import org.apache.hadoop.hbase.util.SoftValueSortedMap; //导入依赖的package包/类
private SoftValueSortedMap<byte [], HRegionLocation> getTableLocations(
    final byte [] tableName) {
  // find the map of cached locations for this table
  Integer key = Bytes.mapKey(tableName);
  SoftValueSortedMap<byte [], HRegionLocation> result;
  synchronized (this.cachedRegionLocations) {
    result = this.cachedRegionLocations.get(key);
    // if tableLocations for this table isn't built yet, make one
    if (result == null) {
      result = new SoftValueSortedMap<byte [], HRegionLocation>(
          Bytes.BYTES_COMPARATOR);
      this.cachedRegionLocations.put(key, result);
    }
  }
  return result;
}
 

import org.apache.hadoop.hbase.util.SoftValueSortedMap; //导入依赖的package包/类
private SortedMap<byte [], HRegionLocation> getTableLocations(
    final byte [] tableName) {
  // find the map of cached locations for this table
  Integer key = Bytes.mapKey(tableName);
  SortedMap<byte [], HRegionLocation> result;
  synchronized (this.cachedRegionLocations) {
    result = this.cachedRegionLocations.get(key);
    // if tableLocations for this table isn't built yet, make one
    if (result == null) {
      result = new SoftValueSortedMap<byte [], HRegionLocation>(
          Bytes.BYTES_COMPARATOR);
      this.cachedRegionLocations.put(key, result);
    }
  }
  return result;
}
 

import org.apache.hadoop.hbase.util.SoftValueSortedMap; //导入依赖的package包/类
HRegionLocation getCachedLocation(final byte [] tableName,
    final byte [] row) {
  SoftValueSortedMap<byte [], HRegionLocation> tableLocations =
    getTableLocations(tableName);

  // start to examine the cache. we can only do cache actions
  // if there's something in the cache for this table.
  if (tableLocations.isEmpty()) {
    return null;
  }

  HRegionLocation possibleRegion = tableLocations.get(row);
  if (possibleRegion != null) {
    return possibleRegion;
  }

  possibleRegion = tableLocations.lowerValueByKey(row);
  if (possibleRegion == null) {
    return null;
  }

  // make sure that the end key is greater than the row we're looking
  // for, otherwise the row actually belongs in the next region, not
  // this one. the exception case is when the endkey is
  // HConstants.EMPTY_END_ROW, signifying that the region we're
  // checking is actually the last region in the table.
  byte[] endKey = possibleRegion.getRegionInfo().getEndKey();
  if (Bytes.equals(endKey, HConstants.EMPTY_END_ROW) ||
      KeyValue.getRowComparator(tableName).compareRows(
          endKey, 0, endKey.length, row, 0, row.length) > 0) {
    return possibleRegion;
  }

  // Passed all the way through, so we got nothin - complete cache miss
  return null;
}