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zstd is a new compression format and it is awesome, yielding higher compression ratios and significantly faster compression and decompression operations compared to zlib (our current compression engine of choice) across the board. We want zstd to be a 1st class citizen in Mercurial and to eventually be the preferred compression format for various operations. This patch starts the formal process of supporting zstd by vendoring a copy of zstd. Why do we need to vendor zstd? Good question. First, zstd is relatively new and not widely available yet. If we didn't vendor zstd or distribute it with Mercurial, most users likely wouldn't have zstd installed or even available to install. What good is a feature if you can't use it? Vendoring and distributing the zstd sources gives us the highest liklihood that zstd will be available to Mercurial installs. Second, the Python bindings to zstd (which will be vendored in a separate changeset) make use of zstd APIs that are only available via static linking. One reason they are only available via static linking is that they are unstable and could change at any time. While it might be possible for the Python bindings to attempt to talk to different versions of the zstd C library, the safest thing to do is link against a specific, known-working version of zstd. This is why the Python zstd bindings themselves vendor zstd and why we must as well. This also explains why the added files are in a "python-zstandard" directory. The added files are from the 1.1.1 release of zstd (Git commit 4c0b44f8ced84c4c8edfa07b564d31e4fa3e8885 from https://github.com/facebook/zstd) and are added without modifications. Not all files from the zstd "distribution" have been added. Notably missing are files to support interacting with "legacy," pre-1.0 versions of zstd. The decision of which files to include is made by the upstream python-zstandard project (which I'm the author of). The files in this commit are a snapshot of the files from the 0.5.0 release of that project, Git commit e637c1b214d5f869cf8116c550dcae23ec13b677 from https://github.com/indygreg/python-zstandard.
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1.9 KiB
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34 lines
1.9 KiB
Plaintext
Additional Grant of Patent Rights Version 2
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"Software" means the Zstandard software distributed by Facebook, Inc.
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Facebook, Inc. ("Facebook") hereby grants to each recipient of the Software
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("you") a perpetual, worldwide, royalty-free, non-exclusive, irrevocable
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(subject to the termination provision below) license under any Necessary
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Claims, to make, have made, use, sell, offer to sell, import, and otherwise
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transfer the Software. For avoidance of doubt, no license is granted under
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Facebook’s rights in any patent claims that are infringed by (i) modifications
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to the Software made by you or any third party or (ii) the Software in
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combination with any software or other technology.
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The license granted hereunder will terminate, automatically and without notice,
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if you (or any of your subsidiaries, corporate affiliates or agents) initiate
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directly or indirectly, or take a direct financial interest in, any Patent
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Assertion: (i) against Facebook or any of its subsidiaries or corporate
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affiliates, (ii) against any party if such Patent Assertion arises in whole or
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in part from any software, technology, product or service of Facebook or any of
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its subsidiaries or corporate affiliates, or (iii) against any party relating
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to the Software. Notwithstanding the foregoing, if Facebook or any of its
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subsidiaries or corporate affiliates files a lawsuit alleging patent
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infringement against you in the first instance, and you respond by filing a
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patent infringement counterclaim in that lawsuit against that party that is
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unrelated to the Software, the license granted hereunder will not terminate
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under section (i) of this paragraph due to such counterclaim.
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A "Necessary Claim" is a claim of a patent owned by Facebook that is
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necessarily infringed by the Software standing alone.
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A "Patent Assertion" is any lawsuit or other action alleging direct, indirect,
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or contributory infringement or inducement to infringe any patent, including a
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cross-claim or counterclaim.
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