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package msgp
type timer interface {
StartTimer()
StopTimer()
}
// EndlessReader is an io.Reader
// that loops over the same data
// endlessly. It is used for benchmarking.
type EndlessReader struct {
tb timer
data []byte
offset int
}
// NewEndlessReader returns a new endless reader
func NewEndlessReader(b []byte, tb timer) *EndlessReader {
// Double until we reach 4K.
for len(b) < 4<<10 {
b = append(b, b...)
}
return &EndlessReader{tb: tb, data: b, offset: 0}
}
// Read implements io.Reader. In practice, it
// always returns (len(p), nil), although it
// fills the supplied slice while the benchmark
// timer is stopped.
func (c *EndlessReader) Read(p []byte) (int, error) {
var n int
l := len(p)
m := len(c.data)
nn := copy(p[n:], c.data[c.offset:])
n += nn
for n < l {
n += copy(p[n:], c.data[:])
}
c.offset = (c.offset + l) % m
return n, nil
}
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