Two year secondary pow ratio fix (#2037)

* Tweak (consensus breaking) secondary_pow_ratio
* Look at chain type for sec pow ratio calc (hardfork is t4 only)

core/src/consensus.rs

@@ -63,7 +63,17 @@ pub const COINBASE_MATURITY: u64 = DAY_HEIGHT;
 /// function of block height (time). Starts at 90% losing a percent
 /// approximately every week. Represented as an integer between 0 and 100.
 pub fn secondary_pow_ratio(height: u64) -> u64 {
+	// TODO - this should all be cleaned up and simplified before mainnet.
+	if global::is_mainnet() {
+		90u64.saturating_sub(height / (2 * YEAR_HEIGHT / 90))
+	} else {
+		if height < T4_CUCKAROO_HARDFORK {
+			// Maintaining pre hardfork testnet4 behavior
 			90u64.saturating_sub(height / WEEK_HEIGHT)
+		} else {
+			90u64.saturating_sub(height / (2 * YEAR_HEIGHT / 90))
+		}
+	}
 }
 
 /// Cuckoo-cycle proof size (cycle length)

core/src/global.rs

@@ -19,8 +19,8 @@
 use consensus::HeaderInfo;
 use consensus::{
 	graph_weight, BASE_EDGE_BITS, BLOCK_TIME_SEC, COINBASE_MATURITY, CUT_THROUGH_HORIZON,
-	DAY_HEIGHT, DIFFICULTY_ADJUST_WINDOW, INITIAL_DIFFICULTY, PROOFSIZE, SECOND_POW_EDGE_BITS,
-	STATE_SYNC_THRESHOLD, T4_CUCKAROO_HARDFORK, UNIT_DIFFICULTY, DEFAULT_MIN_EDGE_BITS,
+	DAY_HEIGHT, DEFAULT_MIN_EDGE_BITS, DIFFICULTY_ADJUST_WINDOW, INITIAL_DIFFICULTY, PROOFSIZE,
+	SECOND_POW_EDGE_BITS, STATE_SYNC_THRESHOLD, T4_CUCKAROO_HARDFORK, UNIT_DIFFICULTY,
 };
 use pow::{self, new_cuckaroo_ctx, new_cuckatoo_ctx, EdgeType, PoWContext};
 /// An enum collecting sets of parameters used throughout the
@@ -294,6 +294,12 @@ pub fn is_production_mode() -> bool {
 		|| ChainTypes::Mainnet == *param_ref
 }
 
+/// Are we in mainnet?
+pub fn is_mainnet() -> bool {
+	let param_ref = CHAIN_TYPE.read();
+	ChainTypes::Mainnet == *param_ref
+}
+
 /// Helper function to get a nonce known to create a valid POW on
 /// the genesis block, to prevent it taking ages. Should be fine for now
 /// as the genesis block POW solution turns out to be the same for every new

core/tests/consensus.rs

@@ -146,8 +146,7 @@ fn get_diff_stats(chain_sim: &Vec<HeaderInfo>) -> DiffStats {
 				time: n.timestamp,
 				duration: dur,
 			}
-		})
-		.collect();
+		}).collect();
 
 	let block_time_sum = sum_entries.iter().fold(0, |sum, t| sum + t.duration);
 	let block_diff_sum = sum_entries.iter().fold(0, |sum, d| sum + d.difficulty);
@@ -472,7 +471,94 @@ fn next_target_adjustment() {
 }
 
