MAINT: remove the entropy c-extension module

doc/release/upcoming_changes/14498.changes.rst

@@ -0,0 +1,7 @@
+Remove ``numpy.random.entropy`` without a deprecation
+-----------------------------------------------------
+
+``numpy.random.entropy`` was added to the `numpy.random` namespace in 1.17.0.
+It was meant to be a private c-extension module, but was exposed as public.
+It has been replaced by `numpy.random.SeedSequence` so the module was
+completely removed.

doc/source/reference/random/index.rst

@@ -151,9 +151,6 @@ What's New or Different
   select distributions
 * Optional ``out`` argument that allows existing arrays to be filled for
   select distributions
-* `~entropy.random_entropy` provides access to the system
-  source of randomness that is used in cryptographic applications (e.g.,
-  ``/dev/urandom`` on Unix).
 * All BitGenerators can produce doubles, uint64s and uint32s via CTypes
   (`~.PCG64.ctypes`) and CFFI (`~.PCG64.cffi`). This allows the bit generators
   to be used in numba.
@@ -203,7 +200,6 @@ Features
    new-or-different
    Comparing Performance <performance>
    extending
-   Reading System Entropy <entropy>
 
 Original Source
 ~~~~~~~~~~~~~~~

doc/source/reference/random/new-or-different.rst

@@ -45,9 +45,6 @@ Feature            Older Equivalent     Notes
 
 And in more detail:
 
-* `~.entropy.random_entropy` provides access to the system
-  source of randomness that is used in cryptographic applications (e.g.,
-  ``/dev/urandom`` on Unix).
 * Simulate from the complex normal distribution
   (`~.Generator.complex_normal`)
 * The normal, exponential and gamma generators use 256-step Ziggurat

numpy/random/__init__.py

@@ -181,7 +181,6 @@
 from . import _pickle
 from . import common
 from . import bounded_integers
-from . import entropy
 
 from .mtrand import *
 from .generator import Generator, default_rng

numpy/random/mt19937.pyx

@@ -5,7 +5,6 @@ cimport numpy as np
 
 from .common cimport *
 from .bit_generator cimport BitGenerator, SeedSequence
-from .entropy import random_entropy
 
 __all__ = ['MT19937']
 
@@ -156,7 +155,8 @@ cdef class MT19937(BitGenerator):
             Random seed initializing the pseudo-random number generator.
             Can be an integer in [0, 2**32-1], array of integers in
             [0, 2**32-1], a `SeedSequence, or ``None``. If `seed`
-            is ``None``, then sample entropy for a seed.
+            is ``None``, then fresh, unpredictable entropy will be pulled from
+            the OS.
 
         Raises
         ------
@@ -167,7 +167,8 @@ cdef class MT19937(BitGenerator):
         with self.lock:
             try:
                 if seed is None:
-                    val = random_entropy(RK_STATE_LEN)
+                    seed = SeedSequence()
+                    val = seed.generate_state(RK_STATE_LEN)
                     # MSB is 1; assuring non-zero initial array
                     self.rng_state.key[0] = 0x80000000UL
                     for i in range(1, RK_STATE_LEN):

numpy/random/setup.py

@@ -61,18 +61,6 @@ def generate_libraries(ext, build_dir):
     # One can force emulated 128-bit arithmetic if one wants.
     #PCG64_DEFS += [('PCG_FORCE_EMULATED_128BIT_MATH', '1')]
 
-    config.add_extension('entropy',
-                         sources=['entropy.c', 'src/entropy/entropy.c'] +
-                                 [generate_libraries],
-                         libraries=EXTRA_LIBRARIES,
-                         extra_compile_args=EXTRA_COMPILE_ARGS,
-                         extra_link_args=EXTRA_LINK_ARGS,
-                         depends=[join('src', 'splitmix64', 'splitmix.h'),
-                                  join('src', 'entropy', 'entropy.h'),
-                                  'entropy.pyx',
-                                  ],
-                         define_macros=defs,
-                         )
     for gen in ['mt19937']:
         # gen.pyx, src/gen/gen.c, src/gen/gen-jump.c
         config.add_extension(gen,