Constant DELIVERY_DATA_SIZE 

pub const DELIVERY_DATA_SIZE: usize = _; // 131_072usize

The chunk size requirement for delivering payloads from the block driver across the delivery queue. The driver must supply DeliveryCommand::Data chunks where the target_offset and length align to DELIVERY_DATA_SIZE boundaries (unless representing the final chunk of the blob).

This chunk size is set as 128 KiB size, matching Fxfs’s target read-ahead size. This is used to set the read size of fuchsia_merkle::ReadSizedMerkleVerifier, which optimizes memory usage when verifying reads. See fuchsia_merkle::ReadSizedMerkleVerifier for more information.