Agent: Add performance-related TODOs to bit_manipulators.py

monkey/infection_monkey/utils/bit_manipulators.py

@@ -2,10 +2,25 @@ def flip_bits(data: bytes) -> bytes:
     flipped_bits = bytearray(len(data))
 
     for i, byte in enumerate(data):
+        # TODO: The function call to flip_bits_in_single_byte() adds significant
+        #       overhead. While python is supposed to "inline" function calls
+        #       like this, I've yet to see any changes in runtime that indicate
+        #       this optimization is actually happening.
+        #
+        #       The value of breaking this into separate functions is the unit
+        #       test that tests all possible bytes (0-255). This gives us
+        #       confidence that our bit-flip operation is correct.
+        #
+        #       Remove the flip_bits_in_single_byte() function and rework the
+        #       unit tests so that we still have a high-degree of confidence
+        #       that this code is correct.
         flipped_bits[i] = flip_bits_in_single_byte(byte)
 
     return bytes(flipped_bits)
 
 
 def flip_bits_in_single_byte(byte) -> int:
+    # TODO: The operation `255 - byte` appears to be 12% faster than 255 ^ byte.
+    #       Switch the operator and thoroughly test the ransomware payload to
+    #       ensure this doesn't introduce any defects.
     return 255 ^ byte