public Map<TableName, SpaceQuotaSnapshot> fetchSnapshotsFromQuotaTable() throws IOException {
    try (Table quotaTable = getConnection().getTable(QuotaUtil.QUOTA_TABLE_NAME);
      ResultScanner scanner = quotaTable.getScanner(QuotaTableUtil.makeQuotaSnapshotScan())) {
      Map<TableName, SpaceQuotaSnapshot> snapshots = new HashMap<>();
      for (Result result : scanner) {
        try {
          extractQuotaSnapshot(result, snapshots);
        } catch (IllegalArgumentException e) {
          final String msg = "Failed to parse result for row " + Bytes.toString(result.getRow());
          LOG.error(msg, e);
          throw new IOException(msg, e);
        }
      }
      return snapshots;
    }
  }
Reads all quota snapshots from the quota table.
@return The current "view" of space use by each table.
hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/SpaceQuotaRefresherChore.java