494 lines
17 KiB
Rust
494 lines
17 KiB
Rust
use std::{
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future::Future,
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pin::Pin,
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sync::Arc,
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task::{Context, Poll},
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time::{Duration, Instant},
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};
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use check::difficulty::{POW_AVERAGING_WINDOW, POW_MEDIAN_BLOCK_SPAN};
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use futures::future::FutureExt;
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use non_finalized_state::{NonFinalizedState, QueuedBlocks};
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use tokio::sync::oneshot;
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use tower::{util::BoxService, Service};
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use tracing::instrument;
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use zebra_chain::{
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block::{self, Block},
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parameters::Network,
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transaction,
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transaction::Transaction,
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transparent,
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};
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use crate::{
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request::HashOrHeight, BoxError, CommitBlockError, Config, FinalizedBlock, PreparedBlock,
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Request, Response, Utxo, ValidateContextError,
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};
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mod check;
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mod finalized_state;
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mod non_finalized_state;
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mod pending_utxos;
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#[cfg(test)]
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mod tests;
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use self::{finalized_state::FinalizedState, pending_utxos::PendingUtxos};
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pub type QueuedBlock = (
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PreparedBlock,
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oneshot::Sender<Result<block::Hash, BoxError>>,
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);
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pub type QueuedFinalized = (
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FinalizedBlock,
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oneshot::Sender<Result<block::Hash, BoxError>>,
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);
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struct StateService {
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/// Holds data relating to finalized chain state.
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disk: FinalizedState,
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/// Holds data relating to non-finalized chain state.
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mem: NonFinalizedState,
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/// Blocks awaiting their parent blocks for contextual verification.
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queued_blocks: QueuedBlocks,
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/// The set of outpoints with pending requests for their associated transparent::Output
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pending_utxos: PendingUtxos,
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/// The configured Zcash network
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network: Network,
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/// Instant tracking the last time `pending_utxos` was pruned
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last_prune: Instant,
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}
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impl StateService {
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const PRUNE_INTERVAL: Duration = Duration::from_secs(30);
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pub fn new(config: Config, network: Network) -> Self {
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let disk = FinalizedState::new(&config, network);
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let mem = NonFinalizedState::default();
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let queued_blocks = QueuedBlocks::default();
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let pending_utxos = PendingUtxos::default();
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Self {
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disk,
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mem,
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queued_blocks,
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pending_utxos,
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network,
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last_prune: Instant::now(),
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}
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}
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/// Queue a non finalized block for verification and check if any queued
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/// blocks are ready to be verified and committed to the state.
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///
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/// This function encodes the logic for [committing non-finalized blocks][1]
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/// in RFC0005.
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///
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/// [1]: https://zebra.zfnd.org/dev/rfcs/0005-state-updates.html#committing-non-finalized-blocks
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#[instrument(level = "debug", skip(self, prepared))]
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fn queue_and_commit_non_finalized(
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&mut self,
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prepared: PreparedBlock,
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) -> oneshot::Receiver<Result<block::Hash, BoxError>> {
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tracing::debug!(block = %prepared.block, "queueing block for contextual verification");
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let parent_hash = prepared.block.header.previous_block_hash;
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if self.mem.any_chain_contains(&prepared.hash) || self.disk.hash(prepared.height).is_some()
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{
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let (rsp_tx, rsp_rx) = oneshot::channel();
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let _ = rsp_tx.send(Err("block is already committed to the state".into()));
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return rsp_rx;
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}
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// Request::CommitBlock contract: a request to commit a block which has
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// been queued but not yet committed to the state fails the older
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// request and replaces it with the newer request.
