LogalDeveloper/Minecraft-Overviewer
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nbt: eagerly load the entire MCR on chunk load

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During the first call to get_chunk, we can simply read the whole
region file into a BytesIO object. By then re-reading location
and timestamp data, we might make scrambled maps a lot less
likely.

Hopefully mitigates #1888.
This commit is contained in:
Nicolas F
2021-06-11 20:59:40 +02:00
parent 70e739916c
commit d8e469b313
1 changed files with 16 additions and 0 deletions
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16
overviewer_core/nbt.py
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@@ -219,12 +219,16 @@ class MCRFileReader(object):
_location_table_format = struct.Struct(">1024I") _location_table_format = struct.Struct(">1024I")
_timestamp_table_format = struct.Struct(">1024i") _timestamp_table_format = struct.Struct(">1024i")
_chunk_header_format = struct.Struct(">I B") _chunk_header_format = struct.Struct(">I B")
_preloaded = False
def __init__(self, fileobj): def __init__(self, fileobj):
"""This creates a region object from the given file-like """This creates a region object from the given file-like
object. Chances are you want to use load_region instead.""" object. Chances are you want to use load_region instead."""
self._file = fileobj self._file = fileobj
self.load_pre_data()
def load_pre_data(self):
self._file.seek(0)
# read in the location table # read in the location table
location_data = self._file.read(4096) location_data = self._file.read(4096)
if not len(location_data) == 4096: if not len(location_data) == 4096:
@@ -245,6 +249,7 @@ class MCRFileReader(object):
""" """
self._file.close() self._file.close()
del self._file
self._file = None self._file = None
def get_chunks(self): def get_chunks(self):
@@ -272,6 +277,16 @@ class MCRFileReader(object):
z = z % 32 z = z % 32
return self._locations[int(x + z * 32)] >> 8 != 0 return self._locations[int(x + z * 32)] >> 8 != 0
def preload_chunks(self):
if not self._preloaded:
self._file.seek(0)
pl_data = BytesIO(self._file.read())
self._file.close()
self._file = pl_data
# re-read location, timestamps
self.load_pre_data()
self._preloaded = True
def load_chunk(self, x, z): def load_chunk(self, x, z):
"""Return a (name, data) tuple for the given chunk, or """Return a (name, data) tuple for the given chunk, or
None if the given chunk doesn't exist in this region file. If None if the given chunk doesn't exist in this region file. If
@@ -279,6 +294,7 @@ class MCRFileReader(object):
modulo'd into this range (x % 32, etc.) This is so you can modulo'd into this range (x % 32, etc.) This is so you can
provide chunk coordinates in global coordinates, and still provide chunk coordinates in global coordinates, and still
have the chunks load out of regions properly.""" have the chunks load out of regions properly."""
self.preload_chunks()
x = x % 32 x = x % 32
z = z % 32 z = z % 32
location = self._locations[int(x + z * 32)] location = self._locations[int(x + z * 32)]