本文整理汇总了Python中tempfile.SpooledTemporaryFile.truncate方法的典型用法代码示例。如果您正苦于以下问题：Python SpooledTemporaryFile.truncate方法的具体用法？Python SpooledTemporaryFile.truncate怎么用？Python SpooledTemporaryFile.truncate使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类tempfile.SpooledTemporaryFile的用法示例。
在下文中一共展示了SpooledTemporaryFile.truncate方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Python代码示例。
示例1: Buffer
# 需要导入模块: from tempfile import SpooledTemporaryFile [as 别名]
# 或者: from tempfile.SpooledTemporaryFile import truncate [as 别名]
class Buffer(FileWrapper):
"""Class implementing buffering of input and output streams.
This class uses a separate buffer file to hold the contents of the
underlying file while they are being manipulated. As data is read
it is duplicated into the buffer, and data is written from the buffer
back to the file on close.
"""
def __init__(self, fileobj, mode=None, max_size_in_memory=1024 * 8):
"""Buffered file wrapper constructor."""
self._buffer = SpooledTemporaryFile(max_size=max_size_in_memory)
self._in_eof = False
self._in_pos = 0
self._was_truncated = False
super(Buffer, self).__init__(fileobj, mode)
def _buffer_size(self):
try:
return len(self._buffer.file.getvalue())
except AttributeError:
return os.fstat(self._buffer.fileno()).st_size
def _buffer_chunks(self):
chunk = self._buffer.read(16 * 1024)
if chunk == "":
yield chunk
else:
while chunk != "":
yield chunk
chunk = self._buffer.read(16 * 1024)
def _write_out_buffer(self):
if self._check_mode("r"):
self._read_rest()
if "a" in self.mode:
self._buffer.seek(self._in_pos)
self._fileobj.seek(self._in_pos)
else:
self._fileobj.seek(0)
self._buffer.seek(0)
else:
self._buffer.seek(0)
if self._was_truncated:
self._fileobj.truncate(0)
self._was_truncated = False
for chunk in self._buffer_chunks():
self._fileobj.write(chunk)
def flush(self):
# flush the buffer; we only write to the underlying file on close
self._buffer.flush()
def close(self):
if self.closed:
return
if self._check_mode("w"):
self._write_out_buffer()
super(Buffer, self).close()
self._buffer.close()
def _read(self, sizehint=-1):
# First return any data available from the buffer.
# Since we don't flush the buffer after every write, certain OSes
# (guess which!) will happily read junk data from the end of it.
# Instead, we explicitly read only up to self._in_pos.
if not self._in_eof:
buffered_size = self._in_pos - self._buffer.tell()
if sizehint >= 0:
buffered_size = min(sizehint, buffered_size)
else:
buffered_size = sizehint
data = self._buffer.read(buffered_size)
if data != "":
return data
# Then look for more data in the underlying file
if self._in_eof:
return None
data = self._fileobj.read(sizehint)
self._in_pos += len(data)
self._buffer.write(data)
if sizehint < 0 or len(data) < sizehint:
self._in_eof = True
self._buffer.flush()
return data
def _write(self, data, flushing=False):
self._buffer.write(data)
if self._check_mode("r") and not self._in_eof:
diff = self._buffer.tell() - self._in_pos
if diff > 0:
junk = self._fileobj.read(diff)
self._in_pos += len(junk)
if len(junk) < diff:
self._in_eof = True
self._buffer.flush()
def _seek(self, offset, whence):
# Ensure we've read enough to simply do the seek on the buffer
if self._check_mode("r") and not self._in_eof:
#.........这里部分代码省略.........