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From ctubbsii <...@git.apache.org>
Subject [GitHub] accumulo pull request #253: ACCUMULO-4086 Improve volume chooser fallback
Date Thu, 27 Jul 2017 18:17:17 GMT
Github user ctubbsii commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/253#discussion_r129897225
  
    --- Diff: server/base/src/main/java/org/apache/accumulo/server/fs/PerTableVolumeChooser.java
---
    @@ -18,61 +18,146 @@
     
     import java.util.concurrent.ConcurrentHashMap;
     
    -import org.apache.accumulo.core.client.impl.Table;
    +import org.apache.accumulo.core.client.AccumuloException;
    +import org.apache.accumulo.core.conf.AccumuloConfiguration;
     import org.apache.accumulo.core.conf.Property;
     import org.apache.accumulo.server.client.HdfsZooInstance;
     import org.apache.accumulo.server.conf.ServerConfigurationFactory;
     import org.apache.accumulo.server.conf.TableConfiguration;
    +import org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
     
     /**
    - * A {@link VolumeChooser} that delegates to another volume chooser based on the presence
of an experimental table property,
    - * {@link Property#TABLE_VOLUME_CHOOSER}. If it isn't found, defaults back to {@link
RandomVolumeChooser}.
    + * A {@link VolumeChooser} that delegates to another volume chooser based on other properties:
table.custom.volume.chooser for tables, and
    + * general.custom.scoped.volume.chooser for scopes. general.custor.{scope}.volume.chooser
can override the system wide setting for
    + * general.custom.scoped.volume.chooser. At the this this was written, the only known
scope was "logger".
      */
     public class PerTableVolumeChooser implements VolumeChooser {
    -
    -  private final VolumeChooser fallbackVolumeChooser = new RandomVolumeChooser();
    +  private static final Logger log = LoggerFactory.getLogger(PerTableVolumeChooser.class);
       // TODO Add hint of expected size to construction, see ACCUMULO-3410
       /* Track VolumeChooser instances so they can keep state. */
    -  private final ConcurrentHashMap<Table.ID,VolumeChooser> tableSpecificChooser
= new ConcurrentHashMap<>();
    +  private final ConcurrentHashMap<String,VolumeChooser> tableSpecificChooser =
new ConcurrentHashMap<>();
    +  private final ConcurrentHashMap<String,VolumeChooser> scopeSpecificChooser =
new ConcurrentHashMap<>();
    +  private final RandomVolumeChooser randomChooser = new RandomVolumeChooser();
    +
       // TODO has to be lazily initialized currently because of the reliance on HdfsZooInstance.
see ACCUMULO-3411
       private volatile ServerConfigurationFactory serverConfs;
     
