Struct FsBuilder

pub struct FsBuilder { /* private fields */ }

Available on crate feature rt-tokio only.

Builder for creating ByteStreams from a file/path, with full control over advanced options.

use aws_smithy_types::byte_stream::{ByteStream, Length};
use std::path::Path;
struct GetObjectInput {
    body: ByteStream
}

async fn bytestream_from_file() -> GetObjectInput {
    let bytestream = ByteStream::read_from()
        .path("docs/some-large-file.csv")
        // Specify the size of the buffer used to read the file (in bytes, default is 4096)
        .buffer_size(32_784)
        // Specify the length of the file used (skips an additional call to retrieve the size)
        .length(Length::UpTo(123_456))
        .build()
        .await
        .expect("valid path");
    GetObjectInput { body: bytestream }
}

Implementations

impl FsBuilder

pub fn new() -> FsBuilder

Create a new FsBuilder (using a default read buffer of 4096 bytes).

You must then call either file or path to specify what to read from.

pub fn path(self, path: impl AsRef<Path>) -> FsBuilder

Sets the path to read from.

NOTE: The resulting ByteStream (after calling build) will be retryable. The returned ByteStream will provide a size hint when used as an HTTP body. If the request fails, the read will begin again by reloading the file handle.

pub fn file(self, file: File) -> FsBuilder

Sets the file to read from.

NOTE: The resulting ByteStream (after calling build) will not be a retryable ByteStream. For a ByteStream that can be retried in the case of upstream failures, use FsBuilder::path.

pub fn length(self, length: Length) -> FsBuilder

Specify the length to read (in bytes).

By pre-specifying the length, this API skips an additional call to retrieve the size from file-system metadata.

When used in conjunction with offset, allows for reading a single “chunk” of a file.

pub fn buffer_size(self, buffer_size: usize) -> FsBuilder

Specify the size of the buffer used to read the file (in bytes).

Increasing the read buffer capacity to higher values than the default (4096 bytes) can result in a large reduction in CPU usage, at the cost of memory increase.

pub fn offset(self, offset: u64) -> FsBuilder

Specify the offset to start reading from (in bytes)

When used in conjunction with length, allows for reading a single “chunk” of a file.

pub async fn build(self) -> Result<ByteStream, Error>

Returns a ByteStream from this builder.

Trait Implementations

impl Default for FsBuilder

fn default() -> FsBuilder

Returns the “default value” for a type.