110 lines
3.4 KiB
Go
110 lines
3.4 KiB
Go
// Copyright 2019 clair authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package lock
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import (
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"database/sql"
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"time"
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"github.com/coreos/clair/database/pgsql/monitoring"
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"github.com/coreos/clair/database/pgsql/util"
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log "github.com/sirupsen/logrus"
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)
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const (
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searchLock = `SELECT until FROM Lock WHERE name = $1`
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updateLock = `UPDATE Lock SET until = $3 WHERE name = $1 AND owner = $2`
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removeLock = `DELETE FROM Lock WHERE name = $1 AND owner = $2`
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removeLockExpired = `DELETE FROM LOCK WHERE until < $1`
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soiLock = `
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WITH new_lock AS (
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INSERT INTO lock (name, owner, until)
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SELECT CAST ($1 AS TEXT), CAST ($2 AS TEXT), CAST ($3 AS TIMESTAMP)
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WHERE NOT EXISTS (SELECT id FROM lock WHERE name = $1)
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RETURNING owner, until
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)
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SELECT * FROM new_lock
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UNION
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SELECT owner, until FROM lock WHERE name = $1`
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)
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func AcquireLock(tx *sql.Tx, lockName, whoami string, desiredDuration time.Duration) (bool, time.Time, error) {
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if lockName == "" || whoami == "" || desiredDuration == 0 {
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panic("invalid lock parameters")
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}
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if err := PruneLocks(tx); err != nil {
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return false, time.Time{}, err
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}
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var (
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desiredLockedUntil = time.Now().UTC().Add(desiredDuration)
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lockedUntil time.Time
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lockOwner string
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)
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defer monitoring.ObserveQueryTime("Lock", "soiLock", time.Now())
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err := tx.QueryRow(soiLock, lockName, whoami, desiredLockedUntil).Scan(&lockOwner, &lockedUntil)
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return lockOwner == whoami, lockedUntil, util.HandleError("AcquireLock", err)
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}
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func ExtendLock(tx *sql.Tx, lockName, whoami string, desiredDuration time.Duration) (bool, time.Time, error) {
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if lockName == "" || whoami == "" || desiredDuration == 0 {
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panic("invalid lock parameters")
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}
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desiredLockedUntil := time.Now().Add(desiredDuration)
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defer monitoring.ObserveQueryTime("Lock", "update", time.Now())
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result, err := tx.Exec(updateLock, lockName, whoami, desiredLockedUntil)
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if err != nil {
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return false, time.Time{}, util.HandleError("updateLock", err)
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}
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if numRows, err := result.RowsAffected(); err == nil {
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// This is the only happy path.
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return numRows > 0, desiredLockedUntil, nil
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}
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return false, time.Time{}, util.HandleError("updateLock", err)
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}
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func ReleaseLock(tx *sql.Tx, name, owner string) error {
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if name == "" || owner == "" {
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panic("invalid lock parameters")
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}
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defer monitoring.ObserveQueryTime("Unlock", "all", time.Now())
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_, err := tx.Exec(removeLock, name, owner)
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return err
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}
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// pruneLocks removes every expired locks from the database
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func PruneLocks(tx *sql.Tx) error {
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defer monitoring.ObserveQueryTime("pruneLocks", "all", time.Now())
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if r, err := tx.Exec(removeLockExpired, time.Now().UTC()); err != nil {
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return util.HandleError("removeLockExpired", err)
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} else if affected, err := r.RowsAffected(); err != nil {
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return util.HandleError("removeLockExpired", err)
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} else {
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log.Debugf("Pruned %d Locks", affected)
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}
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return nil
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}
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