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|
package main
import (
"errors"
"fmt"
"github.com/kch42/gomcmap/mcmap"
)
type CachedRegion struct {
Region *mcmap.Region
cacheChunks []*mcmap.Chunk
cachePos []XZPos
cachesize int
}
func NewCachedRegion(reg *mcmap.Region, cachesize int) *CachedRegion {
if cachesize <= 0 {
panic(errors.New("Cachesize must be >0"))
}
return &CachedRegion{
Region: reg,
cacheChunks: make([]*mcmap.Chunk, cachesize),
cachePos: make([]XZPos, cachesize),
cachesize: cachesize,
}
}
func (cr *CachedRegion) Chunk(x, z int) (*mcmap.Chunk, error) {
pos := XZPos{x, z}
for i, p := range cr.cachePos {
if p == pos {
if cr.cacheChunks[i] != nil {
chunk := cr.cacheChunks[i]
for j := i; j >= 1; j-- {
cr.cacheChunks[j] = cr.cacheChunks[j-1]
cr.cachePos[j] = cr.cachePos[j-1]
}
cr.cacheChunks[0] = chunk
cr.cachePos[0] = pos
return chunk, nil
}
}
}
chunk, err := cr.Region.Chunk(x, z)
if err != nil {
return nil, err
}
if cr.cacheChunks[cr.cachesize-1] != nil {
if err := cr.cacheChunks[cr.cachesize-1].MarkUnused(); err != nil {
return nil, fmt.Errorf("Could not remove oldest cache element: %s", err)
}
}
for i := cr.cachesize - 1; i >= 1; i-- {
cr.cacheChunks[i] = cr.cacheChunks[i-1]
cr.cachePos[i] = cr.cachePos[i-1]
}
cr.cacheChunks[0] = chunk
cr.cachePos[0] = pos
return chunk, nil
}
func (cr *CachedRegion) Flush() error {
for i, chunk := range cr.cacheChunks {
if chunk == nil {
continue
}
if err := chunk.MarkUnused(); err != nil {
return err
}
cr.cacheChunks[i] = nil
}
return nil
}
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