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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
-
- # its recommended not to create big slices when feeding the buffer
- # into consumers (e.g. struct or zlib).
- # Instead, either give the buffer directly, or use pythons buffer command.
- from smmap.util import buffer
- buffer(c.buffer(), 1, 9) # first 9 bytes without copying them
-
- # 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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