223 lines
5.1 KiB
Go
223 lines
5.1 KiB
Go
package main
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import (
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"bytes"
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"context"
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"database/sql"
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"database/sql/driver"
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"encoding/json"
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"flag"
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"fmt"
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"io/ioutil"
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"log"
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"os/exec"
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"strconv"
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"strings"
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"sync"
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"syscall"
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"time"
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"github.com/lib/pq"
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)
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var (
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configPath = flag.String("config", "moncheck.conf", "path to the config file")
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)
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type (
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Config struct {
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DB string `json:"db"`
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Wait string `json:"wait"`
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}
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States []int
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)
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func main() {
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flag.Parse()
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raw, err := ioutil.ReadFile(*configPath)
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if err != nil {
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log.Fatalf("could not read config: %s", err)
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}
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config := Config{}
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if err := json.Unmarshal(raw, &config); err != nil {
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log.Fatalf("could not parse config: %s", err)
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}
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waitDuration, err := time.ParseDuration(config.Wait)
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if err != nil {
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log.Fatalf("could not parse wait duration: %s", err)
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}
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db, err := sql.Open("postgres", config.DB)
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if err != nil {
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log.Fatalf("could not open database connection: %s", err)
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}
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for i := 0; i < 25; i++ {
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go check(i, db, waitDuration)
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}
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wg := sync.WaitGroup{}
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wg.Add(1)
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wg.Wait()
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}
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func check(thread int, db *sql.DB, waitDuration time.Duration) {
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for {
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tx, err := db.Begin()
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if err != nil {
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log.Printf("[%d] could not start transaction: %s", thread, err)
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continue
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}
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rows, err := tx.Query("select check_id, cmdLine, states, notify from active_checks where next_time < now() and enabled order by next_time for update skip locked limit 1;")
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if err != nil {
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log.Printf("[%d] could not start query: %s", thread, err)
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tx.Rollback()
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continue
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}
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var (
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id int64
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cmdLine []string
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states States
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notify bool
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)
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found := false
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for rows.Next() {
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if err := rows.Err(); err != nil {
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log.Printf("could not fetch row: %s", err)
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tx.Rollback()
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break
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}
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if err := rows.Scan(&id, pq.Array(&cmdLine), &states, ¬ify); err != nil {
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log.Printf("could not scan values: %s", err)
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tx.Rollback()
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break
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}
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found = true
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}
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if !found {
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time.Sleep(waitDuration)
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tx.Rollback()
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continue
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}
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ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
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cmd := exec.CommandContext(ctx, cmdLine[0], cmdLine[1:]...)
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output := bytes.NewBuffer([]byte{})
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cmd.Stdout = output
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cmd.Stderr = output
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err = cmd.Run()
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if err != nil && ctx.Err() == context.DeadlineExceeded {
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log.Printf("[%d] check took too long: %s", id, err)
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cancel()
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// TODO which state to choose?
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// TODO add notification handler
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// TODO all this casting should be done better
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states.Add(99)
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output.Write([]byte(ctx.Err().Error()))
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} else if err != nil {
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cancel()
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status, ok := cmd.ProcessState.Sys().(syscall.WaitStatus)
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if !ok {
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log.Printf("[%d]error running check: %s", id, err)
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states.Add(1)
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} else {
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log.Printf("%s", cmd.ProcessState.String())
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states.Add(status.ExitStatus())
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}
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} else {
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cancel()
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states.Add(0)
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}
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msg := output.String()
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if _, err := tx.Exec(`update active_checks
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set next_time = now() + intval, states = $2, msg = $3, acknowledged = case when $4 then false else acknowledged end
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where check_id = $1`, id, &states, &msg, states.ToOK()); err != nil {
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log.Printf("[%d] could not update row '%d': %s", thread, id, err)
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tx.Rollback()
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continue
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}
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if notify {
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if _, err := tx.Exec("insert into notifications(check_id, states, output) values ($1, $2, $3);", &id, &states, &msg); err != nil {
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log.Printf("[%d] could not create notification for '%d': %s", thread, id, err)
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tx.Rollback()
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continue
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}
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}
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tx.Commit()
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}
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}
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func (s *States) Value() (driver.Value, error) {
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last := len(*s)
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if last == 0 {
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return "{}", nil
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}
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result := strings.Builder{}
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_, err := result.WriteString("{")
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if err != nil {
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return "", fmt.Errorf("could not write to buffer: %s", err)
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}
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for i, state := range *s {
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if _, err := fmt.Fprintf(&result, "%d", state); err != nil {
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return "", fmt.Errorf("could not write to buffer: %s", err)
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}
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if i < last-1 {
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if _, err := result.WriteString(","); err != nil {
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return "", fmt.Errorf("could not write to buffer: %s", err)
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}
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}
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}
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if _, err := result.WriteString("}"); err != nil {
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return "", fmt.Errorf("could not write to buffer: %s", err)
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}
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return result.String(), nil
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}
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func (s *States) Scan(src interface{}) error {
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switch src := src.(type) {
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case []byte:
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tmp := bytes.Trim(src, "{}")
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states := bytes.Split(tmp, []byte(","))
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result := make([]int, len(states))
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for i, state := range states {
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var err error
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result[i], err = strconv.Atoi(string(state))
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if err != nil {
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return fmt.Errorf("could not parse element %s: %s", state, err)
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}
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}
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*s = result
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return nil
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default:
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return fmt.Errorf("could not convert %T to states", src)
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}
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}
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// Append prepends the new state before all others.
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func (s *States) Add(state int) {
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vals := *s
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statePos := 5
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if len(vals) < 6 {
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statePos = len(vals)
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}
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*s = append([]int{state}, vals[:statePos]...)
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return
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}
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// ToOK returns true when the state returns from != 0 to 0.
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func (s *States) ToOK() bool {
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vals := *s
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if len(vals) == 0 {
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return false
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}
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if len(vals) <= 1 {
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return vals[0] == 0
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}
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if vals[0] == 0 && vals[1] > 0 {
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return true
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}
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return false
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}
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