TUI Freeze Fix - Add manually maintained hash to difficulty iterator (#3684)

* add manually managed hash to difficulty iterator

* text fix

* fix for hash-of-hash, review feedback

chain/src/store.rs

@@ -441,6 +441,7 @@ pub struct DifficultyIter<'a> {
 	// toward the genesis block (while maintaining current state)
 	header: Option<BlockHeader>,
 	prev_header: Option<BlockHeader>,
+	prev_header_hash: Option<Hash>,
 }
 
 impl<'a> DifficultyIter<'a> {
@@ -453,6 +454,7 @@ impl<'a> DifficultyIter<'a> {
 			batch: None,
 			header: None,
 			prev_header: None,
+			prev_header_hash: None,
 		}
 	}
 
@@ -465,6 +467,7 @@ impl<'a> DifficultyIter<'a> {
 			batch: Some(batch),
 			header: None,
 			prev_header: None,
+			prev_header_hash: None,
 		}
 	}
 }
@@ -479,18 +482,26 @@ impl<'a> Iterator for DifficultyIter<'a> {
 		// Items returned by this iterator cannot be expected to correctly
 		// calculate their own hash - This iterator is purely for iterating through
 		// difficulty information
-		self.header = if self.header.is_none() {
+		let (cur_header, cur_header_hash) = if self.header.is_none() {
 			if let Some(ref batch) = self.batch {
-				batch.get_block_header_skip_proof(&self.start).ok()
+				(
+					batch.get_block_header_skip_proof(&self.start).ok(),
+					Some(self.start),
+				)
 			} else if let Some(ref store) = self.store {
-				store.get_block_header_skip_proof(&self.start).ok()
+				(
+					store.get_block_header_skip_proof(&self.start).ok(),
+					Some(self.start),
+				)
 			} else {
-				None
+				(None, None)
 			}
 		} else {
-			self.prev_header.clone()
+			(self.prev_header.clone(), self.prev_header_hash)
 		};
 
+		self.header = cur_header;
+
 		// If we have a header we can do this iteration.
 		// Otherwise we are done.
 		if let Some(header) = self.header.clone() {
@@ -502,6 +513,8 @@ impl<'a> Iterator for DifficultyIter<'a> {
 				self.prev_header = None;
 			}
 
+			self.prev_header_hash = Some(header.prev_hash);
+
 			let prev_difficulty = self
 				.prev_header
 				.clone()
@@ -510,6 +523,7 @@ impl<'a> Iterator for DifficultyIter<'a> {
 			let scaling = header.pow.secondary_scaling;
 
 			Some(HeaderDifficultyInfo::new(
+				cur_header_hash,
 				header.timestamp.timestamp() as u64,
 				difficulty,
 				scaling,

core/src/consensus.rs

@@ -19,6 +19,7 @@
 //! here.
 
 use crate::core::block::HeaderVersion;
+use crate::core::hash::Hash;
 use crate::global;
 use crate::pow::Difficulty;
 use std::cmp::{max, min};
@@ -231,6 +232,8 @@ pub const INITIAL_DIFFICULTY: u64 = 1_000_000 * UNIT_DIFFICULTY;
 /// the header's PoW proof nonces from being deserialized on read
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct HeaderDifficultyInfo {
+	/// Hash of this block
+	pub hash: Option<Hash>,
 	/// Timestamp of the header, 1 when not used (returned info)
 	pub timestamp: u64,
 	/// Network difficulty or next difficulty to use
@@ -244,12 +247,14 @@ pub struct HeaderDifficultyInfo {
 impl HeaderDifficultyInfo {
 	/// Default constructor
 	pub fn new(
+		hash: Option<Hash>,
 		timestamp: u64,
 		difficulty: Difficulty,
 		secondary_scaling: u32,
 		is_secondary: bool,
 	) -> HeaderDifficultyInfo {
 		HeaderDifficultyInfo {
+			hash,
 			timestamp,
 			difficulty,
 			secondary_scaling,
@@ -261,6 +266,7 @@ impl HeaderDifficultyInfo {
 	/// PoW factor
 	pub fn from_ts_diff(timestamp: u64, difficulty: Difficulty) -> HeaderDifficultyInfo {
 		HeaderDifficultyInfo {
+			hash: None,
 			timestamp,
 			difficulty,
 			secondary_scaling: global::initial_graph_weight(),
@@ -276,6 +282,7 @@ impl HeaderDifficultyInfo {
 		secondary_scaling: u32,
 	) -> HeaderDifficultyInfo {
 		HeaderDifficultyInfo {
+			hash: None,
 			timestamp: 1,
 			difficulty,
 			secondary_scaling,

core/tests/consensus_automated.rs

@@ -213,6 +213,7 @@ fn repeat(
 	pairs
 		.map(|(t, d)| {
 			HeaderDifficultyInfo::new(
+				None,
 				cur_time + t as u64,
 				*d,
 				diff.secondary_scaling,

servers/src/grin/server.rs

@@ -463,19 +463,7 @@ impl Server {
 
 					height += 1;
 
-					// We need to query again for the actual block hash, as
-					// the difficulty iterator doesn't contain enough info to
-					// create a hash
-					// The diff iterator returns 59 block headers 'before' 0 to give callers
-					// enough detail to calculate initial block difficulties. Ignore these.
-					let block_hash = if height < 0 {
-						ZERO_HASH
-					} else {
-						match self.chain.get_header_by_height(height as u64) {
-							Ok(h) => h.hash(),
-							Err(_) => ZERO_HASH,
-						}
-					};
+					let block_hash = next.hash.unwrap_or(ZERO_HASH);
 
 					DiffBlock {
 						block_height: height,