376 lines
11 KiB
Rust
376 lines
11 KiB
Rust
// Copyright 2015-2019 Parity Technologies (UK) Ltd.
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// This file is part of Parity Ethereum.
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// Parity Ethereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity Ethereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity Ethereum. If not, see <http://www.gnu.org/licenses/>.
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//! Request chain builder utility.
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//! Push requests with `push`. Back-references and data required to verify responses must be
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//! supplied as well.
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use request::{IncompleteRequest, NoSuchOutput, Output, OutputKind, ResponseError, ResponseLike};
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use std::{
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collections::HashMap,
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ops::{Deref, DerefMut},
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};
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/// Build chained requests. Push them onto the series with `push`,
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/// and produce a `Batch` object with `build`. Outputs are checked for consistency.
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct Builder<T> {
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output_kinds: HashMap<(usize, usize), OutputKind>,
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requests: Vec<T>,
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}
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impl<T> Default for Builder<T> {
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fn default() -> Self {
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Builder {
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output_kinds: HashMap::new(),
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requests: Vec::new(),
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}
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}
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}
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impl<T: IncompleteRequest> Builder<T> {
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/// Attempt to push a request onto the request chain. Fails if the request
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/// references a non-existent output of a prior request.
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pub fn push(&mut self, request: T) -> Result<(), NoSuchOutput> {
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request.check_outputs(|req, idx, kind| match self.output_kinds.get(&(req, idx)) {
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Some(k) if k == &kind => Ok(()),
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_ => Err(NoSuchOutput),
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})?;
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let req_idx = self.requests.len();
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request.note_outputs(|idx, kind| {
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self.output_kinds.insert((req_idx, idx), kind);
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});
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self.requests.push(request);
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Ok(())
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}
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/// Get a reference to the output kinds map.
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pub fn output_kinds(&self) -> &HashMap<(usize, usize), OutputKind> {
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&self.output_kinds
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}
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/// Convert this into a "batch" object.
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pub fn build(self) -> Batch<T> {
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Batch {
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outputs: HashMap::new(),
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requests: self.requests,
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answered: 0,
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}
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}
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}
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/// Requests pending responses.
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct Batch<T> {
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outputs: HashMap<(usize, usize), Output>,
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requests: Vec<T>,
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answered: usize,
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}
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impl<T> Batch<T> {
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/// Get access to the underlying slice of requests.
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// TODO: unimplemented -> Vec<Request>, // do we _have to_ allocate?
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pub fn requests(&self) -> &[T] {
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&self.requests
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}
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/// Get the number of answered requests.
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pub fn num_answered(&self) -> usize {
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self.answered
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}
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/// Whether the batch is complete.
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pub fn is_complete(&self) -> bool {
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self.answered == self.requests.len()
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}
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/// Map requests from one type into another.
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pub fn map_requests<F, U>(self, f: F) -> Batch<U>
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where
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F: FnMut(T) -> U,
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U: IncompleteRequest,
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{
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Batch {
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outputs: self.outputs,
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requests: self.requests.into_iter().map(f).collect(),
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answered: self.answered,
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}
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}
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}
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impl<T: IncompleteRequest + Clone> Batch<T> {
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/// Get the next request as a filled request. Returns `None` when all requests answered.
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pub fn next_complete(&self) -> Option<T::Complete> {
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if self.is_complete() {
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None
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} else {
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Some(
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self.requests[self.answered]
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.clone()
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.complete()
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.expect("All outputs checked as invariant of `Batch` object; qed"),
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)
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}
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}
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/// Sweep through all unanswered requests, filling them as necessary.
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pub fn fill_unanswered(&mut self) {
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let outputs = &mut self.outputs;
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for req in self.requests.iter_mut().skip(self.answered) {
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req.fill(|req_idx, out_idx| {
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outputs
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.get(&(req_idx, out_idx))
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.cloned()
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.ok_or(NoSuchOutput)
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})
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}
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}
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/// Supply a response, asserting its correctness.
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/// Fill outputs based upon it.
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pub fn supply_response_unchecked<R: ResponseLike>(&mut self, response: &R) {
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if self.is_complete() {
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return;
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}
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let outputs = &mut self.outputs;
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let idx = self.answered;
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response.fill_outputs(|out_idx, output| {
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// we don't need to check output kinds here because all back-references
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// are validated in the builder.
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// TODO: optimization for only storing outputs we "care about"?
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outputs.insert((idx, out_idx), output);
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});
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self.answered += 1;
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// fill as much of the next request as we can.
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if let Some(ref mut req) = self.requests.get_mut(self.answered) {
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req.fill(|req_idx, out_idx| {
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outputs
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.get(&(req_idx, out_idx))
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.cloned()
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.ok_or(NoSuchOutput)
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})
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}
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}
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}
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impl<T: super::CheckedRequest + Clone> Batch<T> {
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/// Supply a response for the next request.
