Struct BlockHeader 

pub struct BlockHeader {
    pub num_records: u32,
    pub metadata_compression: u8,
    pub bitmap_type: u16,
    pub placeholder1: u8,
    pub block_len: u32,
    pub flags_len: u64,
    pub fields_present: u16,
    pub placeholder2: u16,
    pub placeholder3: u64,
}

Block header for encoded data

Always the first 32 bytes at the beginning of a .ahda block.

Must always conform to this format.

The BlockHeader contains the following data:

• Number of records stored in this block.
• The metadata compression method used for BlockFlags.
• Type of bitmap stored in this block.
• A 1 byte unused placeholder value.
• The number of bytes in the block contents that follow the BlockFlags bytes.
• Number of bytes containing the BlockFlags that follow the header.
• Fields that are present in the BlockFlags.
• A 2 byte unused placeholder value.
• A 8 byte unused placeholder value.

Fields

num_records: u32

Number of records (queries) stored in this block

metadata_compression: u8

Compression method used for BlockFlags, see MetadataCompression.

bitmap_type: u16

Bitmap type used to encode this block, see BitmapType for details.

The address space of the block bitmap type must fit within the file bitmap type specified in crate::headers::file::FileHeader. Given that this is satisfied, the block bitmap type may differ from the file bitmap type.

placeholder1: u8

Placeholder:

block_len: u32

Number of bytes in the block contents that follow the flags bytes.

flags_len: u64

Number of bytes in BlockFlags that follow the header bytes.

fields_present: u16

BlockFlags fields that are present for records in this block.

Every block must contain at least the fields given in the crate::headers::file::FileHeader fields_present. A block may also contain extra fields that are not specified in crate::headers::file::FileHeader.

placeholder2: u16

Placeholder

placeholder3: u64

Placeholder

Implementations

impl BlockHeader

pub fn promises_query_names(&self) -> bool

Does the header require the encoded data to contain the query names?

pub fn promises_query_ids(&self) -> bool

Does the header require the encoded data to contain the query indexes?

Trait Implementations

impl<'__de, __Context> BorrowDecode<'__de, __Context> for BlockHeader

fn borrow_decode<__D: BorrowDecoder<'__de, Context = __Context>>( decoder: &mut __D, ) -> Result<Self, DecodeError>

Attempt to decode this type with the given BorrowDecode.

impl Clone for BlockHeader

fn clone(&self) -> BlockHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BlockHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<__Context> Decode<__Context> for BlockHeader

fn decode<__D: Decoder<Context = __Context>>( decoder: &mut __D, ) -> Result<Self, DecodeError>

Attempt to decode this type with the given Decode.

impl Default for BlockHeader

fn default() -> BlockHeader

Initialize a header with default values.

Note: This header is not a valid ahda header for most cases. Update the fields accordingly before using.

If you need to encode individual ahda blocks, prefer using pack_records.

impl Encode for BlockHeader

fn encode<__E: Encoder>(&self, encoder: &mut __E) -> Result<(), EncodeError>

Encode a given type.

impl PartialEq for BlockHeader

fn eq(&self, other: &BlockHeader) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for BlockHeader