package io.ebeaninternal.server.autotune.service;

import io.ebean.config.AutoTuneConfig;
import io.ebean.config.DatabaseConfig;
import io.ebeaninternal.api.SpiEbeanServer;
import io.ebeaninternal.api.SpiQuery;
import io.ebeaninternal.server.autotune.AutoTuneService;
import io.ebeaninternal.server.autotune.model.Autotune;
import io.ebeaninternal.server.autotune.model.Origin;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;

Implementation of the AutoTuneService which is comprised of profiling and query tuning.
/**
 * Implementation of the AutoTuneService which is comprised of profiling and query tuning.
 */
public class DefaultAutoTuneService implements AutoTuneService {

  private static final Logger logger = LoggerFactory.getLogger(DefaultAutoTuneService.class);

  private final ReentrantLock lock = new ReentrantLock();

  private final SpiEbeanServer server;

  private final long defaultGarbageCollectionWait;

  private final boolean skipGarbageCollectionOnShutdown;

  private final boolean skipProfileReportingOnShutdown;

  private final BaseQueryTuner queryTuner;

  private final ProfileManager profileManager;

  private final boolean profiling;

  private final boolean queryTuning;

  private final String tuningFile;

  private final String profilingFile;

  private final String serverName;

  private final int profilingUpdateFrequency;

  private long runtimeChangeCount;

  public DefaultAutoTuneService(SpiEbeanServer server, DatabaseConfig databaseConfig) {
    AutoTuneConfig config = databaseConfig.getAutoTuneConfig();
    this.server = server;
    this.queryTuning = config.isQueryTuning();
    this.profiling = config.isProfiling();
    this.tuningFile = config.getQueryTuningFile();
    this.profilingFile = config.getProfilingFile();
    this.profilingUpdateFrequency = config.getProfilingUpdateFrequency();
    this.serverName = server.getName();
    this.profileManager = new ProfileManager(config, server);
    this.queryTuner = new BaseQueryTuner(config, server, profileManager);
    this.skipGarbageCollectionOnShutdown = config.isSkipGarbageCollectionOnShutdown();
    this.skipProfileReportingOnShutdown = config.isSkipProfileReportingOnShutdown();
    this.defaultGarbageCollectionWait = config.getGarbageCollectionWait();
  }

  
Load the query tuning information from it's data store.
/**
   * Load the query tuning information from it's data store.
   */
  @Override
  public void startup() {

    if (queryTuning) {
      loadTuningFile();
      if (isRuntimeTuningUpdates()) {
        // periodically gather and update query tuning
        server.getBackgroundExecutor().scheduleWithFixedDelay(new ProfilingUpdate(), profilingUpdateFrequency, profilingUpdateFrequency, TimeUnit.SECONDS);
      }
    }
  }


  
Return true if the tuning should update periodically at runtime.
/**
   * Return true if the tuning should update periodically at runtime.
   */
  private boolean isRuntimeTuningUpdates() {
    return profilingUpdateFrequency > 0;
  }

  private class ProfilingUpdate implements Runnable {

    @Override
    public void run() {
      runtimeTuningUpdate();
    }
  }

  
Load tuning information from an existing tuning file.
/**
   * Load tuning information from an existing tuning file.
   */
  private void loadTuningFile() {
    File file = new File(tuningFile);
    if (file.exists()) {
      loadAutoTuneProfiling(AutoTuneXmlReader.read(file));
    } else {
      // look for autotune as a resource
      try (InputStream stream = getClass().getResourceAsStream("/" + tuningFile)) {
        if (stream != null) {
          loadAutoTuneProfiling(AutoTuneXmlReader.read(stream));
        } else {
          logger.warn("AutoTune file {} not found - no initial automatic query tuning", tuningFile);
        }
      } catch (IOException e) {
        throw new IllegalStateException("Error on auto close of " + tuningFile, e);
      }
    }
  }

  private void loadAutoTuneProfiling(Autotune profiling) {
    logger.info("AutoTune loading {} tuning entries", profiling.getOrigin().size());
    for (Origin origin : profiling.getOrigin()) {
      queryTuner.put(origin);
    }
  }

  
Collect profiling, check for new/diff to existing tuning and apply changes.
/**
   * Collect profiling, check for new/diff to existing tuning and apply changes.
   */
  private void runtimeTuningUpdate() {
    lock.lock();
    try {
      try {
        long start = System.currentTimeMillis();

        AutoTuneCollection profiling = profileManager.profilingCollection(false);

        AutoTuneDiffCollection event = new AutoTuneDiffCollection(profiling, queryTuner, true);
        event.process();
        if (event.isEmpty()) {
          long exeMillis = System.currentTimeMillis() - start;
          logger.debug("No query tuning updates for server:{} executionMillis:{}", serverName, exeMillis);

        } else {
          // report the query tuning changes that have been made
          runtimeChangeCount += event.getChangeCount();
          event.writeFile(profilingFile + "-" + serverName + "-update");
          long exeMillis = System.currentTimeMillis() - start;
          logger.info("query tuning updates - new:{} diff:{} for server:{} executionMillis:{}", event.getNewCount(), event.getDiffCount(), serverName, exeMillis);
        }
      } catch (Throwable e) {
        logger.error("Error collecting or applying automatic query tuning", e);
      }
    } finally {
      lock.unlock();
    }
  }

  private void saveProfilingOnShutdown(boolean reset) {
    lock.lock();
    try {
      if (isRuntimeTuningUpdates()) {
        runtimeTuningUpdate();
        outputAllTuning();

