63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
package storage
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import (
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"context"
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"io"
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)
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// opener is something that can be opened and closed.
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type opener interface {
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Open(context.Context) error
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io.Closer // TODO consider a closer-with-context instead
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}
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// openHelper is a helper to abstract the pattern of opening multiple things,
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// exiting early if any open fails, and closing any of the opened things
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// in the case of failure.
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type openHelper struct {
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opened []io.Closer
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err error
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}
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// Open attempts to open the opener. If an error has happened already
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// then no calls are made to the opener.
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func (o *openHelper) Open(ctx context.Context, op opener) {
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if o.err != nil {
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return
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}
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o.err = op.Open(ctx)
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if o.err == nil {
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o.opened = append(o.opened, op)
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}
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}
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// Done returns the error of the first open and closes in reverse
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// order any opens that have already happened if there was an error.
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func (o *openHelper) Done() error {
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if o.err == nil {
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return nil
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}
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for i := len(o.opened) - 1; i >= 0; i-- {
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o.opened[i].Close()
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}
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return o.err
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}
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// closeHelper is a helper to abstract the pattern of closing multiple
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// things and keeping track of the first encountered error.
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type closeHelper struct {
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err error
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}
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// Close closes the closer and keeps track of the first error.
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func (c *closeHelper) Close(cl io.Closer) {
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if err := cl.Close(); c.err == nil {
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c.err = err
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}
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}
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// Done returns the first error.
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func (c *closeHelper) Done() error {
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return c.err
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}
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