Trait BlockWrite

pub trait BlockWrite:
    Send
    + Sync
    + Unpin
    + 'static {
    // Required methods
    fn write_once(
        &self,
        size: u64,
        body: Buffer,
    ) -> impl Future<Output = Result<Metadata>> + MaybeSend;
    fn write_block(
        &self,
        block_id: Uuid,
        size: u64,
        body: Buffer,
    ) -> impl Future<Output = Result<()>> + MaybeSend;
    fn complete_block(
        &self,
        block_ids: Vec<Uuid>,
    ) -> impl Future<Output = Result<Metadata>> + MaybeSend;
    fn abort_block(
        &self,
        block_ids: Vec<Uuid>,
    ) -> impl Future<Output = Result<()>> + MaybeSend;
}

BlockWrite is used to implement oio::Write based on block uploads. By implementing BlockWrite, services don’t need to care about the details of uploading blocks.

Architecture

The architecture after adopting BlockWrite:

• Services impl BlockWrite
• BlockWriter impl Write
• Expose BlockWriter as Accessor::Writer

Notes

BlockWrite has an oneshot optimization when write has been called only once:

w.write(bs).await?;
w.close().await?;

We will use write_once instead of starting a new block upload.

Requirements

Services that implement BlockWrite must fulfill the following requirements:

• Must be a http service that could accept AsyncBody.
• Don’t need initialization before writing.
• Block ID is generated by caller BlockWrite instead of services.
• Complete block by an ordered block id list.

Required Methods

fn write_once( &self, size: u64, body: Buffer, ) -> impl Future<Output = Result<Metadata>> + MaybeSend

write_once is used to write the data to underlying storage at once.

BlockWriter will call this API when:

• All the data has been written to the buffer and we can perform the upload at once.

fn write_block( &self, block_id: Uuid, size: u64, body: Buffer, ) -> impl Future<Output = Result<()>> + MaybeSend

write_block will write a block of the data.

BlockWriter will call this API and stores the result in order.

• block_id is the id of the block.

fn complete_block( &self, block_ids: Vec<Uuid>, ) -> impl Future<Output = Result<Metadata>> + MaybeSend

complete_block will complete the block upload to build the final file.

fn abort_block( &self, block_ids: Vec<Uuid>, ) -> impl Future<Output = Result<()>> + MaybeSend

abort_block will cancel the block upload and purge all data.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors