From e2795b15933d2c69d7096c1dacfe0af0b078f072 Mon Sep 17 00:00:00 2001
From: Antioch Peverell <apeverell@protonmail.com>
Date: Tue, 26 Nov 2019 21:17:28 +0000
Subject: [PATCH] call zip_read fro within the txhashet lock for a consistent
 view on the files (#3142)

---
 chain/src/chain.rs               | 27 ++++++++++-----------------
 chain/src/txhashset/txhashset.rs | 13 +++++++++++++
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/chain/src/chain.rs b/chain/src/chain.rs
index c529d05ea..b468c67c0 100644
--- a/chain/src/chain.rs
+++ b/chain/src/chain.rs
@@ -671,24 +671,17 @@ impl Chain {
 		// The fast sync client does *not* have the necessary data
 		// to rewind after receiving the txhashset zip.
 		let header = self.get_block_header(&h)?;
-		{
-			let mut header_pmmr = self.header_pmmr.write();
-			let mut txhashset = self.txhashset.write();
-			txhashset::extending_readonly(&mut header_pmmr, &mut txhashset, |ext| {
-				pipe::rewind_and_apply_fork(&header, ext)?;
-				let ref mut extension = ext.extension;
-				extension.snapshot()?;
-				Ok(())
-			})?;
-		}
 
-		// prepares the zip and return the corresponding Read
-		let txhashset_reader = txhashset::zip_read(self.db_root.clone(), &header)?;
-		Ok((
-			header.output_mmr_size,
-			header.kernel_mmr_size,
-			txhashset_reader,
-		))
+		let mut header_pmmr = self.header_pmmr.write();
+		let mut txhashset = self.txhashset.write();
+		txhashset::extending_readonly(&mut header_pmmr, &mut txhashset, |ext| {
+			pipe::rewind_and_apply_fork(&header, ext)?;
+			ext.extension.snapshot()?;
+
+			// prepare the zip
+			txhashset::zip_read(self.db_root.clone(), &header)
+				.map(|file| (header.output_mmr_size, header.kernel_mmr_size, file))
+		})
 	}
 
 	/// To support the ability to download the txhashset from multiple peers in parallel,
diff --git a/chain/src/txhashset/txhashset.rs b/chain/src/txhashset/txhashset.rs
index ba2d3ef0f..ba14d9361 100644
--- a/chain/src/txhashset/txhashset.rs
+++ b/chain/src/txhashset/txhashset.rs
@@ -1423,6 +1423,12 @@ pub fn zip_read(root_dir: String, header: &BlockHeader) -> Result<File, Error> {
 	// if file exist, just re-use it
 	let zip_file = File::open(zip_path.clone());
 	if let Ok(zip) = zip_file {
+		debug!(
+			"zip_read: {} at {}: reusing existing zip file: {:?}",
+			header.hash(),
+			header.height,
+			zip_path
+		);
 		return Ok(zip);
 	} else {
 		// clean up old zips.
@@ -1463,6 +1469,13 @@ pub fn zip_read(root_dir: String, header: &BlockHeader) -> Result<File, Error> {
 		temp_txhashset_path
 	};
 
+	debug!(
+		"zip_read: {} at {}: created zip file: {:?}",
+		header.hash(),
+		header.height,
+		zip_path
+	);
+
 	// open it again to read it back
 	let zip_file = File::open(zip_path.clone())?;