ConcurrentRequestManager.java

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package org.dcache.services.bulk.manager;

import static java.util.concurrent.TimeUnit.SECONDS;
import static org.dcache.services.bulk.BulkRequestStatus.STARTED;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ListMultimap;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Collectors;
import javax.annotation.concurrent.GuardedBy;
import org.dcache.services.bulk.BulkRequest;
import org.dcache.services.bulk.BulkRequestStatus;
import org.dcache.services.bulk.BulkServiceException;
import org.dcache.services.bulk.BulkStorageException;
import org.dcache.services.bulk.handler.BulkRequestCompletionHandler;
import org.dcache.services.bulk.handler.BulkSubmissionHandler;
import org.dcache.services.bulk.job.BulkRequestContainerJob;
import org.dcache.services.bulk.manager.scheduler.BulkRequestScheduler;
import org.dcache.services.bulk.manager.scheduler.BulkSchedulerProvider;
import org.dcache.services.bulk.store.BulkRequestStore;
import org.dcache.services.bulk.store.BulkTargetStore;
import org.dcache.services.bulk.util.BulkRequestTarget;
import org.dcache.services.bulk.util.BulkRequestTarget.State;
import org.dcache.services.bulk.util.BulkServiceStatistics;
import org.dcache.util.BoundedCachedExecutor;
import org.dcache.util.FireAndForgetTask;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Required;

/**
 * Initializes a processor thread to handle the promotion of requests from queued to active, and to
 * manage request termination and cancellation.
 * <p>
 * The request container job is held in memory for its entire lifecycle (there is a limit to the
 * number of active requests which can be run concurrently which is configurable).
 * <p>
 * Each container job is launched on the executor provided by its specific activity.
 */
public final class ConcurrentRequestManager implements BulkRequestManager {

    private static final Logger LOGGER = LoggerFactory.getLogger(ConcurrentRequestManager.class);

    private static final int DEFAULT_MAX_ACTIVE_REQUESTS = 100;
    private static final long DEFAULT_PROCESSOR_TIMEOUT = 5;
    private static final TimeUnit DEFAULT_PROCESSOR_TIMEOUT_UNIT = SECONDS;

    class ConcurrentRequestProcessor implements Runnable {

        final BulkRequestScheduler scheduler;

        /*
         *  For reporting operations terminated or cancelled while the consumer thread is doing
         *  work outside the wait monitor.
         */
        AtomicInteger signals = new AtomicInteger(0);

        ConcurrentRequestProcessor(BulkRequestScheduler scheduler) {
            this.scheduler = scheduler;
        }

        @Override
        public void run() {
            try {
                signals.set(0);
                while (!Thread.interrupted()) {
                    doRun();
                    await();
                }
            } catch (InterruptedException e) {
                LOGGER.warn("interrupted.");
            } finally {
                /*
                 *  Report exit even in the case of an uncaught exception.
                 */
                LOGGER.warn("ConcurrentRequestProcessor exiting...");
            }
        }

        public void signal() {
            signals.incrementAndGet();
            synchronized (this) {
                notifyAll();
            }
        }

        private void await() throws InterruptedException {
            if (signals.get() > 0) {
                LOGGER.trace("received {} signals; returning immediately for more work.",
                      signals.get());
                signals.set(0);
                return;
            }
            synchronized (this) {
                LOGGER.trace("waiting ...");
                wait(timeoutUnit.toMillis(timeout));
            }
        }

        private void broadcastTargetCancel() {
            List<String> toCancel;

            synchronized (cancelledTargets) {
                toCancel = cancelledTargets.stream().collect(Collectors.toList());
                cancelledTargets.clear();
            }

            synchronized (requestJobs) {
                toCancel.forEach(key -> {
                    String[] ridId = BulkRequestTarget.parse(key);
                    BulkRequestContainerJob job = requestJobs.get(ridId[0]);
                    if (job != null) {
                        long id = Long.valueOf(ridId[1]);
                        job.cancel(id);
                        targetStore.cancel(id);
                    }
                });
            }
        }

        private void doRun() throws InterruptedException {
            LOGGER.trace("NextJobProcessor, starting doRun().");

            long start = System.currentTimeMillis();

            broadcastTargetCancel();

            if (Thread.interrupted()) {
                throw new InterruptedException();
            }

            removeTerminatedRequests();

            if (Thread.interrupted()) {
                throw new InterruptedException();
            }

            processNextRequests();

            if (Thread.interrupted()) {
                throw new InterruptedException();
            }

            statistics.sweepFinished(System.currentTimeMillis() - start);

