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use std::sync::Arc; use parking_lot::Mutex; use chain::{IndexedTransaction, Transaction, IndexedBlock}; use message::types; use synchronization_executor::TaskExecutor; use synchronization_verifier::{Verifier, TransactionVerificationSink}; use synchronization_client_core::{ClientCore, SynchronizationClientCore}; use types::{PeerIndex, ClientCoreRef, SynchronizationStateRef, EmptyBoxFuture, SyncListenerRef}; #[cfg_attr(feature="cargo-clippy", allow(doc_markdown))] ///! TODO: update with headers-first corrections ///! ///! Blocks synchronization process: ///! ///! When new peer is connected: ///! 1) send `getheaders` message with full block locator hashes (see `LocalNode`) ///! ///! on_new_blocks_headers: When `headers` message is received from peer: ///! 1) queue_intersection = intersect(queue, inventory) ///! 2) if !queue_intersection.is_empty(): ===> responded with blocks within sync window ///! 2.1) remember peer as useful ///! 2.2) inventory_rest = inventory - queue_intersection ///! 2.3) if inventory_rest.is_empty(): ===> no new unknown blocks in inventory ///! 2.3.1) stop (2.3) ///! 2.4) if !inventory_rest.is_empty(): ===> has new unknown blocks in inventory ///! 2.4.1) queue_rest = queue after intersection ///! 2.4.2) if queue_rest.is_empty(): ===> has new unknown blocks in inventory, no fork ///! 2.4.2.1) scheduled_blocks.append(inventory_rest) ///! 2.4.2.2) stop (2.4.2) ///! 2.4.3) if !queue_rest.is_empty(): ===> has new unknown blocks in inventory, fork ///! 2.4.3.1) scheduled_blocks.append(inventory_rest) ///! 2.4.3.2) stop (2.4.3) ///! 2.4.3) stop (2.4) ///! 2.5) stop (2) ///! 3) if queue_intersection.is_empty(): ===> responded with out-of-sync-window blocks ///! 3.1) last_known_block = inventory.last(b => b.is_known()) ///! 3.2) if last_known_block == None: ===> we know nothing about these blocks & we haven't asked for these ///! 3.2.1) if !synchronizing => remember peer as useful + ask for blocks ///! 3.2.1) if synchronizing => peer will be excluded later by management thread ///! 3.2.2) stop (3.2) ///! 3.3) if last_known_block == last(inventory): ===> responded with all-known-blocks ///! 3.3.1) if syncing, remember peer as useful (possibly had failures before && have been excluded from sync) ///! 3.3.2) stop (3.3) ///! 3.4) if last_known_block in the middle of inventory: ===> responded with forked blocks ///! 3.4.1) remember peer as useful ///! 3.4.2) inventory_rest = inventory after last_known_block ///! 3.4.3) scheduled_blocks.append(inventory_rest) ///! 3.4.4) stop (3.4) ///! 3.5) stop (3) ///! ///! on_peer_block: After receiving `block` message: ///! 1) if block_state(block) in (Verifying, Stored): ===> late delivery ///! 1.1) remember peer as useful ///! 1.2) stop (1) ///! 2) if block_state(block) in (Scheduled, Requested): ===> future/on-time delivery ///! 2.1) remember peer as useful ///! 2.2) if block_state(block.parent) in (Verifying, Stored): ===> we can proceed with verification ///! 2.2.1) remove block from current queue (Verifying || Stored) ///! 2.2.2) append block to the verification queue ///! 2.2.3) queue verification().and_then(on_block_verification_success).or_else(on_block_verification_error) ///! 2.2.4) try to verify orphan blocks ///! 2.2.5) stop (2.2) ///! 2.3) if block_state(block.parent) in (Requested, Scheduled): ===> we have found an orphan block ///! 2.3.1) remove block from current queue (Verifying || Stored) ///! 2.3.2) append block to the orphans ///! 2.3.3) stop (2.3) ///! 2.4) if block_state(block.parent) == Unknown: ===> bad block found ///! 2.4.1) remove block from current queue (Verifying || Stored) ///! 2.4.2) stop (2.4) ///! 2.5) stop (2) ///! 3) if block_state(block) == Unknown: ===> maybe we are on-top of chain && new block is announced? ///! 3.1) if block_state(block.parent_hash) == Unknown: ===> we do not know parent ///! 3.1.1) ignore this block ///! 3.1.2) stop (3.1) ///! 3.2) if block_state(block.parent_hash) in (Verifying, Stored): ===> fork found, can verify ///! 3.2.1) ask peer for best inventory (after this block) ///! 3.2.2) append block to verifying queue ///! 3.2.3) queue verification().and_then(on_block_verification_success).or_else(on_block_verification_error) ///! 3.2.4) stop (3.2) ///! 3.3) if block_state(block.parent_hash) in (Requested, Scheduled): ===> fork found, add as orphan ///! 3.3.1) ask peer for best inventory (after this block) ///! 3.3.2) append block to orphan ///! 3.3.3) stop (3.3) ///! 3.4) stop (2) ///! + if no blocks left in scheduled + requested queue => we are saturated => ask all peers for inventory & forget ///! ///! execute_synchronization_tasks: After receiving `headers`/`inventory` message OR receiving `block` message OR when management thread schedules tasks: ///! 1) if there are blocks in `scheduled` queue AND we can fit more blocks into memory: ===> ask for blocks ///! 1.1) select idle peers ///! 1.2) for each idle peer: query chunk of blocks from `scheduled` queue ///! 1.3) move requested blocks from `scheduled` to `requested` queue ///! 1.4) mark idle peers as active ///! 1.5) stop (1) ///! 2) if `scheduled` queue is not yet saturated: ===> ask for new blocks hashes ///! 2.1) for each idle peer: send shortened `getblocks` message ///! 2.2) 'forget' idle peers => they will be added again if respond with inventory ///! 2.3) stop (2) ///! ///! manage_synchronization_peers: When management thread awakes: ///! 