feat(build): allowed invalidating entries in build queue

src/build/queue.v

@@ -8,6 +8,8 @@ import util
 
 struct BuildJob {
 pub:
+	// Time at which this build job was created/queued
+	created time.Time
 	// Next timestamp from which point this job is allowed to be executed
 	timestamp time.Time
 	// Required for calculating next timestamp after having pop'ed a job
@@ -22,6 +24,8 @@ fn (r1 BuildJob) < (r2 BuildJob) bool {
 	return r1.timestamp < r2.timestamp
 }
 
+// The build job queue is responsible for managing the list of scheduled builds
+// for each architecture. Agents receive jobs from this queue.
 pub struct BuildJobQueue {
 	// Schedule to use for targets without explicitely defined cron expression
 	default_schedule CronExpression
@@ -31,15 +35,17 @@ mut:
 	mutex shared util.Dummy
 	// For each architecture, a priority queue is tracked
 	queues map[string]MinHeap<BuildJob>
-	// Each queued build job is also stored in a map, with the keys being the
-	// target IDs. This is used when removing or editing targets.
-	// jobs map[int]BuildJob
+	// When a target is removed from the server or edited, its previous build
+	// configs will be invalid. This map allows for those to be simply skipped
+	// by ignoring any build configs created before this timestamp.
+	invalidated map[int]time.Time
 }
 
 pub fn new_job_queue(default_schedule CronExpression, default_base_image string) BuildJobQueue {
 	return BuildJobQueue{
 		default_schedule: default_schedule
 		default_base_image: default_base_image
+		invalidated: map[int]time.Time{}
 	}
 }
 
@@ -63,6 +69,7 @@ pub fn (mut q BuildJobQueue) insert(target Target, arch string) ! {
 		timestamp := ce.next_from_now()!
 
 		job := BuildJob{
+			created: time.now()
 			timestamp: timestamp
 			ce: ce
 			config: BuildConfig{
@@ -88,6 +95,7 @@ fn (mut q BuildJobQueue) reschedule(job BuildJob, arch string) ! {
 
 	new_job := BuildJob{
 		...job
+		created: time.now()
 		timestamp: new_timestamp
 	}
 
@@ -96,16 +104,26 @@ fn (mut q BuildJobQueue) reschedule(job BuildJob, arch string) ! {
 
 // peek shows the first job for the given architecture that's ready to be
 // executed, if present.
-pub fn (q &BuildJobQueue) peek(arch string) ?BuildJob {
+pub fn (mut q BuildJobQueue) peek(arch string) ?BuildJob {
 	rlock q.mutex {
 		if arch !in q.queues {
 			return none
 		}
 
-		job := q.queues[arch].peek() or { return none }
+		for {
+			job := q.queues[arch].peek() or { return none }
 
-		if job.timestamp < time.now() {
-			return job
+			// Skip any invalidated jobs
+			if job.config.target_id in q.invalidated
+				&& job.created < q.invalidated[job.config.target_id] {
+				// This pop *should* never fail according to the source code
+				q.queues[arch].pop() or { return none }
+				continue
+			}
+
+			if job.timestamp < time.now() {
+				return job
+			}
 		}
 	}
 
@@ -120,17 +138,27 @@ pub fn (mut q BuildJobQueue) pop(arch string) ?BuildJob {
 			return none
 		}
 
-		mut job := q.queues[arch].peek() or { return none }
+		for {
+			mut job := q.queues[arch].peek() or { return none }
 
-		if job.timestamp < time.now() {
-			job = q.queues[arch].pop()?
+			// Skip any invalidated jobs
+			if job.config.target_id in q.invalidated
+				&& job.created < q.invalidated[job.config.target_id] {
+				// This pop *should* never fail according to the source code
+				q.queues[arch].pop() or { return none }
+				continue
+			}
 
-			// TODO how do we handle this properly? Is it even possible for a
-			// cron expression to not return a next time if it's already been
-			// used before?
-			q.reschedule(job, arch) or {}
+			if job.timestamp < time.now() {
+				job = q.queues[arch].pop()?
 
-			return job
+				// TODO how do we handle this properly? Is it even possible for a
+				// cron expression to not return a next time if it's already been
+				// used before?
+				q.reschedule(job, arch) or {}
+
+				return job
+			}
 		}
 	}
 
@@ -146,18 +174,28 @@ pub fn (mut q BuildJobQueue) pop_n(arch string, n int) []BuildJob {
 
 		mut out := []BuildJob{}
 
-		for out.len < n {
-			mut job := q.queues[arch].peek() or { break }
+		outer: for out.len < n {
+			for {
+				mut job := q.queues[arch].peek() or { break outer }
 
-			if job.timestamp < time.now() {
-				job = q.queues[arch].pop() or { break }
+				// Skip any invalidated jobs
+				if job.config.target_id in q.invalidated
+					&& job.created < q.invalidated[job.config.target_id] {
+					// This pop *should* never fail according to the source code
+					q.queues[arch].pop() or { break outer }
+					continue
+				}
 
-				// TODO idem
-				q.reschedule(job, arch) or {}
+				if job.timestamp < time.now() {
+					job = q.queues[arch].pop() or { break outer }
 
-				out << job
-			} else {
-				break
+					// TODO idem
+					q.reschedule(job, arch) or {}
+
+					out << job
+				} else {
+					break outer
+				}
 			}
 		}
 
@@ -166,3 +204,8 @@ pub fn (mut q BuildJobQueue) pop_n(arch string, n int) []BuildJob {
 
 	return []
 }
+
+// invalidate a target's old build jobs.
+pub fn (mut q BuildJobQueue) invalidate(target_id int) {
+	q.invalidated[target_id] = time.now()
+}