Struct opendal::Writer

pub struct Writer { /* private fields */ }

Writer is designed to write data into given path in an asynchronous manner.

Notes

Please make sure either close or abort has been called before dropping the writer otherwise the data could be lost.

Usage

Write Multiple Chunks

Some services support to write multiple chunks of data into given path. Services that doesn’t support write multiple chunks will return ErrorKind::Unsupported error when calling write at the second time.

let mut w = op.writer("path/to/file").await?;
w.write(bs).await?;
w.write(bs).await?;
w.close().await?

Our writer also provides Writer::sink and [Writer::copy] support.

Besides, our writer implements [AsyncWrite] and [tokio::io::AsyncWrite].

Write with append enabled

Writer also supports to write with append enabled. This is useful when users want to append some data to the end of the file.

• If file doesn’t exist, it will be created and just like calling write.
• If file exists, data will be appended to the end of the file.

Possible Errors:

• Some services store normal file and appendable file in different way. Trying to append on non-appendable file could return ErrorKind::ConditionNotMatch error.
• Services that doesn’t support append will return ErrorKind::Unsupported error when creating writer with append enabled.

Implementations

impl Writer

pub async fn write(&mut self, bs: impl Into<Buffer>) -> Result<()>

Write Buffer into inner writer.

pub async fn write_from(&mut self, bs: impl Buf) -> Result<()>

Write bytes::Buf into inner writer.

pub async fn sink<S, T>(&mut self, sink_from: S) -> Result<u64>

where S: Stream<Item = Result<T>>, T: Into<Bytes>,

Sink into writer.

sink will read data from given streamer and write them into writer directly without extra in-memory buffer.

Notes

• Sink doesn’t support to be used with write concurrently.
• Sink doesn’t support to be used without content length now.

Examples

use bytes::Bytes;
use futures::stream;
use futures::StreamExt;
use opendal::Operator;
use opendal::Result;

async fn sink_example(op: Operator) -> Result<()> {
    let mut w = op.writer_with("path/to/file").await?;
    let stream = stream::iter(vec![vec![0; 4096], vec![1; 4096]]).map(Ok);
    w.sink(stream).await?;
    w.close().await?;
    Ok(())
}

pub async fn abort(&mut self) -> Result<()>

Abort the writer and clean up all written data.

Notes

Abort should only be called when the writer is not closed or aborted, otherwise an unexpected error could be returned.

pub async fn close(&mut self) -> Result<()>

Close the writer and make sure all data have been committed.

Notes

Close should only be called when the writer is not closed or aborted, otherwise an unexpected error could be returned.

pub fn into_futures_async_write(self) -> FuturesAsyncWriter

Convert writer into FuturesAsyncWriter which implements [futures::AsyncWrite],