vsifile

---

Documentation: https://vincentsarago.github.io/vsifile/

Source Code: https://github.com/vincentsarago/vsifile

---

Description

Experiment using Rasterio/GDAL Python file opener VSI plugin https://github.com/rasterio/rasterio/pull/2898/files

Future version of rasterio will accept an custom dataset opener:

opener : callable, optional
        A custom dataset opener which can serve GDAL's virtual
        filesystem machinery via Python file-like objects. The
        underlying file-like object is obtained by calling *opener* with
        (*fp*, *mode*) or (*fp*, *mode* + "b") depending on the format
        driver's native mode. *opener* must return a Python file-like
        object that provides read, seek, tell, and close methods.

ref: https://github.com/rasterio/rasterio/blob/d966440c06f3324aca1fa761d490cc780a9f619c/rasterio/__init__.py#L185-L191

Install

You can install vsifile using pip

python -m pip install -U pip
python -m pip install -U vsifile

or install from source:

git clone https://github.com/vincentsarago/vsifile.git
cd vsifile
python -m pip install -U pip
python -m pip install -e .

Usage

from vsifile import VSIFile, FileReader

src_path = "tests/fixture.cog.tif"

with VSIFile(src_path, "rb") as f:
    assert isinstance(f, FileReader)
    assert hash(f)
    assert "FileReader" in str(f)

    assert not f.closed
    assert f.header_cache
    assert len(f.header) == 32768
    assert f.tell() == 0
    assert f.seekable

    b = f.read(100)
    assert len(b) == 100
    assert f.header[0:100] == b
    assert f.tell() == 100

    _ = f.seek(0)
    assert f.tell() == 0

    _ = f.seek(40000)
    assert f.tell() == 40000

    b = f.read(100)
    assert f.tell() == 40100

    # fetch the same block (should be from LRU cache)
    _ = f.seek(40000)
    b_cache = f.read(100)
    assert f.tell() == 40100
    assert b_cache == b

    b = f.get_byte_ranges([100, 200], [10, 20])
    assert len(b) == 2
    assert len(b[0]) == 10
    assert len(b[1]) == 20
    assert f.tell() == 220

With Rasterio

import rasterio
from vsifile.rasterio import opener

with rasterio.open("tests/fixtures/cog.tif",  opener=opener) as src:
    ...

Caches Configuration

Header Cache

vsifile uses DiskCache to create a persistent File Header cache (TTL: Time To Live cache). By default the cache will be cleaned up when closing the file handle, you can change this behaviour by setting VSIFILE_CACHE_DIRECTORY="{your temp directory}" environment variable.

Settings:

• VSIFILE_CACHE_DIRECTORY: Diskcache directory (defaults to None)
• VSIFILE_CACHE_HEADERS_TTL: Time to Live of each object in the cache, in seconds (defaults to 300)
• VSIFILE_CACHE_HEADERS_MAXSIZE: Maximum size of the cache, in Bytes (defaults to 5120000000)

Block Cache

vsifile has a second layer of cache for the blocks (non-header read) based on cachetools.

Settings:

• VSIFILE_CACHE_BLOCKS_TTL: Time to Live of each object in the cache, in seconds (defaults to 300)
• VSIFILE_CACHE_BLOCKS_MAXSIZE: Maximum size of the cache, in number of items (defaults to 512)

Note: you can disable cache by setting: VSIFILE_CACHE_DISABLE=TRUE

Other Configurations

• VSIFILE_INGESTED_BYTES_AT_OPEN: Bytes ingested when opening a file (header) (defaults to 32768)

Contribution & Development

See CONTRIBUTING.md

Changes

See CHANGES.md.

License

See LICENSE