Files
PodTui/tests/audio-pcm-cache.test.ts
Michael Freno d7aec4e810 fix(memory): bound visualizer PCM cache and feed episode cache
The visualizer's PCM cache decoded the entire episode into RAM (22050 Hz
mono s16 ~160 MB/hr of audio) and held it until stop() — a 3-hour episode
pinned ~500 MB and long-form content hit 2.5 GB. The 4x decode also pulled
the whole remote file even when only minutes were listened to.

- audio-pcm-cache: sliding window around the playback position — the
  decode head caps at maxAheadSec (600s) ahead of the cursor, segments
  older than keepBehindSec (300s) are pruned, and the tail refills as
  playback advances. Steady state ~40 MB regardless of episode length;
  a backward seek past the window restarts a segment there (the existing
  seek-hole mechanism, no new failure mode).
- feed: cap the full-parse episode cache at 1000 episodes/feed so
  archive-heavy subscriptions can't pin their entire history in RAM;
  the visible list stays bounded by the user's cache preference and
  fetch-more keeps working within the ceiling.
- tests: pin the new head-cap and prune contracts (8/8 in
  audio-pcm-cache.test.ts; full suite 193 pass).

Also includes the in-flight cleanup/refactor pass (cover-art resolve
helper, page and comment tightening, ESLint config removal).
2026-08-12 21:02:19 -04:00

365 lines
11 KiB
TypeScript

/**
* EpisodePcmCache position-index contract tests.
*
* The visualizer's bars are served from a position-indexed PCM cache that
* ffmpeg fills at full speed. These tests pin the observable contracts the
* fragile paced-ring design kept breaking:
*
* 1. readWindow(out, at) serves the EXACT window ending at playback time
* `at` — position mapping is sample-precise, independent of how fast or
* far the decode has run.
* 2. Reads outside decoded coverage return 0 — the renderer HOLDS the last
* frame. (The old reader CLAMPED to a stale buffer; re-rendering the
* same window decayed cava into a frozen junk pattern after pause.)
* 3. pauseDecode kills ffmpeg but keeps the cache: resume serves bars
* instantly, ensureDecodeAround restarts the tail decode.
* 4. Seeking into an undecoded region starts a new segment there WITHOUT
* invalidating the previously decoded coverage.
*
* Uses a self-generated WAV (440Hz sine, mono, 22050Hz s16le — the cache's
* native rate) so expected samples are computed analytically with no
* resampler tolerance.
*/
import { test, expect } from "bun:test";
import { tmpdir } from "os";
import { join } from "path";
import { EpisodePcmCache } from "../src/utils/audio-pcm-cache";
const SAMPLE_RATE = 22050;
const FREQ = 440;
const AMP = 30000;
/** Write a WAV file containing `seconds` of a 440Hz sine at AMP amplitude. */
function writeSineWav(path: string, seconds: number): void {
const total = Math.round(seconds * SAMPLE_RATE);
const dataSize = total * 2;
const buf = new Uint8Array(44 + dataSize);
const dv = new DataView(buf.buffer);
const ascii = (off: number, s: string) => {
for (let i = 0; i < s.length; i++) buf[off + i] = s.charCodeAt(i);
};
ascii(0, "RIFF");
dv.setUint32(4, 36 + dataSize, true);
ascii(8, "WAVE");
ascii(12, "fmt ");
dv.setUint32(16, 16, true);
dv.setUint16(20, 1, true); // PCM
dv.setUint16(22, 1, true); // mono
dv.setUint32(24, SAMPLE_RATE, true);
dv.setUint32(28, SAMPLE_RATE * 2, true);
dv.setUint16(32, 2, true);
dv.setUint16(34, 16, true);
ascii(36, "data");
dv.setUint32(40, dataSize, true);
for (let i = 0; i < total; i++) {
const v = Math.round(AMP * Math.sin((2 * Math.PI * FREQ * i) / SAMPLE_RATE));
dv.setInt16(44 + i * 2, v, true);
}
Bun.write(path, buf);
}
/** Analytic sample value at a file index, matching the writer's formula. */
function expectedAt(fileIndex: number): number {
return Math.round(AMP * Math.sin((2 * Math.PI * FREQ * fileIndex) / SAMPLE_RATE));
}
/** Block until the cache covers playback time `sec`. */
async function waitForCoverage(
cache: EpisodePcmCache,
sec: number,
timeoutMs = 10000,
): Promise<void> {
const start = Date.now();
while (!cache.covers(sec)) {
if (Date.now() - start > timeoutMs) {
throw new Error(`cache did not cover ${sec}s in time`);
}
await Bun.sleep(25);
}
}
/** Block until the furthest decode pass has hit stream EOF. */
async function waitForFinished(
cache: EpisodePcmCache,
timeoutMs = 10000,
): Promise<void> {
const start = Date.now();
while (!cache.decodeFinished) {
if (Date.now() - start > timeoutMs) {
throw new Error("decode did not finish in time");
}
await Bun.sleep(25);
}
}
function tmpWav(): string {
return join(tmpdir(), `podtui-pcm-${process.pid}-${Math.floor(Math.random() * 1e9)}.wav`);
}
const hasFfmpeg = !!Bun.which("ffmpeg");
test.skipIf(!hasFfmpeg)(
"far-forward seek into undecoded territory restarts decode AT the target (bars recover in seconds, not minutes)",
async () => {
const wav = tmpWav();
writeSineWav(wav, 60);
const cache = new EpisodePcmCache({ url: wav });
try {
cache.startDecode(0);
await waitForCoverage(cache, 1);
// Skipping 45s ahead while the pass still crawls at 4x must restart
// the segment at the target — waiting for the frontier to chew
// through the skipped region is minutes of frozen bars.
