feat(server): initialize job queue on start; api endpoint for polling

jobs

src/build/queue.v

@@ -4,6 +4,7 @@ import models { Target }
 import cron.expression { CronExpression, parse_expression }
 import time
 import datatypes { MinHeap }
+import util
 
 struct BuildJob {
 pub:
@@ -23,6 +24,7 @@ pub struct BuildJobQueue {
 	// Base image to use for targets without defined base image
 	default_base_image string
 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
@@ -39,32 +41,95 @@ pub fn new_job_queue(default_schedule CronExpression, default_base_image string)
 
 // insert a new job into the queue for a given target on an architecture.
 pub fn (mut q BuildJobQueue) insert(target Target, arch string) ! {
-	if arch !in q.queues {
-		q.queues[arch] = MinHeap<BuildJob>{}
-	}
-
-	ce := if target.schedule != '' {
-		parse_expression(target.schedule) or {
-			return error("Error while parsing cron expression '$target.schedule' (id $target.id): $err.msg()")
+	lock q.mutex {
+		if arch !in q.queues {
+			q.queues[arch] = MinHeap<BuildJob>{}
 		}
-	} else {
-		q.default_schedule
-	}
 
-	timestamp := ce.next_from_now()!
-
-	job := BuildJob{
-		timestamp: timestamp
-		config: BuildConfig{
-			target_id: target.id
-			kind: target.kind
-			url: target.url
-			branch: target.branch
-			repo: target.repo
-			// TODO make this configurable
-			base_image: q.default_base_image
+		ce := if target.schedule != '' {
+			parse_expression(target.schedule) or {
+				return error("Error while parsing cron expression '$target.schedule' (id $target.id): $err.msg()")
+			}
+		} else {
+			q.default_schedule
 		}
-	}
 
-	q.queues[arch].insert(job)
+		timestamp := ce.next_from_now()!
+
+		job := BuildJob{
+			timestamp: timestamp
+			config: BuildConfig{
+				target_id: target.id
+				kind: target.kind
+				url: target.url
+				branch: target.branch
+				repo: target.repo
+				// TODO make this configurable
+				base_image: q.default_base_image
+			}
+		}
+
+		q.queues[arch].insert(job)
+	}
+}
+
+// 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 {
+	rlock q.mutex {
+		if arch !in q.queues {
+			return none
+		}
+
+		job := q.queues[arch].peek() or { return none }
+
+		if job.timestamp < time.now() {
+			return job
+		}
+	}
+
+	return none
+}
+
+// pop removes the first job for the given architecture that's ready to be
+// executed from the queue and returns it, if present.
+pub fn (mut q BuildJobQueue) pop(arch string) ?BuildJob {
+	lock q.mutex {
+		if arch !in q.queues {
+			return none
+		}
+
+		job := q.queues[arch].peek() or { return none }
+
+		if job.timestamp < time.now() {
+			return q.queues[arch].pop()
+		}
+	}
+
+	return none
+}
+
+// pop_n tries to pop at most n available jobs for the given architecture.
+pub fn (mut q BuildJobQueue) pop_n(arch string, n int) []BuildJob {
+	lock q.mutex {
+		if arch !in q.queues {
+			return []
+		}
+
+		mut out := []BuildJob{}
+
+		for out.len < n {
+			job := q.queues[arch].peek() or { break }
+
+			if job.timestamp < time.now() {
+				out << q.queues[arch].pop() or { break }
+			} else {
+				break
+			}
+		}
+
+		return out
+	}
+
+	return []
 }