1) for peer in active_peers.where(p => now() - p.last_request_time() > failure_interval): ///! 1.1) return all peer' tasks to the tasks pool ///! 1.2) increase # of failures for this peer ///! 1.3) if # of failures > max_failures: ===> super-bad peer ///! 1.3.1) forget peer ///! 1.3.3) stop (1.3) ///! 1.4) if # of failures <= max_failures: ===> bad peer ///! 1.4.1) move peer to idle pool ///! 1.4.2) stop (1.4) ///! 2) schedule tasks from pool (if any) ///! ///! on_block_verification_success: When verification completes scuccessfully: ///! 1) if block_state(block) != Verifying: ===> parent verification failed ///! 1.1) stop (1) ///! 2) remove from verifying queue ///! 3) insert to the db ///! ///! on_block_verification_error: When verification completes with an error: ///! 1) remove block from verification queue ///! 2) remove all known children from all queues [so that new `block` messages will be ignored in on_peer_block.3.1.1] ///! /// Synchronization client trait pub trait Client : Send + Sync + 'static { fn on_connect(&self, peer_index: PeerIndex); fn on_disconnect(&self, peer_index: PeerIndex); fn on_inventory(&self, peer_index: PeerIndex, message: types::Inv); fn on_headers(&self, peer_index: PeerIndex, message: types::Headers); fn on_block(&self, peer_index: PeerIndex, block: IndexedBlock); fn on_transaction(&self, peer_index: PeerIndex, transaction: IndexedTransaction); fn on_notfound(&self, peer_index: PeerIndex, message: types::NotFound); fn after_peer_nearly_blocks_verified(&self, peer_index: PeerIndex, future: EmptyBoxFuture); fn accept_transaction(&self, transaction: Transaction, sink: Box<TransactionVerificationSink>) -> Result<(), String>; fn install_sync_listener(&self, listener: SyncListenerRef); } /// Synchronization client facade pub struct SynchronizationClient<T: TaskExecutor, U: Verifier> { /// Verification mutex verification_lock: Mutex<()>, /// Shared client state shared_state: SynchronizationStateRef, /// Client core core: ClientCoreRef<SynchronizationClientCore<T>>, /// Verifier verifier: U, } impl<T, U> Client for SynchronizationClient<T, U> where T: TaskExecutor, U: Verifier { fn on_connect(&self, peer_index: PeerIndex) { self.core.lock().on_connect(peer_index); } fn on_disconnect(&self, peer_index: PeerIndex) { self.core.lock().on_disconnect(peer_index); } fn on_inventory(&self, peer_index: PeerIndex, message: types::Inv) { self.core.lock().on_inventory(peer_index, message); } fn on_headers(&self, peer_index: PeerIndex, message: types::Headers) { self.core.lock().on_headers(peer_index, message); } fn on_block(&self, peer_index: PeerIndex, block: IndexedBlock) { // block can became: // ignored, unknown, orphaned => no verification should occur // on-time => this block + all dependent orphaned should be verified { // verification tasks must be scheduled in the same order as they were built in on_block // => here we use verification_lock for this let _verification_lock = self.verification_lock.lock(); let blocks_to_verify = self.core.lock().on_block(peer_index, block); // verify blocks if let Some(mut blocks_to_verify) = blocks_to_verify { while let Some(block) = blocks_to_verify.pop_front() { self.verifier.verify_block(block); } } } // in case if verification was synchronous // => try to switch to saturated state OR execute sync tasks let mut client = self.core.lock(); if !client.try_switch_to_saturated_state() { client.execute_synchronization_tasks(None, None); } } fn on_transaction(&self, peer_index: PeerIndex, transaction: IndexedTransaction) { // block can became: // ignored, orphaned => no verification should occur // on-time => this transaction + all dependent orphaned should be verified let transactions_to_verify = self.core.lock().on_transaction(peer_index, transaction); if let Some(mut transactions_to_verify) = transactions_to_verify { // it is not actual height of block this transaction will be included to // => it possibly will be invalid if included in later blocks // => mined block can be rejected // => we should verify blocks we mine let next_block_height = self.shared_state.best_storage_block_height() + 1; while let Some(tx) = transactions_to_verify.pop_front() { self.verifier.verify_transaction(next_block_height, tx); } } } fn on_notfound(&self, peer_index: PeerIndex, message: types::NotFound) { self.core.lock().on_notfound(peer_index, message); } fn after_peer_nearly_blocks_verified(&self, peer_index: PeerIndex, future: EmptyBoxFuture) { self.core.lock().after_peer_nearly_blocks_verified(peer_index, future); } fn accept_transaction(&self, transaction: Transaction, sink: Box<TransactionVerificationSink>) -> Result<(), String> { let mut transactions_to_verify = try!(self.core.lock().accept_transaction(transaction, sink)); let next_block_height = self.shared_state.best_storage_block_height() + 1; while let Some(tx) = transactions_to_verify.pop_front() { self.verifier.verify_transaction(next_block_height, tx); } Ok(()) } fn install_sync_listener(&self, listener: SyncListenerRef) { self.core.lock().install_sync_listener(listener); } } impl<T, U> SynchronizationClient<T, U> where T: TaskExecutor, U: Verifier { /// Create new synchronization client pub fn new(shared_state: SynchronizationStateRef, core: ClientCoreRef<SynchronizationClientCore<T>>, verifier: U) -> Arc<Self> { Arc::new(SynchronizationClient { verification_lock: Mutex::new(()), shared_state: shared_state, core: core, verifier: verifier, }) } }