More small fixes and improvements to sync

chain/src/pipe.rs

@@ -61,10 +61,7 @@ pub fn process_block(b: &Block, mut ctx: BlockContext) -> Result<Option<Tip>, Er
 	);
 	check_known(b.hash(), &mut ctx)?;
 
-	if !ctx.opts.intersects(SYNC) {
+	validate_header(&b.header, &mut ctx)?;
-		// in sync mode, the header has already been validated
-		validate_header(&b.header, &mut ctx)?;
-	}
 
 	// take the lock on the sum trees and start a chain extension unit of work
 	// dependent on the success of the internal validation and saving operations
@@ -322,6 +319,15 @@ fn update_head(b: &Block, ctx: &mut BlockContext) -> Result<Option<Tip>, Error>
 		// update the block height index
 		ctx.store.setup_height(&b.header).map_err(&Error::StoreErr)?;
 
+    // in sync mode, only update the "body chain", otherwise update both the
+    // "header chain" and "body chain", updating the header chain in sync resets
+		// all additional "future" headers we've received
+    if ctx.opts.intersects(SYNC) {
+      ctx.store.save_body_head(&tip).map_err(&Error::StoreErr)?;
+    } else {
+      ctx.store.save_head(&tip).map_err(&Error::StoreErr)?;
+    }      
+
 		ctx.store.save_head(&tip).map_err(&Error::StoreErr)?;
 		ctx.head = tip.clone();
 		info!(LOGGER, "Updated head to {} at {}.", b.hash(), b.header.height);

grin/src/sync.rs

@@ -152,14 +152,16 @@ impl Syncer {
 		let too_old_pos = (0..blocks_downloading.len())
 			.filter(|p| blocks_downloading[*p].1 < twenty_sec_ago)
 			.collect::<Vec<_>>();
+		let mut offs = 0;
 		for too_old in too_old_pos {
-			let block_h = blocks_downloading.remove(too_old);
+			let block_h = blocks_downloading.remove(too_oldi - offs);
 			debug!(
 				LOGGER,
 				"Download request expired for {}, will re-issue.",
 				block_h.0
 			);
-			blocks_to_download.insert(0, block_h.0);
+			blocks_to_download.push(block_h.0);
+			offs += 1;
 		}
 
 		// consume hashes from blocks to download, place them in downloading and