a25dca0c6 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
@@ -52,12 +52,7 @@ public class JavascriptTaskExecutor extends TaskExecutor {
         super.prepare();
 
         // Create the executor
-        if (javascriptExecutor == null) {
-            javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
-        }
-
-        // Initialize and cleanup the executor to check the Javascript code
-        javascriptExecutor.init(getSubject().getTaskLogic().getLogic());
+        javascriptExecutor = new JavascriptExecutor(getSubject().getKey(), getSubject().getTaskLogic().getLogic());
     }
 
     /**
@@ -72,17 +67,10 @@ 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 {
-
-        // Do execution pre work
+            final Map<String, Object> incomingFields) throws StateMachineException, ContextException {
         executePre(executionId, executionProperties, incomingFields);
-
-        // Execute the Javascript executor
         boolean result = javascriptExecutor.execute(getExecutionContext());
-
-        // Execute the Javascript
         executePost(result);
-
         return getOutgoing();
     }
 
@@ -93,13 +81,9 @@ public class JavascriptTaskExecutor extends TaskExecutor {
      */
     @Override
     public void cleanUp() throws StateMachineException {
-        LOGGER.debug("cleanUp:" + getSubject().getKey().getId() + "," + getSubject().getTaskLogic().getLogicFlavour()
-            + "," + getSubject().getTaskLogic().getLogic());
-
-        if (javascriptExecutor != null) {
-            javascriptExecutor.cleanUp();
-        }
-
-        javascriptExecutor = null;
+        LOGGER.debug("cleanUp:{},{},{}",
+            getSubject().getKey().getId(),
+            getSubject().getTaskLogic().getLogicFlavour(),
+            getSubject().getTaskLogic().getLogic());
     }
 }
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 d7b137f2e..5c28999b5 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
@@ -53,12 +53,8 @@ public class JavascriptTaskSelectExecutor extends TaskSelectExecutor {
         super.prepare();
 
         // Create the executor
-        if (javascriptExecutor == null) {
-            javascriptExecutor = new JavascriptExecutor(getSubject().getKey());
-        }
-
-        // Initialize and cleanup the executor to check the Javascript code
-        javascriptExecutor.init(getSubject().getTaskSelectionLogic().getLogic());
+        javascriptExecutor = new JavascriptExecutor(getSubject().getKey(),
+            getSubject().getTaskSelectionLogic().getLogic());
     }
 
     /**
@@ -73,16 +69,10 @@ public class JavascriptTaskSelectExecutor extends TaskSelectExecutor {
      */
     @Override
     public AxArtifactKey execute(final long executionId, final Properties executionProperties,
-        final EnEvent incomingEvent) throws StateMachineException, ContextException {
-        // Do execution pre work
+            final EnEvent incomingEvent) throws StateMachineException, ContextException {
         executePre(executionId, executionProperties, incomingEvent);
-
-        // Execute the Javascript executor
         boolean result = javascriptExecutor.execute(getExecutionContext());
-
-        // Execute the Javascript
         executePost(result);
-
         return getOutgoing();
     }
 
@@ -93,10 +83,9 @@ public class JavascriptTaskSelectExecutor extends TaskSelectExecutor {
      */
     @Override
     public void cleanUp() throws StateMachineException {
-        LOGGER.debug(
-            "cleanUp:" + getSubject().getKey().getId() + "," + getSubject().getTaskSelectionLogic().getLogicFlavour()
-                + "," + getSubject().getTaskSelectionLogic().getLogic());
-
-        javascriptExecutor.cleanUp();
+        LOGGER.debug("cleanUp:{},{},{}",
+            getSubject().getKey().getId(),
+            getSubject().getTaskSelectionLogic().getLogicFlavour(),
+            getSubject().getTaskSelectionLogic().getLogic());
     }
 }