Struct FlatChainStoreConfig

pub struct FlatChainStoreConfig {
    pub block_index_size: Option<usize>,
    pub headers_file_size: Option<usize>,
    pub cache_size: Option<usize>,
    pub file_permission: Option<u32>,
    pub fork_file_size: Option<usize>,
    pub path: String,
}

Available on crate feature flat-chainstore only.

Configuration for our flat chain store. See each field for more information

Fields

block_index_size: Option<usize>

The index map size, in buckets

This index holds our map from block hashes to block heights. We use an open-addressing hash map to map block hashes to block heights. Ideally, size should be way bigger than the number of blocks we expect to have in our chain, therefore reducing the load factor to a negligible value. The default value is having space for 10 million blocks.

We compute the actual capacity by rounding the requested size up to the next power of two, so we can use hash & (capacity - 1) instead of hash % capacity.

headers_file_size: Option<usize>

The size of the headers file map, in headers

This is the size of the flat file that holds all of our block headers. We keep all headers in a simple flat file, one after the other. That file then gets mmaped into RAM, so we can use pointer arithmetic to find specific block, since pos(h) = h * size_of(DiskBlockHeader) The default value is having space for 10 million blocks.

We compute the actual capacity by rounding the requested size up to the next power of two.

cache_size: Option<usize>

The size of the cache, in blocks

We keep a LRU cache of the last n blocks we’ve touched. This is to avoid going into the map every time we need to find a block. The default value is 1000 blocks.

file_permission: Option<u32>

The permission for all the files we create

This is the permission we give to all the files we create. The default value is 0o660

fork_file_size: Option<usize>

The size of the fork headers file map, in headers

This store keeps headers that are not in our main chain, but may be needed sometime. The default value is having space for 10,000 blocks.

We compute the actual capacity by rounding the requested size up to the next power of two.

path: String

The path where we store our files

We’ll create a few files (namely, the index map, headers file, forks file, and metadata file). We need a directory where we can read and write, it needs at least 880 MiB of free space. And have a file system that supports mmap and sparse files (all the default *unix FS do).

Implementations

impl FlatChainStoreConfig

pub fn new(path: String) -> Self

Creates a new configuration with the default values

Trait Implementations

impl Clone for FlatChainStoreConfig

fn clone(&self) -> FlatChainStoreConfig

Returns a copy of the value.

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

Performs copy-assignment from source.