smmap2 - Shared Memory Map

Warnings

• gotcha The PyPI package is named `smmap2`, but the Python import statement uses `from smmap import ...`. Attempting `from smmap2 import ...` will result in an `ImportError`.
  Fix: Always use `from smmap import ...` for importing modules and classes from the `smmap2` package.
• gotcha The `smmap2` package (v3.0.1) is an older, specific version of the `smmap` library. It does not track the latest developments of the upstream `smmap` project (which is currently at v5.x.x at `gitpython-developers/smmap`). Users expecting the latest `smmap` features or fixes will be disappointed.
  Fix: If you need the latest `smmap` functionality or broad Python compatibility, install `smmap` directly via `pip install smmap`. Be aware of potential API differences between v3.x and v5.x.
• deprecated The `smmap2` package (v3.0.1) specifies very old Python compatibility requirements (`>=2.6, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*`). While it might still run on modern Python versions (3.6+), it is not actively tested or guaranteed to be fully compatible. For modern Python applications, the newer `smmap` v5.x.x is recommended.
  Fix: For new projects or modern Python environments, prefer `pip install smmap`. If you must use `smmap2`, thoroughly test its compatibility with your specific Python version.
• gotcha This package is primarily intended as an internal dependency for specific versions of `GitPython` and similar projects. It is not typically designed for direct, standalone application development, and its API documentation might be sparse or outdated.
  Fix: Consider if you truly need this low-level memory mapping functionality directly, or if a higher-level library that depends on `smmap` (like `GitPython`) would be more appropriate for your use case.
• breaking The `smmap` library underwent significant changes between versions 3.x (as mirrored by `smmap2`) and 5.x. Code written for `smmap` v3.0.1 will likely not be directly compatible with `smmap` v5.x.x without modification due to API changes.
  Fix: If migrating from `smmap2` to `smmap` (v5.x.x), review the `smmap` changelog and update your code to reflect the new API and usage patterns.

Install

• pip install smmap2 Install smmap2

Imports

• SlidingWindowMap

  from smmap import SlidingWindowMap

  Despite the package being named `smmap2` on PyPI, the Python import path for its modules is `smmap`.

Quickstart

Demonstrates how to initialize and use `SlidingWindowMap` to read data from a memory-mapped file. It creates a temporary file, maps it into memory, and then accesses the data via `SlidingWindowMap`.

import os
import mmap
import tempfile
from smmap import SlidingWindowMap

# Create a dummy file for memory mapping
data_to_map = b"This is some test data that will be memory-mapped." * 10 # make it a bit larger
file_size = len(data_to_map)

# Use tempfile to create a temporary file
with tempfile.NamedTemporaryFile(delete=False) as tmp_file:
    tmp_file.write(data_to_map)
    tmp_file_path = tmp_file.name

try:
    # Open the file for reading
    with open(tmp_file_path, "rb") as f:
        # Create an mmap object for the file
        m = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)

        # Create a SlidingWindowMap instance
        # For this example, we'll map the entire file into a single window
        window_size = file_size
        s = SlidingWindowMap(m, begin=0, size=file_size, window_size=window_size)

        # Access data through the sliding window map
        read_data = s[0:file_size]
        print(f"Read data length: {len(read_data)}")
        print(f"First 50 bytes: {read_data[:50].decode()}")

        assert read_data == data_to_map
        print("Data successfully read and verified.")

        s.close()
        m.close()

finally:
    # Clean up the temporary file
    if os.path.exists(tmp_file_path):
        os.remove(tmp_file_path)