Small deserialization speedup (#2852)

When walking AriVtx, parsing integers and nibbles actually becomes a
hotspot - these trivial changes reduces CPU usage during initial key
cache computation by ~15%.

nimbus/db/aristo/aristo_blobify.nim

@@ -68,10 +68,12 @@ proc deblobify*[T: uint64|VertexID](data: openArray[byte], _: type T): Result[T,
   if data.len < 1 or data.len > 8:
     return err(Deblob64LenUnsupported)
 
-  var tmp: array[8, byte]
+  var tmp = 0'u64
-  discard tmp.toOpenArray(8 - data.len, 7).copyFrom(data)
+  let start = 8 - data.len
+  for i in 0..<data.len:
+    tmp += uint64(data[i]) shl (8*(7-(i + start)))
 
-  ok T(uint64.fromBytesBE(tmp))
+  ok T(tmp)
 
 proc deblobify*(data: openArray[byte], _: type UInt256): Result[UInt256,AristoError] =
   if data.len < 1 or data.len > 32:

nimbus/db/aristo/aristo_desc/desc_nibbles.nim

@@ -122,28 +122,33 @@ func startsWith*(lhs, rhs: NibblesBuf): bool =
 
 func fromHexPrefix*(
     T: type NibblesBuf, r: openArray[byte]
-): tuple[isLeaf: bool, nibbles: NibblesBuf] =
+): tuple[isLeaf: bool, nibbles: NibblesBuf] {.noinit.} =
+  result.nibbles.ibegin = 0
+
   if r.len > 0:
     result.isLeaf = (r[0] and 0x20) != 0
     let hasOddLen = (r[0] and 0x10) != 0
 
-    var i = 0'i8
+    result.nibbles.iend =
       if hasOddLen:
-      result.nibbles[0] = r[0] and 0x0f
+        result.nibbles.bytes[0] = r[0] shl 4
-      i += 1
 
-    for j in 1 ..< r.len:
+        let bytes = min(31, r.len - 1)
-      if i >= 64:
+        for j in 0 ..< bytes:
-        break
+          result.nibbles.bytes[j] = result.nibbles.bytes[j] or r[j + 1] shr 4
-      result.nibbles[i] = r[j] shr 4
+          result.nibbles.bytes[j + 1] = r[j + 1] shl 4
-      result.nibbles[i + 1] = r[j] and 0x0f
-      i += 2
 
-    result.nibbles.iend = i
+        int8(bytes) * 2 + 1
+      else:
+        let bytes = min(32, r.len - 1)
+        assign(result.nibbles.bytes.toOpenArray(0, bytes - 1), r.toOpenArray(1, bytes))
+        int8(bytes) * 2
   else:
     result.isLeaf = false
+    result.nibbles.iend = 0
 
 func `&`*(a, b: NibblesBuf): NibblesBuf {.noinit.} =
+  result.ibegin = 0
   for i in 0 ..< a.len:
     result[i] = a[i]
 

tests/test_aristo.nim

@@ -20,6 +20,7 @@ import
   ./replay/pp,
   ./test_aristo/test_blobify,
   ./test_aristo/test_merge_proof,
+  ./test_aristo/test_nibbles,
   ./test_aristo/test_portal_proof,
   ./test_aristo/test_compute,
   ./test_aristo/[

tests/test_aristo/test_nibbles.nim

@@ -0,0 +1,86 @@
+# Nimbus
+# Copyright (c) 2024 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+#    http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+#    http://opensource.org/licenses/MIT)
+# at your option. This file may not be copied, modified, or
+# distributed except according to those terms.
+
+{.used.}
+
+import
+  std/sequtils,
+  stew/byteutils,
+  unittest2,
+  ../../nimbus/db/aristo/aristo_desc/desc_nibbles
+
+suite "Nibbles":
+  test "trivial cases":
+    block:
+      let n = NibblesBuf.fromBytes([])
+      check:
+        n.len == 0
+    block:
+      let n = NibblesBuf.fromBytes([byte 0x10])
+      check:
+        n.len == 2
+        n[0] == 1
+        n[1] == 0
+        $n.slice(1) == "0"
+        $n.slice(2) == ""
+
+    block:
+      let n = NibblesBuf.fromBytes(repeat(byte 0x12, 32))
+      check:
+        n.len == 64
+        n[0] == 1
+        n[63] == 2
+
+    block:
+      let n = NibblesBuf.fromBytes(repeat(byte 0x12, 33))
+      check:
+        n.len == 64
+        n[0] == 1
+        n[63] == 2
+
+  test "to/from hex encoding":
+    block:
+      let n = NibblesBuf.fromBytes([byte 0x12, 0x34, 0x56])
+
+      let
+        he = n.toHexPrefix(true)
+        ho = n.slice(1).toHexPrefix(true)
+
+      check:
+        NibblesBuf.fromHexPrefix(he.data()) == (true, n)
+        NibblesBuf.fromHexPrefix(ho.data()) == (true, n.slice(1))
+    block:
+      let n = NibblesBuf.fromBytes(repeat(byte 0x12, 32))
+
+      let
+        he = n.toHexPrefix(true)
+        ho = n.slice(1).toHexPrefix(true)
+
+      check:
+        NibblesBuf.fromHexPrefix(he.data()) == (true, n)
+        NibblesBuf.fromHexPrefix(ho.data()) == (true, n.slice(1))
+
+        NibblesBuf.fromHexPrefix(@(he.data()) & @[byte 1]) == (true, n)
+        NibblesBuf.fromHexPrefix(@(ho.data()) & @[byte 1]) == (true, n.slice(1))
+
+  test "long":
+    let n = NibblesBuf.fromBytes(
+      hexToSeqByte("0100000000000000000000000000000000000000000000000000000000000000")
+    )
+
+    check $n == "0100000000000000000000000000000000000000000000000000000000000000"
+    check $n.slice(1) == "100000000000000000000000000000000000000000000000000000000000000"
+
+    let
+      he = n.toHexPrefix(true)
+      ho = n.slice(1).toHexPrefix(true)
+    check:
+      NibblesBuf.fromHexPrefix(he.data()) == (true, n)
+      NibblesBuf.fromHexPrefix(ho.data()) == (true, n.slice(1))