mirror of
https://github.com/morpheus65535/bazarr
synced 2024-12-27 01:57:33 +00:00
276 lines
9.1 KiB
Python
276 lines
9.1 KiB
Python
"""Module containing a memory memory manager which provides a sliding window on a number of memory mapped files"""
|
|
import os
|
|
import sys
|
|
|
|
from mmap import mmap, ACCESS_READ
|
|
try:
|
|
from mmap import ALLOCATIONGRANULARITY
|
|
except ImportError:
|
|
# in python pre 2.6, the ALLOCATIONGRANULARITY does not exist as it is mainly
|
|
# useful for aligning the offset. The offset argument doesn't exist there though
|
|
from mmap import PAGESIZE as ALLOCATIONGRANULARITY
|
|
# END handle pythons missing quality assurance
|
|
|
|
__all__ = ["align_to_mmap", "is_64_bit", "buffer",
|
|
"MapWindow", "MapRegion", "MapRegionList", "ALLOCATIONGRANULARITY"]
|
|
|
|
#{ Utilities
|
|
|
|
try:
|
|
# Python 2
|
|
buffer = buffer
|
|
except NameError:
|
|
# Python 3 has no `buffer`; only `memoryview`
|
|
def buffer(obj, offset, size):
|
|
# Actually, for gitpython this is fastest ... .
|
|
return memoryview(obj)[offset:offset+size]
|
|
# doing it directly is much faster !
|
|
# return obj[offset:offset + size]
|
|
|
|
|
|
def string_types():
|
|
if sys.version_info[0] >= 3:
|
|
return str
|
|
else:
|
|
return basestring
|
|
|
|
|
|
def align_to_mmap(num, round_up):
|
|
"""
|
|
Align the given integer number to the closest page offset, which usually is 4096 bytes.
|
|
|
|
:param round_up: if True, the next higher multiple of page size is used, otherwise
|
|
the lower page_size will be used (i.e. if True, 1 becomes 4096, otherwise it becomes 0)
|
|
:return: num rounded to closest page"""
|
|
res = (num // ALLOCATIONGRANULARITY) * ALLOCATIONGRANULARITY
|
|
if round_up and (res != num):
|
|
res += ALLOCATIONGRANULARITY
|
|
# END handle size
|
|
return res
|
|
|
|
|
|
def is_64_bit():
|
|
""":return: True if the system is 64 bit. Otherwise it can be assumed to be 32 bit"""
|
|
return sys.maxsize > (1 << 32) - 1
|
|
|
|
#}END utilities
|
|
|
|
|
|
#{ Utility Classes
|
|
|
|
class MapWindow(object):
|
|
|
|
"""Utility type which is used to snap windows towards each other, and to adjust their size"""
|
|
__slots__ = (
|
|
'ofs', # offset into the file in bytes
|
|
'size' # size of the window in bytes
|
|
)
|
|
|
|
def __init__(self, offset, size):
|
|
self.ofs = offset
|
|
self.size = size
|
|
|
|
def __repr__(self):
|
|
return "MapWindow(%i, %i)" % (self.ofs, self.size)
|
|
|
|
@classmethod
|
|
def from_region(cls, region):
|
|
""":return: new window from a region"""
|
|
return cls(region._b, region.size())
|
|
|
|
def ofs_end(self):
|
|
return self.ofs + self.size
|
|
|
|
def align(self):
|
|
"""Assures the previous window area is contained in the new one"""
|
|
nofs = align_to_mmap(self.ofs, 0)
|
|
self.size += self.ofs - nofs # keep size constant
|
|
self.ofs = nofs
|
|
self.size = align_to_mmap(self.size, 1)
|
|
|
|
def extend_left_to(self, window, max_size):
|
|
"""Adjust the offset to start where the given window on our left ends if possible,
|
|
but don't make yourself larger than max_size.
|
|
The resize will assure that the new window still contains the old window area"""
|
|
rofs = self.ofs - window.ofs_end()
|
|
nsize = rofs + self.size
|
|
rofs -= nsize - min(nsize, max_size)
|
|
self.ofs = self.ofs - rofs
|
|
self.size += rofs
|
|
|
|
def extend_right_to(self, window, max_size):
|
|
"""Adjust the size to make our window end where the right window begins, but don't
|
|
get larger than max_size"""
|
|
self.size = min(self.size + (window.ofs - self.ofs_end()), max_size)
|
|
|
|
|
|
class MapRegion(object):
|
|
|
|
"""Defines a mapped region of memory, aligned to pagesizes
|
|
|
|
**Note:** deallocates used region automatically on destruction"""
|
|
__slots__ = [
|
|
'_b', # beginning of mapping
|
|
'_mf', # mapped memory chunk (as returned by mmap)
|
|
'_uc', # total amount of usages
|
|
'_size', # cached size of our memory map
|
|
'__weakref__'
|
|
]
|
|
_need_compat_layer = sys.version_info[:2] < (2, 6)
|
|
|
|
if _need_compat_layer:
|
|
__slots__.append('_mfb') # mapped memory buffer to provide offset
|
|
# END handle additional slot
|
|
|
|
#{ Configuration
|
|
#} END configuration
|
|
|
|
def __init__(self, path_or_fd, ofs, size, flags=0):
|
|
"""Initialize a region, allocate the memory map
|
|
:param path_or_fd: path to the file to map, or the opened file descriptor
|
|
:param ofs: **aligned** offset into the file to be mapped
|
|
:param size: if size is larger then the file on disk, the whole file will be
|
|
allocated the the size automatically adjusted
|
|
:param flags: additional flags to be given when opening the file.
