Don't unconditionally set CLOEXEC twice on every fd we open on Linux #50638
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r? @dtolnay (rust_highfive has picked a reviewer for you, use r? to override) |
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@bors r+ |
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@bors r- Failed in rollup #50704 (comment). |
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May 13, 2018
src/libstd/sys/unix/fs.rs
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| @@ -18,6 +18,7 @@ use mem; | |||
| use path::{Path, PathBuf}; | |||
| use ptr; | |||
| use sync::Arc; | |||
| use sync::atomic::{AtomicUsize, Ordering}; | |||
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[00:24:14] error: unused imports: `AtomicUsize`, `Ordering`
[00:24:14] --> libstd/sys/unix/fs.rs:21:20
[00:24:14] |
[00:24:14] 21 | use sync::atomic::{AtomicUsize, Ordering};
[00:24:14] | ^^^^^^^^^^^ ^^^^^^^^
[00:24:14] = note: `-D unused-imports` implied by `-D warnings`
[00:24:14]
[00:24:17] error: aborting due to previous error
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@kennytm Sorry for the compilation failure. Second one in a row due to only checking the Linux build. :( I moved the imports into the function. |
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@bors r+ |
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⌛ Testing commit f3956e9ff16dc78031dc93c0cf11c275e6cbd1e1 with merge bbd6f38235858820ce7b1fdfe78acf7d064560d0... |
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💔 Test failed - status-travis |
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src/libstd/sys/unix/fs.rs
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| } | ||
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| #[cfg(not(target_os = "linux"))] | ||
| fn ensure_cloexec(fd: &FileDesc) -> io::Result<()> { |
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Replace the fd by _ to fix the warning 🤷
Previously, every `open64` was accompanied by a `ioctl(…, FIOCLEX)`, because some old Linux version would ignore the `O_CLOEXEC` flag we pass to the `open64` function. Now, we check whether the `CLOEXEC` flag is set on the first file we open – if it is, we won't do extra syscalls for every opened file. If it is not set, we fall back to the old behavior of unconditionally calling `ioctl(…, FIOCLEX)` on newly opened files. On old Linuxes, this amounts to one extra syscall per process, namely the `fcntl(…, F_GETFD)` call to check the `CLOEXEC` flag. On new Linuxes, this reduces the number of syscalls per opened file by one, except for the first file, where it does the same number of syscalls as before (`fcntl(…, F_GETFD)` to check the flag instead of `ioctl(…, FIOCLEX)` to set it).
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:( Fixed. |
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Don't unconditionally set CLOEXEC twice on every fd we open on Linux Previously, every `open64` was accompanied by a `ioctl(…, FIOCLEX)`, because some old Linux version would ignore the `O_CLOEXEC` flag we pass to the `open64` function. Now, we check whether the `CLOEXEC` flag is set on the first file we open – if it is, we won't do extra syscalls for every opened file. If it is not set, we fall back to the old behavior of unconditionally calling `ioctl(…, FIOCLEX)` on newly opened files. On old Linuxes, this amounts to one extra syscall per process, namely the `fcntl(…, F_GETFD)` call to check the `CLOEXEC` flag. On new Linuxes, this reduces the number of syscalls per opened file by one, except for the first file, where it does the same number of syscalls as before (`fcntl(…, F_GETFD)` to check the flag instead of `ioctl(…, FIOCLEX)` to set it).
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May 15, 2018
Don't unconditionally set CLOEXEC twice on every fd we open on Linux Previously, every `open64` was accompanied by a `ioctl(…, FIOCLEX)`, because some old Linux version would ignore the `O_CLOEXEC` flag we pass to the `open64` function. Now, we check whether the `CLOEXEC` flag is set on the first file we open – if it is, we won't do extra syscalls for every opened file. If it is not set, we fall back to the old behavior of unconditionally calling `ioctl(…, FIOCLEX)` on newly opened files. On old Linuxes, this amounts to one extra syscall per process, namely the `fcntl(…, F_GETFD)` call to check the `CLOEXEC` flag. On new Linuxes, this reduces the number of syscalls per opened file by one, except for the first file, where it does the same number of syscalls as before (`fcntl(…, F_GETFD)` to check the flag instead of `ioctl(…, FIOCLEX)` to set it).
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May 16, 2018
Don't unconditionally set CLOEXEC twice on every fd we open on Linux Previously, every `open64` was accompanied by a `ioctl(…, FIOCLEX)`, because some old Linux version would ignore the `O_CLOEXEC` flag we pass to the `open64` function. Now, we check whether the `CLOEXEC` flag is set on the first file we open – if it is, we won't do extra syscalls for every opened file. If it is not set, we fall back to the old behavior of unconditionally calling `ioctl(…, FIOCLEX)` on newly opened files. On old Linuxes, this amounts to one extra syscall per process, namely the `fcntl(…, F_GETFD)` call to check the `CLOEXEC` flag. On new Linuxes, this reduces the number of syscalls per opened file by one, except for the first file, where it does the same number of syscalls as before (`fcntl(…, F_GETFD)` to check the flag instead of `ioctl(…, FIOCLEX)` to set it).
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Rollup of 17 pull requests Successful merges: - #50170 (Implement From for more types on Cow) - #50638 (Don't unconditionally set CLOEXEC twice on every fd we open on Linux) - #50656 (Fix `fn main() -> impl Trait` for non-`Termination` trait) - #50669 (rustdoc: deprecate `#![doc(passes, plugins, no_default_passes)]`) - #50726 (read2: Use inner function instead of closure) - #50728 (Fix rustdoc panic with `impl Trait` in type parameters) - #50736 (env: remove unwrap in examples in favor of try op) - #50740 (Remove LazyBTreeMap.) - #50752 (Add missing error codes in libsyntax-ext asm) - #50779 (Make mutable_noalias and arg_align_attributes be tracked) - #50787 (Fix run-make wasm tests) - #50788 (Fix an ICE when casting a nonexistent const) - #50789 (Ensure libraries built in stage0 have unique metadata) - #50793 (tidy: Add a check for empty UI test files) - #50797 (fix a typo in signed-integer::from_str_radix()) - #50808 (Stabilize num::NonZeroU*) - #50809 (GitHub: Stop treating Cargo.lock as a generated file.) Failed merges:
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Just wondering: how come this isn't implemented using |
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From the documentation of
The implementation in this PR never blocks, that means that opening of files never blocks on this cached value. As an effect of this, the initialization routine might be called multiple times, but this is no problem. |
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Previously, every
open64was accompanied by aioctl(…, FIOCLEX),because some old Linux version would ignore the
O_CLOEXECflag we passto the
open64function.Now, we check whether the
CLOEXECflag is set on the first file weopen – if it is, we won't do extra syscalls for every opened file. If it
is not set, we fall back to the old behavior of unconditionally calling
ioctl(…, FIOCLEX)on newly opened files.On old Linuxes, this amounts to one extra syscall per process, namely
the
fcntl(…, F_GETFD)call to check theCLOEXECflag.On new Linuxes, this reduces the number of syscalls per opened file by
one, except for the first file, where it does the same number of
syscalls as before (
fcntl(…, F_GETFD)to check the flag instead ofioctl(…, FIOCLEX)to set it).