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clair/database/pgsql/lock.go

108 lines
2.8 KiB

// Copyright 2017 clair authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pgsql
import (
"time"
log "github.com/sirupsen/logrus"
"github.com/coreos/clair/pkg/commonerr"
)
// Lock tries to set a temporary lock in the database.
//
// Lock does not block, instead, it returns true and its expiration time
// is the lock has been successfully acquired or false otherwise
func (pgSQL *pgSQL) Lock(name string, owner string, duration time.Duration, renew bool) (bool, time.Time) {
if name == "" || owner == "" || duration == 0 {
log.Warning("could not create an invalid lock")
return false, time.Time{}
}
defer observeQueryTime("Lock", "all", time.Now())
// Compute expiration.
until := time.Now().Add(duration)
if renew {
// Renew lock.
r, err := pgSQL.Exec(updateLock, name, owner, until)
if err != nil {
handleError("updateLock", err)
return false, until
}
if n, _ := r.RowsAffected(); n > 0 {
// Updated successfully.
return true, until
}
} else {
// Prune locks.
pgSQL.pruneLocks()
}
// Lock.
_, err := pgSQL.Exec(insertLock, name, owner, until)
if err != nil {
if !isErrUniqueViolation(err) {
handleError("insertLock", err)
}
return false, until
}
return true, until
}
// Unlock unlocks a lock specified by its name if I own it
func (pgSQL *pgSQL) Unlock(name, owner string) {
if name == "" || owner == "" {
log.Warning("could not delete an invalid lock")
return
}
defer observeQueryTime("Unlock", "all", time.Now())
pgSQL.Exec(removeLock, name, owner)
}
// FindLock returns the owner of a lock specified by its name and its
// expiration time.
func (pgSQL *pgSQL) FindLock(name string) (string, time.Time, error) {
if name == "" {
log.Warning("could not find an invalid lock")
return "", time.Time{}, commonerr.NewBadRequestError("could not find an invalid lock")
}
defer observeQueryTime("FindLock", "all", time.Now())
var owner string
var until time.Time
err := pgSQL.QueryRow(searchLock, name).Scan(&owner, &until)
if err != nil {
return owner, until, handleError("searchLock", err)
}
return owner, until, nil
}
// pruneLocks removes every expired locks from the database
func (pgSQL *pgSQL) pruneLocks() {
defer observeQueryTime("pruneLocks", "all", time.Now())
if _, err := pgSQL.Exec(removeLockExpired); err != nil {
handleError("removeLockExpired", err)
}
}