 #[test]
-fn secondary_pow_scale() {
+fn test_secondary_pow_ratio() {
+	// Tests for mainnet chain type.
+	{
+		global::set_mining_mode(global::ChainTypes::Mainnet);
+		assert_eq!(global::is_mainnet(), true);
+
+		assert_eq!(secondary_pow_ratio(1), 90);
+		assert_eq!(secondary_pow_ratio(89), 90);
+		assert_eq!(secondary_pow_ratio(90), 90);
+		assert_eq!(secondary_pow_ratio(91), 90);
+		assert_eq!(secondary_pow_ratio(179), 90);
+		assert_eq!(secondary_pow_ratio(180), 90);
+		assert_eq!(secondary_pow_ratio(181), 90);
+
+		let one_week = 60 * 24 * 7;
+		assert_eq!(secondary_pow_ratio(one_week - 1), 90);
+		assert_eq!(secondary_pow_ratio(one_week), 90);
+		assert_eq!(secondary_pow_ratio(one_week + 1), 90);
+
+		let two_weeks = one_week * 2;
+		assert_eq!(secondary_pow_ratio(two_weeks - 1), 89);
+		assert_eq!(secondary_pow_ratio(two_weeks), 89);
+		assert_eq!(secondary_pow_ratio(two_weeks + 1), 89);
+
+		let t4_fork_height = 64_000;
+		assert_eq!(secondary_pow_ratio(t4_fork_height - 1), 85);
+		assert_eq!(secondary_pow_ratio(t4_fork_height), 85);
+		assert_eq!(secondary_pow_ratio(t4_fork_height + 1), 85);
+
+		let one_year = one_week * 52;
+		assert_eq!(secondary_pow_ratio(one_year), 45);
+
+		let ninety_one_weeks = one_week * 91;
+		assert_eq!(secondary_pow_ratio(ninety_one_weeks - 1), 12);
+		assert_eq!(secondary_pow_ratio(ninety_one_weeks), 12);
+		assert_eq!(secondary_pow_ratio(ninety_one_weeks + 1), 12);
+
+		let two_year = one_year * 2;
+		assert_eq!(secondary_pow_ratio(two_year - 1), 1);
+		assert_eq!(secondary_pow_ratio(two_year), 0);
+		assert_eq!(secondary_pow_ratio(two_year + 1), 0);
+	}
+
+	// Tests for testnet4 chain type (covers pre and post hardfork).
+	{
+		global::set_mining_mode(global::ChainTypes::Testnet4);
+		assert_eq!(global::is_mainnet(), false);
+
+		assert_eq!(secondary_pow_ratio(1), 90);
+		assert_eq!(secondary_pow_ratio(89), 90);
+		assert_eq!(secondary_pow_ratio(90), 90);
+		assert_eq!(secondary_pow_ratio(91), 90);
+		assert_eq!(secondary_pow_ratio(179), 90);
+		assert_eq!(secondary_pow_ratio(180), 90);
+		assert_eq!(secondary_pow_ratio(181), 90);
+
+		let one_week = 60 * 24 * 7;
+		assert_eq!(secondary_pow_ratio(one_week - 1), 90);
+		assert_eq!(secondary_pow_ratio(one_week), 89);
+		assert_eq!(secondary_pow_ratio(one_week + 1), 89);
+
+		let two_weeks = one_week * 2;
+		assert_eq!(secondary_pow_ratio(two_weeks - 1), 89);
+		assert_eq!(secondary_pow_ratio(two_weeks), 88);
+		assert_eq!(secondary_pow_ratio(two_weeks + 1), 88);
+
+		let t4_fork_height = 64_000;
+		assert_eq!(secondary_pow_ratio(t4_fork_height - 1), 84);
+		assert_eq!(secondary_pow_ratio(t4_fork_height), 85);
+		assert_eq!(secondary_pow_ratio(t4_fork_height + 1), 85);
+
+		let one_year = one_week * 52;
+		assert_eq!(secondary_pow_ratio(one_year), 45);
+
+		let ninety_one_weeks = one_week * 91;
+		assert_eq!(secondary_pow_ratio(ninety_one_weeks - 1), 12);
+		assert_eq!(secondary_pow_ratio(ninety_one_weeks), 12);
+		assert_eq!(secondary_pow_ratio(ninety_one_weeks + 1), 12);
+
+		let two_year = one_year * 2;
+		assert_eq!(secondary_pow_ratio(two_year - 1), 1);
+		assert_eq!(secondary_pow_ratio(two_year), 0);
+		assert_eq!(secondary_pow_ratio(two_year + 1), 0);
+	}
+}
+
+#[test]
+fn test_secondary_pow_scale() {
 	let window = DIFFICULTY_ADJUST_WINDOW;
 	let mut hi = HeaderInfo::from_diff_scaling(Difficulty::from_num(10), 100);
 
@@ -501,7 +587,10 @@ fn secondary_pow_scale() {
 	let mut low_hi = HeaderInfo::from_diff_scaling(Difficulty::from_num(10), MIN_DIFFICULTY as u32);
 	low_hi.is_secondary = true;
 	assert_eq!(
-		secondary_pow_scaling(890_000, &(0..window).map(|_| low_hi.clone()).collect::<Vec<_>>()),
+		secondary_pow_scaling(
+			890_000,
+			&(0..window).map(|_| low_hi.clone()).collect::<Vec<_>>()
+		),
 		MIN_DIFFICULTY as u32
 	);
 	// just about the right ratio, also no longer playing with median