/usr/share/gocode/src/github.com/influxdata/influxdb/influxql/task_manager.go is in golang-github-influxdb-influxdb-dev 1.0.2+dfsg1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"fmt"
"io/ioutil"
"log"
"sync"
"time"
"github.com/influxdata/influxdb/models"
)
const (
// DefaultQueryTimeout is the default timeout for executing a query.
// A value of zero will have no query timeout.
DefaultQueryTimeout = time.Duration(0)
)
// TaskManager takes care of all aspects related to managing running queries.
type TaskManager struct {
// Query execution timeout.
QueryTimeout time.Duration
// Log queries if they are slower than this time.
// If zero, slow queries will never be logged.
LogQueriesAfter time.Duration
// Maximum number of concurrent queries.
MaxConcurrentQueries int
// Logger to use for all logging.
// Defaults to discarding all log output.
Logger *log.Logger
// Used for managing and tracking running queries.
queries map[uint64]*QueryTask
nextID uint64
mu sync.RWMutex
shutdown bool
}
// NewTaskManager creates a new TaskManager.
func NewTaskManager() *TaskManager {
return &TaskManager{
QueryTimeout: DefaultQueryTimeout,
Logger: log.New(ioutil.Discard, "[query] ", log.LstdFlags),
queries: make(map[uint64]*QueryTask),
nextID: 1,
}
}
// ExecuteStatement executes a statement containing one of the task management queries.
func (t *TaskManager) ExecuteStatement(stmt Statement, ctx ExecutionContext) error {
switch stmt := stmt.(type) {
case *ShowQueriesStatement:
rows, err := t.executeShowQueriesStatement(stmt)
if err != nil {
return err
}
ctx.Results <- &Result{
StatementID: ctx.StatementID,
Series: rows,
}
case *KillQueryStatement:
var messages []*Message
if ctx.ReadOnly {
messages = append(messages, ReadOnlyWarning(stmt.String()))
}
if err := t.executeKillQueryStatement(stmt); err != nil {
return err
}
ctx.Results <- &Result{
StatementID: ctx.StatementID,
Messages: messages,
}
default:
return ErrInvalidQuery
}
return nil
}
func (t *TaskManager) executeKillQueryStatement(stmt *KillQueryStatement) error {
return t.KillQuery(stmt.QueryID)
}
func (t *TaskManager) executeShowQueriesStatement(q *ShowQueriesStatement) (models.Rows, error) {
t.mu.RLock()
defer t.mu.RUnlock()
now := time.Now()
values := make([][]interface{}, 0, len(t.queries))
for id, qi := range t.queries {
d := now.Sub(qi.startTime)
var ds string
if d == 0 {
ds = "0s"
} else if d < time.Second {
ds = fmt.Sprintf("%du", d)
} else {
ds = (d - (d % time.Second)).String()
}
values = append(values, []interface{}{id, qi.query, qi.database, ds})
}
return []*models.Row{{
Columns: []string{"qid", "query", "database", "duration"},
Values: values,
}}, nil
}
func (t *TaskManager) query(qid uint64) (*QueryTask, bool) {
t.mu.RLock()
query, ok := t.queries[qid]
t.mu.RUnlock()
return query, ok
}
// AttachQuery attaches a running query to be managed by the TaskManager.
// Returns the query id of the newly attached query or an error if it was
// unable to assign a query id or attach the query to the TaskManager.
// This function also returns a channel that will be closed when this
// query finishes running.
//
// After a query finishes running, the system is free to reuse a query id.
func (t *TaskManager) AttachQuery(q *Query, database string, interrupt <-chan struct{}) (uint64, *QueryTask, error) {
t.mu.Lock()
defer t.mu.Unlock()
if t.shutdown {
return 0, nil, ErrQueryEngineShutdown
}
if t.MaxConcurrentQueries > 0 && len(t.queries) >= t.MaxConcurrentQueries {
return 0, nil, ErrMaxConcurrentQueriesReached
}
qid := t.nextID
query := &QueryTask{
query: q.String(),
database: database,
startTime: time.Now(),
closing: make(chan struct{}),
monitorCh: make(chan error),
}
t.queries[qid] = query
go t.waitForQuery(qid, query.closing, interrupt, query.monitorCh)
if t.LogQueriesAfter != 0 {
go query.monitor(func(closing <-chan struct{}) error {
timer := time.NewTimer(t.LogQueriesAfter)
defer timer.Stop()
select {
case <-timer.C:
t.Logger.Printf("Detected slow query: %s (qid: %d, database: %s, threshold: %s)",
query.query, qid, query.database, t.LogQueriesAfter)
case <-closing:
}
return nil
})
}
t.nextID++
return qid, query, nil
}
// KillQuery stops and removes a query from the TaskManager.
// This method can be used to forcefully terminate a running query.
func (t *TaskManager) KillQuery(qid uint64) error {
t.mu.Lock()
defer t.mu.Unlock()
query, ok := t.queries[qid]
if !ok {
return fmt.Errorf("no such query id: %d", qid)
}
close(query.closing)
delete(t.queries, qid)
return nil
}
// QueryInfo represents the information for a query.
type QueryInfo struct {
ID uint64 `json:"id"`
Query string `json:"query"`
Database string `json:"database"`
Duration time.Duration `json:"duration"`
}
// Queries returns a list of all running queries with information about them.
func (t *TaskManager) Queries() []QueryInfo {
t.mu.RLock()
defer t.mu.RUnlock()
now := time.Now()
queries := make([]QueryInfo, 0, len(t.queries))
for id, qi := range t.queries {
queries = append(queries, QueryInfo{
ID: id,
Query: qi.query,
Database: qi.database,
Duration: now.Sub(qi.startTime),
})
}
return queries
}
func (t *TaskManager) waitForQuery(qid uint64, interrupt <-chan struct{}, closing <-chan struct{}, monitorCh <-chan error) {
var timerCh <-chan time.Time
if t.QueryTimeout != 0 {
timer := time.NewTimer(t.QueryTimeout)
timerCh = timer.C
defer timer.Stop()
}
select {
case <-closing:
query, ok := t.query(qid)
if !ok {
break
}
query.setError(ErrQueryInterrupted)
case err := <-monitorCh:
if err == nil {
break
}
query, ok := t.query(qid)
if !ok {
break
}
query.setError(err)
case <-timerCh:
query, ok := t.query(qid)
if !ok {
break
}
query.setError(ErrQueryTimeoutReached)
case <-interrupt:
// Query was manually closed so exit the select.
return
}
t.KillQuery(qid)
}
// Close kills all running queries and prevents new queries from being attached.
func (t *TaskManager) Close() error {
t.mu.Lock()
defer t.mu.Unlock()
t.shutdown = true
for _, query := range t.queries {
query.setError(ErrQueryEngineShutdown)
close(query.closing)
}
t.queries = nil
return nil
}
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