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//! A cross-platform library for fast and safe memory-mapped IO //! //! This library defines a convenient API for reading and writing to files //! using the hosts virtual memory system. The design of the API strives to //! both minimize the frequency of mapping system calls while still retaining //! safe access. Critically, it never attempts the own the `File` object used //! for mapping. That is, it never clones it or in any way retains it. While //! this has some implications for the API (i.e. [`.flush()`]), it cannot cause //! bugs outside of this library through `File`'s leaky abstraction when cloned //! and then closed. //! //! The [`Map`] and [`MapMut`] types are primary means for allocating virtual //! memory regions, both for a file and anonymously. Generally, the //! [`Map::with_options()`] and [`MapMut::with_options()`] are used to specify //! the mapping requirements. See [`Options`] for more information. //! //! The [`MapMut`] type maintains interior mutability for the mapped memory, //! while the [`Map`] is read-only. However, it is possible to convert between //! these types ([`.into_map_mut()`] and [`.into_map()`]) assuming the proper //! [`Options`] are specified. //! //! Additionally, a variety of buffer implementations are provided in the //! [`vmap::io`] module. The [`Ring`] and [`InfiniteRing`] use circular memory //! address allocations using cross-platform optimizations to minimize excess //! resources where possible. The [`BufReader`] and [`BufWriter`] implement //! buffered I/O using a [`Ring`] as a backing layer. //! //! # Examples //! //! ``` //! use vmap::Map; //! use std::path::PathBuf; //! use std::str::from_utf8; //! # use std::fs; //! //! # fn main() -> vmap::Result<()> { //! # let tmp = tempdir::TempDir::new("vmap")?; //! let path: PathBuf = /* path to file */ //! # tmp.path().join("example"); //! # fs::write(&path, b"this is a test")?; //! //! // Map the first 4 bytes //! let (map, file) = Map::with_options().len(4).open(&path)?; //! assert_eq!(Ok("this"), from_utf8(&map[..])); //! //! // Reuse the file to map a different region //! let map = Map::with_options().offset(10).len(4).map(&file)?; //! assert_eq!(Ok("test"), from_utf8(&map[..])); //! # Ok(()) //! # } //! ``` //! //! If opened properly, the `Map` can be moved into a `MapMut` and modifications //! to the underlying file can be performed: //! //! ``` //! use vmap::{Map, Flush}; //! use std::path::PathBuf; //! use std::str::from_utf8; //! # use std::fs; //! //! # fn main() -> vmap::Result<()> { //! # let tmp = tempdir::TempDir::new("vmap")?; //! let path: PathBuf = /* path to file */ //! # tmp.path().join("example"); //! # fs::write(&path, b"this is a test")?; //! //! // Open with write permissions so the Map can be converted into a MapMut //! let (map, file) = Map::with_options().write().len(14).open(&path)?; //! assert_eq!(Ok("this is a test"), from_utf8(&map[..])); //! //! // Move the Map into a MapMut //! // ... we could have started with MapMut::with_options() //! let mut map = map.into_map_mut()?; //! map[..4].clone_from_slice(b"that"); //! //! // Flush the changes to disk synchronously //! map.flush(&file, Flush::Sync)?; //! //! // Move the MapMut back into a Map //! let map = map.into_map()?; //! assert_eq!