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From ctubbsii <...@git.apache.org>
Subject [GitHub] accumulo pull request #253: ACCUMULO-4086 Improve volume chooser fallback
Date Tue, 25 Apr 2017 19:56:00 GMT
Github user ctubbsii commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/253#discussion_r113294170
  
    --- Diff: server/base/src/main/java/org/apache/accumulo/server/fs/PerTableVolumeChooser.java
---
    @@ -18,36 +18,65 @@
     
     import java.util.concurrent.ConcurrentHashMap;
     
    +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}.
      */
     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<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;
    +  private volatile VolumeChooser fallbackVolumeChooser = null;
     
       @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;
    -      }
    -      final TableConfiguration tableConf = localConf.getTableConfiguration(env.getTableId());
    +  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();
    +    lazilyCreateFallbackChooser();
    +    if (env.hasScope()) {
    --- End diff --
    
    `env.hasTableId()` and `env.hasScope()` are mutually exclusive right now. It's possible
that could change, but we'd have to think about what that might mean. Currently, the only
scope is "logger" and it has no table associated with it.


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