RRD footers 1: framing

Cargo.lock

@@ -9070,6 +9070,7 @@ dependencies = [
  "bytes",
  "criterion",
  "ehttp",
+ "itertools 0.14.0",
  "js-sys",
  "lz4_flex 0.12.0",
  "mimalloc",
@@ -9092,6 +9093,7 @@ dependencies = [
  "wasm-bindgen-futures",
  "web-sys",
  "web-time",
+ "xxhash-rust",
 ]
 
 [[package]]

Cargo.toml

@@ -427,6 +427,7 @@ wgpu = { version = "27.0.1", default-features = false, features = [
   "fragile-send-sync-non-atomic-wasm",
 ] }
 xshell = "0.2.7"
+xxhash-rust = { version = "0.8", features = ["xxh32"] }
 
 # ---------------------------------------------------------------------------------
 [profile]

crates/store/re_log_encoding/Cargo.toml

@@ -53,10 +53,12 @@ re_tracing.workspace = true
 
 # External:
 arrow = { workspace = true, features = ["ipc"] }
+itertools.workspace = true
 lz4_flex = { workspace = true }
 parking_lot.workspace = true
 thiserror.workspace = true
 tracing.workspace = true
+xxhash-rust.workspace = true
 
 # Optional external dependencies:
 bytes = { workspace = true, optional = true }

crates/store/re_log_encoding/src/rrd/decoder/iterator.rs

@@ -139,7 +139,7 @@ impl<T: DecoderEntrypoint, R: std::io::BufRead> std::iter::Iterator for DecoderI
 
                         // …and the underlying decoder already considers that it's done (i.e. it's
                         // waiting for a whole new stream to begin): time to stop.
-                        Ok(None) if self.decoder.state == DecoderState::StreamHeader => {
+                        Ok(None) if self.decoder.state == DecoderState::WaitingForStreamHeader => {
                             return None;
                         }
 

crates/store/re_log_encoding/src/rrd/decoder/stream.rs

@@ -151,7 +151,7 @@ impl<T: DecoderEntrypoint + Unpin, R: AsyncBufRead + Unpin> Stream for DecoderSt
 
                         // …and the underlying decoder already considers that it's done (i.e. it's
                         // waiting for a whole new stream to begin): time to stop.
-                        Ok(None) if decoder.state == DecoderState::StreamHeader => {
+                        Ok(None) if decoder.state == DecoderState::WaitingForStreamHeader => {
                             return std::task::Poll::Ready(None);
                         }
 

crates/store/re_log_encoding/src/rrd/encoder.rs

@@ -5,11 +5,11 @@ use std::borrow::Borrow;
 use re_build_info::CrateVersion;
 use re_chunk::{ChunkError, ChunkResult};
 use re_log_types::LogMsg;
+use re_sorbet::SorbetError;
 
-use crate::ToTransport as _;
-use crate::rrd::{
+use crate::{
     CodecError, Compression, Encodable as _, EncodingOptions, MessageHeader, MessageKind,
-    Serializer, StreamHeader,
+    Serializer, StreamFooter, StreamHeader, ToTransport as _,
 };
 
 // ----------------------------------------------------------------------------
@@ -31,6 +31,9 @@ pub enum EncodeError {
 
     #[error("Chunk error: {0}")]
     Chunk(Box<ChunkError>),
+
+    #[error("Sorbet error: {0}")]
+    Sorbet(Box<SorbetError>),
 }
 
 const _: () = assert!(
@@ -50,6 +53,12 @@ impl From<ChunkError> for EncodeError {
     }
 }
 
+impl From<SorbetError> for EncodeError {
+    fn from(err: SorbetError) -> Self {
+        Self::Sorbet(Box::new(err))
+    }
+}
+
 // ----------------------------------------------------------------------------
 
 /// Encode a stream of [`LogMsg`] into an `.rrd` file.
@@ -64,13 +73,63 @@ pub struct Encoder<W: std::io::Write> {
     /// Optional so that we can `take()` it in `into_inner`, while still being allowed to implement `Drop`.
     write: Option<W>,
 
-    /// So we don't ever successfully write partial messages.
+    /// How many bytes written out so far?
+    num_written: u64,
+
+    /// * So we don't ever successfully write partial messages.
+    /// * Because `prost` only supports buffers, not IO traits.
     scratch: Vec<u8>,
 
