Fix race condition between set() and push() (#14)

A worker can end up picking up a job between `set()` and `push()`,
causing a race condition that results in the job running twice. Fix
the race by adding an `initial` state for jobs that haven't yet
been pushed.

Fixes #13.

.github/workflows/test.yml

@@ -57,10 +57,10 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - macos-version: macos-13
-            xcode-version: '~15.2'
           - macos-version: macos-14
             xcode-version: latest-stable
+          - macos-version: macos-15
+            xcode-version: latest-stable
     runs-on: ${{ matrix.macos-version }}
     timeout-minutes: 60
     steps:

Sources/QueuesFluentDriver/FluentQueue.swift

@@ -38,7 +38,7 @@ public struct FluentQueue: AsyncQueue, Sendable {
                 .bind(jobStorage.jobName),
                 .bind(jobStorage.queuedAt),
                 .bind(jobStorage.delayUntil),
-                .literal(StoredJobState.pending),
+                .literal(StoredJobState.initial),
                 .bind(jobStorage.maxRetryCount),
                 .bind(jobStorage.attempts),
                 .bind(Data(jobStorage.payload)),

Sources/QueuesFluentDriver/JobModel.swift

@@ -6,6 +6,9 @@ import struct Queues.QueueName
 
 /// The state of a job currently stored in the database.
 enum StoredJobState: String, Codable, CaseIterable {
+    /// Job has been set up but is not yet ready to execute.
+    case initial
+
     /// Job is ready to be picked up for execution.
     case pending