push green meta builds to the attic cache and record cached

swarm-wire/src/agent_closures.rs

@@ -32,6 +32,10 @@ pub struct AgentClosure {
     pub system: String,
     /// When the controller recorded the build, in unix seconds.
     pub built_unix: i64,
+    /// Whether the builder pushed the closure to the binary cache. A record
+    /// written before the field existed reads as false.
+    #[serde(default)]
+    pub cached: bool,
 }
 
 #[cfg(test)]
@@ -51,12 +55,14 @@ mod tests {
             store_path: "/nix/store/x".to_owned(),
             system: "x86_64-linux".to_owned(),
             built_unix: 7,
+            cached: true,
         };
         let wire = serde_json::json!({
             "meta_rev": "abc",
             "store_path": "/nix/store/x",
             "system": "x86_64-linux",
             "built_unix": 7,
+            "cached": true,
         });
         assert_eq!(serde_json::to_value(&value).expect("encodes"), wire);
         assert_eq!(
@@ -64,4 +70,16 @@ mod tests {
             value
         );
     }
+
+    #[test]
+    fn a_record_without_the_field_reads_as_not_cached() {
+        let old = serde_json::json!({
+            "meta_rev": "abc",
+            "store_path": "/nix/store/x",
+            "system": "x86_64-linux",
+            "built_unix": 7,
+        });
+        let record = serde_json::from_value::<AgentClosure>(old).expect("decodes");
+        assert!(!record.cached);
+    }
 }

swarm-wire/src/builder.rs

@@ -140,8 +140,16 @@ pub struct BuildFromMeta {
 #[serde(tag = "state", rename_all = "kebab-case")]
 pub enum FromMetaReply {
     /// The toplevel built; `out_path` is its store path in the builder host's
-    /// store and `system` the platform the builder host builds for.
-    Built { out_path: String, system: String },
+    /// store and `system` the platform the builder host builds for. `cached`
+    /// is whether the builder pushed the closure to the binary cache; a failed
+    /// push leaves the build green with `cached` false. A builder that predates
+    /// the field answers without it, which reads as false.
+    Built {
+        out_path: String,
+        system: String,
+        #[serde(default)]
+        cached: bool,
+    },
     /// The build did not succeed: the last lines `nix` printed, or why it
     /// stopped (it timed out, or could not start). The controller holds the
     /// deploy back and builds again on its next round.
@@ -253,8 +261,14 @@ mod tests {
                 FromMetaReply::Built {
                     out_path: "/nix/store/x".to_owned(),
                     system: "x86_64-linux".to_owned(),
+                    cached: true,
                 },
-                json!({"state": "built", "out_path": "/nix/store/x", "system": "x86_64-linux"}),
+                json!({
+                    "state": "built",
+                    "out_path": "/nix/store/x",
+                    "system": "x86_64-linux",
+                    "cached": true,
+                }),
             ),
             (
                 FromMetaReply::Failed {
@@ -277,6 +291,19 @@ mod tests {
         }
     }
 
+    #[test]
+    fn a_built_reply_from_a_builder_without_the_field_reads_as_not_cached() {
+        let old = json!({"state": "built", "out_path": "/nix/store/x", "system": "s"});
+        assert_eq!(
+            serde_json::from_value::<FromMetaReply>(old).expect("decodes"),
+            FromMetaReply::Built {
+                out_path: "/nix/store/x".to_owned(),
+                system: "s".to_owned(),
+                cached: false,
+            }
+        );
+    }
+
     #[test]
     fn the_subjects_are_pinned() {
         assert_eq!(SUBJECT, "$SWARM.builder.build");