job runs now log their started/finished_at times, and that time is retrievable with the API

spec/mosquito/api/job_run_spec.cr

@@ -1,6 +1,11 @@
 require "../../spec_helper"
 
 describe Mosquito::Api::JobRun do
+  # the job run timestamps are stored as a unix epoch with millis, so nanosecond precision is lost.
+  def at_beginning_of_millisecond(time)
+    time - (time.nanosecond.nanoseconds) + (time.millisecond.milliseconds)
+  end
+
   getter job : QueuedTestJob { QueuedTestJob.new }
   getter job_run : Mosquito::JobRun { job.build_job_run }
   getter api : Mosquito::Api::JobRun { Mosquito::Api::JobRun.new job_run.id }
@@ -33,13 +38,34 @@ describe Mosquito::Api::JobRun do
       job_run.store
     end
 
-    # the enqueue time is stored as a unix epoch with millis, so nanosecond precision is lost.
-    expected_time = now - (now.nanosecond.nanoseconds) + (now.millisecond.milliseconds)
+    expected_time = at_beginning_of_millisecond now
     assert_equal expected_time, api.enqueue_time
   end
 
   it "can retrieve the retry count" do
     job_run.store
     assert_equal 0, api.retry_count
   end
+
+  it "can retrieve the started at timestamp" do
+    now = at_beginning_of_millisecond Time.utc
+    job_run = create_job_run
+    Timecop.freeze now do
+      job_run.run
+    end
+
+    api = Mosquito::Api::JobRun.new(job_run.id)
+    assert_equal now, api.started_at
+  end
+
+  it "can retrieve the finished_at timestamp" do
+    now = at_beginning_of_millisecond Time.utc
+    job_run = create_job_run
+    Timecop.freeze now do
+      job_run.run
+    end
+
+    api = Mosquito::Api::JobRun.new(job_run.id)
+    assert_equal now, api.finished_at
+  end
 end

spec/mosquito/runners/overseer_spec.cr

@@ -93,7 +93,7 @@ describe "Mosquito::Runners::Overseer" do
         assert_in_epsilon(
           overseer.idle_wait.total_seconds,
           tick_time.total_seconds,
-          epsilon: 0.05
+          epsilon: 0.06
         )
       end
     end

src/mosquito/api/job_run.cr

@@ -11,7 +11,7 @@ module Mosquito::Api
 
     def runtime_parameters : Hash(String, String)
       config.reject do |key, _|
-        ["id", "type", "enqueue_time", "retry_count"].includes? key
+        ["id", "type", "enqueue_time", "retry_count", "started_at", "finished_at"].includes? key
       end
     end
 
@@ -33,6 +33,18 @@ module Mosquito::Api
       Time.unix_ms config["enqueue_time"].to_i64
     end
 
+    def started_at : Time?
+      if time = config["started_at"]
+        Time.unix_ms time.to_i64
+      end
+    end
+
+    def finished_at : Time?
+      if time = config["finished_at"]
+        Time.unix_ms time.to_i64
+      end
+    end
+
     # The number of times this job has been retried.
     def retry_count : Int
       config["retry_count"].to_i

src/mosquito/job_run.cr

@@ -14,6 +14,8 @@ module Mosquito
     getter id : String
     getter retry_count = 0
     getter job : Mosquito::Job?
+    @started_at : Time?
+    @finished_at : Time?
 
     def job! : Mosquito::Job
       job || raise RuntimeError.new("No job yet retrieved for job_run.")
@@ -57,6 +59,14 @@ module Mosquito
       fields["type"] = type
       fields["retry_count"] = retry_count.to_s
 
+      if started_at_ = @started_at
+        fields["started_at"] = started_at_.to_unix_ms.to_s
+      end
+
+      if finished_at_ = @finished_at
+        fields["finished_at"] = finished_at_.to_unix_ms.to_s
+      end
+
       Mosquito.backend.store config_key, fields
     end
 
@@ -86,12 +96,15 @@ module Mosquito
     # Builds and runs the job with this job_run config.
     def run
       instance = build_job
+
+      @started_at = Time.utc
       instance.run
+      @finished_at = Time.utc
 
       if executed? && failed?
         @retry_count += 1
-        store
       end
+      store
     end
 
     # Fails this job run and make sure it's persisted as such.