Antioch Peverell
e56cd55980
* initial support for kernel data download * fix vec backend for tests * cleanup after rebase
94 lines
2.9 KiB
Rust
94 lines
2.9 KiB
Rust
// Copyright 2018 The Grin Developers
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//! Lightweight readonly view into kernel MMR for convenience.
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use std::fs::File;
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use crate::core::core::pmmr::RewindablePMMR;
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use crate::core::core::{BlockHeader, TxKernel};
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use crate::error::{Error, ErrorKind};
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use crate::store::Batch;
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use grin_store::pmmr::PMMRBackend;
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/// Rewindable (but readonly) view of the kernel set (based on kernel MMR).
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pub struct RewindableKernelView<'a> {
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pmmr: RewindablePMMR<'a, TxKernel, PMMRBackend<TxKernel>>,
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batch: &'a Batch<'a>,
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header: BlockHeader,
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}
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impl<'a> RewindableKernelView<'a> {
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/// Build a new readonly kernel view.
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pub fn new(
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pmmr: RewindablePMMR<'a, TxKernel, PMMRBackend<TxKernel>>,
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batch: &'a Batch<'_>,
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header: BlockHeader,
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) -> RewindableKernelView<'a> {
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RewindableKernelView {
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pmmr,
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batch,
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header,
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}
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}
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/// Accessor for the batch used in this view.
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/// We will discard this batch (rollback) at the end, so be aware of this.
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/// Nothing will get written to the db/index via this view.
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pub fn batch(&self) -> &'a Batch<'_> {
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self.batch
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}
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/// Rewind this readonly view to a previous block.
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/// We accomplish this in a readonly way because we can rewind the PMMR
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/// via last_pos, without rewinding the underlying backend files.
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pub fn rewind(&mut self, header: &BlockHeader) -> Result<(), Error> {
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self.pmmr
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.rewind(header.kernel_mmr_size)
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.map_err(&ErrorKind::TxHashSetErr)?;
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// Update our header to reflect the one we rewound to.
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self.header = header.clone();
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Ok(())
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}
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/// Special handling to make sure the whole kernel set matches each of its
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/// roots in each block header, without truncation. We go back header by
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/// header, rewind and check each root. This fixes a potential weakness in
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/// fast sync where a reorg past the horizon could allow a whole rewrite of
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/// the kernel set.
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pub fn validate_root(&self) -> Result<(), Error> {
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let root = self.pmmr.root().map_err(|_| ErrorKind::InvalidRoot)?;
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if root != self.header.kernel_root {
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return Err(ErrorKind::InvalidTxHashSet(format!(
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"Kernel root at {} does not match",
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self.header.height
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))
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.into());
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}
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Ok(())
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}
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/// Read the "raw" kernel backend data file (via temp file for consistent view on data).
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pub fn kernel_data_read(&self) -> Result<File, Error> {
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let file = self
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.pmmr
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.backend()
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.data_as_temp_file()
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.map_err(|_| ErrorKind::FileReadErr("Data file woes".into()))?;
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Ok(file)
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}
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}
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