cache.ensureDecodeAround(45);
expect(cache.decoding).toBe(true);
expect(cache.activeDecodeBaseSec).toBe(45);
await waitForCoverage(cache, 45.1);
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
{ timeout: 20000 },
);
test.skipIf(!hasFfmpeg)(
"small forward gap closes in place — no needless reconnect",
async () => {
const wav = tmpWav();
writeSineWav(wav, 60);
const cache = new EpisodePcmCache({ url: wav });
try {
cache.startDecode(0);
await waitForCoverage(cache, 2);
// ~5s past the running frontier: at 4x pacing this closes in ~1.5s,
// cheaper than a reconnect — the pass must NOT restart.
const target = cache.coverageEndSec + 5;
cache.ensureDecodeAround(target);
expect(cache.activeDecodeBaseSec).toBe(0);
await waitForCoverage(cache, target);
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
{ timeout: 20000 },
);
const FIVE_SEC_BASE = 5 * SAMPLE_RATE; // decode offset for position-mapping tests
test.skipIf(!hasFfmpeg)(
"readWindow serves the exact window ending at the requested position",
async () => {
const wav = tmpWav();
writeSineWav(wav, 30);
const cache = new EpisodePcmCache({ url: wav });
try {
cache.startDecode(5);
await waitForCoverage(cache, 6.5);
const out = new Float64Array(512);
expect(cache.readWindow(out, 5.1)).toBe(512);
// Window ENDS at the target: out[i] is the sample at
// round(5.1*SR) - (len-1) + i (5s offset + 0.1s).
const endIdx = Math.round(5.1 * SAMPLE_RATE);
for (let i = 0; i < 512; i++) {
const idx = endIdx - (out.length - 1) + i;
expect(Math.abs(out[i] - expectedAt(idx))).toBeLessThanOrEqual(1);
}
// A 5ms later window is the same stream shifted by exactly
// round(0.005*SR)=110 samples — pins position mapping precision.
const later = new Float64Array(512);
expect(cache.readWindow(later, 5.105)).toBe(512);
for (let i = 0; i <= 512 - 111; i++) {
expect(later[i]).toBe(out[i + 110]);
}
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
);
test.skipIf(!hasFfmpeg)(
"reads outside decoded coverage return 0 (renderer holds last frame, never stale junk)",
async () => {
const wav = tmpWav();
writeSineWav(wav, 30);
const cache = new EpisodePcmCache({ url: wav });
try {
cache.startDecode(5);
await waitForCoverage(cache, 5.5);
const out = new Float64Array(512);
out.fill(-999);
// Beyond the decode frontier.
expect(cache.readWindow(out, 999)).toBe(0);
// Before the segment base (decode started at 5s).
expect(cache.readWindow(out, 4.0)).toBe(0);
// Buffer untouched — no partial/stale samples leak through.
for (let i = 0; i < 16; i++) expect(out[i]).toBe(-999);
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
);
test.skipIf(!hasFfmpeg)(
"pauseDecode keeps the cache: resume serves instantly, tail decode continues",
async () => {
const wav = tmpWav();
writeSineWav(wav, 12); // short: full tail decode lands well under a second
const cache = new EpisodePcmCache({ url: wav });
try {
cache.startDecode(0);
await waitForCoverage(cache, 1.5);
// Pause: decode dies, cache must survive.
