Module solana_ledger::erasure
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Erasure Coding and Recovery
Shreds are logically grouped into erasure sets or blocks. Each set contains 16 sequential data shreds and 4 sequential coding shreds.
Coding shreds in each set starting from start_idx:
For each erasure set:
generate NUM_CODING coding_shreds.
index the coding shreds from start_idx to start_idx + NUM_CODING - 1.
model of an erasure set, with top row being data shreds and second being coding |<======================= NUM_DATA ==============================>| |<==== NUM_CODING ===>| +—+ +—+ +—+ +—+ +—+ +—+ +—+ +—+ +—+ +—+ | D | | D | | D | | D | | D | | D | | D | | D | | D | | D | +—+ +—+ +—+ +—+ +—+ . . . +—+ +—+ +—+ +—+ +—+ | C | | C | | C | | C | | | | | | | | | | | | | +—+ +—+ +—+ +—+ +—+ +—+ +—+ +—+ +—+ +—+
shred structure for coding shreds
- —–– meta is set and used by transport, meta.size is actual length | of data in the byte array shred.data | | + – data is stuff shipped over the wire, and has an included | | header V V +–––––+————————————————————+ | meta | data | |+—+– |+—+—+—+—+——————————————+| || s | . || i | | f | s | || || i | . || n | i | l | i | || || z | . || d | d | a | z | shred.data(), or shred.data_mut() || || e | || e | | g | e | || |+—+– || x | | s | | || | |+—+—+—+—+——————————————+| +–––––+————————————————————+ | |<=== coding shred part for “coding” =======>| | | |<============== data shred part for “coding” ==============>|
Structs
Represents an erasure “session” with a particular configuration and number of data and coding shreds