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let rsp_rx = if let Some((_, old_rsp_tx)) = self.queued_blocks.get_mut(&prepared.hash) {
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tracing::debug!("replacing older queued request with new request");
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let (mut rsp_tx, rsp_rx) = oneshot::channel();
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std::mem::swap(old_rsp_tx, &mut rsp_tx);
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let _ = rsp_tx.send(Err("replaced by newer request".into()));
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rsp_rx
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} else {
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let (rsp_tx, rsp_rx) = oneshot::channel();
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self.queued_blocks.queue((prepared, rsp_tx));
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rsp_rx
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};
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if !self.can_fork_chain_at(&parent_hash) {
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tracing::trace!("unready to verify, returning early");
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return rsp_rx;
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}
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self.process_queued(parent_hash);
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while self.mem.best_chain_len() > crate::constants::MAX_BLOCK_REORG_HEIGHT {
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tracing::trace!("finalizing block past the reorg limit");
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let finalized = self.mem.finalize();
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self.disk
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.commit_finalized_direct(finalized)
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.expect("expected that disk errors would not occur");
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}
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self.queued_blocks
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.prune_by_height(self.disk.finalized_tip_height().expect(
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"Finalized state must have at least one block before committing non-finalized state",
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));
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tracing::trace!("finished processing queued block");
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rsp_rx
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}
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/// Run contextual validation on the prepared block and add it to the
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/// non-finalized state if it is contextually valid.
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fn validate_and_commit(&mut self, prepared: PreparedBlock) -> Result<(), CommitBlockError> {
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self.check_contextual_validity(&prepared)?;
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let parent_hash = prepared.block.header.previous_block_hash;
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if self.disk.finalized_tip_hash() == parent_hash {
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self.mem.commit_new_chain(prepared);
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} else {
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self.mem.commit_block(prepared);
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}
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Ok(())
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}
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/// Returns `true` if `hash` is a valid previous block hash for new non-finalized blocks.
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fn can_fork_chain_at(&self, hash: &block::Hash) -> bool {
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self.mem.any_chain_contains(hash) || &self.disk.finalized_tip_hash() == hash
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}
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/// Attempt to validate and commit all queued blocks whose parents have
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/// recently arrived starting from `new_parent`, in breadth-first ordering.
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fn process_queued(&mut self, new_parent: block::Hash) {
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let mut new_parents = vec![new_parent];
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while let Some(parent_hash) = new_parents.pop() {
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let queued_children = self.queued_blocks.dequeue_children(parent_hash);
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for (child, rsp_tx) in queued_children {
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let child_hash = child.hash;
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tracing::trace!(?child_hash, "validating queued child");
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let result = self
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.validate_and_commit(child)
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.map(|()| child_hash)
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.map_err(BoxError::from);
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let _ = rsp_tx.send(result);
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new_parents.push(child_hash);
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}
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}
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}
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/// Check that the prepared block is contextually valid for the configured
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/// network, based on the committed finalized and non-finalized state.
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fn check_contextual_validity(
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&mut self,
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prepared: &PreparedBlock,
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) -> Result<(), ValidateContextError> {
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let relevant_chain = self.chain(prepared.block.header.previous_block_hash);
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assert!(relevant_chain.len() >= POW_AVERAGING_WINDOW + POW_MEDIAN_BLOCK_SPAN,
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"contextual validation requires at least 28 (POW_AVERAGING_WINDOW + POW_MEDIAN_BLOCK_SPAN) blocks");
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check::block_is_contextually_valid(
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prepared,
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self.network,
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self.disk.finalized_tip_height(),
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relevant_chain,
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)?;
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Ok(())
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}
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/// Create a block locator for the current best chain.
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fn block_locator(&self) -> Option<Vec<block::Hash>> {
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let tip_height = self.tip()?.0;
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let heights = crate::util::block_locator_heights(tip_height);
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let mut hashes = Vec::with_capacity(heights.len());
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for height in heights {
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if let Some(hash) = self.hash(height) {
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hashes.push(hash);
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}
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}
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Some(hashes)
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}
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/// Return the tip of the current best chain.
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pub fn tip(&self) -> Option<(block::Height, block::Hash)> {
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self.mem.tip().or_else(|| self.disk.tip())
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}
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/// Return the depth of block `hash` in the current best chain.
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pub fn depth(&self, hash: block::Hash) -> Option<u32> {
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let tip = self.tip()?.0;
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let height = self.mem.height(hash).or_else(|| self.disk.height(hash))?;
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Some(tip.0 - height.0)
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}
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/// Return the block identified by either its `height` or `hash` if it exists
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/// in the current best chain.
