Method findTableRegions

src/HBaseClient.java:2314–2406

Scans the meta table for regions belonging to the given table. It can be used to prefetch the region information and/or return the actual regions to the user. NOTE: If the requested table is the meta or root table, the result will be null. @param table The name of the table whose metadata you in

(final byte[] table,
                                        final byte[] start,
                                        final byte[] stop, 
                                        final boolean cache,
                                        final boolean return_locations)

   * If false, the result will be null on a successful scan.
   */
  private Deferred<Object> findTableRegions(final byte[] table,
                                        final byte[] start,
                                        final byte[] stop, 
                                        final boolean cache,
                                        final boolean return_locations) {
    // We're going to scan .META. for the table between the row keys and filter
    // out all but the latest entries on the client side.  Whatever remains
    // will be inserted into the region cache.
    // But we don't want to do this for hbase:meta, .META. or -ROOT-.
    if (Bytes.equals(table, HBASE96_META) || 
        Bytes.equals(table, META) || 
        Bytes.equals(table, ROOT) || 
        Bytes.equals(table, HBASE98_ROOT)) {
      return Deferred.fromResult(null);
    }
    
    // Create the scan bounds.
    final byte[] meta_start = createRegionSearchKey(table, start);
    // In this case, we want the scan to start immediately at the
    // first entry, but createRegionSearchKey finds the last entry.
    meta_start[meta_start.length - 1] = 0;

    // The stop bound is trickier.  If the user wants the whole table,
    // expressed by passing EMPTY_ARRAY, then we need to append a null
    // byte to the table name (thus catching all rows in the desired
    // table, but excluding those from others.)  If the user specifies
    // an explicit stop key, we must leave the table name alone.
    final byte[] meta_stop;
    if (stop.length == 0) {
      meta_stop = createRegionSearchKey(table, stop); // will return "table,,:"
      meta_stop[table.length] = 0;  // now have "table\0,:"
      meta_stop[meta_stop.length - 1] = ',';  // now have "table\0,,"
    } else {
      meta_stop = createRegionSearchKey(table, stop);
    }
    
    if (rootregion == null) {
      // If we don't know where the root region is, we don't yet know whether
      // there is even a -ROOT- region at all (pre HBase 0.95).  So we can't
      // start scanning meta right away, because we don't yet know whether
      // meta is named ".META." or "hbase:meta".  So instead we first check
      // whether the table exists, which will force us to do a first meta
      // lookup (and therefore figure out what the name of meta is).
      class Retry implements Callback<Object, Object> {
        @Override
        public Object call(final Object unused) {
          return findTableRegions(table, start, stop, cache, return_locations);
        }
        @Override
        public String toString() {
          return "retry (" + Bytes.pretty(table) + ", "
            + Bytes.pretty(start) + ", " + Bytes.pretty(stop) + ")";
        }
      }
      return ensureTableExists(table).addCallback(new Retry());
    }
    
    final List<RegionLocation> regions =