55 lines
1.5 KiB
Go
55 lines
1.5 KiB
Go
package locker
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import (
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"context"
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"time"
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"github.com/FAU-CDI/wisski-distillery/internal/models"
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"github.com/FAU-CDI/wisski-distillery/internal/wisski/ingredient"
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"github.com/FAU-CDI/wisski-distillery/pkg/cancel"
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"github.com/tkw1536/goprogram/exit"
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)
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// Locker provides facitilites for locking this WissKI instance
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type Locker struct {
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ingredient.Base
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}
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var (
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_ ingredient.WissKIFetcher = (*Locker)(nil)
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)
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var Locked = exit.Error{
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Message: "instance is locked for administrative operations",
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ExitCode: exit.ExitGeneric,
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}
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// TryLock attemps to lock this WissKI and returns if it suceeded
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func (lock *Locker) TryLock(ctx context.Context) bool {
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table, err := lock.Malt.SQL.QueryTable(ctx, lock.Malt.LockTable)
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if err != nil {
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return false
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}
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result := table.FirstOrCreate(&models.Lock{}, models.Lock{Slug: lock.Slug})
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return result.Error == nil && result.RowsAffected == 1
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}
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// TryUnlock attempts to unlock this WissKI and reports if it succeeded.
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// An Unlock is also attempted when ctx is cancelled.
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func (lock *Locker) TryUnlock(ctx context.Context) bool {
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ctx, close := cancel.Anyways(ctx, time.Second)
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defer close()
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table, err := lock.Malt.SQL.QueryTable(ctx, lock.Malt.LockTable)
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if err != nil {
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return false
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}
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result := table.Where("slug = ?", lock.Slug).Delete(&models.Lock{})
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return result.Error == nil && result.RowsAffected == 1
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}
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// Unlock unlocks this WissKI, ignoring any error.
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func (lock *Locker) Unlock(ctx context.Context) {
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lock.TryUnlock(ctx)
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}
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