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//! This crate provides I/O-related utilities complimenting the Rust Standard //! Library `std::io`, `std::fs`, etc. //! //! ## Overview //! //! The [_fs_ module](fs/index.html) includes a `PosRead` trait, offering a //! uniform `pread` for positioned file reads, and a `ReadSlice` supporting //! multiple independent reader instances limited to a fixed //! start..end range. //! //! The [_io_ module](io/index.html) includes a `GatheringReader`, which //! presents a continuous `Read` interface over N non-contiguous byte buffers. //! //! The [_mem_ module](mem/index.html) includes a `MemHandle` supporting //! prioritized concurrent memory access advice (e.g. madvise (2) on unix). //! //! ## Optional Features //! //! _mmap (default):_ Adds `fs::ReadSlice::<File>::mem_map` support for memory //! mapping. #![warn(rust_2018_idioms)] /// The crate version string. pub static VERSION: &str = env!("CARGO_PKG_VERSION"); /// Filesystem extensions and utilities. /// /// The `PosRead` trait offers a uniform `pread` for positioned reads. /// /// The `ReadPos` and `ReadSlice` types re-implement `Read` and `Seek` over /// any `Borrow` of a `PosRead` type. For `File` in particular, this enables /// multiple independent reader instances, without needing a path to open an /// independent new `File` instance. Thus these types are compatible with /// "unnamed" (not linked) temporary files, and can reduce the number of /// necessary file handles. Note that unix `dup`/`dup2` and the standard /// `File::try_clone` do _not_ provide independent file positions. /// /// ## Example /// /// ``` rust /// # use std::io; /// use std::fs::File; /// use std::io::{Read, Write}; /// use olio::fs::{ReadPos, ReadSlice}; /// use tempfile::tempfile; /// /// # fn run() -> Result<(), io::Error> { /// let mut file = tempfile()?; /// file.write_all(b"0123456789")?; /// /// // ReadPos by &File so that we can subslice by shared reference /// let mut rpos = ReadPos::new(&file, 10); /// /// // Read the first half /// let mut buf = [0u8; 5]; /// rpos.read_exact(&mut buf)?; /// assert_eq!(&buf, b"01234"); /// /// // Create an independent ReadSlice and read to end /// let mut rslice = rpos.subslice(2, 7); /// let mut buf = Vec::new(); /// rslice.read_to_end(&mut buf)?; /// assert_eq!(&buf, b"23456"); /// /// // Read the second half from the original ReadPos /// assert_eq!(rpos.tell(), 5); /// let mut buf = [0u8; 5]; /// rpos.read_exact(&mut buf)?; /// assert_eq!(&buf, b"56789"); /// # Ok(()) /// # } /// # run().unwrap(); /// ``` pub mod fs { mod pos_read; pub use self::pos_read::PosRead; mod read; pub use self::read::{ReadPos, ReadSlice}; /// Compatibility type aliases. pub mod rc { use std::fs::File; use std::sync::Arc; pub type ReadPos = super::ReadPos<Arc<File>>; pub type ReadSlice = super::ReadSlice<Arc<File>>; } } /// I/O extensions and utilities pub mod io { mod gather; pub use self::gather::GatheringReader; } /// Random access memory utilities pub mod mem { mod handle; pub use self::handle::{MemAdviseError, MemHandle, MemAdvice}; }