Fix a memory leak in header downloader's downloaded

The header downloader has two queues. The first one is the downloaded queue, and the second one is the "queued" queue. If a header is downloaded, downloader enqueues the header to the downloaded queue. When starting to import the header, the downloader removes the header from the downloaded queue and enqueues the header to the "queued" queue. When the importing is done, the downloader removes the header from the "queued" queue. However, if a header(let's call it A) is downloaded and is imported already, A is not removed from the downloaded queue forever. This commit removes A from the downloaded header.

Author: majecty

sync/src/block/downloader/header.rs

@@ -179,6 +179,7 @@ impl HeaderDownloader {
  pub fn mark_as_imported(&mut self, hashes: Vec<H256>) {
  for hash in hashes {
  self.queued.remove(&hash);
+ self.downloaded.remove(&hash);
 
  if self.best_hash == hash {
  self.pivot = Pivot {