instr(buffer): Measure envelope size

relay-server/src/services/buffer/envelope_buffer/mod.rs

@@ -78,6 +78,11 @@ impl PolymorphicEnvelopeBuffer {
 
  /// Adds an envelope to the buffer.
  pub async fn push(&mut self, envelope: Box<Envelope>) -> Result<(), EnvelopeBufferError> {
+ relay_statsd::metric!(
+ histogram(RelayHistograms::BufferEnvelopeBodySize) =
+ envelope.items().map(Item::len).sum()
+ );
+
  relay_statsd::metric!(timer(RelayTimers::BufferPush), {
  match self {
  Self::Sqlite(buffer) => buffer.push(envelope).await,

relay-server/src/statsd.rs

@@ -181,6 +181,11 @@ pub enum RelayHistograms {
  /// Number of envelopes in the backpressure buffer between the envelope buffer
  /// and the project cache.
  BufferBackpressureEnvelopesCount,
+ /// The amount of bytes in the item payloads of an envelope pushed to the envelope buffer.
+ ///
+ /// This is not quite the same as the actual size of a serialized envelope, because it ignores
+ /// the envelope header and item headers.
+ BufferEnvelopeBodySize,
  /// The number of batches emitted per partition.
  BatchesPerPartition,
  /// The number of buckets in a batch emitted.
@@ -309,6 +314,7 @@ impl HistogramMetric for RelayHistograms {
  RelayHistograms::BufferBackpressureEnvelopesCount => {
  "buffer.backpressure_envelopes_count"
  }
+ RelayHistograms::BufferEnvelopeBodySize => "buffer.envelope_body_size",
  RelayHistograms::ProjectStatePending => "project_state.pending",
  RelayHistograms::ProjectStateAttempts => "project_state.attempts",
  RelayHistograms::ProjectStateRequestBatchSize => "project_state.request.batch_size",