-    /// Tracks whether the end-of-stream marker has been written out already.
+    /// Tracks the state required to build the RRD manifest for this stream.
+    ///
+    /// If set to `None`, the footer will not be computed.
+    ///
+    /// Calling [`Self::append_transport`] will automatically disable footers.
+    footer_state: Option<FooterState>,
+
+    /// Tracks whether the end-of-stream marker, and optionally the associated footer, have been
+    /// written out already.
     is_finished: bool,
 }
 
+/// The accumulated state used to build the footer when closing the [`Encoder`].
+///
+/// This is automatically updated when calling [`Encoder::append`].
+#[derive(Default)]
+struct FooterState {
+    /// What is the currently active recording ID according to the state of the encoder, if any?
+    ///
+    /// Put another way: was there a `SetStoreInfo` message earlier in the stream? If so, we will
+    /// want to override the recording ID of each chunk with that one (because that's the existing
+    /// behavior, certainly not because it's nice).
+    recording_id_scope: Option<re_log_types::StoreId>,
+}
+
+impl FooterState {
+    #[expect(clippy::unnecessary_wraps)] // won't stay for long
+    fn append(
+        &mut self,
+        _byte_offset: u64,
+        _byte_size: u64,
+        msg: &re_log_types::LogMsg,
+    ) -> Result<(), EncodeError> {
+        match msg {
+            LogMsg::SetStoreInfo(msg) => {
+                self.recording_id_scope = Some(msg.info.store_id.clone());
+            }
+
+            LogMsg::ArrowMsg(_, _) | LogMsg::BlueprintActivationCommand(_) => {}
+        }
+
+        Ok(())
+    }
+
+    #[expect(clippy::unnecessary_wraps, clippy::unused_self)] // won't stay for long
+    fn finish(self) -> Result<crate::RrdFooter, EncodeError> {
+        Ok(crate::RrdFooter {})
+    }
+}
+
 impl Encoder<Vec<u8>> {
     pub fn local() -> Result<Self, EncodeError> {
         Self::new_eager(
@@ -126,7 +185,9 @@ impl<W: std::io::Write> Encoder<W> {
             serializer: options.serializer,
             compression: options.compression,
             write: Some(write),
+            num_written: out.len() as u64,
             scratch: Vec::new(),
+            footer_state: Some(FooterState::default()),
             is_finished: false,
         })
     }
@@ -137,22 +198,54 @@ impl<W: std::io::Write> Encoder<W> {
             return Err(EncodeError::AlreadyFinished);
         }
 
-        if self.write.is_none() {
+        let Some(w) = self.write.as_mut() else {
             return Err(EncodeError::AlreadyUnwrapped);
-        }
+        };
 
         re_tracing::profile_function!();
 
-        let message = message.to_transport(self.compression)?;
-        // Safety: the compression settings of this message are consistent with this stream.
-        #[expect(unsafe_code)]
-        unsafe {
-            self.append_transport(&message)
+        let transport = message.to_transport(self.compression)?;
+
+        let byte_offset_excluding_header =
+            self.num_written + crate::MessageHeader::ENCODED_SIZE_BYTES as u64;
+
+        self.scratch.clear();
+        let n = match self.serializer {
+            Serializer::Protobuf => {
+                transport.to_rrd_bytes(&mut self.scratch)?;
+                let n = w
+                    .write_all(&self.scratch)
+                    .map(|_| self.scratch.len() as u64)
+                    .map_err(EncodeError::Write)?;
+                self.num_written += n;
+                n
+            }
+        };
+
+        let byte_size_excluding_header = n - crate::MessageHeader::ENCODED_SIZE_BYTES as u64;
+
+        if let Some(footer_state) = self.footer_state.as_mut() {
+            footer_state.append(
+                byte_offset_excluding_header,
+                byte_size_excluding_header,
+                message,
+            )?;
         }
+
+        Ok(n)
+    }
+
+    /// Instructs the encoder to _not_ emit a footer at the end of the stream.
+    ///
+    /// This cannot be reverted.
+    pub fn do_not_emit_footer(&mut self) {
+        self.footer_state = None;
     }
 
     /// Returns the size in bytes of the encoded data.
     ///
+    /// ⚠️ This implies [`Self::do_not_emit_footer`]. ⚠️
+    ///
     /// ## Safety
     ///
     /// `message` must respect the global settings of the encoder (e.g. the compression used),
@@ -166,19 +259,27 @@ impl<W: std::io::Write> Encoder<W> {
             return Err(EncodeError::AlreadyFinished);
         }
 
