the last 4 bits of hdfsconstants.block _ group_index_mask 15 is 1111 , so the last 4 bits of ~ hdfsconstants.block _ group_index_mask is 0000 and the other 60 bits are 1 . group id is the first 60 bits of any data/parity block id in the same striped block group . concode_field_sep GenerationStamp legacyGenerationStamp concode_elem_sep SequentialBlockGroupIdGenerator blockGroupIdGenerator concode_elem_sep GenerationStamp generationStamp concode_elem_sep SequentialBlockIdGenerator blockIdGenerator concode_elem_sep long legacyGenerationStampLimit concode_field_sep long getGenerationStampAtblockIdSwitch concode_elem_sep void setLastAllocatedContiguousBlockId concode_elem_sep long getNextGenerationStamp concode_elem_sep boolean isLegacyBlock concode_elem_sep boolean isStripedBlockID concode_elem_sep void clear concode_elem_sep void setLegacyGenerationStampLimit concode_elem_sep SequentialBlockIdGenerator getBlockIdGenerator concode_elem_sep long nextGenerationStamp concode_elem_sep byte getBlockIndex concode_elem_sep void setLegacyGenerationStamp concode_elem_sep boolean isGenStampInFuture concode_elem_sep void setLastAllocatedStripedBlockId concode_elem_sep long getGenerationStamp concode_elem_sep void setGenerationStamp concode_elem_sep long getNextLegacyGenerationStamp concode_elem_sep long getLastAllocatedStripedBlockId concode_elem_sep long getLegacyGenerationStamp concode_elem_sep long nextBlockId concode_elem_sep long upgradeLegacyGenerationStamp concode_elem_sep long getLastAllocatedContiguousBlockId concode_elem_sep long getLegacyGenerationStampLimit concode_elem_sep SequentialBlockGroupIdGenerator getBlockGroupIdGenerator
long function ( long arg0 ) { return arg0 & ( ~ HdfsServerConstants . BLOCK_GROUP_INDEX_MASK ) ; }