From 0baaabc43e3027b1676874c536d5ade27abe14b8 Mon Sep 17 00:00:00 2001 From: Florian Klink Date: Sun, 26 Feb 2023 22:31:50 +0100 Subject: refactor(tvix/store): move blob splitting into a BlobWriter struct 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 --- tvix/store/src/blobwriter.rs | 149 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 149 insertions(+) create mode 100644 tvix/store/src/blobwriter.rs (limited to 'tvix/store/src/blobwriter.rs') diff --git a/tvix/store/src/blobwriter.rs b/tvix/store/src/blobwriter.rs new file mode 100644 index 000000000000..8cb09ecc6d3c --- /dev/null +++ b/tvix/store/src/blobwriter.rs @@ -0,0 +1,149 @@ +use crate::chunkservice::ChunkService; +use crate::{proto, Error}; +use tracing::{debug, instrument}; + +pub struct BlobWriter<'a, CS: ChunkService> { + chunk_service: &'a CS, + + blob_hasher: blake3::Hasher, + + blob_meta: proto::BlobMeta, + + // filled with data from previous writes that didn't end up producing a full chunk. + buf: Vec, +} + +impl<'a, CS: ChunkService> BlobWriter<'a, CS> { + pub fn new(chunk_service: &'a CS) -> Self { + Self { + chunk_service, + blob_hasher: blake3::Hasher::new(), + blob_meta: proto::BlobMeta::default(), + buf: vec![], + } + } + + // Return the digest of the blob, as well as the blobmeta containing info of all the chunks, + // or an error if there's still bytes left to be flushed. + // In case there was still data to be written a last unfinalized chunk, + // it's written as well. + #[instrument(skip(self))] + pub fn finalize(&mut self) -> Result<(Vec, proto::BlobMeta), Error> { + // If there's something still left in self.buf, upload this as the last + // chunk to the chunk service and record it in BlobMeta. + if !self.buf.is_empty() { + // Also upload the last chunk (what's left in `self.buf`) to the chunk + // service and record it in BlobMeta. + let buf_len = self.buf.len() as u32; + let chunk_digest = self.upload_chunk(self.buf.clone())?; + + self.blob_meta.chunks.push(proto::blob_meta::ChunkMeta { + digest: chunk_digest, + size: buf_len, + }); + + self.buf.clear(); + } + return Ok(( + self.blob_hasher.finalize().as_bytes().to_vec(), + self.blob_meta.clone(), + )); + } + + // upload a chunk to the chunk service, and return its digest (or an error) when done. + #[instrument(skip(self, chunk_data))] + fn upload_chunk(&mut self, chunk_data: Vec) -> Result, Error> { + let mut hasher = blake3::Hasher::new(); + if chunk_data.len() >= 128 * 1024 { + hasher.update_rayon(&chunk_data); + } else { + hasher.update(&chunk_data); + } + let digest = hasher.finalize(); + + if self.chunk_service.has(digest.as_bytes())? { + debug!("already has chunk, skipping"); + } + let digest_resp = self.chunk_service.put(chunk_data)?; + + assert_eq!(digest_resp, digest.as_bytes()); + + Ok(digest.as_bytes().to_vec()) + } +} + +/// This chunks up all data written using fastcdc, uploads all chunks to the +// [ChunkService], and fills a [proto::BlobMeta] linking to these chunks. +impl std::io::Write for BlobWriter<'_, CS> { + fn write(&mut self, input_buf: &[u8]) -> std::io::Result { + // calculate input_buf.len(), we need to return that later. + let input_buf_len = input_buf.len(); + + // update calculate blob hash, and use rayon if data is > 128KiB. + if input_buf.len() > 128 * 1024 { + self.blob_hasher.update_rayon(input_buf); + } else { + self.blob_hasher.update(input_buf); + } + + // prepend buf with existing data (from self.buf) + let buf: Vec = { + let mut b = Vec::new(); + b.append(&mut self.buf); + b.append(&mut input_buf.to_vec()); + b + }; + + // 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 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_usize; + let rest = 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[start_pos..].to_vec(); + } + + // 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(chunk_data.to_vec())?; + + self.blob_meta.chunks.push(proto::blob_meta::ChunkMeta { + digest: chunk_digest, + size: chunk_data.len() as u32, + }); + + // move start_pos over the processed chunk. + start_pos = end_pos; + }; + + self.buf = rest; + + Ok(input_buf_len) + } + + fn flush(&mut self) -> std::io::Result<()> { + Ok(()) + } +} -- cgit 1.4.1