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use std::sync::Arc;
use parking_lot::RwLock;
use chain::Block;
use db;
use primitives::hash::H256;
use best_block::BestBlock;
use hash_queue::{HashQueue, HashQueueChain, HashPosition};
use verification;
/// Thread-safe reference to `Chain`
pub type ChainRef = Arc<RwLock<Chain>>;
/// Index of 'verifying' queue
const VERIFYING_QUEUE: usize = 0;
/// Index of 'requested' queue
const REQUESTED_QUEUE: usize = 1;
/// Index of 'scheduled' queue
const SCHEDULED_QUEUE: usize = 2;
/// Number of hash queues
const NUMBER_OF_QUEUES: usize = 3;
/// Block synchronization state
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum BlockState {
/// Block is unknown
Unknown,
/// Scheduled for requesting
Scheduled,
/// Requested from peers
Requested,
/// Currently verifying
Verifying,
/// In storage
Stored,
}
/// Synchronization chain information
#[derive(Debug)]
pub struct Information {
/// Number of blocks currently scheduled for requesting
pub scheduled: u64,
/// Number of blocks currently requested from peers
pub requested: u64,
/// Number of blocks currently verifying
pub verifying: u64,
/// Number of blocks in the storage
pub stored: u64,
}
/// Blockchain from synchroniation point of view, consisting of:
/// 1) all blocks from the `storage` [oldest blocks]
/// 2) all blocks currently verifying by `verification_queue`
/// 3) all blocks currently requested from peers
/// 4) all blocks currently scheduled for requesting [newest blocks]
pub struct Chain {
/// Genesis block hash (stored for optimizations)
genesis_block_hash: H256,
/// Best storage block hash (stored for optimizations)
best_storage_block_hash: H256,
/// Local blocks storage
storage: Arc<db::Store>,
/// Verification queue
verification_queue: verification::Queue,
/// In-memory queue of blocks hashes
hash_chain: HashQueueChain,
}
impl BlockState {
pub fn from_queue_index(queue_index: usize) -> BlockState {
match queue_index {
SCHEDULED_QUEUE => BlockState::Scheduled,
REQUESTED_QUEUE => BlockState::Requested,
VERIFYING_QUEUE => BlockState::Verifying,
_ => panic!("Unsupported queue_index: {}", queue_index),
}
}
pub fn to_queue_index(&self) -> usize {
match self {
&BlockState::Scheduled => SCHEDULED_QUEUE,
&BlockState::Requested => REQUESTED_QUEUE,
&BlockState::Verifying => VERIFYING_QUEUE,
_ => panic!("Unsupported queue: {:?}", self),
}
}
}
impl Chain {
/// Create new `Chain` with given storage
pub fn new(storage: Arc<db::Store>) -> Self {
// we only work with storages with genesis block
let genesis_block_hash = storage.block_hash(0)
.expect("storage with genesis block is required");
let best_storage_block_number = storage.best_block_number()
.expect("non-empty storage is required");
let best_storage_block_hash = storage.block_hash(best_storage_block_number)
.expect("checked above");
// default verification queue
let verifier = Box::new(verification::ChainVerifier::new(storage.clone()));
let verification_queue = verification::Queue::new(verifier);
Chain {
genesis_block_hash: genesis_block_hash,
best_storage_block_hash: best_storage_block_hash,
storage: storage,
verification_queue: verification_queue,
hash_chain: HashQueueChain::with_number_of_queues(NUMBER_OF_QUEUES),
}
}
#[cfg(test)]
/// Create new `Chain` with in-memory test storage
pub fn with_test_storage() -> Self {
// we only work with storages with genesis block
let storage = Arc::new(db::TestStorage::with_genesis_block());
let genesis_block_hash = storage.block_hash(0)
.expect("storage with genesis block is required");
let best_storage_block_number = storage.best_block_number()
