diff --git a/ethcore/sync/src/snapshot.rs b/ethcore/sync/src/snapshot.rs index e5632e652..c7f0d284f 100644 --- a/ethcore/sync/src/snapshot.rs +++ b/ethcore/sync/src/snapshot.rs @@ -17,7 +17,6 @@ use ethcore::snapshot::{ManifestData, SnapshotService}; use ethereum_types::H256; use hash::keccak; -use rand::{thread_rng, Rng}; use std::collections::HashSet; use std::iter::FromIterator; @@ -114,35 +113,32 @@ impl Snapshot { Err(()) } - /// Find a random chunk to download + /// Find a chunk to download pub fn needed_chunk(&mut self) -> Option { - // Find all random chunks: first blocks, then state - let needed_chunks = { + // Find next needed chunk: first block, then state chunks + let chunk = { let chunk_filter = |h| !self.downloading_chunks.contains(h) && !self.completed_chunks.contains(h); - let needed_block_chunks = self.pending_block_chunks.iter() + let needed_block_chunk = self.pending_block_chunks.iter() .filter(|&h| chunk_filter(h)) .map(|h| *h) - .collect::>(); + .next(); // If no block chunks to download, get the state chunks - if needed_block_chunks.len() == 0 { + if needed_block_chunk.is_none() { self.pending_state_chunks.iter() .filter(|&h| chunk_filter(h)) .map(|h| *h) - .collect::>() + .next() } else { - needed_block_chunks + needed_block_chunk } }; - // Get a random chunk - let chunk = thread_rng().choose(&needed_chunks); - if let Some(hash) = chunk { self.downloading_chunks.insert(hash.clone()); } - chunk.map(|h| *h) + chunk } pub fn clear_chunk_download(&mut self, hash: &H256) {