(Ok("that is a test"), from_utf8(&map[..])); //! # Ok(()) //! # } //! ``` //! //! This library contains a [`Ring`] that constructs a circular memory //! allocation where values can wrap from around from the end of the buffer back //! to the beginning with sequential memory addresses. The [`InfiniteRing`] is //! similar, however it allows writes to overwrite reads. //! //! ``` //! use vmap::io::{Ring, SeqWrite}; //! use std::io::{BufRead, Read, Write}; //! //! # fn main() -> std::io::Result<()> { //! let mut buf = Ring::new(4000).unwrap(); //! let mut i = 1; //! //! // Fill up the buffer with lines. //! while buf.write_len() > 20 { //! write!(&mut buf, "this is test line {}\n", i)?; //! i += 1; //! } //! //! // No more space is available. //! assert!(write!(&mut buf, "this is test line {}\n", i).is_err()); //! //! let mut line = String::new(); //! //! // Read the first line written. //! let len = buf.read_line(&mut line)?; //! assert_eq!(line, "this is test line 1\n"); //! //! line.clear(); //! //! // Read the second line written. //! let len = buf.read_line(&mut line)?; //! assert_eq!(line, "this is test line 2\n"); //! //! // Now there is enough space to write more. //! write!(&mut buf, "this is test line {}\n", i)?; //! # Ok(()) //! # } //! ``` //! //! [`.flush()`]: struct.MapMut.html#method.flush //! [`.into_map()`]: struct.MapMut.html#method.into_map //! [`.into_map_mut()`]: struct.Map.html#method.into_map_mut //! [`BufReader`]: io/struct.BufReader.html //! [`BufWriter`]: io/struct.BufWriter.html //! [`InfiniteRing`]: io/struct.InfiniteRing.html //! [`Map::with_options()`]: struct.Map.html#method.with_options //! [`MapMut::with_options()`]: struct.MapMut.html#method.with_options //! [`MapMut`]: struct.MapMut.html //! [`Map`]: struct.Map.html //! [`Options`]: struct.Options.html //! [`Ring`]: io/struct.Ring.html //! [`vmap::io`]: io/index.html #![deny(missing_docs)] use std::ops::{Deref, DerefMut}; use std::sync::atomic::{AtomicUsize, Ordering}; use std::{mem, ptr}; #[cfg(feature = "os")] pub mod os; #[cfg(not(feature = "os"))] mod os; mod error; pub use self::error::{ConvertResult, Error, Input, Operation, Result}; mod map; pub use self::map::{Map, MapMut, Options}; #[cfg(feature = "io")] pub mod io; /// Protection level for a page. #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] pub enum Protect { /// The page(s) may only be read from. ReadOnly, /// The page(s) may be read from and written to. ReadWrite, /// Like `ReadWrite`, but changes are not shared. ReadCopy, } /// Desired behavior when flushing write changes. #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] pub enum Flush { /// Request dirty pages to be written immediately and block until completed. Sync, /// Request dirty pages to be written but do not wait for completion. Async, } /// Hint for the access pattern of the underlying mapping. #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] pub enum AdviseAccess { /// Use the system default behavior. Normal, /// The map will be accessed in a sequential manner. Sequential, /// The map will be accessed in a random manner. Random, } /// Hint for the immediacy of accessing the underlying mapping. #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] pub enum AdviseUsage { /// Use the system default behavior. Normal, /// The map is expected to be accessed soon. WillNeed, /// The map is not expected to be accessed soon. WillNotNeed, } /// Byte extent type used for length and resize options. /// /// For usage information, see the [`.len()`] or [`.resize()`] methods of the /// [`Options`] builder type. /// /// [`.len()`]: struct.Options.html#method.len /// [`.resize()`]: struct.Options.html#method.resize /// [`Options`]: struct.Options.html pub enum Extent { /// A dynamic extent that implies the end byte position of