File size: 3,560 Bytes
b91e262 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 | import { deleteMapEntry } from './cache-map'
import type { UnknownMapEntry } from './cache-map'
// We use an LRU for memory management. We must update this whenever we add or
// remove a new cache entry, or when an entry changes size.
let head: UnknownMapEntry | null = null
let didScheduleCleanup: boolean = false
let lruSize: number = 0
// TODO: I chose the max size somewhat arbitrarily. Consider setting this based
// on navigator.deviceMemory, or some other heuristic. We should make this
// customizable via the Next.js config, too.
const maxLruSize = 50 * 1024 * 1024 // 50 MB
export function lruPut(node: UnknownMapEntry) {
if (head === node) {
// Already at the head
return
}
const prev = node.prev
const next = node.next
if (next === null || prev === null) {
// This is an insertion
lruSize += node.size
// Whenever we add an entry, we need to check if we've exceeded the
// max size. We don't evict entries immediately; they're evicted later in
// an asynchronous task.
ensureCleanupIsScheduled()
} else {
// This is a move. Remove from its current position.
prev.next = next
next.prev = prev
}
// Move to the front of the list
if (head === null) {
// This is the first entry
node.prev = node
node.next = node
} else {
// Add to the front of the list
const tail = head.prev
node.prev = tail
// In practice, this is never null, but that isn't encoded in the type
if (tail !== null) {
tail.next = node
}
node.next = head
head.prev = node
}
head = node
}
export function updateLruSize(node: UnknownMapEntry, newNodeSize: number) {
// This is a separate function from `put` so that we can resize the entry
// regardless of whether it's currently being tracked by the LRU.
const prevNodeSize = node.size
node.size = newNodeSize
if (node.next === null) {
// This entry is not currently being tracked by the LRU.
return
}
// Update the total LRU size
lruSize = lruSize - prevNodeSize + newNodeSize
ensureCleanupIsScheduled()
}
export function deleteFromLru(deleted: UnknownMapEntry) {
const next = deleted.next
const prev = deleted.prev
if (next !== null && prev !== null) {
lruSize -= deleted.size
deleted.next = null
deleted.prev = null
// Remove from the list
if (head === deleted) {
// Update the head
if (next === head) {
// This was the last entry
head = null
} else {
head = next
}
} else {
prev.next = next
next.prev = prev
}
} else {
// Already deleted
}
}
function ensureCleanupIsScheduled() {
if (didScheduleCleanup || lruSize <= maxLruSize) {
return
}
didScheduleCleanup = true
requestCleanupCallback(cleanup)
}
function cleanup() {
didScheduleCleanup = false
// Evict entries until we're at 90% capacity. We can assume this won't
// infinite loop because even if `maxLruSize` were 0, eventually
// `deleteFromLru` sets `head` to `null` when we run out entries.
const ninetyPercentMax = maxLruSize * 0.9
while (lruSize > ninetyPercentMax && head !== null) {
const tail = head.prev
// In practice, this is never null, but that isn't encoded in the type
if (tail !== null) {
// Delete the entry from the map. In turn, this will remove it from
// the LRU.
deleteMapEntry(tail)
}
}
}
const requestCleanupCallback =
typeof requestIdleCallback === 'function'
? requestIdleCallback
: (cb: () => void) => setTimeout(cb, 0)
|