v1.9.0 Random subclass, fetch timeout

Author: calebj

quantumrandom/__init__.py

@@ -38,14 +38,16 @@
 except ImportError:
     import simplejson as json
 
-VERSION = '1.9.0'
+from quantumrandom.qrandom import QuantumRandom
+
+VERSION = '1.10.0'
 URL = 'https://qrng.anu.edu.au/API/jsonI.php'
 DATA_TYPES = ['uint16', 'hex16']
 MAX_LEN = 1024
 INT_BITS = 16
 
 
-def get_data(data_type='uint16', array_length=1, block_size=1):
+def get_data(data_type='uint16', array_length=1, block_size=1, timeout=None):
     """Fetch data from the ANU Quantum Random Numbers JSON API"""
     if data_type not in DATA_TYPES:
         raise Exception("data_type must be one of %s" % DATA_TYPES)
@@ -58,15 +60,15 @@ def get_data(data_type='uint16', array_length=1, block_size=1):
         'length': array_length,
         'size': block_size,
     })
-    data = get_json(url)
+    data = get_json(url, timeout=timeout)
     assert data['success'] is True, data
     assert data['length'] == array_length, data
     return data['data']
 
 
 if sys.version_info[0] == 2:
-    def get_json(url):
-        return json.loads(urlopen(url).read(), object_hook=_object_hook)
+    def get_json(url, timeout=None):
+        return json.loads(urlopen(url, timeout=timeout).read(), object_hook=_object_hook)
 
     def _object_hook(obj):
         """We are only dealing with ASCII characters"""
@@ -84,21 +86,21 @@ def next(it, default=_sentinel):
                     raise
                 return default
 else:
-    def get_json(url):
-        return json.loads(urlopen(url).read().decode('ascii'))
+    def get_json(url, timeout=None):
+        return json.loads(urlopen(url, timeout=timeout).read().decode('ascii'))
 
 
-def binary(array_length=100, block_size=100):
+def binary(array_length=100, block_size=100, **kwargs):
     """Return a chunk of binary data"""
-    return binascii.unhexlify(six.b(hex(array_length, block_size)))
+    return binascii.unhexlify(six.b(hex(array_length, block_size, **kwargs)))
 
 
-def hex(array_length=100, block_size=100):
+def hex(array_length=100, block_size=100, **kwargs):
     """Return a chunk of hex"""
-    return ''.join(get_data('hex16', array_length, block_size))
+    return ''.join(get_data('hex16', array_length, block_size, **kwargs))
 
 
-def randint(min=0, max=10, generator=None):
+def randint(min=0, max=10, generator=None, **kwargs):
     """Return an int between min and max. If given, takes from generator instead.
     This can be useful to reuse the same cached_generator() instance over multiple calls."""
     rand_range = max - min
@@ -107,7 +109,7 @@ def randint(min=0, max=10, generator=None):
         return min
 
     if generator is None:
-        generator = cached_generator()
+        generator = cached_generator(**kwargs)
 
     source_bits = int(math.ceil(math.log(rand_range + 1, 2)))
     source_size = int(math.ceil(source_bits / float(INT_BITS)))
@@ -126,17 +128,17 @@ def randint(min=0, max=10, generator=None):
             return num / modulos + min
 
 
-def uint16(array_length=100):
+def uint16(array_length=100, **kwargs):
     """Return a numpy array of uint16 numbers"""
     import numpy
-    return numpy.array(get_data('uint16', array_length), dtype=numpy.uint16)
+    return numpy.array(get_data('uint16', array_length, **kwargs), dtype=numpy.uint16)
 
 
-def cached_generator(data_type='uint16', cache_size=1024):
+def cached_generator(data_type='uint16', cache_size=1024, **kwargs):
     """Returns numbers. Caches numbers to avoid latency."""
     while 1:
-        for n in get_data(data_type, cache_size, cache_size):
+        for n in get_data(data_type, cache_size, cache_size, **kwargs):
             yield n
 
