def test_name_for_region(self):
"""
From RegionFile.java's comments.
"""
self.assertEqual(name_for_region(30, -3), "r.0.-1.mcr")
self.assertEqual(name_for_region(70, -30), "r.2.-1.mcr")
def load_chunk(self, chunk):
region = name_for_region(chunk.x, chunk.z)
fp = self.folder.child("region").child(region)
if not fp.exists():
return
x, z = chunk.x % 32, chunk.z % 32
if region not in self.regions:
self.cache_region_pages(region)
positions = self.regions[region][0]
if (x, z) not in positions:
return
position, pages = positions[x, z]
if not position or not pages:
return
with fp.open("r") as handle:
handle.seek(position * 4096)
data = handle.read(pages * 4096)
length = unpack(">L", data[:4])[0] - 1
version = ord(data[4])
data = data[5:length+5]
if version == 1:
data = data.decode("gzip")
fileobj = GzipFile(fileobj=StringIO(data))
elif version == 2:
fileobj = StringIO(data.decode("zlib"))
tag = NBTFile(buffer=fileobj)
return self._load_chunk_from_tag(chunk, tag)
def load_chunk(self, chunk):
region = name_for_region(chunk.x, chunk.z)
fp = self.folder.child("region").child(region)
if not fp.exists():
return
x, z = chunk.x % 32, chunk.z % 32
if region not in self.regions:
self.cache_region_pages(region)
positions = self.regions[region][0]
if (x, z) not in positions:
return
position, pages = positions[x, z]
if not position or not pages:
return
with fp.open("r") as handle:
handle.seek(position * 4096)
data = handle.read(pages * 4096)
length = unpack(">L", data[:4])[0] - 1
version = ord(data[4])
data = data[5:length+5]
if version == 1:
data = data.decode("gzip")
fileobj = GzipFile(fileobj=StringIO(data))
elif version == 2:
fileobj = StringIO(data.decode("zlib"))
tag = NBTFile(buffer=fileobj)
return self._load_chunk_from_tag(chunk, tag)
def save_chunk(self, chunk):
tag = self._save_chunk_to_tag(chunk)
b = StringIO()
tag.write_file(buffer=b)
data = b.getvalue().encode("zlib")
region = name_for_region(chunk.x, chunk.z)
fp = self.folder.child("region")
if not fp.exists():
fp.makedirs()
fp = fp.child(region)
if not fp.exists():
# Create the file and zero out the header, plus a spare page for
# Notchian software.
handle = fp.open("w")
handle.write("\x00" * 8192)
handle.close()
if region not in self.regions:
self.cache_region_pages(region)
positions = self.regions[region][0]
x, z = chunk.x % 32, chunk.z % 32
if (x, z) in positions:
position, pages = positions[x, z]
else:
position, pages = 0, 0
# Pack up the data, all ready to go.
data = "%s\x02%s" % (pack(">L", len(data) + 1), data)
needed_pages = (len(data) + 4095) // 4096
handle = fp.open("r+")
# I should comment this, since it's not obvious in the original MCR
# code either. The reason that we might want to reallocate pages if we
# have shrunk, and not just grown, is that it allows the region to
# self-vacuum somewhat by reusing single unused pages near the
# beginning of the file. While this isn't an absolute guarantee, the
# potential savings, and the guarantee that sometime during this
# method we *will* be blocking, makes it worthwhile computationally.
# This is a lot cheaper than an explicit vacuum, by the way!
if not position or not pages or pages != needed_pages:
free_pages = self.regions[region][1]
# Deallocate our current home.
for i in xrange(pages):
free_pages.add(position + i)
# Find a new home for us.
found = False
for candidate in sorted(free_pages):
if all(candidate + i in free_pages
for i in range(needed_pages)):
# Excellent.
position = candidate
found = True
break
# If we couldn't find a reusable run of pages, we should just go
# to the end of the file.
if not found:
position = (fp.getsize() + 4095) // 4096
# And allocate our new home.
for i in xrange(needed_pages):
free_pages.discard(position + i)
pages = needed_pages
positions[x, z] = position, pages
# Write our payload.
handle.seek(position * 4096)
handle.write(data)
# Write our position and page count.
offset = 4 * (x + z * 32)
position = position << 8 | pages
handle.seek(offset)
handle.write(pack(">L", position))
handle.close()
def save_chunk(self, chunk):
tag = self._save_chunk_to_tag(chunk)
b = StringIO()
tag.write_file(buffer=b)
data = b.getvalue().encode("zlib")
region = name_for_region(chunk.x, chunk.z)
fp = self.folder.child("region")
if not fp.exists():
fp.makedirs()
fp = fp.child(region)
if not fp.exists():
# Create the file and zero out the header, plus a spare page for
# Notchian software.
with fp.open("w") as handle:
handle.write("\x00" * 8192)
if region not in self.regions:
self.cache_region_pages(region)
positions = self.regions[region][0]
x, z = chunk.x % 32, chunk.z % 32
if (x, z) in positions:
position, pages = positions[x, z]
else:
position, pages = 0, 0
# Pack up the data, all ready to go.
data = "%s\x02%s" % (pack(">L", len(data) + 1), data)
needed_pages = (len(data) + 4095) // 4096
# I should comment this, since it's not obvious in the original MCR
# code either. The reason that we might want to reallocate pages if we
# have shrunk, and not just grown, is that it allows the region to
# self-vacuum somewhat by reusing single unused pages near the
# beginning of the file. While this isn't an absolute guarantee, the
# potential savings, and the guarantee that sometime during this
# method we *will* be blocking, makes it worthwhile computationally.
# This is a lot cheaper than an explicit vacuum, by the way!
if not position or not pages or pages != needed_pages:
free_pages = self.regions[region][1]
# Deallocate our current home.
for i in xrange(pages):
free_pages.add(position + i)
# Find a new home for us.
found = False
for candidate in sorted(free_pages):
if all(candidate + i in free_pages
for i in range(needed_pages)):
# Excellent.
position = candidate
found = True
break
# If we couldn't find a reusable run of pages, we should just go
# to the end of the file.
if not found:
position = (fp.getsize() + 4095) // 4096
# And allocate our new home.
for i in xrange(needed_pages):
free_pages.discard(position + i)
pages = needed_pages
positions[x, z] = position, pages
# Write our payload.
with fp.open("r+") as handle:
handle.seek(position * 4096)
handle.write(data)
# Write our position and page count.
offset = 4 * (x + z * 32)
position = position << 8 | pages
handle.seek(offset)
handle.write(pack(">L", position))
