Optimize POW read (#3035)

* Optimize POW read

This functionality is used to deserialize header (from network or from
DB), it was taking up to 40% cpu time during initial header sync. This
PR brings it down to 3-4%. Function read_number would look better as
closure, unfortunately the compliler doesn't inline it in this case, so
it would be 2x slower.

* Remove unused code

core/src/global.rs

@@ -42,10 +42,10 @@ use crate::util::RwLock;
 pub const PROTOCOL_VERSION: u32 = 1;
 
 /// Automated testing edge_bits
-pub const AUTOMATED_TESTING_MIN_EDGE_BITS: u8 = 9;
+pub const AUTOMATED_TESTING_MIN_EDGE_BITS: u8 = 10;
 
 /// Automated testing proof size
-pub const AUTOMATED_TESTING_PROOF_SIZE: usize = 4;
+pub const AUTOMATED_TESTING_PROOF_SIZE: usize = 8;
 
 /// User testing edge_bits
 pub const USER_TESTING_MIN_EDGE_BITS: u8 = 15;

core/src/pow/types.rs

@@ -391,6 +391,23 @@ impl Proof {
 	}
 }
 
+#[inline(always)]
+fn read_number(bits: &Vec<u8>, bit_start: usize, bit_count: usize) -> u64 {
+	if bit_count == 0 {
+		return 0;
+	}
+	let mut buf: [u8; 8] = [0; 8];
+	let mut byte_start = bit_start / 8;
+	if byte_start + 8 > bits.len() {
+		byte_start = bits.len() - 8;
+	}
+	buf.copy_from_slice(&bits[byte_start..byte_start + 8]);
+	buf.reverse();
+	let mut nonce = u64::from_be_bytes(buf);
+	nonce = nonce << 64 - (bit_start - byte_start * 8) - bit_count;
+	nonce >> 64 - bit_count
+}
+
 impl Readable for Proof {
 	fn read(reader: &mut dyn Reader) -> Result<Proof, ser::Error> {
 		let edge_bits = reader.read_u8()?;
@@ -405,24 +422,15 @@ impl Readable for Proof {
 		let bytes_len = BitVec::bytes_len(bits_len);
 		let bits = reader.read_fixed_bytes(bytes_len)?;
 
-		// set our nonces from what we read in the bitvec
-		let bitvec = BitVec { bits };
 		for n in 0..global::proofsize() {
-			let mut nonce = 0;
-			for bit in 0..nonce_bits {
-				if bitvec.bit_at(n * nonce_bits + (bit as usize)) {
-					nonce |= 1 << bit;
-				}
-			}
-			nonces.push(nonce);
+			nonces.push(read_number(&bits, n * nonce_bits, nonce_bits));
 		}
 
-		// check the last bits of the last byte are zeroed, we don't use them but
-		// still better to enforce to avoid any malleability
-		for n in bits_len..(bytes_len * 8) {
-			if bitvec.bit_at(n) {
-				return Err(ser::Error::CorruptedData);
-			}
+		//// check the last bits of the last byte are zeroed, we don't use them but
+		//// still better to enforce to avoid any malleability
+		let end_of_data = global::proofsize() * nonce_bits;
+		if read_number(&bits, end_of_data, bytes_len * 8 - end_of_data) != 0 {
+			return Err(ser::Error::CorruptedData);
 		}
 
 		Ok(Proof { edge_bits, nonces })
@@ -469,8 +477,4 @@ impl BitVec {
 	fn set_bit_at(&mut self, pos: usize) {
 		self.bits[pos / 8] |= 1 << (pos % 8) as u8;
 	}
-
-	fn bit_at(&self, pos: usize) -> bool {
-		self.bits[pos / 8] & (1 << (pos % 8) as u8) != 0
-	}
 }

core/tests/block.rs

@@ -269,7 +269,7 @@ fn empty_block_serialized_size() {
 	let b = new_block(vec![], &keychain, &builder, &prev, &key_id);
 	let mut vec = Vec::new();
 	ser::serialize_default(&mut vec, &b).expect("serialization failed");
-	let target_len = 1_107;
+	let target_len = 1_112;
 	assert_eq!(vec.len(), target_len);
 }
 
@@ -284,7 +284,7 @@ fn block_single_tx_serialized_size() {
 	let b = new_block(vec![&tx1], &keychain, &builder, &prev, &key_id);
 	let mut vec = Vec::new();
 	ser::serialize_default(&mut vec, &b).expect("serialization failed");
-	let target_len = 2_689;
+	let target_len = 2_694;
 	assert_eq!(vec.len(), target_len);
 }
 
@@ -299,7 +299,7 @@ fn empty_compact_block_serialized_size() {
 	let cb: CompactBlock = b.into();
 	let mut vec = Vec::new();
 	ser::serialize_default(&mut vec, &cb).expect("serialization failed");
-	let target_len = 1_115;
+	let target_len = 1_120;
 	assert_eq!(vec.len(), target_len);
 }
 
@@ -315,7 +315,7 @@ fn compact_block_single_tx_serialized_size() {
 	let cb: CompactBlock = b.into();
 	let mut vec = Vec::new();
 	ser::serialize_default(&mut vec, &cb).expect("serialization failed");
-	let target_len = 1_121;
+	let target_len = 1_126;
 	assert_eq!(vec.len(), target_len);
 }
 
@@ -335,7 +335,7 @@ fn block_10_tx_serialized_size() {
 	let b = new_block(txs.iter().collect(), &keychain, &builder, &prev, &key_id);
 	let mut vec = Vec::new();
 	ser::serialize_default(&mut vec, &b).expect("serialization failed");
-	let target_len = 16_927;
+	let target_len = 16_932;
 	assert_eq!(vec.len(), target_len,);
 }
 
@@ -356,7 +356,7 @@ fn compact_block_10_tx_serialized_size() {
 	let cb: CompactBlock = b.into();
 	let mut vec = Vec::new();
 	ser::serialize_default(&mut vec, &cb).expect("serialization failed");
-	let target_len = 1_175;
+	let target_len = 1_180;
 	assert_eq!(vec.len(), target_len,);
 }