spooled memory

spool.py

# the _rolled attribute of SpooledTemporaryFile object is a boolean, it returns True 
# if the file is rolled over(written from the memory buffer to the disk) else False 
import tempfile
temp = tempfile.SpooledTemporaryFile(max_size=10,mode="w+b")
# the dize of input is 11(greater than max_size)
temp.write(b"aaaaaaaaaaa")
temp._rolled

Output: True
  
# for binary data
import tempfile
with tempfile.SpooledTemporaryFile(max_size=100,mode="w+b") as temp:
    print(temp)
    while not temp._rolled:
        temp.write(b"Hello World Hello Worlddddd")
        print(temp._rolled,temp._file)
        
"""
Output: 
<tempfile.SpooledTemporaryFile object at 0x0000019D426DE5C8>
False <_io.BytesIO object at 0x0000019D41F7A888>
False <_io.BytesIO object at 0x0000019D41F7A888>
False <_io.BytesIO object at 0x0000019D41F7A888>
True <tempfile._TemporaryFileWrapper object at 0x0000019D42A26C88>
"""

# for textual data
import tempfile
with tempfile.SpooledTemporaryFile(max_size=100,mode="w+t",encoding="utf-8") as temp:
    print(temp)
    while not temp._rolled:
        temp.write("Hello World Hello Worlddddd")
        print(temp._rolled,temp._file)
        
"""
Output: 

<tempfile.SpooledTemporaryFile object at 0x0000019D42ADF388>
False <_io.TextIOWrapper encoding='utf-8'>
False <_io.TextIOWrapper encoding='utf-8'>
False <_io.TextIOWrapper encoding='utf-8'>
True <tempfile._TemporaryFileWrapper object at 0x0000019D425EC0C8>
"""

# to explictly cause the buffer to be written on the disk
# using fileno()
import tempfile
with tempfile.SpooledTemporaryFile(max_size = 1000,mode = "w+b") as temp:
    print(temp)
    for i in range(5):
        temp.write(b"byteman")
        print(temp._rolled,temp._file)
    print("Let's rollover this function")
    temp.fileno()
    print(temp._rolled,temp._file)
"""
<tempfile.SpooledTemporaryFile object at 0x0000019D433EB788>
False <_io.BytesIO object at 0x0000019D41F7AE28>
False <_io.BytesIO object at 0x0000019D41F7AE28>
False <_io.BytesIO object at 0x0000019D41F7AE28>
False <_io.BytesIO object at 0x0000019D41F7AE28>
False <_io.BytesIO object at 0x0000019D41F7AE28>
Let's rollover this function
True <tempfile._TemporaryFileWrapper object at 0x0000019D433EBD08>
"""