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implement LRU cache

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This commit is contained in:
Brandon Liu
2021-02-18 19:46:27 +08:00
parent 0c55b7e115
commit 01602c6846
1 changed files with 18 additions and 7 deletions
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25
js/pmtiles.js
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@@ -57,7 +57,7 @@
}) })
} }
}) })
// TODO make this LRU this.step = 0
this.leaves = new Map() this.leaves = new Map()
this.outstanding_requests = new Map() this.outstanding_requests = new Map()
} }
@@ -65,7 +65,8 @@
getLeaf = (offset, len) => { getLeaf = (offset, len) => {
return new Promise((resolve,reject) => { return new Promise((resolve,reject) => {
if (this.leaves.has(offset)) { if (this.leaves.has(offset)) {
resolve(this.leaves.get(offset)) this.leaves.get(offset)[0]++
resolve(this.leaves.get(offset)[1])
} else if (this.outstanding_requests.has(offset)) { } else if (this.outstanding_requests.has(offset)) {
this.outstanding_requests.get(offset).push(resolve) this.outstanding_requests.get(offset).push(resolve)
} else { } else {
@@ -74,12 +75,22 @@
return resp.arrayBuffer() return resp.arrayBuffer()
}).then(buf => { }).then(buf => {
var map = bytesToMap(new DataView(buf),len/17) var map = bytesToMap(new DataView(buf),len/17)
this.leaves.set(offset,map) if (this.leaves.size > 32) {
resolve(map) var minStep = Infinity
this.outstanding_requests.get(offset).forEach(f => { var minKey = undefined
f(map) this.leaves.forEach((val,key) => {
if (val[0] < minStep) {
minStep = val[0]
minKey = key
}
}) })
console.log("leaves: ", this.leaves.size) this.leaves.delete(minKey)
}
this.leaves.set(offset,[this.step++,map])
resolve(map)
this.outstanding_requests.get(offset).forEach(f => f(map))
this.outstanding_requests.delete(offset)
}) })
} }
}) })