Restructure shared types and db columns

Now, the server sends the runner pretty much all run metadata. This way,
the reservation the server makes for the runner is accurate, providing
the runner responds with the same metadata it was sent. It also means
that only the server's system clock is relevant for tie breakers, and a
run's duration spans from the moment it is reserved to the moment it is
saved.

Also, the bench method is now always called `bench_method` and a
human-readable description is stored in the database for each run.

src/shared.rs

@@ -10,6 +10,14 @@ fn is_false(b: &bool) -> bool {
     !b
 }
 
+#[derive(Clone, Serialize_repr, Deserialize_repr, sqlx::Type)]
+#[repr(u8)]
+pub enum Source {
+    // Stdin would be fd 0
+    Stdout = 1,
+    Stderr = 2,
+}
+
 #[derive(Clone, Serialize_repr, Deserialize_repr, sqlx::Type)]
 #[repr(i8)]
 pub enum Direction {
@@ -29,34 +37,40 @@ pub struct Measurement {
     pub direction: Option<Direction>,
 }
 
-#[derive(Clone, Serialize_repr, Deserialize_repr, sqlx::Type)]
-#[repr(u8)]
-pub enum Source {
-    // Stdin would be fd 0
-    Stdout = 1,
-    Stderr = 2,
+#[derive(Clone, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+#[serde(tag = "type")]
+pub enum BenchMethod {
+    Internal,
+    Repo { hash: String },
+}
+
+#[derive(Clone, Serialize, Deserialize)]
+pub struct Run {
+    pub id: String,
+    pub hash: String,
+    pub bench_method: BenchMethod,
+    pub start: OffsetDateTime,
 }
 
 #[derive(Clone, Serialize, Deserialize)]
 pub struct UnfinishedRun {
-    pub id: String,
-    pub hash: String,
-    pub start: OffsetDateTime,
+    #[serde(flatten)]
+    pub run: Run,
     #[serde(default)]
     pub last_output: Vec<(Source, String)>,
 }
 
 #[derive(Clone, Serialize, Deserialize)]
 pub struct FinishedRun {
-    pub id: String,
-    pub hash: String,
-    pub start: OffsetDateTime,
-    pub end: OffsetDateTime,
+    #[serde(flatten)]
+    pub run: Run,
     #[serde(default)]
     pub exit_code: i32,
-    pub measurements: HashMap<String, Measurement>,
     #[serde(default)]
     pub output: Vec<(Source, String)>,
+    #[serde(default)]
+    pub measurements: HashMap<String, Measurement>,
 }
 
 #[derive(Clone, Serialize, Deserialize)]
@@ -84,48 +98,28 @@ pub struct WorkerRequest {
     /// What the worker is currently working on.
     pub status: WorkerStatus,
 
-    /// Whether the worker wants new work from the server.
+    /// The worker wants a new run from the server.
     ///
     /// If the server has a commit available, it should respond with a non-null
-    /// [`Response::work`].
+    /// [`ServerResponse::work`].
     #[serde(default, skip_serializing_if = "is_false")]
-    pub request_work: bool,
+    pub request_run: bool,
 
     /// The worker has finished a run and wants to submit the results.
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub submit_work: Option<FinishedRun>,
-}
-
-#[derive(Clone, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-#[serde(tag = "type")]
-pub enum BenchMethod {
-    /// Use internal (deterministic) benchmarking code.
-    Internal,
-    /// Use a commit from a bench repo.
-    Repo { hash: String },
-}
-
-#[derive(Clone, Serialize, Deserialize)]
-pub struct Work {
-    /// Id of the run.
-    pub id: String,
-    /// Hash of commit to benchmark.
-    pub hash: String,
-    /// How to benchmark the commit.
-    pub bench: BenchMethod,
+    pub submit_run: Option<FinishedRun>,
 }
 
 #[derive(Serialize, Deserialize)]
 pub struct ServerResponse {
-    /// Work the worker requested using [`Request::request_work].
+    /// Run the worker requested using [`RunnerRequest::request_run`].
     ///
-    /// The worker may ignore this work and do something else. However, until
-    /// the next update request sent by the worker, the server will consider the
+    /// The worker may ignore this run and do something else. However, until the
+    /// next update request sent by the worker, the server will consider the
     /// worker as preparing to work on the commit, and will not give out the
     /// same commit to other workers.
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub work: Option<Work>,
+    pub run: Option<Run>,
 
     /// The worker should abort the current run.
     ///
@@ -133,5 +127,5 @@ pub struct ServerResponse {
     /// the same commit as another worker and has broken the tie in favor of the
     /// other worker. The worker may continue the run despite this flag.
     #[serde(default, skip_serializing_if = "is_false")]
-    pub abort_work: bool,
+    pub abort_run: bool,
 }