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65a5010e25
Fixes #1873: previously any run of `make` caused the `postgres-v15-headers` target to build. It copied a bunch of headers via `install -C`. Unfortunately, some origins were symlinks in the `./pg_install/build` directory pointing inside `./vendor/postgres-v15` (e.g. `pg_config_os.h` pointing to `linux.h`). GNU coreutils' `install` ignores the `-C` key for non-regular files and always overwrites the destination if the origin is a symlink. That in turn made Cargo rebuild the `postgres_ffi` crate and all its dependencies because it thinks that Postgres headers changed, even if they did not. That was slow. Now we use a custom script that wraps the `install` program. It handles one specific case and makes sure individual headers are never copied if their content did not change. Hence, `postgres_ffi` is not rebuilt unless there were some changes to the C code. One may still have slow incremental single-threaded builds because Postgres Makefiles spawn about 2800 sub-makes even if no files have been changed. A no-op build takes "only" 3-4 seconds on my machine now when run with `-j30`, and 20 seconds when run with `-j1`.
25 lines
1.1 KiB
Bash
Executable File
25 lines
1.1 KiB
Bash
Executable File
#!/bin/bash
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set -euo pipefail
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# GNU coreutil's `install -C` always overrides the destination if the source
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# is not a regular file, which is the case with lots of headers symlinked into
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# the build directory by `./configure`. That causes Rust's Cargo to think that
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# Postgres headers have been updated after `make` call even if no files have been
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# touched. That causes long recompilation of `postgres_ffi` and all dependent
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# packages. To counter that, we handle a special case here: do not copy the file
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# if its content did not change. We only handle a single case where `install`
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# installs a single file with a specific set of arguments, the rest does not
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# matter in our configuration.
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#
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# Such behavior may be incorrect if e.g. permissions have changed, but it should
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# not happen during normal Neon development that often, and rebuild should help.
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#
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# See https://github.com/neondatabase/neon/issues/1873
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if [ "$#" == "5" ]; then
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if [ "$1" == "-C" ] && [ "$2" == "-m" ] && [ "$3" == "644" ]; then
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if [ -e "$5" ] && diff -q "$4" "$5" >/dev/null 2>&1; then
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exit 0
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fi
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fi
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fi
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install "$@"
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