Add a metadata map to the RunMeta struct

Author: bkirwi

src/persist-client/build.rs

@@ -53,10 +53,11 @@ fn main() {
         .btree_map(["."])
         .bytes([
             ".mz_persist_client.internal.diff.ProtoStateFieldDiffs",
+            ".mz_persist_client.internal.service.ProtoPushDiff",
+            ".mz_persist_client.internal.state.ProtoEncodedSchemas",
             ".mz_persist_client.internal.state.ProtoHollowBatchPart",
+            ".mz_persist_client.internal.state.ProtoRunMeta",
             ".mz_persist_client.internal.state.ProtoVersionedData",
-            ".mz_persist_client.internal.state.ProtoEncodedSchemas",
-            ".mz_persist_client.internal.service.ProtoPushDiff",
         ]);
 
     // Setting `emit_rerun_if_changed(false)` below causes tonic to entirely

src/persist-client/src/batch.rs

@@ -717,6 +717,7 @@ where
                 } else {
                     None
                 },
+                meta: MetadataMap::default(),
             });
             run_parts.extend(parts);
         }
@@ -862,6 +863,7 @@ impl<T: Timestamp + Codec64> BatchParts<T> {
                                         } else {
                                             None
                                         },
+                                        meta: MetadataMap::default(),
                                     },
                                     completed_run.parts,
                                 )

src/persist-client/src/internal/encoding.rs

@@ -1518,6 +1518,7 @@ impl RustType<ProtoRunMeta> for RunMeta {
             deprecated_schema_id: self.deprecated_schema.into_proto(),
             id: self.id.into_proto(),
             len: self.len.into_proto(),
+            meta: self.meta.into_proto(),
         }
     }
 
@@ -1534,6 +1535,7 @@ impl RustType<ProtoRunMeta> for RunMeta {
             deprecated_schema: proto.deprecated_schema_id.into_rust()?,
             id: proto.id.into_rust()?,
             len: proto.len.into_rust()?,
+            meta: proto.meta.into_rust()?,
         })
     }
 }

src/persist-client/src/internal/state.proto

@@ -95,6 +95,8 @@ message ProtoRunMeta {
   optional uint64 deprecated_schema_id = 2;
   optional string id = 4;
   optional uint64 len = 5;
+
+  map<string, bytes> meta = 6;
 }
 
 message ProtoHollowRun {

src/persist-client/src/internal/state.rs

@@ -820,6 +820,10 @@ pub struct RunMeta {
 
     /// The number of updates in this run, or `None` if the number is unknown.
     pub(crate) len: Option<usize>,
+
+    /// Additional unstructured metadata.
+    #[serde(skip_serializing_if = "MetadataMap::is_empty")]
+    pub(crate) meta: MetadataMap,
 }
 
 /// A subset of a [HollowBatch] corresponding 1:1 to a blob.