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pub fn block(&self, hash_or_height: HashOrHeight) -> Option<Arc<Block>> {
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self.mem
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.block(hash_or_height)
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.or_else(|| self.disk.block(hash_or_height))
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}
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/// Return the transaction identified by `hash` if it exists in the current
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/// best chain.
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pub fn transaction(&self, hash: transaction::Hash) -> Option<Arc<Transaction>> {
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self.mem
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.transaction(hash)
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.or_else(|| self.disk.transaction(hash))
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}
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/// Return the hash for the block at `height` in the current best chain.
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pub fn hash(&self, height: block::Height) -> Option<block::Hash> {
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self.mem.hash(height).or_else(|| self.disk.hash(height))
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}
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/// Return the height for the block at `hash` in any chain.
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pub fn height_by_hash(&self, hash: block::Hash) -> Option<block::Height> {
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self.mem
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.height_by_hash(hash)
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.or_else(|| self.disk.height(hash))
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}
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/// Return the [`Utxo`] pointed to by `outpoint` if it exists in any chain.
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pub fn utxo(&self, outpoint: &transparent::OutPoint) -> Option<Utxo> {
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self.mem
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.utxo(outpoint)
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.or_else(|| self.queued_blocks.utxo(outpoint))
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.or_else(|| self.disk.utxo(outpoint))
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}
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/// Return an iterator over the relevant chain of the block identified by
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/// `hash`.
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///
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/// The block identified by `hash` is included in the chain of blocks yielded
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/// by the iterator.
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pub fn chain(&self, hash: block::Hash) -> Iter<'_> {
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Iter {
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service: self,
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state: IterState::NonFinalized(hash),
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}
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}
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}
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struct Iter<'a> {
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service: &'a StateService,
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state: IterState,
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}
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enum IterState {
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NonFinalized(block::Hash),
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Finalized(block::Height),
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Finished,
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}
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impl Iter<'_> {
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fn next_non_finalized_block(&mut self) -> Option<Arc<Block>> {
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let Iter { service, state } = self;
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let hash = match state {
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IterState::NonFinalized(hash) => *hash,
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IterState::Finalized(_) | IterState::Finished => unreachable!(),
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};
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if let Some(block) = service.mem.block_by_hash(hash) {
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let hash = block.header.previous_block_hash;
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self.state = IterState::NonFinalized(hash);
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Some(block)
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} else {
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None
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}
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}
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fn next_finalized_block(&mut self) -> Option<Arc<Block>> {
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let Iter { service, state } = self;
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let hash_or_height: HashOrHeight = match *state {
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IterState::Finalized(height) => height.into(),
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IterState::NonFinalized(hash) => hash.into(),
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IterState::Finished => unreachable!(),
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};
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if let Some(block) = service.disk.block(hash_or_height) {
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let height = block
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.coinbase_height()
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.expect("valid blocks have a coinbase height");
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if let Some(next_height) = height - 1 {
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self.state = IterState::Finalized(next_height);
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} else {
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self.state = IterState::Finished;
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}
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Some(block)
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} else {
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self.state = IterState::Finished;
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None
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}
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}
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}
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impl Iterator for Iter<'_> {
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type Item = Arc<Block>;
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fn next(&mut self) -> Option<Self::Item> {
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match self.state {
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IterState::NonFinalized(_) => self
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.next_non_finalized_block()
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.or_else(|| self.next_finalized_block()),
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IterState::Finalized(_) => self.next_finalized_block(),
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IterState::Finished => None,
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}
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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let len = self.len();
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(len, Some(len))
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}
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}
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impl std::iter::FusedIterator for Iter<'_> {}
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impl ExactSizeIterator for Iter<'_> {
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fn len(&self) -> usize {
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match self.state {
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IterState::NonFinalized(hash) => self
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.service
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.height_by_hash(hash)
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.map(|height| (height.0 + 1) as _)
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.unwrap_or(0),
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IterState::Finalized(height) => (height.0 + 1) as _,
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IterState::Finished => 0,
