Struct mmap_storage::anonim::Storage

pub struct Storage { /* fields omitted */ }

Anonymous memory map backed storage

It provides byte storage over anonymous memory map.

When new data is written the storage may be extended using following strategy:

• If new data is small enough, resize to double size.
• Otherwise resize to new data_size.

If needed you can use resize method to shrink or extend storage.

Unless otherwise stated all methods that modify content of storage doesn't perform flushes, it is callee's responsibility to call it when required

Methods

impl Storage

pub fn new(size: usize) -> Result<Self>

Creates storage with specified size.

pub fn as_slice(&self) -> &[u8]

Returns slice with view on written data.

pub fn as_mut_slice(&mut self) -> &mut [u8]

Returns slice with view on written data.

pub fn capacity(&self) -> usize

Returns overall size of storage(including extra space).

pub fn flush_async(&self) -> Result<()>

Asynchronously flushes outstanding memory map modifications to disk.

This method initiates flushing modified pages to durable storage, but it will not wait for the operation to complete before returning.

pub fn flush_sync(&self) -> Result<()>

Synchronously flushes outstanding memory map modifications to disk.

pub fn extend_from_slice(&mut self, data: &[u8]) -> Result<()>

Appends data to storage

Note that it resizes storage if needed. Therefore error can happen.

pub fn copy_from_slice(&mut self, data: &[u8])

Copies data from slice into storage.

Function panics if data has greater len.

Note: It copies data up to storage capacity.

pub fn resize(&mut self, new_size: usize) -> Result<()>

Resizes storage by appending or truncating.

As it requires re-create mmap, the error is possible to happen. In case of error, original storage is preserved.

After successfully creating new storage, previous storage content gets copied.

pub fn clear(&mut self)

Clears content of storage.

Note that it doesn't affect capacity in any way.

pub fn to_vec(&self) -> Vec<u8>

Creates Vec from content of storage.

Trait Implementations

impl Default for Storage

fn default() -> Self

Creates default storage with capacity 1024

Note that it panics on error

impl Write for Storage

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Write.