.expect("non-empty storage is required");
let best_storage_block_hash = storage.block_hash(best_storage_block_number)
.expect("checked above");
// default verification queue
let verifier = Box::new(verification::ChainVerifier::new(storage.clone()));
let verification_queue = verification::Queue::new(verifier);
Chain {
genesis_block_hash: genesis_block_hash,
best_storage_block_hash: best_storage_block_hash,
storage: storage,
verification_queue: verification_queue,
hash_chain: HashQueueChain::with_number_of_queues(NUMBER_OF_QUEUES),
}
}
/// Get information on current blockchain state
pub fn information(&self) -> Information {
Information {
scheduled: self.hash_chain.len_of(SCHEDULED_QUEUE) as u64,
requested: self.hash_chain.len_of(REQUESTED_QUEUE) as u64,
verifying: self.hash_chain.len_of(VERIFYING_QUEUE) as u64,
stored: self.storage.best_block_number().map_or(0, |number| number + 1),
}
}
/// Get total blockchain length
pub fn length(&self) -> u64 {
self.storage.best_block_number().expect("storage with genesis block is required") + 1
+ self.hash_chain.len() as u64
}
/// Get number of blocks in given state
pub fn length_of_state(&self, state: BlockState) -> u64 {
self.hash_chain.len_of(state.to_queue_index()) as u64
}
/// Returns true if has blocks of given type
pub fn has_blocks_of_state(&self, state: BlockState) -> bool {
!self.hash_chain.is_empty_at(state.to_queue_index())
}
/// Get best block
pub fn best_block(&self) -> BestBlock {
let storage_best_block_number = self.storage.best_block_number().expect("storage with genesis block is required");
match self.hash_chain.back() {
Some(hash) => BestBlock {
height: storage_best_block_number + self.hash_chain.len() as u64,
hash: hash.clone(),
},
None => BestBlock {
height: storage_best_block_number,
hash: self.storage.block_hash(storage_best_block_number).expect("storage with genesis block is required"),
}
}
}
/// Check if block has given state
pub fn block_has_state(&self, hash: &H256, state: BlockState) -> bool {
match state {
BlockState::Scheduled => self.hash_chain.is_contained_in(SCHEDULED_QUEUE, hash),
BlockState::Requested => self.hash_chain.is_contained_in(REQUESTED_QUEUE, hash),
BlockState::Verifying => self.hash_chain.is_contained_in(VERIFYING_QUEUE, hash),
BlockState::Stored => self.storage.contains_block(db::BlockRef::Hash(hash.clone())),
BlockState::Unknown => self.block_state(hash) == BlockState::Unknown,
}
}
/// Get block state
pub fn block_state(&self, hash: &H256) -> BlockState {
match self.hash_chain.contains_in(hash) {
Some(queue_index) => BlockState::from_queue_index(queue_index),
None => if self.storage.contains_block(db::BlockRef::Hash(hash.clone())) {
BlockState::Stored
} else {
BlockState::Unknown
},
}
}
/// Prepare best block locator hashes
pub fn best_block_locator_hashes(&self) -> Vec<H256> {
vec![self.best_block().hash]
}
/// Prepare block locator hashes, as described in protocol documentation:
/// https://en.bitcoin.it/wiki/Protocol_documentation#getblocks
pub fn block_locator_hashes(&self) -> Vec<H256> {
let mut block_locator_hashes: Vec<H256> = Vec::new();
// calculate for hash_queue
let (local_index, step) = self.block_locator_hashes_for(0, 1, SCHEDULED_QUEUE, &mut block_locator_hashes);
let (local_index, step) = self.block_locator_hashes_for(local_index, step, REQUESTED_QUEUE, &mut block_locator_hashes);
let (local_index, step) = self.block_locator_hashes_for(local_index, step, VERIFYING_QUEUE, &mut block_locator_hashes);
// calculate for storage
let storage_best_block_number = self.storage.best_block_number().expect("storage with genesis block is required");
