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Merge pull request #10218 from overleaf/jpa-adjust-prefetching

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[web] pdf-caching: try to prefetch other smaller chunks

GitOrigin-RevId: 2bf1d33d48c2026ec3794baaaef8346dc9104db3
This commit is contained in:
Jakob Ackermann 2022-11-01 15:22:49 +00:00 committed by Copybot
parent 6f00659865
commit 28c1cc2ea9
1 changed files with 33 additions and 12 deletions
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45
services/web/frontend/js/features/pdf-preview/util/pdf-caching.js
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@ -536,10 +536,10 @@ function addPrefetchingChunks({
return
}
let extra = []
let extraChunks = []
if (prefetchXRefTable) {
// Prefetch the dynamic chunks around the xref table.
extra = skipPrefetched(
extraChunks = skipPrefetched(
getInterleavingDynamicChunks(
getMatchingChunks(file.ranges, startXRefTableRange, file.size),
startXRefTableRange,
@ -552,7 +552,7 @@ function addPrefetchingChunks({
}
// Stop at the xref table range if present -- we may prefetch it early ^^^.
const prefetchEnd = startXRefTableRange || file.size
extra = extra.concat(
extraChunks = extraChunks.concat(
skipPrefetched(
getInterleavingDynamicChunks(
getMatchingChunks(file.ranges, end, prefetchEnd),
@ -568,28 +568,49 @@ function addPrefetchingChunks({
let sum =
countBytes(dynamicChunks) +
HEADER_OVERHEAD_PER_MULTI_PART_CHUNK * dynamicChunks.length
for (const chunk of extra) {
sum += chunk.end - chunk.start + HEADER_OVERHEAD_PER_MULTI_PART_CHUNK
if (sum > PDF_JS_CHUNK_SIZE) {
// Stop prefetching when the range is full.
for (const chunk of extraChunks) {
const downloadSize =
chunk.end - chunk.start + HEADER_OVERHEAD_PER_MULTI_PART_CHUNK
if (sum + downloadSize > PDF_JS_CHUNK_SIZE) {
// In prefetching this chunk we would exceed the bandwidth limit.
// Try to prefetch another (smaller) chunk.
continue
}
const sibling = dynamicChunks.find(
sibling => sibling.end === chunk.start || sibling.start === chunk.end
)
if (sibling) {
// Just expand the chunk.
sum += downloadSize
// Just expand the existing dynamic chunk.
sibling.start = Math.min(sibling.start, chunk.start)
sibling.end = Math.max(sibling.end, chunk.end)
continue
}
if (dynamicChunks.length === MULTI_PART_THRESHOLD) {
// Stop prefetching when we would switch to a multipart request.
// (We continue in case we are already doing a multipart request.)
break
if (dynamicChunks.length > MULTI_PART_THRESHOLD) {
// We are already performing a multipart request. Add another part.
} else if (dynamicChunks.length < MULTI_PART_THRESHOLD) {
// We are not yet performing a multipart request. Add another request.
} else {
// In prefetching this chunk we would switch to a multipart request.
// Try to prefetch another (smaller) chunk.
continue
}
sum += downloadSize
dynamicChunks.push(chunk)
}
dynamicChunks.sort(sortByStartASC)
// Ensure that no chunks are overlapping.
let lastEnd = 0
for (const [idx, chunk] of dynamicChunks.entries()) {
if (chunk.start < lastEnd) {
throw new OError('detected overlapping dynamic chunks', {
chunk,
lastChunk: dynamicChunks[idx - 1],
})
}
lastEnd = chunk.end
}
}
class Timer {