rename MIN_DIFFICULTY to UNIT_DIFFICULTY; define Difficulty::unit, fix INITIAL_DIFFICULTY

core/src/consensus.rs

@@ -158,18 +158,15 @@ pub fn graph_weight(edge_bits: u8) -> u64 {
 	(2 << (edge_bits - global::base_edge_bits()) as u64) * (edge_bits as u64)
 }
 
-/// minimum possible difficulty equal to graph_weight(SECOND_POW_EDGE_BITS)
-pub const MIN_DIFFICULTY: u64 =
+/// unit difficulty, equal to graph_weight(SECOND_POW_EDGE_BITS)
+pub const UNIT_DIFFICULTY: u64 =
 	((2 as u64) << (SECOND_POW_EDGE_BITS - BASE_EDGE_BITS)) * (SECOND_POW_EDGE_BITS as u64);
 
 /// The initial difficulty at launch. This should be over-estimated
 /// and difficulty should come down at launch rather than up
 /// Currently grossly over-estimated at 10% of current
 /// ethereum GPUs (assuming 1GPU can solve a block at diff 1 in one block interval)
-/// FOR MAINNET, use
-/// pub const INITIAL_DIFFICULTY: u64 = 1_000_000 * MIN_DIFFICULTY;
-/// Pick MUCH more modest value for TESTNET4:
-pub const INITIAL_DIFFICULTY: u64 = 1_000 * MIN_DIFFICULTY;
+pub const INITIAL_DIFFICULTY: u64 = 1_000_000 * UNIT_DIFFICULTY;
 
 /// Consensus errors
 #[derive(Clone, Debug, Eq, PartialEq, Fail)]

core/src/global.rs

@@ -20,6 +20,7 @@ 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,
+	UNIT_DIFFICULTY
 };
 use pow::{self, CuckatooContext, EdgeType, PoWContext};
 /// An enum collecting sets of parameters used throughout the
@@ -71,7 +72,7 @@ pub const STUCK_PEER_KICK_TIME: i64 = 2 * 3600 * 1000;
 
 /// Testnet 4 initial block difficulty
 /// 1_000 times natural scale factor for cuckatoo29
-pub const TESTNET4_INITIAL_DIFFICULTY: u64 = 1_000 * (2 << (29 - 24)) * 29;
+pub const TESTNET4_INITIAL_DIFFICULTY: u64 = 1_000 * UNIT_DIFFICULTY;
 
 /// Trigger compaction check on average every day for FAST_SYNC_NODE,
 /// roll the dice on every block to decide,

core/src/pow/types.rs

@@ -70,6 +70,11 @@ impl Difficulty {
 		Difficulty { num: 1 }
 	}
 
+	/// Difficulty unit, which is the graph weight of minimal graph
+	pub fn unit() -> Difficulty {
+		Difficulty { num: global::initial_graph_weight() }
+	}
+
 	/// Convert a `u32` into a `Difficulty`
 	pub fn from_num(num: u64) -> Difficulty {
 		// can't have difficulty lower than 1

core/tests/consensus.rs

@@ -383,36 +383,37 @@ fn next_target_adjustment() {
 	let cur_time = Utc::now().timestamp() as u64;
 
 	let diff_one = Difficulty::one();
+	let diff_unit = Difficulty::unit();
 	assert_eq!(
 		next_difficulty(1, vec![HeaderInfo::from_ts_diff(cur_time, diff_one)]),
-		HeaderInfo::from_diff_scaling(Difficulty::one(), 1),
+		HeaderInfo::from_diff_scaling(diff_one, diff_unit),
 	);
 	assert_eq!(
 		next_difficulty(1, vec![HeaderInfo::new(cur_time, diff_one, 10, true)]),
-		HeaderInfo::from_diff_scaling(Difficulty::one(), 1),
+		HeaderInfo::from_diff_scaling(diff_one, 1),
 	);
 
 	let mut hi = HeaderInfo::from_diff_scaling(diff_one, 1);
 	assert_eq!(
 		next_difficulty(1, repeat(60, hi.clone(), DIFFICULTY_ADJUST_WINDOW, None)),
-		HeaderInfo::from_diff_scaling(Difficulty::one(), 1),
+		HeaderInfo::from_diff_scaling(diff_one, 1),
 	);
 	hi.is_secondary = true;
 	assert_eq!(
 		next_difficulty(1, repeat(60, hi.clone(), DIFFICULTY_ADJUST_WINDOW, None)),
-		HeaderInfo::from_diff_scaling(Difficulty::one(), 1),
+		HeaderInfo::from_diff_scaling(diff_one, 1),
 	);
 	hi.secondary_scaling = 100;
 	assert_eq!(
 		next_difficulty(1, repeat(60, hi.clone(), DIFFICULTY_ADJUST_WINDOW, None)),
-		HeaderInfo::from_diff_scaling(Difficulty::one(), 96),
+		HeaderInfo::from_diff_scaling(diff_one, 96),
 	);
 
 	// Check we don't get stuck on difficulty 1
 	let mut hi = HeaderInfo::from_diff_scaling(Difficulty::from_num(10), 1);
 	assert_ne!(
 		next_difficulty(1, repeat(1, hi.clone(), DIFFICULTY_ADJUST_WINDOW, None)).difficulty,
-		Difficulty::one()
+		diff_one
 	);
 
 	// just enough data, right interval, should stay constant