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/// Fails on: wrong request kind, all requests answered already.
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pub fn supply_response(
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&mut self,
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env: &T::Environment,
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response: &T::Response,
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) -> Result<T::Extract, ResponseError<T::Error>> {
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let idx = self.answered;
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// check validity.
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if idx == self.requests.len() {
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return Err(ResponseError::Unexpected);
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}
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let completed = self.next_complete().expect(
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"only fails when all requests have been answered; this just checked against; qed",
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);
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let extracted = self.requests[idx]
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.check_response(&completed, env, response)
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.map_err(ResponseError::Validity)?;
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self.supply_response_unchecked(response);
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Ok(extracted)
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}
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}
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impl Batch<super::Request> {
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/// For each request, produce a response.
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/// The responses vector produced goes up to the point where the responder
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/// first returns `None`, an invalid response, or until all requests have been responded to.
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pub fn respond_to_all<F>(mut self, responder: F) -> Vec<super::Response>
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where
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F: Fn(super::CompleteRequest) -> Option<super::Response>,
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{
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let mut responses = Vec::new();
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while let Some(response) = self.next_complete().and_then(&responder) {
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match self.supply_response(&(), &response) {
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Ok(()) => responses.push(response),
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Err(e) => {
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debug!(target: "pip", "produced bad response to request: {:?}", e);
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return responses;
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}
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}
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}
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responses
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}
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}
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impl<T: IncompleteRequest> Deref for Batch<T> {
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type Target = [T];
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fn deref(&self) -> &[T] {
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&self.requests[..]
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}
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}
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impl<T: IncompleteRequest> DerefMut for Batch<T> {
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fn deref_mut(&mut self) -> &mut [T] {
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&mut self.requests[..]
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}
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}
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#[cfg(test)]
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mod tests {
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use super::Builder;
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use ethereum_types::H256;
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use request::*;
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#[test]
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fn all_scalar() {
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let mut builder = Builder::default();
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: 100.into(),
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}))
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.unwrap();
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builder
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.push(Request::Receipts(IncompleteReceiptsRequest {
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hash: H256::default().into(),
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}))
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.unwrap();
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}
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#[test]
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#[should_panic]
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fn missing_backref() {
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let mut builder = Builder::default();
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: Field::BackReference(100, 3),
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}))
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.unwrap();
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}
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#[test]
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#[should_panic]
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fn wrong_kind() {
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let mut builder = Builder::default();
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assert!(builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: 100.into(),
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}))
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.is_ok());
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: Field::BackReference(0, 0),
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}))
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.unwrap();
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}
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#[test]
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fn good_backreference() {
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let mut builder = Builder::default();
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: 100.into(), // header proof puts hash at output 0.
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}))
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.unwrap();
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builder
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.push(Request::Receipts(IncompleteReceiptsRequest {
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hash: Field::BackReference(0, 0),
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}))
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.unwrap();
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}
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#[test]
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fn batch_tx_index_backreference() {
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let mut builder = Builder::default();
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: 100.into(), // header proof puts hash at output 0.
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}))
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.unwrap();
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builder
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.push(Request::TransactionIndex(
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IncompleteTransactionIndexRequest {
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hash: Field::BackReference(0, 0),
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},
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))
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.unwrap();
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let mut batch = builder.build();
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batch.requests[1].fill(|_req_idx, _out_idx| Ok(Output::Hash(42.into())));
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assert!(batch.next_complete().is_some());
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batch.answered += 1;
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assert!(batch.next_complete().is_some());
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}
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#[test]
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fn batch_tx_index_backreference_public_api() {
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let mut builder = Builder::default();
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: 100.into(), // header proof puts hash at output 0.
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}))
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.unwrap();
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builder
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.push(Request::TransactionIndex(
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IncompleteTransactionIndexRequest {
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hash: Field::BackReference(0, 0),
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},
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))
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.unwrap();
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let mut batch = builder.build();
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assert!(batch.next_complete().is_some());
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let hdr_proof_res = header_proof::Response {
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proof: vec![],
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hash: 12.into(),
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td: 21.into(),
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};
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batch.supply_response_unchecked(&hdr_proof_res);
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assert!(batch.next_complete().is_some());
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}
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#[test]
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fn batch_receipts_backreference() {
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let mut builder = Builder::default();
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builder
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.push(Request::HeaderProof(IncompleteHeaderProofRequest {
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num: 100.into(), // header proof puts hash at output 0.
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}))
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.unwrap();
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builder
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.push(Request::Receipts(IncompleteReceiptsRequest {
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hash: Field::BackReference(0, 0),
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}))
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.unwrap();
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let mut batch = builder.build();
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batch.requests[1].fill(|_req_idx, _out_idx| Ok(Output::Hash(42.into())));
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assert!(batch.next_complete().is_some());
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batch.answered += 1;
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assert!(batch.next_complete().is_some());
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}
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}
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