67 lines
2 KiB
Go
67 lines
2 KiB
Go
package lock
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import (
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"fmt"
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"github.com/ente-io/museum/pkg/repo"
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"github.com/ente-io/stacktrace"
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log "github.com/sirupsen/logrus"
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)
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// LockController exposes functions to obtain locks before entering critical sections
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type LockController struct {
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TaskLockingRepo *repo.TaskLockRepository
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HostName string
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}
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// Try to obtain a lock with the given lockID.
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//
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// Return false if the lock is already taken.
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//
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// A call to this function should be matched by a call to ReleaseLock. A common
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// pattern is to put the ReleaseLock into a defer statement immediately
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// following the lock acquisition.
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//
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// However, it is also fine to omit the release. Such would be useful for cases
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// where we want to ensure the same job cannot run again until the expiry time
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// is past.
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func (c *LockController) TryLock(lockID string, lockUntil int64) bool {
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lockStatus, err := c.TaskLockingRepo.AcquireLock(lockID, lockUntil, c.HostName)
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if err != nil || !lockStatus {
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return false
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}
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return true
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}
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// ExtendLock refreshes an existing lock by updating its locked_at to now and
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// extending its lockUntil.
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//
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// It is only valid to call this method when holding an existing lock previously
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// obtained using TryLock.
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func (c *LockController) ExtendLock(lockID string, lockUntil int64) error {
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foundLock, err := c.TaskLockingRepo.ExtendLock(lockID, lockUntil, c.HostName)
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if err != nil {
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return stacktrace.Propagate(err, "Unable to extend lock %v", lockID)
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}
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if !foundLock {
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return fmt.Errorf("no existing lock for %v", lockID)
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}
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return nil
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}
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// Release a lock that was obtained earlier using TryLock.
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func (c *LockController) ReleaseLock(lockID string) {
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err := c.TaskLockingRepo.ReleaseLock(lockID)
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if err != nil {
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log.Errorf("Error while releasing lock %v: %s", lockID, err)
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}
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}
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func (c *LockController) ReleaseHostLock() {
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count, err := c.TaskLockingRepo.ReleaseLocksBy(c.HostName)
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if err != nil {
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log.Errorf("Error while releasing host lock: %s", err)
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}
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log.Infof("Released %d locks held by %s", *count, c.HostName)
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}
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