note places that need to be updated for task dependencies

along with logic

[ci skip]

client/allocrunner/alloc_runner.go

@@ -29,6 +29,11 @@ import (
 	"github.com/hashicorp/nomad/plugins/drivers"
 )
 
+// TODO (TaskDependencies): for coordinating tasks blocking, introduce a helper
+// structs that is passed Tasks and becomes the condition for unblocking
+// TaskRunner.Run function.
+// Need to be set as a field in allocRunner and taskRunner and passed along when creating TRs.
+
 // allocRunner is used to run all the tasks in a given allocation
 type allocRunner struct {
 	// id is the ID of the allocation. Can be accessed without a lock
@@ -399,6 +404,12 @@ func (ar *allocRunner) TaskStateUpdated() {
 func (ar *allocRunner) handleTaskStateUpdates() {
 	defer close(ar.taskStateUpdateHandlerCh)
 
+	// TODO (TaskDependencies): Update logic here to inspect completed task
+	// and unblock appropriate task runners
+	// e.g. unblock main tasks when all prestart tasks started and
+	// prestart/block_until=completed finished
+	//
+
 	for done := false; !done; {
 		select {
 		case <-ar.taskStateUpdatedCh:

client/allocrunner/taskrunner/task_runner.go

@@ -326,6 +326,10 @@ func NewTaskRunner(config *Config) (*TaskRunner, error) {
 		tr.logger.Error("alloc missing task group")
 		return nil, fmt.Errorf("alloc missing task group")
 	}
+
+	// TODO (TaskDependencies): Set the appropriate RestartPolicy here depending on
+	// job and hook types; consider having restart policy be a task field rather than
+	// a group setting
 	tr.restartTracker = restarts.NewRestartTracker(tg.RestartPolicy, tr.alloc.Job.Type)
 
 	// Get the driver
@@ -460,6 +464,10 @@ func (tr *TaskRunner) Run() {
 		}
 	}
 
+	// TODO (TaskDependencies): Block here until the phase corresponding to task
+	// is reached.  Use channels for coordination and consider killCtx and shutdownCtx
+	// as well like above
+
 MAIN:
 	for !tr.Alloc().TerminalStatus() {
 		select {
@@ -511,6 +519,8 @@ MAIN:
 			if resultCh, err := handle.WaitCh(context.Background()); err != nil {
 				tr.logger.Error("wait task failed", "error", err)
 			} else {
+				// TODO (TaskDependencies): wait for deadline if task is prestart/until_completed
+				// and cause it to fail if resultCh hasn't returned by deadline
 				select {
 				case <-tr.killCtx.Done():
 					// We can go through the normal should restart check since

nomad/structs/funcs.go

@@ -113,6 +113,8 @@ func AllocsFit(node *Node, allocs []*Allocation, netIdx *NetworkIndex, checkDevi
 			continue
 		}
 
+		// TODO (TaskDependencies): update this call to use
+		// alloc.AllocatedResources.Comparable()
 		used.Add(alloc.ComparableResources())
 	}
 

nomad/structs/structs.go

@@ -2879,6 +2879,9 @@ func (n *NodeReservedNetworkResources) ParseReservedHostPorts() ([]uint64, error
 }
 
 // AllocatedResources is the set of resources to be used by an allocation.
+// TODO (TaskDependencies): Update this struct and initializer to track
+// task hooks and have Comparable() returns cpu/memory according the following
+//   MAX(SUM(prestart_completed_hooks), SUM(main))+SUM(prestart_running_hooks)
 type AllocatedResources struct {
 	// Tasks is a mapping of task name to the resources for the task.
 	Tasks map[string]*AllocatedTaskResources