Struct futures_util::io::BufWriter

source · [−]
pub struct BufWriter<W> { /* private fields */ }
Expand description

Wraps a writer and buffers its output.

It can be excessively inefficient to work directly with something that implements AsyncWrite. A BufWriter keeps an in-memory buffer of data and writes it to an underlying writer in large, infrequent batches.

BufWriter can improve the speed of programs that make small and repeated write calls to the same file or network socket. It does not help when writing very large amounts at once, or writing just one or a few times. It also provides no advantage when writing to a destination that is in memory, like a Vec<u8>.

When the BufWriter is dropped, the contents of its buffer will be discarded. Creating multiple instances of a BufWriter on the same stream can cause data loss. If you need to write out the contents of its buffer, you must manually call flush before the writer is dropped.

Implementations

Creates a new BufWriter with a default buffer capacity. The default is currently 8 KB, but may change in the future.

Creates a new BufWriter with the specified buffer capacity.

Acquires a reference to the underlying sink or stream that this combinator is pulling from.

Acquires a mutable reference to the underlying sink or stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.

Acquires a pinned mutable reference to the underlying sink or stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.

Consumes this combinator, returning the underlying sink or stream.

Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.

Returns a reference to the internally buffered data.

Trait Implementations

Attempt to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read. Read more

Attempt to read from the AsyncRead into buf. Read more

Attempt to read from the AsyncRead into bufs using vectored IO operations. Read more

Seek to the offset, in bytes, in the underlying writer.

Seeking always writes out the internal buffer before seeking.

Attempt to write bytes from buf into the object. Read more

Attempt to write bytes from bufs into the object using vectored IO operations. Read more

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more

Attempt to close the object. Read more

Formats the value using the given formatter. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Creates a future which will wait for a non-empty buffer to be available from this I/O object or EOF to be reached. Read more

A convenience for calling AsyncBufRead::consume on Unpin IO types. Read more

Creates a future which will read all the bytes associated with this I/O object into buf until the delimiter byte or EOF is reached. This method is the async equivalent to BufRead::read_until. Read more

Creates a future which will read all the bytes associated with this I/O object into buf until a newline (the 0xA byte) or EOF is reached, This method is the async equivalent to BufRead::read_line. Read more

Returns a stream over the lines of this reader. This method is the async equivalent to BufRead::lines. Read more

Creates an adaptor which will chain this stream with another. Read more

Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type. Read more

Creates a future which will read from the AsyncRead into bufs using vectored IO operations. Read more

Creates a future which will read exactly enough bytes to fill buf, returning an error if end of file (EOF) is hit sooner. Read more

Creates a future which will read all the bytes from this AsyncRead. Read more

Creates a future which will read all the bytes from this AsyncRead. Read more

Helper method for splitting this read/write object into two halves. Read more

Creates an AsyncRead adapter which will read at most limit bytes from the underlying reader. Read more

Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more

Creates a future which will return the current seek position from the start of the stream. Read more

Creates a future which will entirely flush this AsyncWrite. Read more

Creates a future which will entirely close this AsyncWrite.

Creates a future which will write bytes from buf into the object. Read more

Creates a future which will write bytes from bufs into the object using vectored IO operations. Read more

Write data into this object. Read more

Attempts to write multiple buffers into this writer. Read more

Allow using an AsyncWrite as a Sink<Item: AsRef<[u8]>>. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.