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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_r129914902
  
    --- Diff: server/base/src/main/java/org/apache/accumulo/server/fs/PreferredVolumeChooser.java
---
    @@ -39,73 +40,139 @@
     
     /**
      * A {@link RandomVolumeChooser} that limits its choices from a given set of options
to the subset of those options preferred for a particular table. Defaults
    - * to selecting from all of the options presented. Can be customized via the table property
{@value #PREFERRED_VOLUMES_CUSTOM_KEY}, which should contain a comma
    + * to selecting from all of the options presented. Can be customized via the table property
table.custom.preferredVolumes, which should contain a comma
      * separated list of {@link Volume} URIs. Note that both the property name and the format
of its value are specific to this particular implementation.
      */
     public class PreferredVolumeChooser extends RandomVolumeChooser {
       private static final Logger log = LoggerFactory.getLogger(PreferredVolumeChooser.class);
     
    -  /**
    -   * This should match {@link Property#TABLE_ARBITRARY_PROP_PREFIX}
    -   */
    -  public static final String PREFERRED_VOLUMES_CUSTOM_KEY = "table.custom.preferredVolumes";
    -  // TODO ACCUMULO-3417 replace this with the ability to retrieve by String key.
    -  private static final Predicate<String> PREFERRED_VOLUMES_FILTER = key -> PREFERRED_VOLUMES_CUSTOM_KEY.equals(key);
    +  public static final String TABLE_PREFERRED_VOLUMES = Property.TABLE_ARBITRARY_PROP_PREFIX.getKey()
+ "preferred.volumes";
    +
    +  public static final String SCOPED_PREFERRED_VOLUMES(String scope) {
    +    return Property.GENERAL_ARBITRARY_PROP_PREFIX.getKey() + scope + ".preferred.volumes";
    +  }
    +
    +  public static final String DEFAULT_SCOPED_PREFERRED_VOLUMES = SCOPED_PREFERRED_VOLUMES("scoped");
     
       @SuppressWarnings("unchecked")
       private final Map<String,Set<String>> parsedPreferredVolumes = Collections.synchronizedMap(new
LRUMap(1000));
       // TODO has to be lazily initialized currently because of the reliance on HdfsZooInstance.
see ACCUMULO-3411
       private volatile ServerConfigurationFactory serverConfs;
     
       @Override
    -  public String choose(VolumeChooserEnvironment env, String[] options) {
    -    if (!env.hasTableId())
    +  public String choose(VolumeChooserEnvironment env, String[] options) throws AccumuloException
{
    +    if (!env.hasTableId() && !env.hasScope()) {
    +      // this should only happen during initialize
    +      log.warn("No table id or scope, so it's not possible to determine preferred volumes.
 Using all volumes.");
           return super.choose(env, options);
    +    }
     
    -    // Get the current table's properties, and find the preferred volumes property
    -    // 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;
    +    // get the volumes property
    +    ServerConfigurationFactory localConf = loadConf();
    +    List<String> volumes;
    +    if (env.hasTableId()) {
    +      volumes = getPreferredVolumesForTable(env, localConf, options);
    +      // localConf.getTableConfiguration(env.getTableId()).get(PREFERRED_VOLUMES_CUSTOM_KEY);
    +    } else { // env.hasScope()
    +      volumes = getPreferredVolumesForNonTable(env, localConf, options);
    +      // localConf.getSystemConfiguration().get(PREFERRED_VOLUMES_SCOPED_KEY(env.getScope()));
         }
    -    TableConfiguration tableConf = localConf.getTableConfiguration(env.getTableId());
    -    final Map<String,String> props = new HashMap<>();
    -    tableConf.getProperties(props, PREFERRED_VOLUMES_FILTER);
    -    if (props.isEmpty()) {
    -      log.warn("No preferred volumes specified. Defaulting to randomly choosing from
instance volumes");
    -      return super.choose(env, options);
    +
    +    // Randomly choose the volume from the preferred volumes
    +    String choice = super.choose(env, volumes.toArray(EMPTY_STRING_ARRAY));
    +    if (log.isTraceEnabled()) {
    +      log.trace("Choice = " + choice);
         }
    -    String volumes = props.get(PREFERRED_VOLUMES_CUSTOM_KEY);
    +    return choice;
    +  }
     
    +  private List<String> getPreferredVolumesForTable(VolumeChooserEnvironment env,
ServerConfigurationFactory localConf, String[] options)
    +      throws AccumuloException {
         if (log.isTraceEnabled()) {
    -      log.trace("In custom chooser");
    -      log.trace("Volumes: " + volumes);
    -      log.trace("TableID: " + env.getTableId());
    +      log.trace("Looking up property " + TABLE_PREFERRED_VOLUMES + " for Table id: "
+ env.getTableId());
         }
    -    // If the preferred volumes property was specified, split the returned string by
the comma and add use it to filter the given options.
    -    Set<String> preferred = parsedPreferredVolumes.get(volumes);
    -    if (preferred == null) {
    -      preferred = new HashSet<>(Arrays.asList(StringUtils.split(volumes, ',')));
    -      parsedPreferredVolumes.put(volumes, preferred);
    +    final TableConfiguration tableConf = localConf.getTableConfiguration(env.getTableId());
    +    String volumes = tableConf.get(TABLE_PREFERRED_VOLUMES);
    +
    +    return getFilteredOptions(TABLE_PREFERRED_VOLUMES, volumes, options);
    +  }
    +
    +  private List<String> getPreferredVolumesForNonTable(VolumeChooserEnvironment
env, ServerConfigurationFactory localConf, String[] options)
    +      throws AccumuloException {
    +    String property = SCOPED_PREFERRED_VOLUMES(env.getScope());
    +
    +    if (log.isTraceEnabled()) {
    +      log.trace("Looking up property: " + property);
    +    }
    +
    +    AccumuloConfiguration systemConfiguration = localConf.getSystemConfiguration();
    +    String volumes = systemConfiguration.get(property);
    +
    +    // only if the custom property is not set to we fallback to the default scoped preferred
volumes
    +    if (null == volumes) {
    +      log.debug("Property not found: " + property + " using " + DEFAULT_SCOPED_PREFERRED_VOLUMES);
    +      property = DEFAULT_SCOPED_PREFERRED_VOLUMES;
    +      volumes = systemConfiguration.get(DEFAULT_SCOPED_PREFERRED_VOLUMES);
    --- End diff --
    
    Again, this one is handled differently, and will not fail as expected, if a scope's chooser
is not set. And, falling back to a catch-all chooser for all scopes I'm not sure is a good
idea.


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