an underlying /// file resource or anonymous allocation. End, /// A static extent that referers to an exact byte position. Exact(usize), /// A dynamic extent that referes a byte position of at least a particular /// offset. Min(usize), /// A dynamic extent that referes a byte position of no greater than a /// particular offset. Max(usize), } impl From<usize> for Extent { fn from(v: usize) -> Self { Self::Exact(v) } } /// Gets a cached version of the system page size. /// /// # Examples /// /// ``` /// let page_size = vmap::page_size(); /// println!("the system page size is {} bytes", page_size); /// assert!(page_size >= 4096); /// ``` pub fn page_size() -> usize { let size = PAGE_SIZE.load(Ordering::Relaxed); if size == 0 { load_system_info().0 as usize } else { size } } /// Gets a cached version of the system allocation granularity size. /// /// On Windows this value is typically 64k. Otherwise it is the same as the /// page size. /// /// # Examples /// /// ``` /// let alloc_size = vmap::allocation_size(); /// println!("the system allocation granularity is {} bytes", alloc_size); /// if cfg!(windows) { /// assert!(alloc_size >= 65536); /// } else { /// assert!(alloc_size >= 4096); /// } /// ``` pub fn allocation_size() -> usize { let size = ALLOC_SIZE.load(Ordering::Relaxed); if size == 0 { load_system_info().1 as usize } else { size } } static PAGE_SIZE: AtomicUsize = AtomicUsize::new(0); static ALLOC_SIZE: AtomicUsize = AtomicUsize::new(0); #[inline] fn load_system_info() -> (u32, u32) { let (page, alloc) = self::os::system_info(); PAGE_SIZE.store(page as usize, Ordering::Relaxed); ALLOC_SIZE.store(alloc as usize, Ordering::Relaxed); (page, alloc) } /// Type for calculation system page or allocation size information. /// /// # Examples /// /// ``` /// let size = vmap::AllocSize::new(); /// let pages = size.count(200); /// assert_eq!(pages, 1); /// /// let round = size.round(200); /// println!("200 bytes requires a {} byte mapping", round); /// /// let count = size.count(10000); /// println!("10000 bytes requires {} pages", count); /// /// let size = size.size(3); /// println!("3 pages are {} bytes", size); /// ``` #[deprecated(since = "0.4.0", note = "use Size instead")] pub type AllocSize = Size; /// Type for calculation system page or allocation size information. /// /// # Examples /// /// ``` /// let size = vmap::Size::alloc(); /// let pages = size.count(200); /// assert_eq!(pages, 1); /// /// let round = size.round(200); /// println!("200 bytes requires a {} byte mapping", round); /// /// let count = size.count(10000); /// println!("10000 bytes requires {} pages", count); /// /// let size = size.size(3); /// println!("3 pages are {} bytes", size); /// ``` #[derive(Copy, Clone)] pub struct Size(usize); impl Size { /// Creates a type for calculating allocation numbers and byte offsets. /// /// The size is determined from the system's configurated allocation /// granularity. This value is cached making it very cheap to construct. #[inline] #[deprecated(since = "0.4.0", note = "use Size::alloc() instead")] pub fn new() -> Self { Self::alloc() } /// Creates a type for calculating page numbers and byte offsets. /// /// The size is determined from the system's configurated page size. /// This value is cached making it very cheap to construct. #[inline] pub fn page() -> Self { unsafe { Self::with_size(page_size()) } } /// Creates a type for calculating allocation numbers and byte offsets. /// /// The size is determined from the system's configurated allocation /// granularity. This value is cached