Gibheer
e2b479c34f
With this, it is now possible to support multiple check instances and balance the load.
242 lines
5.9 KiB
Go
242 lines
5.9 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"
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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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Timeout string `json:"timeout"`
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Wait string `json:"wait"`
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Path []string `json:"path"`
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Workers int `json:"workers"`
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CheckerID int `json:"checker_id"`
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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{Timeout: "30s", Wait: "30s", Workers: 25}
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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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if err := os.Setenv("PATH", strings.Join(config.Path, ":")); err != nil {
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log.Fatalf("could not set PATH: %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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timeout, err := time.ParseDuration(config.Timeout)
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if err != nil {
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log.Fatalf("could not parse timeout: %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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hostname, err := os.Hostname()
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if err != nil {
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log.Fatalf("could not resolve hostname: %s", err)
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}
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for i := 0; i < config.Workers; i++ {
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go check(i, db, waitDuration, timeout, hostname, config.CheckerID)
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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, timeout time.Duration, hostname string, checker_id int) {
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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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row := tx.QueryRow(`select check_id, cmdLine, states, mapping_id
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from active_checks
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where next_time < now()
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and enabled
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and checker_id = $1
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order by next_time
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for update skip locked
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limit 1;`, checker_id)
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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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mapId int
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state int
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)
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err = row.Scan(&id, pq.Array(&cmdLine), &states, &mapId)
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if err != nil && err == sql.ErrNoRows {
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tx.Rollback()
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time.Sleep(waitDuration)
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continue
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} else if 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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ctx, cancel := context.WithTimeout(context.Background(), timeout)
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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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cancel()
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state = 2
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fmt.Fprintf(output, "check took longer than %s", timeout)
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} else if err != nil && cmd.ProcessState == nil {
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log.Printf("[%d] error running check: %s", id, err)
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state = 3
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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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state = 2
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} else {
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state = status.ExitStatus()
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}
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} else {
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cancel()
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state = 0
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}
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msg := output.String()
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if _, err := tx.Exec(`update active_checks ac
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set next_time = now() + intval, states = ARRAY[$2::int] || states[1:4],
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msg = $3,
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acknowledged = case when $4 then false else acknowledged end,
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state_since = case $2 when states[1] then state_since else now() end
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where check_id = $1`, id, &state, &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 _, err := tx.Exec(`insert into notifications(check_id, states, output, mapping_id, notifier_id, check_host)
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select $1, array_agg(ml.target), $2, $3, cn.notifier_id, $4
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from active_checks ac
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cross join lateral unnest(ac.states) s
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join checks_notify cn on ac.check_id = cn.check_id
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join mapping_level ml on ac.mapping_id = ml.mapping_id and s.s = ml.source
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where ac.check_id = $1
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and ac.acknowledged = false
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group by cn.notifier_id;`, &id, &msg, &mapId, &hostname); 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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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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