|
|
:raise Exception: if no memory can be allocated"""
|
|
self._b = ofs
|
|
self._size = 0
|
|
self._uc = 0
|
|
|
|
if isinstance(path_or_fd, int):
|
|
fd = path_or_fd
|
|
else:
|
|
fd = os.open(path_or_fd, os.O_RDONLY | getattr(os, 'O_BINARY', 0) | flags)
|
|
# END handle fd
|
|
|
|
try:
|
|
kwargs = dict(access=ACCESS_READ, offset=ofs)
|
|
corrected_size = size
|
|
sizeofs = ofs
|
|
if self._need_compat_layer:
|
|
del(kwargs['offset'])
|
|
corrected_size += ofs
|
|
sizeofs = 0
|
|
# END handle python not supporting offset ! Arg
|
|
|
|
# have to correct size, otherwise (instead of the c version) it will
|
|
# bark that the size is too large ... many extra file accesses because
|
|
# if this ... argh !
|
|
actual_size = min(os.fstat(fd).st_size - sizeofs, corrected_size)
|
|
self._mf = mmap(fd, actual_size, **kwargs)
|
|
# END handle memory mode
|
|
|
|
self._size = len(self._mf)
|
|
|
|
if self._need_compat_layer:
|
|
self._mfb = buffer(self._mf, ofs, self._size)
|
|
# END handle buffer wrapping
|
|
finally:
|
|
if isinstance(path_or_fd, string_types()):
|
|
os.close(fd)
|
|
# END only close it if we opened it
|
|
# END close file handle
|
|
# We assume the first one to use us keeps us around
|
|
self.increment_client_count()
|
|
|
|
def __repr__(self):
|
|
return "MapRegion<%i, %i>" % (self._b, self.size())
|
|
|
|
#{ Interface
|
|
|
|
def buffer(self):
|
|
""":return: a buffer containing the memory"""
|
|
return self._mf
|
|
|
|
def map(self):
|
|
""":return: a memory map containing the memory"""
|
|
return self._mf
|
|
|
|
def ofs_begin(self):
|
|
""":return: absolute byte offset to the first byte of the mapping"""
|
|
return self._b
|
|
|
|
def size(self):
|
|
""":return: total size of the mapped region in bytes"""
|
|
return self._size
|
|
|
|
def ofs_end(self):
|
|
""":return: Absolute offset to one byte beyond the mapping into the file"""
|
|
return self._b + self._size
|
|
|
|
def includes_ofs(self, ofs):
|
|
""":return: True if the given offset can be read in our mapped region"""
|
|
return self._b <= ofs < self._b + self._size
|
|
|
|
def client_count(self):
|
|
""":return: number of clients currently using this region"""
|
|
return self._uc
|
|
|
|
def increment_client_count(self, ofs = 1):
|
|
"""Adjust the usage count by the given positive or negative offset.
|
|
If usage count equals 0, we will auto-release our resources
|
|
:return: True if we released resources, False otherwise. In the latter case, we can still be used"""
|
|
self._uc += ofs
|
|
assert self._uc > -1, "Increments must match decrements, usage counter negative: %i" % self._uc
|
|
|
|
if self.client_count() == 0:
|
|
self.release()
|
|
return True
|
|
else:
|
|
return False
|
|
# end handle release
|
|
|
|
def release(self):
|
|
"""Release all resources this instance might hold. Must only be called if there usage_count() is zero"""
|
|
self._mf.close()
|
|
|
|
# re-define all methods which need offset adjustments in compatibility mode
|
|
if _need_compat_layer:
|
|
def size(self):
|
|
return self._size - self._b
|
|
|
|
def ofs_end(self):
|
|
# always the size - we are as large as it gets
|
|
return self._size
|
|
|
|
def buffer(self):
|
|
return self._mfb
|
|
|
|
def includes_ofs(self, ofs):
|
|
return self._b <= ofs < self._size
|
|
# END handle compat layer
|
|
|
|
#} END interface
|
|
|
|
|
|
class MapRegionList(list):
|
|
|
|
"""List of MapRegion instances associating a path with a list of regions."""
|
|
__slots__ = (
|
|
'_path_or_fd', # path or file descriptor which is mapped by all our regions
|
|
'_file_size' # total size of the file we map
|
|
)
|
|
|
|
def __new__(cls, path):
|
|
return super(MapRegionList, cls).__new__(cls)
|
|
|
|
def __init__(self, path_or_fd):
|
|
self._path_or_fd = path_or_fd
|
|
self._file_size = None
|
|
|
|
def path_or_fd(self):
|
|
""":return: path or file descriptor we are attached to"""
|
|
return self._path_or_fd
|
|
|
|
def file_size(self):
|
|
""":return: size of file we manager"""
|
|
if self._file_size is None:
|
|
if isinstance(self._path_or_fd, string_types()):
|
|
self._file_size = os.stat(self._path_or_fd).st_size
|
|
else:
|
|
self._file_size = os.fstat(self._path_or_fd).st_size
|
|
# END handle path type
|
|
# END update file size
|
|
return self._file_size
|
|
|
|
#} END utility classes
|