making it very cheap to construct. #[inline] pub fn alloc() -> Self { unsafe { Self::with_size(allocation_size()) } } /// Creates a type for calculating allocations numbers and byte offsets /// using a known size. /// /// # Safety /// /// The size *must* be a power-of-2. To successfully map pages, the size /// must also be a mutliple of the actual system allocation granularity. /// Hypothetically this could be used to simulate larger page sizes, but /// this has no bearing on the TLB cache. /// /// # Examples /// /// ``` /// use vmap::Size; /// /// let sys = vmap::allocation_size(); /// let size = unsafe { Size::with_size(sys << 2) }; /// assert_eq!(size.round(1), sys << 2); // probably 16384 /// ``` #[inline] pub unsafe fn with_size(size: usize) -> Self { Size(size) } /// Round a byte size up to the nearest unit size. /// /// # Examples /// /// ``` /// use vmap::Size; /// /// let sys = vmap::page_size(); /// let size = Size::page(); /// assert_eq!(size.round(0), 0); /// assert_eq!(size.round(1), sys); // probably 4096 /// assert_eq!(size.round(sys-1), sys); // probably 4096 /// assert_eq!(size.round(sys), sys); // probably 4096 /// assert_eq!(size.round(sys+1), sys*2); // probably 8192 /// ``` #[inline] pub fn round(&self, len: usize) -> usize { self.truncate(len + self.0 - 1) } /// Round a byte size down to the nearest unit size. /// /// # Examples /// /// ``` /// use vmap::Size; /// /// let sys = vmap::page_size(); /// let size = Size::page(); /// assert_eq!(size.truncate(0), 0); /// assert_eq!(size.truncate(1), 0); /// assert_eq!(size.truncate(sys-1), 0); /// assert_eq!(size.truncate(sys), sys); // probably 4096 /// assert_eq!(size.truncate(sys+1), sys); // probably 4096 /// ``` #[inline] pub fn truncate(&self, len: usize) -> usize { len & !(self.0 - 1) } /// Calculate the byte offset from size unit containing the position. /// /// # Examples /// /// ``` /// use vmap::Size; /// /// let sys = vmap::page_size(); /// let size = Size::page(); /// assert_eq!(size.offset(1), 1); /// assert_eq!(size.offset(sys-1), sys-1); /// assert_eq!(size.offset(sys*2 + 123), 123); /// ``` #[inline] pub fn offset(&self, len: usize) -> usize { len & (self.0 - 1) } /// Convert a unit count into a byte size. /// /// # Examples /// /// ``` /// use vmap::Size; /// /// let sys = vmap::page_size(); /// let size = Size::page(); /// assert_eq!(size.size(0), 0); /// assert_eq!(size.size(1), sys); // probably 4096 /// assert_eq!(size.size(2), sys*2); // probably 8192 /// ``` #[inline] pub fn size(&self, count: u32) -> usize { (count as usize) << self.0.trailing_zeros() } /// Covert a byte size into the number of units necessary to contain it. /// /// # Examples /// /// ``` /// use vmap::Size; /// /// let sys = vmap::page_size(); /// let size = Size::page(); /// assert_eq!(size.count(0), 0); /// assert_eq!(size.count(1), 1); /// assert_eq!(size.count(sys-1), 1); /// assert_eq!(size.count(sys), 1); /// assert_eq!(size.count(sys+1), 2); /// assert_eq!(size.count(sys*2), 2); /// ``` #[inline] pub fn count(&self, len: usize) -> u32 { (self.round(len) >> self.0.trailing_zeros()) as u32 } /// Calculates the unit bounds for a pointer and length. /// /// # Safety /// /// There is no verification that the pointer is a mapped page nor that /// the calculated offset may be dereferenced. #[inline] pub unsafe fn bounds(&self, ptr: *mut u8, len: usize) -> (*mut u8, usize) { let off = self.offset(ptr as usize); (ptr.offset(-(off as isize)), self.round(len + off)) } } impl Default for Size { fn default() -> Self { Self::alloc() } } /// General