package main
import (
- "bufio"
+ "bytes"
"log"
"os/exec"
+ "strings"
"sync"
"time"
)
// Squeue implements asynchronous polling monitor of the SLURM queue using the
// command 'squeue'.
-type Squeue struct {
- squeueContents []string
- squeueDone chan struct{}
- squeueCond *sync.Cond
- SlurmLock sync.Mutex
+type SqueueChecker struct {
+ Period time.Duration
+ uuids map[string]bool
+ startOnce sync.Once
+ done chan struct{}
+ sync.Cond
}
-// squeueFunc
func squeueFunc() *exec.Cmd {
return exec.Command("squeue", "--all", "--format=%j")
}
var squeueCmd = squeueFunc
-// RunSqueue runs squeue once and captures the output. If it succeeds, set
-// "squeueContents" and then wake up any goroutines waiting squeueCond in
-// CheckSqueue(). If there was an error, log it and leave the threads blocked.
-func (squeue *Squeue) RunSqueue() {
- var newSqueueContents []string
+// HasUUID checks if a given container UUID is in the slurm queue.
+// This does not run squeue directly, but instead blocks until woken
+// up by next successful update of squeue.
+func (sqc *SqueueChecker) HasUUID(uuid string) bool {
+ sqc.startOnce.Do(sqc.start)
+ sqc.L.Lock()
+ defer sqc.L.Unlock()
+
+ // block until next squeue broadcast signaling an update.
+ sqc.Wait()
+ return sqc.uuids[uuid]
+}
+
+// Stop stops the squeue monitoring goroutine. Do not call HasUUID
+// after calling Stop.
+func (sqc *SqueueChecker) Stop() {
+ if sqc.done != nil {
+ close(sqc.done)
+ }
+}
+
+// check gets the names of jobs in the SLURM queue (running and
+// queued). If it succeeds, it updates squeue.uuids and wakes up any
+// goroutines that are waiting in HasUUID() or All().
+func (sqc *SqueueChecker) check() {
// Mutex between squeue sync and running sbatch or scancel. This
// establishes a sequence so that squeue doesn't run concurrently with
// sbatch or scancel; the next update of squeue will occur only after
// sbatch or scancel has completed.
- squeue.SlurmLock.Lock()
- defer squeue.SlurmLock.Unlock()
-
- // Also ensure unlock on all return paths
+ sqc.L.Lock()
+ defer sqc.L.Unlock()
cmd := squeueCmd()
- sq, err := cmd.StdoutPipe()
- if err != nil {
- log.Printf("Error creating stdout pipe for squeue: %v", err)
- return
- }
- err = cmd.Start()
- if err != nil {
- log.Printf("Error running squeue: %v", err)
- return
- }
- scanner := bufio.NewScanner(sq)
- for scanner.Scan() {
- newSqueueContents = append(newSqueueContents, scanner.Text())
- }
- if err := scanner.Err(); err != nil {
- cmd.Wait()
- log.Printf("Error reading from squeue pipe: %v", err)
+ stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}
+ cmd.Stdout, cmd.Stderr = stdout, stderr
+ if err := cmd.Run(); err != nil {
+ log.Printf("Error running %q %q: %s %q", cmd.Path, cmd.Args, err, stderr.String())
return
}
- err = cmd.Wait()
- if err != nil {
- log.Printf("Error running squeue: %v", err)
- return
+ uuids := strings.Split(stdout.String(), "\n")
+ sqc.uuids = make(map[string]bool, len(uuids))
+ for _, uuid := range uuids {
+ sqc.uuids[uuid] = true
}
-
- squeue.squeueCond.L.Lock()
- squeue.squeueContents = newSqueueContents
- squeue.squeueCond.Broadcast()
- squeue.squeueCond.L.Unlock()
+ sqc.Broadcast()
}
-// CheckSqueue checks if a given container UUID is in the slurm queue. This
-// does not run squeue directly, but instead blocks until woken up by next
-// successful update of squeue.
-func (squeue *Squeue) CheckSqueue(uuid string) bool {
- squeue.squeueCond.L.Lock()
- // block until next squeue broadcast signaling an update.
- squeue.squeueCond.Wait()
- contents := squeue.squeueContents
- squeue.squeueCond.L.Unlock()
-
- for _, k := range contents {
- if k == uuid {
- return true
+// Initialize, and start a goroutine to call check() once per
+// squeue.Period until terminated by calling Stop().
+func (sqc *SqueueChecker) start() {
+ sqc.L = &sync.Mutex{}
+ sqc.done = make(chan struct{})
+ go func() {
+ ticker := time.NewTicker(sqc.Period)
+ for {
+ select {
+ case <-sqc.done:
+ ticker.Stop()
+ return
+ case <-ticker.C:
+ sqc.check()
+ }
}
- }
- return false
+ }()
}
-// StartMonitor starts the squeue monitoring goroutine.
-func (squeue *Squeue) StartMonitor(pollInterval time.Duration) {
- squeue.squeueCond = sync.NewCond(&sync.Mutex{})
- squeue.squeueDone = make(chan struct{})
- go squeue.SyncSqueue(pollInterval)
-}
-
-// Done stops the squeue monitoring goroutine.
-func (squeue *Squeue) Done() {
- squeue.squeueDone <- struct{}{}
- close(squeue.squeueDone)
-}
-
-// SyncSqueue periodically polls RunSqueue() at the given duration until
-// terminated by calling Done().
-func (squeue *Squeue) SyncSqueue(pollInterval time.Duration) {
- ticker := time.NewTicker(pollInterval)
- for {
- select {
- case <-squeue.squeueDone:
- return
- case <-ticker.C:
- squeue.RunSqueue()
- }
+// All waits for the next squeue invocation, and returns all job
+// names reported by squeue.
+func (sqc *SqueueChecker) All() []string {
+ sqc.startOnce.Do(sqc.start)
+ sqc.L.Lock()
+ defer sqc.L.Unlock()
+ sqc.Wait()
+ var uuids []string
+ for uuid := range sqc.uuids {
+ uuids = append(uuids, uuid)
}
+ return uuids
}
projects / arvados.git / blobdiff