Skip to content
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
Cannot retrieve contributors at this time
#[cxx::bridge(namespace = "org::blobstore")]
mod ffi {
// Shared structs with fields visible to both languages.
struct BlobMetadata {
size: usize,
tags: Vec<String>,
// Rust types and signatures exposed to C++.
extern "Rust" {
type MultiBuf;
fn next_chunk(buf: &mut MultiBuf) -> &[u8];
// C++ types and signatures exposed to Rust.
unsafe extern "C++" {
type BlobstoreClient;
fn new_blobstore_client() -> UniquePtr<BlobstoreClient>;
fn put(&self, parts: &mut MultiBuf) -> u64;
fn tag(&self, blobid: u64, tag: &str);
fn metadata(&self, blobid: u64) -> BlobMetadata;
// An iterator over contiguous chunks of a discontiguous file object.
// Toy implementation uses a Vec<Vec<u8>> but in reality this might be iterating
// over some more complex Rust data structure like a rope, or maybe loading
// chunks lazily from somewhere.
pub struct MultiBuf {
chunks: Vec<Vec<u8>>,
pos: usize,
pub fn next_chunk(buf: &mut MultiBuf) -> &[u8] {
let next = buf.chunks.get(buf.pos);
buf.pos += 1;
next.map_or(&[], Vec::as_slice)
fn main() {
let client = ffi::new_blobstore_client();
// Upload a blob.
let chunks = vec![b"fearless".to_vec(), b"concurrency".to_vec()];
let mut buf = MultiBuf { chunks, pos: 0 };
let blobid = client.put(&mut buf);
println!("blobid = {}", blobid);
// Add a tag.
client.tag(blobid, "rust");
// Read back the tags.
let metadata = client.metadata(blobid);
println!("tags = {:?}", metadata.tags);