trait for working with any memory-safe representation of a /// contiguous region of arbitrary memory. pub trait Span: Deref<Target = [u8]> + Sized + sealed::Span { /// Get the length of the allocated region. fn len(&self) -> usize; /// Get the pointer to the start of the allocated region. fn as_ptr(&self) -> *const u8; /// Tests if the span covers zero bytes. #[inline] fn is_empty(&self) -> bool { self.len() == 0 } /// Performs a volatile read of the value at a given offset. /// /// Volatile operations are intended to act on I/O memory, and are /// guaranteed to not be elided or reordered by the compiler across /// other volatile operations. #[inline] fn read_volatile<T: sealed::Scalar>(&self, offset: usize) -> T { assert_capacity::<T>(offset, self.len()); assert_alignment::<T>(offset, self.as_ptr()); unsafe { ptr::read_volatile(self.as_ptr().add(offset) as *const T) } } /// Performs an unaligned read of the value at a given offset. #[inline] fn read_unaligned<T: sealed::Scalar>(&self, offset: usize) -> T { assert_capacity::<T>(offset, self.len()); unsafe { ptr::read_unaligned(self.as_ptr().add(offset) as *const T) } } } /// General trait for working with any memory-safe representation of a /// contiguous region of arbitrary mutable memory. pub trait SpanMut: Span + DerefMut { /// Get a mutable pointer to the start of the allocated region. fn as_mut_ptr(&mut self) -> *mut u8; /// Performs a volatile write of the value at a given offset. /// /// Volatile operations are intended to act on I/O memory, and are /// guaranteed to not be elided or reordered by the compiler across /// other volatile operations. #[inline] fn write_volatile<T: sealed::Scalar>(&mut self, offset: usize, value: T) { assert_capacity::<T>(offset, self.len()); assert_alignment::<T>(offset, self.as_ptr()); unsafe { ptr::write_volatile(self.as_mut_ptr().add(offset) as *mut T, value) } } /// Performs an unaligned write of the value at a given offset. #[inline] fn write_unaligned<T: sealed::Scalar>(&mut self, offset: usize, value: T) { assert_capacity::<T>(offset, self.len()); unsafe { ptr::write_unaligned(self.as_mut_ptr().add(offset) as *mut T, value) } } } impl<'a> Span for &'a [u8] { #[inline] fn len(&self) -> usize { <[u8]>::len(self) } #[inline] fn as_ptr(&self) -> *const u8 { <[u8]>::as_ptr(self) } } impl<'a> Span for &'a mut [u8] { #[inline] fn len(&self) -> usize { <[u8]>::len(self) } #[inline] fn as_ptr(&self) -> *const u8 { <[u8]>::as_ptr(self) } } impl<'a> SpanMut for &'a mut [u8] { #[inline] fn as_mut_ptr(&mut self) -> *mut u8 { <[u8]>::as_mut_ptr(self) } } mod sealed { pub trait Span {} impl Span for super::Map {} impl Span for super::MapMut {} impl<'a> Span for &'a [u8] {} impl<'a> Span for &'a mut [u8] {} pub trait FromPtr { unsafe fn from_ptr(ptr: *mut u8, len: usize) -> Self; } pub trait Scalar: Default {} impl Scalar for u8 {} impl Scalar for i8 {} impl Scalar for u16 {} impl Scalar for i16 {} impl Scalar for u32 {} impl Scalar for i32 {} impl Scalar for u64 {} impl Scalar for i64 {} impl Scalar for u128 {} impl Scalar for i128 {} impl Scalar for usize {} impl Scalar for isize {} impl Scalar for f32 {} impl Scalar for f64 {} } #[inline] fn assert_alignment<T>(offset: usize, ptr: *const u8) { if unsafe { ptr.add(offset) } as usize % mem::align_of::<T>() != 0 { panic!( "offset improperly aligned: the requirement is {} but the offset is +{}/-{}", mem::align_of::<T>(), ptr as usize % mem::align_of::<T>(), mem::align_of::<T>() - (ptr as usize % mem::align_of::<T>()), ) } } #[inline] fn assert_capacity<T>(offset: usize, len: usize) { if offset + mem::size_of::<T>() > len { panic!