 
-__all__ = ['get_data', 'binary', 'hex', 'uint16', 'cached_generator', 'randint']
+__all__ = ['get_data', 'binary', 'hex', 'uint16', 'cached_generator', 'randint', 'QuantumRandom']

quantumrandom/qrandom.py

@@ -0,0 +1,121 @@
+from binascii import hexlify as _hexlify
+from random import Random, RECIP_BPF
+import quantumrandom
+import six
+import threading
+
+
+_longint = int if six.PY3 else long
+
+
+class _QRBackgroundFetchThread(threading.Thread):
+    def __init__(self, qr):
+        self.qr = qr
+        self.should_fetch = threading.Event()
+        self.idle = threading.Event()
+        threading.Thread.__init__(self)
+        self.daemon = True
+        self.start()
+
+    def run(self):
+        while self.should_fetch.wait():
+            self.idle.clear()
+            try:
+                self.qr._refresh()
+            finally:
+                self.idle.set()
+                self.should_fetch.clear()
+
+
+class QuantumRandom(Random):
+    "An implementation of random.Random that uses the ANU quantum random API"
+    def __init__(self, x=None, cached_bytes=1024, autofetch_at=1024-64, fetch_timeout=None):
+        self._fetcher = None
+        self._autofetch_at = autofetch_at
+        self._fetch_timeout = fetch_timeout
+
+        if cached_bytes:
+            self._buf_idx = 1024  # start uninitialized
+            self._buf_len = cached_bytes
+            self._buf_lock = threading.RLock()
+            self._cache_buf = bytearray(cached_bytes)
+
+            if autofetch_at:
+                self._fetcher = _QRBackgroundFetchThread(self)
+                self._fetcher.should_fetch.set()
+        else:
+            self._autofetch_at = None
+            self._cache_buf = None
+
+        Random.__init__(self, x)
+
+    def _fetch_qr(self, b):
+        if b > 1024:
+            blocks = (b + 1023) // 1024
+            block_size = 1024
+        else:
+            blocks = 1
+            block_size = b
+
+        return quantumrandom.binary(blocks, block_size, timeout=self._fetch_timeout)
+
+    def _refresh(self, over=0):
+        refresh = self._fetch_qr(self._buf_len + over)
+
+        with self._buf_lock:
+            self._cache_buf[:] = refresh[over:]
+            self._buf_idx = 0
+
+        if over:
+            return refresh[:over]
+
+    def _qrandom(self, b):
+        if self._cache_buf:
+            with self._buf_lock:
+                ret = self._cache_buf[self._buf_idx : self._buf_idx + b]
+                over = self._buf_idx + b - self._buf_len
+
+            if over > 0:
+                if self._fetcher and self._fetcher.idle.is_set():
+                    ret += self._refresh(over)
+                else:
+                    self._fetcher and self._fetcher.idle.wait()
+                    ret += self._qrandom(over)
+            else:
+                self._buf_idx += b
+
+            # notify the background thread that we need more data
+            if (self._autofetch_at and self._buf_idx > self._autofetch_at
+                    and not self._fetcher.should_fetch.is_set()):
+                self._fetcher.should_fetch.set()
+
+            return ret
+        else:
+            return self._fetch_qr(b)
+
+    def random(self):
+        intstr = _hexlify(self._qrandom(7))
+        return (_longint(intstr, 16) >> 3) * RECIP_BPF
+
+    def getrandbits(self, k):
+        if k <= 0:
+            raise ValueError('number of bits must be greater than zero')
+        if k != int(k):
+            raise TypeError('number of bits should be an integer')
+
+        # bits / 8 and rounded up
+        numbytes = (k + 7) // 8
+        x = _longint(_hexlify(self._qrandom(numbytes)), 16)
+        # trim excess bits
+        return x >> (numbytes * 8 - k)
+
+    def seed(self, *args, **kwds):
+        return None
+
+    def _notimplemented(self, *args, **kwds):
+        raise NotImplementedError('Quantum entropy source does not have state.')
+
+    getstate = setstate = _notimplemented
+
+
+__all__ = ['QuantumRandom']

setup.py

@@ -1,7 +1,7 @@
 from setuptools import setup, find_packages
 import sys
 
-version = '1.9.0'
+version = '1.10.0'
 
 f = open('README.rst')
 long_description = f.read()