Struct aws_smithy_http::byte_stream::FsBuilder

pub struct FsBuilder { /* private fields */ }

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

Example usage:

use aws_smithy_http::byte_stream::ByteStream;
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)
        .file_size(123_456)
        .build()
        .await
        .expect("valid path");
    GetObjectInput { body: bytestream }
}

Implementations

impl FsBuilder

pub fn new() -> Self

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>) -> Self

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) -> Self

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 file_size(self, file_size: u64) -> Self

Specify the length of the file to read (in bytes).

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

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

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

Returns a ByteStream from this builder. NOTE: If both file and path have been called for this FsBuilder, build will read from the path specified by path.

Panics

Panics if neither of the file orpath setters were called.

Trait Implementations

impl Default for FsBuilder

fn default() -> Self

Returns the “default value” for a type.