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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
 *
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package org.graalvm.tools.lsp.server;

import java.util.concurrent.Callable;
import java.util.concurrent.Future;

/**
 * This service interface defines methods to submit a task, i.e. a {@link Callable}, which will be
 * executed in a Polyglot-Context-entered Thread to access features of the Truffle API.
 *
 */
public interface ContextAwareExecutor {

    /**
     * Execute a task in a default Polyglot Context. Use this method to access the Truffle API to
     * parse source code or do language specific look-ups. To execute source code, use
     * {@link ContextAwareExecutor#executeWithNestedContext(Callable)}.
     *
     * @param taskWithResult a task which shall be executed in a Polyglot-Context-entered Thread
     * @return a {@link Future} to await the task's result
     */
     Future executeWithDefaultContext(Callable taskWithResult);

    /**
     * Execute a task in a newly created Polyglot Context. This is useful if the task executes
     * arbitrary source code which will change the state of the language contexts. The created
     * Polyglot Context will be closed and removed afterwards. Remember, that creating new Polyglot
     * Contexts might be expensive, depending on the installed languages.
     *
     *
     * @param taskWithResult a task which shall be executed in a Polyglot-Context-entered Thread,
     *            which might have unwanted side-effects
     * @return a {@link Future} to await the task's result
     */
    default  Future executeWithNestedContext(Callable taskWithResult) {
        return executeWithNestedContext(taskWithResult, false);
    }

    /**
     * Same as {@link ContextAwareExecutor#executeWithNestedContext(Callable)}, but allowing to
     * reuse nested Context instances.
     *
     * @param taskWithResult a task which shall be executed in a Polyglot-Context-entered Thread,
     *            which might have unwanted side-effects
     * @param cached As creating new Polyglot Context instances might be expensive, this parameter
     *            allows to reuse the last nested Context instance for this call. To enforce using a
     *            fresh Context instance, {@link ContextAwareExecutor#resetContextCache()} can be
     *            called.
     * @return a {@link Future} to await the task's result
     */
     Future executeWithNestedContext(Callable taskWithResult, boolean cached);

    /**
     * Same as {@link ContextAwareExecutor#executeWithNestedContext(Callable)}, but allowing the
     * definition of a timeout and an onTimeoutTask for the execution.
     *
     * @param taskWithResult a task which shall be executed in a Polyglot-Context-entered Thread,
     *            which might have unwanted side-effects
     * @param timeoutMillis time in milliseconds that taskWithResult is allowed to run.
     * @param onTimeoutTask a task which is executed if the timeout is triggered.
     * @return a {@link Future} to await the task's result, or the onTimeoutTask's result if the
     *         timeout triggered.
     */
     Future executeWithNestedContext(Callable taskWithResult, int timeoutMillis, Callable onTimeoutTask);

    /**
     * Explicitly closes and removes all cached nested Context instances.
     */
    void resetContextCache();

    /**
     * Shutdown this executor without waiting for tasks to finish.
     */
    void shutdown();

}