Add gil_release_mode to CRC32CHash.__init__

This makes the API more symmetric with crc32c, offering its full set of
possibilities to users.

Signed-off-by: Rodrigo Tobar <rtobar@icrar.org>

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Development
 
+* Added a `gil_relese_mode` parameter to the `CRC32CHash` constructor
+  used by all underlying `crc32c` function calls (#51).
+
 ## [2.6]
 
 * Added new `crc32c.CRC32CHash` class

README.rst

@@ -57,7 +57,7 @@ It can be set to the following values:
 * Positive: Always release the GIL
 
 On top of the ``crc32c`` function,
-a ``CRC32CHash`` class is also offered.
+a ``CRC32CHash(data=b"", gil_release_mode=-1)`` class is also offered.
 It is modelled after the "hash objects" of the ``hashlib`` module
 of the standard library:
 

src/crc32c/__init__.py

@@ -36,19 +36,23 @@ def name(self) -> str:
         """
         return "crc32c"
 
-    def __init__(self, data: Buffer = b"") -> None:
+    def __init__(self, data: Buffer = b"", gil_release_mode: int = -1) -> None:
         """
         Initialise the hash object with an optional bytes-like object.
+        Uses the given GIL release mode on each checksum calculation.
         """
-        self._checksum = crc32c(data)
+        self._checksum = crc32c(data, gil_release_mode=gil_release_mode)
+        self._gil_release_mode = gil_release_mode
 
     def update(self, data: Buffer) -> None:
         """
         Update the hash object with the bytes-like object.
         Repeated calls are equivalent to a single call with the concatenation of all the arguments:
         m.update(a); m.update(b) is equivalent to m.update(a+b).
         """
-        self._checksum = crc32c(data, self._checksum)
+        self._checksum = crc32c(
+            data, self._checksum, gil_release_mode=self._gil_release_mode
+        )
 
     def digest(self) -> bytes:
         """
@@ -72,4 +76,5 @@ def copy(self) -> Self:
         """
         res = type(self)()
         res._checksum = self._checksum
+        res._gil_release_mode = self._gil_release_mode
         return res