mirror of https://github.com/ceph/go-ceph
65 lines
1.7 KiB
Go
65 lines
1.7 KiB
Go
package retry
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// Hint is a type for retry hints
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type Hint interface {
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If(bool) Hint
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size() int
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}
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type hintInt int
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func (hint hintInt) size() int {
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return int(hint)
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}
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// If is a convenience function, that returns a given hint only if a certain
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// condition is met (for example a test for a "buffer too small" error).
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// Otherwise it returns a nil which stops the retries.
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func (hint hintInt) If(cond bool) Hint {
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if cond {
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return hint
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}
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return nil
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}
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// DoubleSize is a hint to retry with double the size
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const DoubleSize = hintInt(0)
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// Size returns a hint for a specific size
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func Size(s int) Hint {
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return hintInt(s)
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}
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// SizeFunc is used to implement 'resize loops' that hides the complexity of the
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// sizing away from most of the application. It's a function that takes a size
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// argument and returns nil, if no retry is necessary, or a hint indicating the
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// size for the next retry. If errors or other results are required from the
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// function, the function can write them to function closures of the surrounding
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// scope. See tests for examples.
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type SizeFunc func(size int) (hint Hint)
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// WithSizes repeatingly calls a SizeFunc with increasing sizes until either it
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// returns nil, or the max size has been reached. If the returned hint is
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// DoubleSize or indicating a size not greater than the current size, the size
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// is doubled. If the hint or next size is greater than the max size, the max
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// size is used for a last retry.
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func WithSizes(size int, max int, f SizeFunc) {
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if size > max {
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return
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}
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for {
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hint := f(size)
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if hint == nil || size == max {
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break
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}
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if hint.size() > size {
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size = hint.size()
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} else {
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size *= 2
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}
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if size > max {
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size = max
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}
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}
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}
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