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// META: title=IDB-backed composite blobs maintain coherency
// META: script=resources/support-promises.js
// META: timeout=long
// This test file is intended to help validate browser handling of complex blob
// scenarios where one or more levels of multipart blobs are used and varying
// IPC serialization strategies may be used depending on various complexity
// heuristics.
//
// A variety of approaches of reading the blob's contents are attempted for
// completeness:
// - `fetch-blob-url`: fetch of a URL created via URL.createObjectURL
// - Note that this is likely to involve multi-process behavior in a way that
// the next 2 currently will not unless their Blobs are round-tripped
// through a MessagePort.
// - `file-reader`: FileReader
// - `direct`: Blob.prototype.arrayBuffer()
function composite_blob_test({ blobCount, blobSize, name }) {
// NOTE: In order to reduce the runtime of this test and due to the similarity
// of the "file-reader" mechanism to the "direct", "file-reader" is commented
// out, but if you are investigating failures detected by this test, you may
// want to uncomment it.
for (const mode of ["fetch-blob-url", /*"file-reader",*/ "direct"]) {
promise_test(async testCase => {
const key = "the-blobs";
let memBlobs = [];
for (let iBlob = 0; iBlob < blobCount; iBlob++) {
memBlobs.push(new Blob([make_arraybuffer_contents(iBlob, blobSize)]));
}
const db = await createDatabase(testCase, db => {
db.createObjectStore("blobs");
});
const write_tx = db.transaction("blobs", "readwrite");
let store = write_tx.objectStore("blobs");
store.put(memBlobs, key);
// Make the blobs eligible for GC which is most realistic and most likely
// to cause problems.
memBlobs = null;
await promiseForTransaction(testCase, write_tx);
const read_tx = db.transaction("blobs", "readonly");
store = read_tx.objectStore("blobs");
const read_req = store.get(key);
await promiseForTransaction(testCase, read_tx);
const diskBlobs = read_req.result;
const compositeBlob = new Blob(diskBlobs);
if (mode === "fetch-blob-url") {
const blobUrl = URL.createObjectURL(compositeBlob);
let urlResp = await fetch(blobUrl);
let urlFetchArrayBuffer = await urlResp.arrayBuffer();
urlResp = null;
URL.revokeObjectURL(blobUrl);
validate_arraybuffer_contents("fetched URL", urlFetchArrayBuffer, blobCount, blobSize);
urlFetchArrayBuffer = null;
} else if (mode === "file-reader") {
let reader = new FileReader();
let readerPromise = new Promise(resolve => {
reader.onload = () => {
resolve(reader.result);
}
})
reader.readAsArrayBuffer(compositeBlob);
let readArrayBuffer = await readerPromise;
readerPromise = null;
reader = null;
validate_arraybuffer_contents("FileReader", readArrayBuffer, blobCount, blobSize);
readArrayBuffer = null;
} else if (mode === "direct") {
let directArrayBuffer = await compositeBlob.arrayBuffer();
validate_arraybuffer_contents("arrayBuffer", directArrayBuffer, blobCount, blobSize);
}
}, `Composite Blob Handling: ${name}: ${mode}`);
}
}
// Create an ArrayBuffer whose even bytes are the index identifier and whose
// odd bytes are a sequence incremented by 3 (wrapping at 256) so that
// discontinuities at power-of-2 boundaries are more detectable.
function make_arraybuffer_contents(index, size) {
const arr = new Uint8Array(size);
for (let i = 0, counter = 0; i < size; i += 2, counter = (counter + 3) % 256) {
arr[i] = index;
arr[i + 1] = counter;
}
return arr.buffer;
}
function validate_arraybuffer_contents(source, buffer, blobCount, blobSize) {
// Accumulate a list of problems we perceive so we can report what seems to
// have happened all at once.
const problems = [];
const arr = new Uint8Array(buffer);
const expectedLength = blobCount * blobSize;
const actualCount = arr.length / blobSize;
if (arr.length !== expectedLength) {
problems.push(`ArrayBuffer only holds ${actualCount} blobs' worth instead of ${blobCount}.`);
problems.push(`Actual ArrayBuffer is ${arr.length} bytes but expected ${expectedLength}`);
}
const counterBlobStep = (blobSize / 2 * 3) % 256;
let expectedBlob = 0;
let blobSeenSoFar = 0;
let expectedCounter = 0;
let counterDrift = 0;
for (let i = 0; i < arr.length; i += 2) {
if (arr[i] !== expectedBlob || blobSeenSoFar >= blobSize) {
if (blobSeenSoFar !== blobSize) {
problems.push(`Truncated blob ${expectedBlob} after ${blobSeenSoFar} bytes.`);
} else {
expectedBlob++;
}
if (expectedBlob !== arr[i]) {
problems.push(`Expected blob ${expectedBlob} but found ${arr[i]}, compensating.`);
expectedBlob = arr[i];
}
blobSeenSoFar = 0;
expectedCounter = (expectedBlob * counterBlobStep) % 256;
counterDrift = 0;
}
if (arr[i + 1] !== (expectedCounter + counterDrift) % 256) {
const newDrift = expectedCounter - arr[i + 1];
problems.push(`In blob ${expectedBlob} at ${blobSeenSoFar + 1} bytes in, counter drift now ${newDrift} was ${counterDrift}`);
counterDrift = newDrift;
}
blobSeenSoFar += 2;
expectedCounter = (expectedCounter + 3) % 256;
}
if (problems.length) {
assert_true(false, `${source} blob payload problem: ${problems.join("\n")}`);
} else {
assert_true(true, `${source} blob payloads validated.`);
}
}
composite_blob_test({
blobCount: 16,
blobSize: 256 * 1024,
name: "Many blobs",
});
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