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Chandler Carruth
07cee1b82a
The Bazel disk cache provides a stable, durable, and supported persistent cache of the intermediate steps of Bazel builds. This is like `ccache` but covering more steps and more reliable. It is based on the same fundamental infrastructure that enables a *remote* build cache, and at some point we may want to enable that so that our CI can pre-seed a cache for users. But for now, this just enables local support for this. For local builds this will ensure that intermediate artifacts are re-used when changing branches, syncing, across Bazel server restarts or even upgrades. It should dramatically reduce the need to re-build large and slow components like all of Clang and LLVM. Largely, those should only be rebuilt when we update our pinned revision of upstream and then cached persistently on a given machine. Enabling this by default requires hard-coding a path, and so I've also added built-in support for importing a user config file if present so that folks can customize this (and any other Bazel features) as desired. This also wires the disk cache up for the GitHub cache in our CI. By using the designated Bazel disk cache for this, we get a *much* simpler and *much* more robust solution. So much so that I've re-arranged the key structure so we can more aggressively re-use old caches. The only downside is that nothing ever gets removed automatically from the cache. I've added a layer that will trim any unused file roughly once a day. For CI, the benefits of this are huge. None of the previous hacks are needed to locate and preserve the cache. The design of the cache is deeply durable and so we don't need to aggressively invalidate it. Last but not least, it focuses the cache on the raw artifacts, which compress exceptionally well. With the other changes to shrink the build outputs and this one combined, I expect we will be able to enable all of the build targets across all four config/os combinations without any significant pressure on our space quota for GitHub action caches.
26 lines
552 B
Plaintext
26 lines
552 B
Plaintext
# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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# Exceptions. See /LICENSE for license information.
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# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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# Directories and symlinks generated by bazel.
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/bazel-*
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# Directories created by python.
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**/__pycache__/
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# Ignore the user's VSCode settings.
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/.vscode/settings.json
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# Directories created by clangd
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/.cache/clangd
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# User-specific Bazel configuration.
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/user.bazelrc
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# Compilation database used by clangd
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compile_commands.json
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# Emacs temporary files
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*~
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\#*\#
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