python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Lib/multiprocessing/heap.py

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+#
+# Module which supports allocation of memory from an mmap
+#
+# multiprocessing/heap.py
+#
+# Copyright (c) 2006-2008, R Oudkerk
+# Licensed to PSF under a Contributor Agreement.
+#
+
+import bisect
+import mmap
+import os
+import sys
+import tempfile
+import threading
+
+from .context import reduction, assert_spawning
+from . import util
+
+__all__ = ['BufferWrapper']
+
+#
+# Inheritable class which wraps an mmap, and from which blocks can be allocated
+#
+
+if sys.platform == 'win32':
+
+    import _winapi
+
+    class Arena(object):
+
+        _rand = tempfile._RandomNameSequence()
+
+        def __init__(self, size):
+            self.size = size
+            for i in range(100):
+                name = 'pym-%d-%s' % (os.getpid(), next(self._rand))
+                buf = mmap.mmap(-1, size, tagname=name)
+                if _winapi.GetLastError() == 0:
+                    break
+                # We have reopened a preexisting mmap.
+                buf.close()
+            else:
+                raise FileExistsError('Cannot find name for new mmap')
+            self.name = name
+            self.buffer = buf
+            self._state = (self.size, self.name)
+
+        def __getstate__(self):
+            assert_spawning(self)
+            return self._state
+
+        def __setstate__(self, state):
+            self.size, self.name = self._state = state
+            self.buffer = mmap.mmap(-1, self.size, tagname=self.name)
+            # XXX Temporarily preventing buildbot failures while determining
+            # XXX the correct long-term fix. See issue 23060
+            #assert _winapi.GetLastError() == _winapi.ERROR_ALREADY_EXISTS
+
+else:
+
+    class Arena(object):
+
+        def __init__(self, size, fd=-1):
+            self.size = size
+            self.fd = fd
+            if fd == -1:
+                self.fd, name = tempfile.mkstemp(
+                     prefix='pym-%d-'%os.getpid(), dir=util.get_temp_dir())
+                os.unlink(name)
+                util.Finalize(self, os.close, (self.fd,))
+                with open(self.fd, 'wb', closefd=False) as f:
+                    bs = 1024 * 1024
+                    if size >= bs:
+                        zeros = b'\0' * bs
+                        for _ in range(size // bs):
+                            f.write(zeros)
+                        del zeros
+                    f.write(b'\0' * (size % bs))
+                    assert f.tell() == size
+            self.buffer = mmap.mmap(self.fd, self.size)
+
+    def reduce_arena(a):
+        if a.fd == -1:
+            raise ValueError('Arena is unpicklable because '
+                             'forking was enabled when it was created')
+        return rebuild_arena, (a.size, reduction.DupFd(a.fd))
+
+    def rebuild_arena(size, dupfd):
+        return Arena(size, dupfd.detach())
+
+    reduction.register(Arena, reduce_arena)
+
+#
+# Class allowing allocation of chunks of memory from arenas
+#
+
+class Heap(object):
+
+    _alignment = 8
+
+    def __init__(self, size=mmap.PAGESIZE):
+        self._lastpid = os.getpid()
+        self._lock = threading.Lock()
+        self._size = size
+        self._lengths = []
+        self._len_to_seq = {}
+        self._start_to_block = {}
+        self._stop_to_block = {}
+        self._allocated_blocks = set()
+        self._arenas = []
+        # list of pending blocks to free - see free() comment below
+        self._pending_free_blocks = []
+
+    @staticmethod
+    def _roundup(n, alignment):
+        # alignment must be a power of 2
+        mask = alignment - 1
+        return (n + mask) & ~mask
+
+    def _malloc(self, size):
+        # returns a large enough block -- it might be much larger
+        i = bisect.bisect_left(self._lengths, size)
+        if i == len(self._lengths):
+            length = self._roundup(max(self._size, size), mmap.PAGESIZE)
+            self._size *= 2
+            util.info('allocating a new mmap of length %d', length)
+            arena = Arena(length)
+            self._arenas.append(arena)
+            return (arena, 0, length)
+        else:
+            length = self._lengths[i]
+            seq = self._len_to_seq[length]