cache.pauseDecode();
expect(cache.decoding).toBe(false);
expect(cache.covers(1)).toBe(true);
// Serve from cache immediately after pause — this is the resume
// fast path: zero ffmpeg cold start.
const out = new Float64Array(512);
expect(cache.readWindow(out, 1.0)).toBe(512);
const endIdx = Math.round(1.0 * SAMPLE_RATE);
for (let i = 0; i < 512; i++) {
const idx = endIdx - (out.length - 1) + i;
expect(Math.abs(out[i] - expectedAt(idx))).toBeLessThanOrEqual(1);
}
// Resume: tail decode restarts and eventually covers the file.
cache.ensureDecodeAround(1.0);
await waitForFinished(cache);
expect(cache.coverageEndSec).toBeGreaterThanOrEqual(11.9);
expect(cache.readWindow(out, 11.5)).toBe(512);
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
{ timeout: 20000 },
);
test.skipIf(!hasFfmpeg)(
"seek into an undecoded region starts a new segment without losing earlier coverage",
async () => {
const wav = tmpWav();
writeSineWav(wav, 30);
const cache = new EpisodePcmCache({ url: wav });
try {
// Decoded the back half only...
cache.startDecode(10);
await waitForCoverage(cache, 11);
expect(cache.covers(2)).toBe(false);
// ...then the user seeks to 2s: a new segment decodes the front,
// and the back-half coverage stays valid throughout.
cache.ensureDecodeAround(2);
await waitForCoverage(cache, 2.2);
expect(cache.covers(10.5)).toBe(true);
const out = new Float64Array(512);
expect(cache.readWindow(out, 10.5)).toBe(512);
const endIdx = Math.round(10.5 * SAMPLE_RATE);
for (let i = 0; i < 512; i++) {
const idx = endIdx - (out.length - 1) + i;
expect(Math.abs(out[i] - expectedAt(idx))).toBeLessThanOrEqual(1);
}
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
{ timeout: 20000 },
);
test.skipIf(!hasFfmpeg)(
"decode head caps at maxAheadSec ahead of the cursor — the cache is a window, not a whole-episode dump",
async () => {
const wav = tmpWav();
writeSineWav(wav, 30);
const cache = new EpisodePcmCache({
url: wav,
maxAheadSec: 4,
keepBehindSec: 2,
});
try {
cache.startDecode(0);
// The 8s initial burst delivers the front of the file instantly.
await waitForCoverage(cache, 5);
// Park the cursor at 0 and drive the cap (the render loop reads
// every frame; the cap applies on the first read past the head).
const out = new Float64Array(512);
for (let i = 0; i < 30 && cache.decoding; i++) {
cache.readWindow(out, 0);
await Bun.sleep(20);
}
// Paused at the head budget (4s) + one 8s burst of slack — NOT
// decoded to the 30s EOF.
expect(cache.decoding).toBe(false);
expect(cache.coverageEndSec).toBeGreaterThanOrEqual(4);
expect(cache.coverageEndSec).toBeLessThanOrEqual(4 + 8 + 1);
expect(cache.decodeFinished).toBe(false);
// A parked cursor keeps the cap: more reads must not restart
// the pass or grow the cache.
const cappedAt = cache.coverageEndSec;
for (let i = 0; i < 10; i++) {
cache.readWindow(out, 0);
await Bun.sleep(20);
}
expect(cache.decoding).toBe(false);
expect(cache.coverageEndSec).toBeLessThanOrEqual(cappedAt + 1);
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
{ timeout: 20000 },
);
test.skipIf(!hasFfmpeg)(
"the window prunes segments behind the cursor as playback advances",
async () => {
const wav = tmpWav();
writeSineWav(wav, 30);
const cache = new EpisodePcmCache({
url: wav,
maxAheadSec: 4,
keepBehindSec: 2,
});
try {
// Two segments: the back half [10, ~18] and, after the seek,
// the front [2, ~10].
cache.startDecode(10);
await waitForCoverage(cache, 11);
cache.ensureDecodeAround(2);
await waitForCoverage(cache, 2.2);
expect(cache.covers(2.5)).toBe(true);
expect(cache.covers(10.5)).toBe(true);
// Cursor advances past the front segment's end + keepBehind:
// the front must fall out of the window, the back must survive.
const out = new Float64Array(512);
for (let i = 0; i < 40 && cache.covers(2.5); i++) {
cache.readWindow(out, 13);
await Bun.sleep(25);
}
expect(cache.covers(2.5)).toBe(false);
expect(cache.covers(10.5)).toBe(true);
} finally {
cache.stop();
await Bun.$`rm -f ${wav}`.quiet();
}
},
{ timeout: 20000 },
);