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head_buffer.go
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head_buffer.go
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package headbuffer
import (
"container/list"
"github.com/filecoin-project/lotus/api"
)
type HeadChangeStackBuffer struct {
buffer *list.List
size int
}
// NewHeadChangeStackBuffer buffer HeadChange events to avoid having to
// deal with revert changes. Initialized size should be the average reorg
// size + 1
func NewHeadChangeStackBuffer(size int) *HeadChangeStackBuffer {
buffer := list.New()
buffer.Init()
return &HeadChangeStackBuffer{
buffer: buffer,
size: size,
}
}
// Push adds a HeadChange to stack buffer. If the length of
// the stack buffer grows larger than the initizlized size, the
// oldest HeadChange is returned.
func (h *HeadChangeStackBuffer) Push(hc *api.HeadChange) (rethc *api.HeadChange) {
if h.buffer.Len() >= h.size {
var ok bool
el := h.buffer.Front()
rethc, ok = el.Value.(*api.HeadChange)
if !ok {
// This shouldn't be possible, this method is typed and is the only place data
// pushed to the buffer.
panic("A cosmic ray made me do it")
}
h.buffer.Remove(el)
}
h.buffer.PushBack(hc)
return
}
// Pop removes the last added HeadChange
func (h *HeadChangeStackBuffer) Pop() {
el := h.buffer.Back()
if el != nil {
h.buffer.Remove(el)
}
}