( "index out of bounds: the len is {} but the index is {}", len, offset + mem::size_of::<T>() ) } } #[cfg(test)] mod tests { use std::fs; use std::path::PathBuf; use std::str::from_utf8; use super::*; #[test] fn allocation_size() { let sz = unsafe { Size::with_size(4096) }; assert_eq!(sz.round(0), 0); assert_eq!(sz.round(1), 4096); assert_eq!(sz.round(4095), 4096); assert_eq!(sz.round(4096), 4096); assert_eq!(sz.round(4097), 8192); assert_eq!(sz.truncate(0), 0); assert_eq!(sz.truncate(1), 0); assert_eq!(sz.truncate(4095), 0); assert_eq!(sz.truncate(4096), 4096); assert_eq!(sz.truncate(4097), 4096); assert_eq!(sz.size(0), 0); assert_eq!(sz.size(1), 4096); assert_eq!(sz.size(2), 8192); assert_eq!(sz.count(0), 0); assert_eq!(sz.count(1), 1); assert_eq!(sz.count(4095), 1); assert_eq!(sz.count(4096), 1); assert_eq!(sz.count(4097), 2); assert_eq!(sz.count(8192), 2); assert_eq!(sz.offset(0), 0); assert_eq!(sz.offset(1), 1); assert_eq!(sz.offset(4095), 4095); assert_eq!(sz.offset(4096), 0); assert_eq!(sz.offset(4097), 1); } #[test] fn alloc_min() -> Result<()> { let sz = Size::alloc(); let mut map = MapMut::with_options().len(Extent::Min(100)).alloc()?; assert_eq!(map.len(), sz.round(100)); assert_eq!(Ok("\0\0\0\0\0"), from_utf8(&map[..5])); map[..5].clone_from_slice(b"hello"); assert_eq!(Ok("hello"), from_utf8(&map[..5])); Ok(()) } #[test] fn alloc_exact() -> Result<()> { let mut map = MapMut::with_options().len(5).alloc()?; assert_eq!(map.len(), 5); assert_eq!(Ok("\0\0\0\0\0"), from_utf8(&map[..])); map[..5].clone_from_slice(b"hello"); assert_eq!(Ok("hello"), from_utf8(&map[..])); Ok(()) } #[test] fn alloc_offset() -> Result<()> { // map to the offset of the last 5 bytes of an allocation size, but map 6 bytes let off = Size::alloc().size(1) - 5; let mut map = MapMut::with_options().offset(off).len(6).alloc()?; // force the page after the 5 bytes to be read-only unsafe { os::protect(map.as_mut_ptr().add(5), 1, Protect::ReadOnly)? }; assert_eq!(map.len(), 6); assert_eq!(Ok("\0\0\0\0\0\0"), from_utf8(&map[..])); // writing one more byte will segfault map[..5].clone_from_slice(b"hello"); assert_eq!(Ok("hello\0"), from_utf8(&map[..])); Ok(()) } #[test] fn read_end() -> Result<()> { let (_tmp, path, len) = write_default("read_end")?; let (map, _) = Map::with_options().offset(29).open(&path)?; assert!(map.len() >= 30); assert_eq!(len - 29, map.len()); assert_eq!(Ok("fast and safe memory-mapped IO"), from_utf8(&map[..30])); Ok(()) } #[test] fn read_min() -> Result<()> { let (_tmp, path, len) = write_default("read_min")?; let (map, _) = Map::with_options() .offset(29) .len(Extent::Min(30)) .open(&path)?; println!("path = {:?}, len = {}, map = {}", path, len, map.len()); assert!(map.len() >= 30); assert_eq!(len - 29, map.len()); assert_eq!(Ok("fast and safe memory-mapped IO"), from_utf8(&map[..30])); Ok(()) } #[test] fn read_max() -> Result<()> { let (_tmp, path, _len) = write_default("read_max")?; let (map, _) = Map::with_options() .offset(29) .len(Extent::Max(30)) .open(&path)?; assert!(map.len() == 30); assert_eq!(Ok("fast and safe memory-mapped IO"), from_utf8(&map[..])); Ok(()) } #[test] fn read_exact() -> Result<()> { let (_tmp, path, _len) = write_default("read_exact")?; let (map, _) = Map::with_options().offset(29).len(30).open(&path)?; assert!(map.len() == 30); assert_eq!(Ok("fast and safe memory-mapped IO"), from_utf8(&map[..])); Ok(()) } #[test] fn copy() -> Result<()> { let (_tmp, path, _len) = write_default("copy")?; let (mut map, _) = MapMut::with_options() .offset(29) .len(30) .copy() .open(&path)?; assert_eq!