+        re_tracing::profile_function!();
+
+        // We cannot update the RRD manifest without decoding the message, which would defeat the
+        // entire purposes of using this method in the first place.
+        // Therefore, we disable footers if and when this method is used.
+        self.do_not_emit_footer();
+
         let Some(w) = self.write.as_mut() else {
             return Err(EncodeError::AlreadyUnwrapped);
         };
 
-        re_tracing::profile_function!();
-
         self.scratch.clear();
         match self.serializer {
             Serializer::Protobuf => {
                 message.to_rrd_bytes(&mut self.scratch)?;
-                w.write_all(&self.scratch)
-                    .map(|_| self.scratch.len() as _)
-                    .map_err(EncodeError::Write)
+                let n = w
+                    .write_all(&self.scratch)
+                    .map(|_| self.scratch.len() as u64)
+                    .map_err(EncodeError::Write)?;
+                self.num_written += n;
+                Ok(n)
             }
         }
     }
@@ -200,22 +301,52 @@ impl<W: std::io::Write> Encoder<W> {
             return Err(EncodeError::AlreadyUnwrapped);
         };
 
-        match self.serializer {
-            Serializer::Protobuf => {
-                // TODO(cmc): the extra heap-alloc and copy could be easily avoided with the
-                // introduction of an InMemoryWriter trait or similar. In practice it makes no
-                // difference and the cognitive overhead of this crate is already through the roof.
-                let mut header = Vec::new();
-                MessageHeader {
-                    kind: MessageKind::End,
-                    len: 0,
-                }
-                .to_rrd_bytes(&mut header)?;
-                w.write_all(&header)?;
-            }
+        self.is_finished = true;
+
+        let Some(footer_state) = self.footer_state.take() else {
+            return Ok(());
+        };
+
+        // TODO(cmc): the extra heap-allocs and copies could be easily avoided with the
+        // introduction of an InMemoryWriter trait or similar. In practice it makes no
+        // difference and the cognitive overhead of this crate is already through the roof.
+
+        use re_protos::external::prost::Message as _;
+
+        // Message Header (::End)
+
+        let rrd_footer = footer_state.finish()?;
+        let rrd_footer = rrd_footer.to_transport(())?;
+
+        let mut out_header = Vec::new();
+        MessageHeader {
+            kind: MessageKind::End,
+            len: rrd_footer.encoded_len() as u64,
         }
+        .to_rrd_bytes(&mut out_header)?;
+        w.write_all(&out_header).map_err(EncodeError::Write)?;
+        self.num_written += out_header.len() as u64;
 
-        self.is_finished = true;
+        let end_msg_byte_offset_from_start_excluding_header = self.num_written;
+
+        // Message payload (re_protos::RrdFooter)
+
+        let mut out_rrd_footer = Vec::new();
+        rrd_footer.to_rrd_bytes(&mut out_rrd_footer)?;
+        w.write_all(&out_rrd_footer).map_err(EncodeError::Write)?;
+        self.num_written += out_rrd_footer.len() as u64;
+
+        // StreamFooter
+
+        let mut out_stream_footer = Vec::new();
+        StreamFooter::from_rrd_footer_bytes(
+            end_msg_byte_offset_from_start_excluding_header,
+            &out_rrd_footer,
+        )
+        .to_rrd_bytes(&mut out_stream_footer)?;
+        w.write_all(&out_stream_footer)
+            .map_err(EncodeError::Write)?;
+        self.num_written += out_stream_footer.len() as u64;
 
         Ok(())
     }
@@ -255,8 +386,6 @@ impl<W: std::io::Write> Encoder<W> {
     }
 }
 
-// TODO(cmc): It seems a bit suspicious to me that we send an EOS marker on drop, but don't flush.
-// But I don't want to change any flushing behavior at the moment, so I'll keep it that way for now.
 impl<W: std::io::Write> std::ops::Drop for Encoder<W> {
     fn drop(&mut self) {
         if self.write.is_none() {
@@ -267,5 +396,9 @@ impl<W: std::io::Write> std::ops::Drop for Encoder<W> {
         if let Err(err) = self.finish() {
             re_log::warn!("encoder couldn't be finished: {err}");
         }
+
+        if let Err(err) = self.flush_blocking() {
+            re_log::warn!("encoder couldn't be flushed: {err}");
+        }
     }
 }