let storage_index = if storage_best_block_number < local_index { 0 } else { storage_best_block_number - local_index };
self.block_locator_hashes_for_storage(storage_index, step, &mut block_locator_hashes);
block_locator_hashes
}
/// Schedule blocks for requesting
pub fn schedule_blocks_hashes(&mut self, hashes: Vec<H256>) {
self.hash_chain.push_back_n_at(SCHEDULED_QUEUE, hashes)
}
/// Pops block with givent state
pub fn request_blocks_hashes(&mut self, num_blocks: u64) -> Vec<H256> {
let scheduled = self.hash_chain.pop_front_n_at(SCHEDULED_QUEUE, num_blocks as usize);
self.hash_chain.push_back_n_at(REQUESTED_QUEUE, scheduled.clone());
scheduled
}
/// Schedule block for verification
pub fn verify_and_insert_block(&mut self, hash: H256, block: Block) {
// TODO: add another basic verifications here (use verification package)
// TODO: return error if basic verification failed && reset synchronization state
if block.block_header.previous_header_hash != self.best_storage_block_hash {
// TODO: penalize peer
// if let Some(peer_index) = peer_index {
// peers.on_wrong_block_received(peer_index);
// }
trace!(target: "sync", "Out-of order block dropped: {:?}", hash);
return;
}
self.storage.insert_block(&block);
self.best_storage_block_hash = hash;
/* TODO: fails on first 500 blocks
// TODO: async verification
match self.verification_queue.push(block) {
Err(err) => {
// TODO: penalize peer
trace!(target: "sync", "Cannot push block {:?} to verification queue: {:?}", hash, err);
unimplemented!();
},
_ => (),
}
self.verification_queue.process();
match self.verification_queue.pop_valid() {
Some((hash, block)) => {
// TODO: check block.chain here when working on forks
match self.storage.insert_block(&block.block) {
Err(err) => {
trace!(target: "sync", "Cannot insert block {:?} to database: {:?}", hash, err);
unimplemented!();
},
_ => {
self.best_storage_block_hash = hash;
},
}
},
_ => {
trace!(target: "sync", "Error verifying block {:?}: {:?}", hash, self.verification_queue.block_status(&hash));
unimplemented!();
},
}*/
}
/// Remove block by hash if it is currently in given state
pub fn remove_block_with_state(&mut self, hash: &H256, state: BlockState) -> HashPosition {
self.hash_chain.remove_at(state.to_queue_index(), hash)
}
/// Calculate block locator hashes for qiven hash queue
fn block_locator_hashes_for(&self, local_index: u64, mut step: u64, queue_index: usize, hashes: &mut Vec<H256>) -> (u64, u64) {
let queue = self.hash_chain.queue_at(queue_index);
let queue_len = queue.len() as u64;
// no items in queue => proceed to next storage
if queue_len == 0 {
return (local_index, step);
}
// there are less items in the queue than we need to skip => proceed to next storage
if queue_len - 1 < local_index {
return (local_index - queue_len - 1, step);
}
let mut local_index = queue_len - 1 - local_index;
loop {
let hash = queue[local_index as usize].clone();
hashes.push(hash);
if hashes.len() >= 10 {
step <<= 1;
}
if local_index < step {
return (step - local_index - 1, step);
}
local_index -= step;
}
}
/// Calculate block locator hashes for storage
fn block_locator_hashes_for_storage(&self, mut index: u64, mut step: u64, hashes: &mut Vec<H256>) {
loop {
let block_hash = self.storage.block_hash(index)
.expect("private function; index calculated in `block_locator_hashes`; qed");
hashes.push(block_hash);
if hashes.len() >= 10 {
step <<= 1;
}
if index < step {
// always include genesis hash
if index != 0 {
hashes.push(self.genesis_block_hash.clone())
}
break;
}
index -= step;
}
}
}