+            block = seq.pop()
+            if not seq:
+                del self._len_to_seq[length], self._lengths[i]
+
+        (arena, start, stop) = block
+        del self._start_to_block[(arena, start)]
+        del self._stop_to_block[(arena, stop)]
+        return block
+
+    def _free(self, block):
+        # free location and try to merge with neighbours
+        (arena, start, stop) = block
+
+        try:
+            prev_block = self._stop_to_block[(arena, start)]
+        except KeyError:
+            pass
+        else:
+            start, _ = self._absorb(prev_block)
+
+        try:
+            next_block = self._start_to_block[(arena, stop)]
+        except KeyError:
+            pass
+        else:
+            _, stop = self._absorb(next_block)
+
+        block = (arena, start, stop)
+        length = stop - start
+
+        try:
+            self._len_to_seq[length].append(block)
+        except KeyError:
+            self._len_to_seq[length] = [block]
+            bisect.insort(self._lengths, length)
+
+        self._start_to_block[(arena, start)] = block
+        self._stop_to_block[(arena, stop)] = block
+
+    def _absorb(self, block):
+        # deregister this block so it can be merged with a neighbour
+        (arena, start, stop) = block
+        del self._start_to_block[(arena, start)]
+        del self._stop_to_block[(arena, stop)]
+
+        length = stop - start
+        seq = self._len_to_seq[length]
+        seq.remove(block)
+        if not seq:
+            del self._len_to_seq[length]
+            self._lengths.remove(length)
+
+        return start, stop
+
+    def _free_pending_blocks(self):
+        # Free all the blocks in the pending list - called with the lock held.
+        while True:
+            try:
+                block = self._pending_free_blocks.pop()
+            except IndexError:
+                break
+            self._allocated_blocks.remove(block)
+            self._free(block)
+
+    def free(self, block):
+        # free a block returned by malloc()
+        # Since free() can be called asynchronously by the GC, it could happen
+        # that it's called while self._lock is held: in that case,
+        # self._lock.acquire() would deadlock (issue #12352). To avoid that, a
+        # trylock is used instead, and if the lock can't be acquired
+        # immediately, the block is added to a list of blocks to be freed
+        # synchronously sometimes later from malloc() or free(), by calling
+        # _free_pending_blocks() (appending and retrieving from a list is not
+        # strictly thread-safe but under cPython it's atomic thanks to the GIL).
+        assert os.getpid() == self._lastpid
+        if not self._lock.acquire(False):
+            # can't acquire the lock right now, add the block to the list of
+            # pending blocks to free
+            self._pending_free_blocks.append(block)
+        else:
+            # we hold the lock
+            try:
+                self._free_pending_blocks()
+                self._allocated_blocks.remove(block)
+                self._free(block)
+            finally:
+                self._lock.release()
+
+    def malloc(self, size):
+        # return a block of right size (possibly rounded up)
+        assert 0 <= size < sys.maxsize
+        if os.getpid() != self._lastpid:
+            self.__init__()                     # reinitialize after fork
+        with self._lock:
+            self._free_pending_blocks()
+            size = self._roundup(max(size,1), self._alignment)
+            (arena, start, stop) = self._malloc(size)
+            new_stop = start + size
+            if new_stop < stop:
+                self._free((arena, new_stop, stop))
+            block = (arena, start, new_stop)
+            self._allocated_blocks.add(block)
+            return block
+
+#
+# Class representing a chunk of an mmap -- can be inherited by child process
+#
+
+class BufferWrapper(object):
+
+    _heap = Heap()
+
+    def __init__(self, size):
+        assert 0 <= size < sys.maxsize
+        block = BufferWrapper._heap.malloc(size)
+        self._state = (block, size)
+        util.Finalize(self, BufferWrapper._heap.free, args=(block,))
+
+    def create_memoryview(self):
+        (arena, start, stop), size = self._state
+        return memoryview(arena.buffer)[start:start+size]