From 2e421191e20a6c968c6b0025fd6ed45fb85de8a9 Mon Sep 17 00:00:00 2001
From: Antioch Peverell <apeverell@protonmail.com>
Date: Wed, 14 Nov 2018 14:52:43 +0000
Subject: [PATCH] implement read_multi with an internal iterating reader
(#1981)
* rework read_multi to use an "iterating reader" internally
we are going to use this for reading headers in batches
* rustfmt
---
core/src/ser.rs | 48 +++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 45 insertions(+), 3 deletions(-)
diff --git a/core/src/ser.rs b/core/src/ser.rs
index 4a4648f09..34e07d271 100644
--- a/core/src/ser.rs
+++ b/core/src/ser.rs
@@ -25,6 +25,7 @@ use core::hash::{Hash, Hashed};
use keychain::{BlindingFactor, Identifier, IDENTIFIER_SIZE};
use std::fmt::Debug;
use std::io::{self, Read, Write};
+use std::marker;
use std::{cmp, error, fmt};
use util::secp::constants::{
AGG_SIGNATURE_SIZE, MAX_PROOF_SIZE, PEDERSEN_COMMITMENT_SIZE, SECRET_KEY_SIZE,
@@ -46,6 +47,8 @@ pub enum Error {
},
/// Data wasn't in a consumable format
CorruptedData,
+ /// Incorrect number of elements (when deserializing a vec via read_multi say).
+ CountError,
/// When asked to read too much data
TooLargeReadErr,
/// Consensus rule failure (currently sort order)
@@ -75,6 +78,7 @@ impl fmt::Display for Error {
received: ref r,
} => write!(f, "expected {:?}, got {:?}", e, r),
Error::CorruptedData => f.write_str("corrupted data"),
+ Error::CountError => f.write_str("count error"),
Error::TooLargeReadErr => f.write_str("too large read"),
Error::ConsensusError(ref e) => write!(f, "consensus error {:?}", e),
Error::HexError(ref e) => write!(f, "hex error {:?}", e),
@@ -95,6 +99,7 @@ impl error::Error for Error {
Error::IOErr(ref e, _) => e,
Error::UnexpectedData { .. } => "unexpected data",
Error::CorruptedData => "corrupted data",
+ Error::CountError => "count error",
Error::TooLargeReadErr => "too large read",
Error::ConsensusError(_) => "consensus error (sort order)",
Error::HexError(_) => "hex error",
@@ -201,10 +206,44 @@ pub trait Writeable {
fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error>;
}
+struct IteratingReader<'a, T> {
+ count: u64,
+ curr: u64,
+ reader: &'a mut Reader,
+ _marker: marker::PhantomData<T>,
+}
+
+impl<'a, T> IteratingReader<'a, T> {
+ fn new(reader: &'a mut Reader, count: u64) -> IteratingReader<'a, T> {
+ let curr = 0;
+ IteratingReader {
+ count,
+ curr,
+ reader,
+ _marker: marker::PhantomData,
+ }
+ }
+}
+
+impl<'a, T> Iterator for IteratingReader<'a, T>
+where
+ T: Readable,
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<T> {
+ if self.curr >= self.count {
+ return None;
+ }
+ self.curr += 1;
+ T::read(self.reader).ok()
+ }
+}
+
/// Reads multiple serialized items into a Vec.
pub fn read_multi<T>(reader: &mut Reader, count: u64) -> Result<Vec<T>, Error>
where
- T: Readable + Hashed + Writeable,
+ T: Readable,
{
// Very rudimentary check to ensure we do not overflow anything
// attempting to read huge amounts of data.
@@ -213,8 +252,11 @@ where
return Err(Error::TooLargeReadErr);
}
- let result: Vec<T> = try!((0..count).map(|_| T::read(reader)).collect());
- Ok(result)
+ let res: Vec<T> = IteratingReader::new(reader, count).collect();
+ if res.len() as u64 != count {
+ return Err(Error::CountError);
+ }
+ Ok(res)
}
/// Trait that every type that can be deserialized from binary must implement.