(map.len(), 30); assert_eq!(Ok("fast and safe memory-mapped IO"), from_utf8(&map[..])); map[..4].clone_from_slice(b"nice"); assert_eq!(Ok("nice and safe memory-mapped IO"), from_utf8(&map[..])); Ok(()) } #[test] fn write_into_mut() -> Result<()> { let tmp = tempdir::TempDir::new("vmap")?; let path: PathBuf = tmp.path().join("write_into_mut"); fs::write(&path, "this is a test").expect("failed to write file"); let (map, _) = Map::with_options().write().resize(16).open(&path)?; assert_eq!(16, map.len()); assert_eq!(Ok("this is a test"), from_utf8(&map[..14])); assert_eq!(Ok("this is a test\0\0"), from_utf8(&map[..])); let mut map = map.into_map_mut()?; map[..4].clone_from_slice(b"that"); assert_eq!(Ok("that is a test"), from_utf8(&map[..14])); assert_eq!(Ok("that is a test\0\0"), from_utf8(&map[..])); let map = map.into_map()?; assert_eq!(Ok("that is a test"), from_utf8(&map[..14])); assert_eq!(Ok("that is a test\0\0"), from_utf8(&map[..])); let (map, _) = Map::with_options().open(&path)?; assert_eq!(16, map.len()); assert_eq!(Ok("that is a test"), from_utf8(&map[..14])); assert_eq!(Ok("that is a test\0\0"), from_utf8(&map[..])); Ok(()) } #[test] fn truncate() -> Result<()> { let tmp = tempdir::TempDir::new("vmap")?; let path: PathBuf = tmp.path().join("truncate"); fs::write(&path, "this is a test").expect("failed to write file"); let (map, _) = Map::with_options() .write() .truncate(true) .resize(16) .open(&path)?; assert_eq!(16, map.len()); assert_eq!(Ok("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"), from_utf8(&map[..])); Ok(()) } type WriteResult = Result<(tempdir::TempDir, PathBuf, usize)>; fn write_tmp(name: &'static str, msg: &'static str) -> WriteResult { let tmp = tempdir::TempDir::new("vmap")?; let path: PathBuf = tmp.path().join(name); fs::write(&path, msg)?; Ok((tmp, path, msg.len())) } fn write_default(name: &'static str) -> WriteResult { write_tmp( name, "A cross-platform library for fast and safe memory-mapped IO in Rust", ) } #[test] fn volatile() -> Result<()> { let tmp = tempdir::TempDir::new("vmap")?; let path: PathBuf = tmp.path().join("volatile"); let (mut map, _) = MapMut::with_options() .write() .truncate(true) .create(true) .resize(16) .open(&path)?; assert_eq!(16, map.len()); assert_eq!(0u64, map.read_volatile(0)); assert_eq!(0u64, map.read_volatile(8)); map.write_volatile(0, 0xc3a5c85c97cb3127u64); map.write_volatile(8, 0xb492b66fbe98f273u64); assert_eq!(0xc3a5c85c97cb3127u64, map.read_volatile(0)); assert_eq!(0xb492b66fbe98f273u64, map.read_volatile(8)); let (map, _) = Map::with_options().open(&path)?; assert_eq!(16, map.len()); assert_eq!(0xc3a5c85c97cb3127u64, map.read_volatile(0)); assert_eq!(0xb492b66fbe98f273u64, map.read_volatile(8)); Ok(()) } #[test] fn unaligned() -> Result<()> { let tmp = tempdir::TempDir::new("vmap")?; let path: PathBuf = tmp.path().join("unaligned"); let (mut map, _) = MapMut::with_options() .write() .truncate(true) .create(true) .resize(17) .open(&path)?; assert_eq!(17, map.len()); assert_eq!(0u64, map.read_unaligned(1)); assert_eq!(0u64, map.read_unaligned(9)); map.write_unaligned(1, 0xc3a5c85c97cb3127u64); map.write_unaligned(9, 0xb492b66fbe98f273u64); assert_eq!(0xc3a5c85c97cb3127u64, map.read_unaligned(1)); assert_eq!(0xb492b66fbe98f273u64, map.read_unaligned(9)); let (map, _) = Map::with_options().open(&path)?; assert_eq!(17, map.len()); assert_eq!(0xc3a5c85c97cb3127u64, map.read_unaligned(1)); assert_eq!(0xb492b66fbe98f273u64, map.read_unaligned(9)); Ok(()) } }