refactor: Optimize data hashing and improve empty input handling in DataHasherV0

Author: titusz

iscc_core/code_data.py

@@ -84,26 +84,19 @@ def __init__(self, data=None):
         self.push(data)
 
     def push(self, data):
-        # type: (ic.Data) -> None
-        """Push data to the Data-Hash generator."""
         if self.tail:
             data = self.tail + data
-            self.tail = None
-
         chunks = ic.alg_cdc_chunks(
             data, utf32=False, avg_chunk_size=ic.core_opts.data_avg_chunk_size
         )
-
-        # Process chunks one at a time but keep track of last one
-        last_chunk = None
+        prev_chunk = None
         for chunk in chunks:
-            if last_chunk is not None:
-                self.chunk_sizes.append(len(last_chunk))
-                self.chunk_features.append(xxhash.xxh32_intdigest(last_chunk))
-            last_chunk = chunk
-
-        # Buffer the last chunk as it may be incomplete
-        self.tail = last_chunk if last_chunk is not None else None
+            if prev_chunk is not None:  # Process only if we’ve seen a prior chunk
+                self.chunk_sizes.append(len(prev_chunk))
+                self.chunk_features.append(xxhash.xxh32_intdigest(prev_chunk))
+            prev_chunk = chunk
+        # Handle the case where no chunks were yielded (empty input)
+        self.tail = prev_chunk if prev_chunk is not None else b""
 
     def digest(self):
         # type: () -> bytes
@@ -131,8 +124,12 @@ def code(self, bits=ic.core_opts.data_bits):
 
     def _finalize(self):
         if self.tail is not None:
-            self.chunk_features.append(xxhash.xxh32_intdigest(self.tail))
-            self.chunk_sizes.append(len(self.tail))
+            if self.tail:  # Append non-empty tail
+                self.chunk_features.append(xxhash.xxh32_intdigest(self.tail))
+                self.chunk_sizes.append(len(self.tail))
+            elif not self.chunk_features:  # Empty input case: ensure at least one feature
+                self.chunk_features.append(xxhash.xxh32_intdigest(b""))
+                self.chunk_sizes.append(0)
             self.tail = None
 
 

iscc_core/iscc_id.py

@@ -173,3 +173,8 @@ def alg_simhash_from_iscc_id(iscc_id, wallet):
     iscc_id_xor_digest = iscc_tuple[4][:8]
     iscc_id_digest = bytes(a ^ b for (a, b) in zip(iscc_id_xor_digest, wallet_hash_digest))
     return iscc_id_digest.hex()
+
+
+####################################################################################################
+# ISCC-IDv1 - New Timestamp/Server-ID based ISCC-ID                                                #
+####################################################################################################