      } else {

        AutoTuneCollection profiling = profileManager.profilingCollection(reset);

        AutoTuneDiffCollection event = new AutoTuneDiffCollection(profiling, queryTuner, false);
        event.process();
        if (event.isEmpty()) {
          logger.info("No new or diff entries for profiling server:{}", serverName);

        } else {
          event.writeFile(profilingFile + "-" + serverName);
          logger.info("writing new:{} diff:{} profiling entries for server:{}", event.getNewCount(), event.getDiffCount(), serverName);
        }
      }
    } finally {
      lock.unlock();
    }
  }

  
Output all the query tuning (the "all" file).

This is the originally loaded tuning plus any tuning changes picked up and applied at runtime.


This "all" file can be used as the next "ebean-autotune.xml" file.

/**
   * Output all the query tuning (the "all" file).
   * <p>
   * This is the originally loaded tuning plus any tuning changes picked up and applied at runtime.
   * </p>
   * <p>
   * This "all" file can be used as the next "ebean-autotune.xml" file.
   * </p>
   */
  private void outputAllTuning() {

    if (runtimeChangeCount == 0) {
      logger.info("no runtime query tuning changes for server:{}", serverName);

    } else {
      AutoTuneAllCollection event = new AutoTuneAllCollection(queryTuner);
      int size = event.size();
      File existingTuning = new File(tuningFile);
      if (existingTuning.exists()) {
        // rename the existing autotune.xml file (appending 'now')
        if (!existingTuning.renameTo(new File(tuningFile + "." + AutoTuneXmlWriter.now()))) {
          logger.warn("Failed to rename autotune file [{}]", tuningFile);
        }
      }

      event.writeFile(tuningFile, false);
      logger.info("query tuning detected [{}] changes, writing all [{}] tuning entries for server:{}", runtimeChangeCount, size, serverName);
    }
  }

  
Shutdown the listener.

We should try to collect the usage statistics by calling a System.gc().
This is necessary for use with short lived applications where garbage
collection may not otherwise occur at all.

/**
   * Shutdown the listener.
   * <p>
   * We should try to collect the usage statistics by calling a System.gc().
   * This is necessary for use with short lived applications where garbage
   * collection may not otherwise occur at all.
   * </p>
   */
  @Override
  public void shutdown() {
    if (profiling) {
      if (!skipGarbageCollectionOnShutdown && !skipProfileReportingOnShutdown) {
        // trigger GC to update profiling information on recently executed queries
        collectProfiling(-1);
      }
      if (!skipProfileReportingOnShutdown) {
        saveProfilingOnShutdown(false);
      }
    }
  }

  
Output the profiling.

When profiling updates are applied to tuning at runtime this reports all tuning and profiling combined.
When profiling is not applied at runtime then this reports the diff report with new and diff entries relative
to the existing tuning.

/**
   * Output the profiling.
   * <p>
   * When profiling updates are applied to tuning at runtime this reports all tuning and profiling combined.
   * When profiling is not applied at runtime then this reports the diff report with new and diff entries relative
   * to the existing tuning.
   * </p>
   */
  @Override
  public void reportProfiling() {
    saveProfilingOnShutdown(false);
  }

  
Ask for a System.gc() so that we gather node usage information.

Really only want to do this sparingly but useful just prior to shutdown
for short run application where garbage collection may otherwise not
occur at all.


waitMillis will do a thread sleep to give the garbage collection a little
time to do its thing assuming we are shutting down the VM.


If waitMillis is -1 then the defaultGarbageCollectionWait is used which
defaults to 100 milliseconds.

/**
   * Ask for a System.gc() so that we gather node usage information.
   * <p>
   * Really only want to do this sparingly but useful just prior to shutdown
   * for short run application where garbage collection may otherwise not
   * occur at all.
   * </p>
   * <p>
   * waitMillis will do a thread sleep to give the garbage collection a little
   * time to do its thing assuming we are shutting down the VM.
   * </p>
   * <p>
   * If waitMillis is -1 then the defaultGarbageCollectionWait is used which
   * defaults to 100 milliseconds.
   * </p>
   */
  @Override
  public void collectProfiling() {
    collectProfiling(-1);
  }

  public void collectProfiling(long waitMillis) {
    System.gc();
    try {
      if (waitMillis < 0) {
        waitMillis = defaultGarbageCollectionWait;
      }
      Thread.sleep(waitMillis);
    } catch (InterruptedException e) {
      // restore the interrupted status
      Thread.currentThread().interrupt();
      logger.warn("Error while sleeping after System.gc() request.", e);
    }
  }

  
Auto tune the query and enable profiling.
/**
   * Auto tune the query and enable profiling.
   */
  @Override
  public boolean tuneQuery(SpiQuery<?> query) {
    return queryTuner.tuneQuery(query);
  }

}