Viewing file:  test_tutorial.py (3.1 KB) -rw-r--r--
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from .lib import TestBase
class TestTutorial(TestBase):
def test_example(self):
# Memory Managers
##################
import smmap
# This instance should be globally available in your application
# It is configured to be well suitable for 32-bit or 64 bit applications.
mman = smmap.SlidingWindowMapManager()
# the manager provides much useful information about its current state
# like the amount of open file handles or the amount of mapped memory
assert mman.num_file_handles() == 0
assert mman.mapped_memory_size() == 0
# and many more ...
# Cursors
##########
import smmap.test.lib
with smmap.test.lib.FileCreator(1024 * 1024 * 8, "test_file") as fc:
# obtain a cursor to access some file.
c = mman.make_cursor(fc.path)
# the cursor is now associated with the file, but not yet usable
assert c.is_associated()
assert not c.is_valid()
# before you can use the cursor, you have to specify a window you want to
# access. The following just says you want as much data as possible starting
# from offset 0.
# To be sure your region could be mapped, query for validity
assert c.use_region().is_valid() # use_region returns self
# once a region was mapped, you must query its dimension regularly
# to assure you don't try to access its buffer out of its bounds
assert c.size()
c.buffer()[0] # first byte
c.buffer()[1:10] # first 9 bytes
c.buffer()[c.size() - 1] # last byte
# you can query absolute offsets, and check whether an offset is included
# in the cursor's data.
assert c.ofs_begin() < c.ofs_end()
assert c.includes_ofs(100)
# If you are over out of bounds with one of your region requests, the
# cursor will be come invalid. It cannot be used in that state
assert not c.use_region(fc.size, 100).is_valid()
# map as much as possible after skipping the first 100 bytes
assert c.use_region(100).is_valid()
# You can explicitly free cursor resources by unusing the cursor's region
c.unuse_region()
assert not c.is_valid()
# Buffers
#########
# Create a default buffer which can operate on the whole file
buf = smmap.SlidingWindowMapBuffer(mman.make_cursor(fc.path))
# you can use it right away
assert buf.cursor().is_valid()
buf[0] # access the first byte
buf[-1] # access the last ten bytes on the file
buf[-10:] # access the last ten bytes
# If you want to keep the instance between different accesses, use the
# dedicated methods
buf.end_access()
assert not buf.cursor().is_valid() # you cannot use the buffer anymore
assert buf.begin_access(offset=10) # start using the buffer at an offset
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