refactor(tvix/store): move blob splitting into a BlobWriter struct r/5927

This will moves the chunking-as-we-receive logic that so far only lived
in grpc_blobservice_wrapper.rs into a generic BlobWriter.

Change-Id: Ief7d1bda3c6280129f7139de3f6c4174be2ca6ea
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8154
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

1 files changed, 11 insertions, 76 deletions

diff --git a/tvix/store/src/proto/grpc_blobservice_wrapper.rs b/tvix/store/src/proto/grpc_blobservice_wrapper.rs
index 4ae3093492..52d0670307 100644
--- a/tvix/store/src/proto/grpc_blobservice_wrapper.rs
+++ b/tvix/store/src/proto/grpc_blobservice_wrapper.rs
@@ -1,9 +1,10 @@
 use crate::{blobservice::BlobService, chunkservice::ChunkService, Error};
 use data_encoding::BASE64;
+use std::io::Write;
 use tokio::{sync::mpsc::channel, task};
 use tokio_stream::wrappers::ReceiverStream;
 use tonic::{async_trait, Request, Response, Status, Streaming};
-use tracing::{debug, instrument};
+use tracing::{debug, error, instrument, warn};
 
 pub struct GRPCBlobServiceWrapper<BS: BlobService, CS: ChunkService> {
     blob_service: BS,
@@ -164,86 +165,20 @@ impl<
     ) -> Result<Response<super::PutBlobResponse>, Status> {
         let mut req_inner = request.into_inner();
 
-        // initialize a blake3 hasher calculating the hash of the whole blob.
-        let mut blob_hasher = blake3::Hasher::new();
+        let mut blob_writer = crate::BlobWriter::new(&self.chunk_service);
 
-        // start a BlobMeta, which we'll fill while looping over the chunks
-        let mut blob_meta = super::BlobMeta::default();
-
-        // is filled with bytes received from the client.
-        let mut buf: Vec<u8> = vec![];
-
-        // This reads data from the client, chunks it up using fastcdc,
-        // uploads all chunks to the [ChunkService], and fills a
-        // [super::BlobMeta] linking to these chunks.
+        // receive data from the client, and keep writing it to the blob writer.
         while let Some(blob_chunk) = req_inner.message().await? {
-            // calculate blob hash, and use rayon if data is > 128KiB.
-            if blob_chunk.data.len() > 128 * 1024 {
-                blob_hasher.update_rayon(&blob_chunk.data);
-            } else {
-                blob_hasher.update(&blob_chunk.data);
-            }
-
-            // extend buf with the newly received data
-            buf.append(&mut blob_chunk.data.clone());
-
-            // TODO: play with chunking sizes
-            let chunker_avg_size = 64 * 1024;
-            let chunker_min_size = chunker_avg_size / 4;
-            let chunker_max_size = chunker_avg_size * 4;
-
-            // initialize a chunker with the current buffer
-            let chunker = fastcdc::v2020::FastCDC::new(
-                &buf,
-                chunker_min_size,
-                chunker_avg_size,
-                chunker_max_size,
-            );
-
-            // ask the chunker for cutting points in the buffer.
-            let mut start_pos = 0 as usize;
-            buf = loop {
-                // ask the chunker for the next cutting point.
-                let (_fp, end_pos) = chunker.cut(start_pos, buf.len() - start_pos);
-
-                // whenever the last cut point is pointing to the end of the buffer,
-                // keep that chunk left in there.
-                // We don't know if the chunker decided to cut here simply because it was
-                // at the end of the buffer, or if it would also cut if there
-                // were more data.
-                //
-                // Split off all previous chunks and keep this chunk data in the buffer.
-                if end_pos == buf.len() {
-                    break buf.split_off(start_pos);
-                }
-
-                // Upload that chunk to the chunk service and record it in BlobMeta.
-                // TODO: make upload_chunk async and upload concurrently?
-                let chunk_data = &buf[start_pos..end_pos];
-                let chunk_digest =
-                    Self::upload_chunk(self.chunk_service.clone(), chunk_data.to_vec())?;
-
-                blob_meta.chunks.push(super::blob_meta::ChunkMeta {
-                    digest: chunk_digest,
-                    size: chunk_data.len() as u32,
-                });
-
-                // move start_pos over the processed chunk.
-                start_pos = end_pos;
+            if let Err(e) = blob_writer.write_all(&blob_chunk.data) {
+                error!(e=%e,"unable to write blob data");
+                return Err(Status::internal("unable to write blob data"));
             }
         }
 
-        // Also upload the last chunk (what's left in `buf`) to the chunk
-        // service and record it in BlobMeta.
-        let buf_len = buf.len() as u32;
-        let chunk_digest = Self::upload_chunk(self.chunk_service.clone(), buf)?;
-
-        blob_meta.chunks.push(super::blob_meta::ChunkMeta {
-            digest: chunk_digest,
-            size: buf_len,
-        });
-
-        let blob_digest = blob_hasher.finalize().as_bytes().to_vec();
+        // run finalize
+        let (blob_digest, blob_meta) = blob_writer
+            .finalize()
+            .map_err(|_| Status::internal("unable to finalize blob"))?;
 
         // check if we have the received blob in the [BlobService] already.
         let resp = self.blob_service.stat(&super::StatBlobRequest {