    +  public static final String TABLE_VOLUME_CHOOSER = Property.TABLE_ARBITRARY_PROP_PREFIX.getKey()
+ "volume.chooser";
    +
    +  public static final String SCOPED_VOLUME_CHOOSER(String scope) {
    +    return Property.GENERAL_ARBITRARY_PROP_PREFIX.getKey() + scope + ".volume.chooser";
    +  }
    +
    +  public static final String DEFAULT_SCOPED_VOLUME_CHOOSER = SCOPED_VOLUME_CHOOSER("scoped");
    +
       @Override
    -  public String choose(VolumeChooserEnvironment env, String[] options) {
    -    VolumeChooser chooser = null;
    -    if (env.hasTableId()) {
    -      // This local variable is an intentional component of the single-check idiom.
    -      ServerConfigurationFactory localConf = serverConfs;
    -      if (localConf == null) {
    -        // If we're under contention when first getting here we'll throw away some initializations.
    -        localConf = new ServerConfigurationFactory(HdfsZooInstance.getInstance());
    -        serverConfs = localConf;
    +  public String choose(VolumeChooserEnvironment env, String[] options) throws AccumuloException
{
    +    if (log.isTraceEnabled()) {
    +      log.trace("PerTableVolumeChooser.choose");
    +    }
    +    VolumeChooser chooser;
    +    if (!env.hasTableId() && !env.hasScope()) {
    +      // Should only get here during Initialize. Configurations are not yet available.
    +      return randomChooser.choose(env, options);
    +    }
    +
    +    ServerConfigurationFactory localConf = loadConf();
    +    if (env.hasScope()) {
    +      // use the system configuration
    +      chooser = getVolumeChooserForNonTable(env, localConf);
    +    } else { // if (env.hasTableId()) {
    +      // use the table configuration
    +      chooser = getVolumeChooserForTable(env, localConf);
    +    }
    +
    +    return chooser.choose(env, options);
    +  }
    +
    +  private VolumeChooser getVolumeChooserForTable(VolumeChooserEnvironment env, ServerConfigurationFactory
localConf) throws AccumuloException {
    +    if (log.isTraceEnabled()) {
    +      log.trace("Looking up property " + TABLE_VOLUME_CHOOSER + " for Table id: " + env.getTableId());
    +    }
    +    final TableConfiguration tableConf = localConf.getTableConfiguration(env.getTableId());
    +    String clazz = tableConf.get(TABLE_VOLUME_CHOOSER);
    +
    +    return createVolumeChooser(clazz, TABLE_VOLUME_CHOOSER, env.getTableId().canonicalID(),
tableSpecificChooser);
    +  }
    +
    +  private VolumeChooser getVolumeChooserForNonTable(VolumeChooserEnvironment env, ServerConfigurationFactory
localConf) throws AccumuloException {
    +    String property = SCOPED_VOLUME_CHOOSER(env.getScope());
    +
    +    if (log.isTraceEnabled()) {
    +      log.trace("Looking up property: " + property);
    +    }
    +
    +    AccumuloConfiguration systemConfiguration = localConf.getSystemConfiguration();
    +    String clazz = systemConfiguration.get(property);
    +    // only if the custom property is not set to we fallback to the table volume chooser
setting
    +    if (null == clazz) {
    +      log.debug("Property not found: " + property + " using " + DEFAULT_SCOPED_VOLUME_CHOOSER);
    +      property = DEFAULT_SCOPED_VOLUME_CHOOSER;
    +      clazz = systemConfiguration.get(DEFAULT_SCOPED_VOLUME_CHOOSER);
    +    }
    +
    +    return createVolumeChooser(clazz, property, env.getScope(), scopeSpecificChooser);
    +  }
    +
    +  private VolumeChooser createVolumeChooser(String clazz, String property, String key,
ConcurrentHashMap<String,VolumeChooser> cache) throws AccumuloException {
    +    if (null == clazz || clazz.isEmpty()) {
    +      String msg = "Property " + property + " must be set" + (null == clazz ? " " : "
properly ") + "to use the " + getClass().getSimpleName();
    +      log.error(msg);
    +      throw new AccumuloException(msg);
    +    }
    +
    +    VolumeChooser chooser = cache.get(key);
    +    if (chooser == null || !(chooser.getClass().getName().equals(clazz))) {
    +      if (log.isTraceEnabled() && chooser != null) {
    +        // TODO stricter definition of when the updated property is used, ref ACCUMULO-3412
    +        log.trace("Change detected for " + property + " for " + key);
    +      }
    +      VolumeChooser temp;
    +      try {
    +        temp = loadClass(clazz);
    +      } catch (Exception e) {
    +        String msg = "Failed to create instance for " + key + " configured to use " +
clazz + " via " + property;
    +        log.error(msg);
    +        throw new AccumuloException(msg, e);
           }
    -      final TableConfiguration tableConf = localConf.getTableConfiguration(env.getTableId());
    -      chooser = tableSpecificChooser.get(env.getTableId());
           if (chooser == null) {
    -        VolumeChooser temp = Property.createTableInstanceFromPropertyName(tableConf,
Property.TABLE_VOLUME_CHOOSER, VolumeChooser.class, fallbackVolumeChooser);
    -        chooser = tableSpecificChooser.putIfAbsent(env.getTableId(), temp);
    +        chooser = cache.putIfAbsent(key, temp);
    --- End diff --
    
    If cache is synchronized, the check for null in next line seems moot.


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