            LOGGER.trace("doRun() completed");
        }

        @GuardedBy("requestJobs")
        private boolean isTerminated(String rid) {
            BulkRequestContainerJob job = requestJobs.get(rid);
            if (job != null && job.getTarget().getState() == State.CANCELLED) {
                return completionHandler.checkTerminated(rid, true);
            }
            return completionHandler.checkTerminated(rid, false);
        }

        private void processNextRequests() {
            LOGGER.trace("processNextRequests()");

            try {
                List<BulkRequest> next = scheduler.processNextRequests(maxActiveRequests);
                if (next.isEmpty()) {
                    LOGGER.debug(
                          "processNextRequests(), no more QUEUED requests to process.");
                } else {
                    next.forEach(ConcurrentRequestManager.this::activateRequest);
                }
            } catch (BulkServiceException e) {
                LOGGER.error(
                      "processNextRequests(), problem retrieving queued requests: {}",
                      e.toString());
            }

            /*
             *   The activated requests have been stored, placed in the map and can now be
             *   immediately started.
             */
            synchronized (requestJobs) {
                requestJobs.values().stream().filter(BulkRequestContainerJob::isReady)
                      .forEach(ConcurrentRequestManager.this::startJob);
            }
        }

        private void removeTerminatedRequests() {
            LOGGER.trace("removeTerminatedRequests");
            synchronized (requestJobs) {
                userRequests().values().stream().filter(this::isTerminated)
                      .forEach(requestJobs::remove);
            }
        }

        private ListMultimap<String, String> userRequests() {
            ListMultimap<String, String> requestsByUser;
            try {
                requestsByUser = requestStore.getActiveRequestsByUser();
            } catch (BulkStorageException e) {
                LOGGER.error("userRequests, could not get requests: {}.", e.toString());
                return ArrayListMultimap.create();
            }

            if (requestsByUser.isEmpty()) {
                LOGGER.trace("userRequests, no requests currently active.");
                return ArrayListMultimap.create();
            }

            LOGGER.trace("found next requests by user {}.", requestsByUser);

            return requestsByUser;
        }
    }

    /**
     * Used to fetch ready requests to run.
     */
    private BulkRequestStore requestStore;

    /**
     * Used to fetch ready targets to run, and to update state.
     */
    private BulkTargetStore targetStore;

    /**
     * Handles callback to check for request cancellation or termination.
     */
    private BulkRequestCompletionHandler completionHandler;

    /**
     * Handles the initial request activation.
     */
    private BulkSubmissionHandler submissionHandler;

    /**
     * Provides the implementation of the request scheduler
     */
    private BulkSchedulerProvider schedulerProvider;

    /**
     * Thread dedicated to running the processor.
     */
    private ExecutorService processorExecutorService;

    /**
     * Thread dedicated to job callbacks.
     */
    private ExecutorService callbackExecutor;

    /**
     * Thread dedicated to jobs.
     */
    private ExecutorService executorService;

    /**
     * Records number of jobs and requests processed.
     */
    private BulkServiceStatistics statistics;

    /**
     * Maximum time to wait until running the processing loop again.
     */
    private long timeout = DEFAULT_PROCESSOR_TIMEOUT;
    private TimeUnit timeoutUnit = DEFAULT_PROCESSOR_TIMEOUT_UNIT;

    /**
     * Serves as the upper limit on the number of requests that can be active.
     */
    private int maxActiveRequests = DEFAULT_MAX_ACTIVE_REQUESTS;

    /**
     * Held for the lifetime of the container run.
     */
    private Map<String, BulkRequestContainerJob> requestJobs;

    /**
     * Ids of jobs cancelled individually. To avoid doing cancellation on the calling thread.
     */
    private Collection<String> cancelledTargets;

    /**
     * Handles the promotion of jobs to running.
     */
    private ConcurrentRequestProcessor processor;

    /**
     * For clearing state (=> HA).
     */
    private Future processorFuture;

    @Override
    public void initialize() throws Exception {
        requestJobs = new LinkedHashMap<>();
        cancelledTargets = new HashSet<>();
        schedulerProvider.initialize();
        processor = new ConcurrentRequestProcessor(schedulerProvider.getRequestScheduler());
        processorExecutorService = Executors.newSingleThreadScheduledExecutor();
        processorFuture = processorExecutorService.submit(processor);
    }

    @Override
    public void cancel(BulkRequestTarget target) {
        synchronized (cancelledTargets) {
            cancelledTargets.add(target.getKey());
        }
        processor.signal();
    }

    @Override
    public boolean cancelRequest(String requestId) {
        synchronized (requestJobs) {
            BulkRequestContainerJob job = requestJobs.get(requestId);
            if (job != null) {
                job.cancel();
                processor.signal();
                LOGGER.debug("Request container job cancelled for {}.", requestId);
                return true;
            }
        }

        LOGGER.debug("Request {} cancelled, no container running.", requestId);
        return false;
    }

    @Override
    public void cancelTargets(String id, List<String> targetPaths) {
        synchronized (requestJobs) {
            BulkRequestContainerJob job = requestJobs.get(id);
            if (job != null) {
                targetPaths.forEach(job::cancel);
                LOGGER.trace("{} request targets cancelled for {}.", targetPaths.size(), id);
            } else {
                LOGGER.debug(
                      "No currently running container for {} exists; target cancellation is void.",
                      id);
            }
        }
    }