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}
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}
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}
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impl Service<Request> for StateService {
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type Response = Response;
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type Error = BoxError;
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type Future =
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Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send + 'static>>;
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fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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let now = Instant::now();
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if self.last_prune + Self::PRUNE_INTERVAL < now {
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let tip = self.tip();
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let old_len = self.pending_utxos.len();
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self.pending_utxos.prune();
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self.last_prune = now;
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let new_len = self.pending_utxos.len();
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let prune_count = old_len
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.checked_sub(new_len)
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.expect("prune does not add any utxo requests");
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if prune_count > 0 {
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tracing::info!(
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?old_len,
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?new_len,
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?prune_count,
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?tip,
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"pruned utxo requests"
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);
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} else {
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tracing::debug!(len = ?old_len, ?tip, "no utxo requests needed pruning");
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}
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}
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Poll::Ready(Ok(()))
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}
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#[instrument(name = "state", skip(self, req))]
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fn call(&mut self, req: Request) -> Self::Future {
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match req {
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Request::CommitBlock(prepared) => {
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metrics::counter!("state.requests", 1, "type" => "commit_block");
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self.pending_utxos.check_against(&prepared.new_outputs);
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let rsp_rx = self.queue_and_commit_non_finalized(prepared);
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async move {
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rsp_rx
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.await
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.expect("sender is not dropped")
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.map(Response::Committed)
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.map_err(Into::into)
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}
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.boxed()
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}
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Request::CommitFinalizedBlock(finalized) => {
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metrics::counter!("state.requests", 1, "type" => "commit_finalized_block");
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let (rsp_tx, rsp_rx) = oneshot::channel();
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self.pending_utxos.check_against(&finalized.new_outputs);
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self.disk.queue_and_commit_finalized((finalized, rsp_tx));
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async move {
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rsp_rx
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.await
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.expect("sender is not dropped")
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.map(Response::Committed)
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.map_err(Into::into)
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}
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.boxed()
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}
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Request::Depth(hash) => {
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metrics::counter!("state.requests", 1, "type" => "depth");
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let rsp = Ok(self.depth(hash)).map(Response::Depth);
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async move { rsp }.boxed()
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}
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Request::Tip => {
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metrics::counter!("state.requests", 1, "type" => "tip");
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let rsp = Ok(self.tip()).map(Response::Tip);
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async move { rsp }.boxed()
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}
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Request::BlockLocator => {
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metrics::counter!("state.requests", 1, "type" => "block_locator");
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let rsp = Ok(self.block_locator().unwrap_or_default()).map(Response::BlockLocator);
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async move { rsp }.boxed()
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}
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Request::Transaction(hash) => {
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metrics::counter!("state.requests", 1, "type" => "transaction");
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let rsp = Ok(self.transaction(hash)).map(Response::Transaction);
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async move { rsp }.boxed()
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}
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Request::Block(hash_or_height) => {
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metrics::counter!("state.requests", 1, "type" => "block");
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let rsp = Ok(self.block(hash_or_height)).map(Response::Block);
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async move { rsp }.boxed()
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}
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Request::AwaitUtxo(outpoint) => {
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metrics::counter!("state.requests", 1, "type" => "await_utxo");
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let fut = self.pending_utxos.queue(outpoint);
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if let Some(utxo) = self.utxo(&outpoint) {
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self.pending_utxos.respond(&outpoint, utxo);
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}
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fut.boxed()
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}
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}
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}
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}
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|
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/// Initialize a state service from the provided [`Config`].
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///
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/// Each `network` has its own separate on-disk database.
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///
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/// To share access to the state, wrap the returned service in a `Buffer`. It's
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/// possible to construct multiple state services in the same application (as
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/// long as they, e.g., use different storage locations), but doing so is
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/// probably not what you want.
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pub fn init(config: Config, network: Network) -> BoxService<Request, Response, BoxError> {
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BoxService::new(StateService::new(config, network))
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}
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