Merge pull request #1590 from jacqueswww/minor-speed-ups

Just for fun: Minor speedup on CodeStream.

Author: carver

eth/vm/code_stream.py

@@ -15,20 +15,24 @@
 class CodeStream(object):
     stream = None
     depth_processed = None
+    _length_cache = None
+    _raw_code_bytes = None
 
     logger = logging.getLogger('eth.vm.CodeStream')
 
     def __init__(self, code_bytes: bytes) -> None:
         validate_is_bytes(code_bytes, title="CodeStream bytes")
         self.stream = io.BytesIO(code_bytes)
+        self._raw_code_bytes = code_bytes
+        self._length_cache = len(code_bytes)
         self.invalid_positions = set()  # type: Set[int]
         self.depth_processed = 0
 
     def read(self, size: int) -> bytes:
         return self.stream.read(size)
 
     def __len__(self) -> int:
-        return len(self.stream.getvalue())
+        return self._length_cache
 
     def __iter__(self) -> 'CodeStream':
         return self
@@ -37,7 +41,7 @@ def __next__(self) -> int:
         return self.next()
 
     def __getitem__(self, i: int) -> int:
-        return self.stream.getvalue()[i]
+        return self._raw_code_bytes[i]
 
     def next(self) -> int:
         next_opcode_as_byte = self.read(1)
@@ -73,7 +77,7 @@ def seek(self, pc: int) -> Iterator['CodeStream']:
     invalid_positions = None
 
     def is_valid_opcode(self, position: int) -> bool:
-        if position >= len(self):
+        if position >= self._length_cache:
             return False
         if position in self.invalid_positions:
             return False