    @Override
    public void shutdown() throws Exception {
        if (processorFuture != null) {
            processorFuture.cancel(true);
        }
        requestJobs = null;
        cancelledTargets = null;
        requestStore.clearCache();
    }

    @Override
    public int countSignals() {
        return processor.signals.get();
    }

    @Override
     public int getMaxActiveRequests() {
        return maxActiveRequests;
    }

    @Required
    public void setCallbackExecutor(BoundedCachedExecutor callbackExecutor) {
        this.callbackExecutor = callbackExecutor;
    }

    @Required
    public void setCompletionHandler(BulkRequestCompletionHandler completionHandler) {
        this.completionHandler = completionHandler;
    }

    @Required
    public void setExecutor(BoundedCachedExecutor pooledExecutor) {
        this.executorService = pooledExecutor;
    }

    @Required
    public void setTargetStore(BulkTargetStore targetStore) {
        this.targetStore = targetStore;
    }

    @Required
    public void setMaxActiveRequests(int maxActiveRequests) {
        this.maxActiveRequests = maxActiveRequests;
    }

    @Required
    public void setRequestStore(BulkRequestStore requestStore) {
        this.requestStore = requestStore;
    }

    @Required
    public void setSchedulerProvider(BulkSchedulerProvider schedulerProvider) {
        this.schedulerProvider = schedulerProvider;
    }

    @Required
    public void setStatistics(BulkServiceStatistics statistics) {
        this.statistics = statistics;
    }

    @Required
    public void setSubmissionHandler(BulkSubmissionHandler submissionHandler) {
        this.submissionHandler = submissionHandler;
    }

    @Required
    public void setTimeout(long timeout) {
        this.timeout = timeout;
    }

    @Required
    public void setTimeoutUnit(TimeUnit timeoutUnit) {
        this.timeoutUnit = timeoutUnit;
    }

    /**
     * For external calls (from the service, request handler and admin interface).
     */
    @Override
    public void signal() {
        /*
         *  Wake up the job processor.
         */
        processor.signal();
    }

    @Override
    public void submit(BulkRequestContainerJob job) {
        synchronized (requestJobs) {
            requestJobs.put(job.getTarget().getRuid(), job);
        }

        processor.signal();
    }

    /*
     *   The submission handler creates the job and stores it as a target, then calls
     *   submit() above.
     */
    void activateRequest(BulkRequest request) {
        LOGGER.trace("activateRequest {}.", request.getUid());
        try {
            submissionHandler.submitRequestJob(request);
            LOGGER.debug("activateRequest, updating {} to STARTED.", request.getUid());
            requestStore.update(request.getUid(), STARTED);
        } catch (BulkStorageException e) {
            LOGGER.error(
                  "Unrecoverable storage update error for {}: {}; aborting.",
                  request.getUid(),
                  e.toString());
            requestStore.abort(request, e);
        } catch (BulkServiceException e) {
            LOGGER.error(
                  "Problem activating request for {}: {}; aborting.", request.getUid(),
                  e.toString());
            requestStore.abort(request, e);
        } catch (RuntimeException e) {
            requestStore.abort(request, e);
            Thread thisThread = Thread.currentThread();
            UncaughtExceptionHandler ueh = thisThread.getUncaughtExceptionHandler();
            ueh.uncaughtException(thisThread, e);
        }
    }

    void startJob(BulkRequestContainerJob job) {
        String key = job.getTarget().getKey();
        LOGGER.trace("submitting job {} to executor, target {}.", key,
              job.getTarget());
        job.setExecutor(executorService);
        job.setCallbackExecutor(callbackExecutor);
        job.setCallback(this);
        try {
            if (isJobValid(job)) { /* possibly cancelled in flight */
                job.update(State.RUNNING);
                executorService.submit(new FireAndForgetTask(job));
            }
        } catch (RuntimeException e) {
            job.getTarget().setErrorObject(e);
            job.cancel();
            Thread thisThread = Thread.currentThread();
            UncaughtExceptionHandler ueh = thisThread.getUncaughtExceptionHandler();
            ueh.uncaughtException(thisThread, e);
        }
    }

    /*
     *  This is here mostly in order to catch jobs which have changed state on the fly
     *  during cancellation. It is only called by the processor thread (when it invokes startJob).
     */
    private boolean isJobValid(BulkRequestContainerJob job) {
        BulkRequestTarget target = job.getTarget();

        if (target.isTerminated()) {
            return false;
        }

        Optional<BulkRequestStatus> status;
        try {
            status = requestStore.getRequestStatus(target.getRuid());
        } catch (BulkStorageException e) {
            LOGGER.error("isJobValid {}: {}", target, e.toString());
            return false;
        }

        if (status.isPresent()) {
            switch (status.get()) {
                case CANCELLING:
                case CANCELLED:
                    job.update(State.CANCELLED);
                    try {
                        targetStore.update(target.getId(), State.CANCELLED, target.getErrorType(),
                              target.getErrorMessage());
                    } catch (BulkStorageException e) {
                        LOGGER.error("updateJobState", e.toString());
                    }
                    return false;
            }
        }

        return true;
    }
}