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Merged
hackall360 merged 1 commit into from
Sep 24, 2025
Merged

Improve TTS fetch scheduling #23

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216 changes: 168 additions & 48 deletions src/main.js
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Original file line number Diff line number Diff line change
Expand Up @@ -804,6 +804,17 @@ async function playMessageAudio(message) {
let currentTtsJob = null;
const ttsQueue = [];
const ttsJobsByMessage = new Map();
const ttsFetchQueue = [];
let ttsFetchWorkerActive = false;
let lastTtsFetchEndedAt = 0;
let ttsFetchCooldownMs = 750;
const TTS_PREFETCH_AHEAD = 3;
const TTS_FETCH_MAX_RETRIES = 4;
const TTS_FETCH_MIN_COOLDOWN_MS = 350;
const TTS_FETCH_MAX_COOLDOWN_MS = 4500;
const TTS_FETCH_FAST_THRESHOLD_MS = 1800;
const TTS_FETCH_SLOW_THRESHOLD_MS = 4200;
const TTS_FETCH_VERY_SLOW_THRESHOLD_MS = 6500;
const SILENT_WAV_DATA_URL = 'data:audio/wav;base64,UklGRhYAAABXQVZFZm10IBIAAAABAAEAIlYAAESsAAACABAAZGF0YQAAAAA=';
const TTS_CHUNK_MAX_CHARS = 250;
const TTS_CHUNK_ERROR = Symbol('tts-chunk-error');
Expand Down Expand Up @@ -1043,6 +1054,154 @@ async function fetchTtsAudioUrl(text, voice) {
throw new Error('TTS fetch failed for all attempts');
}

function clampTtsCooldown(value) {
return Math.max(TTS_FETCH_MIN_COOLDOWN_MS, Math.min(TTS_FETCH_MAX_COOLDOWN_MS, value));
}

function adjustTtsCooldownOnSuccess(durationMs) {
if (!Number.isFinite(durationMs) || durationMs <= 0) {
ttsFetchCooldownMs = clampTtsCooldown(Math.round(ttsFetchCooldownMs * 0.9) || TTS_FETCH_MIN_COOLDOWN_MS);
return;
}
if (durationMs >= TTS_FETCH_VERY_SLOW_THRESHOLD_MS) {
const target = clampTtsCooldown(Math.round(durationMs * 0.35));
ttsFetchCooldownMs = Math.max(ttsFetchCooldownMs, target);
} else if (durationMs >= TTS_FETCH_SLOW_THRESHOLD_MS) {
ttsFetchCooldownMs = clampTtsCooldown(Math.round(ttsFetchCooldownMs * 1.1));
} else if (durationMs <= TTS_FETCH_FAST_THRESHOLD_MS) {
ttsFetchCooldownMs = clampTtsCooldown(Math.round(ttsFetchCooldownMs * 0.7));
} else {
ttsFetchCooldownMs = clampTtsCooldown(Math.round(ttsFetchCooldownMs * 0.85));
}
}

function adjustTtsCooldownOnError() {
ttsFetchCooldownMs = clampTtsCooldown(Math.round(ttsFetchCooldownMs * 1.65 + 320));
}

function removeQueuedFetchesForJob(job) {
if (!job) return;
for (let i = ttsFetchQueue.length - 1; i >= 0; i -= 1) {
if (ttsFetchQueue[i]?.job === job) {
ttsFetchQueue.splice(i, 1);
}
}
if (job.pendingFetches && typeof job.pendingFetches.clear === 'function') {
job.pendingFetches.clear();
}
}

function queueTtsFetch(job, index, attempt = 0, delayMs = 0) {
if (!job || job.cancelled || job.completed) return;
if (!Array.isArray(job.groups) || !job.groups[index]) return;
if (job.pendingFetches?.has(index)) return;
const task = {
job,
index,
attempt,
readyAt: Date.now() + Math.max(0, delayMs || 0),
};
if (job.pendingFetches) {
job.pendingFetches.add(index);
}
ttsFetchQueue.push(task);
ttsFetchQueue.sort((a, b) => (a.readyAt || 0) - (b.readyAt || 0));
runTtsFetchQueue();
}

function scheduleMoreTtsFetches(job) {
if (!job || job.cancelled || job.completed || currentTtsJob !== job) return;
while (
job.nextFetchIndex < job.groups.length &&
(job.nextFetchIndex - job.playIndex) <= TTS_PREFETCH_AHEAD &&
((job.pendingFetches?.size ?? 0) + job.inflight) < (TTS_PREFETCH_AHEAD + 1)
) {
queueTtsFetch(job, job.nextFetchIndex);
job.nextFetchIndex += 1;
}
}

function runTtsFetchQueue() {
if (ttsFetchWorkerActive) return;
ttsFetchWorkerActive = true;
(async () => {
try {
while (ttsFetchQueue.length) {
const task = ttsFetchQueue[0];
if (!task) break;
const now = Date.now();
if (task.readyAt && task.readyAt > now) {
await sleep(Math.min(task.readyAt - now, 250));
continue;
}
ttsFetchQueue.shift();
const { job, index, attempt } = task;
if (!job) continue;
job.pendingFetches?.delete(index);
if (job.cancelled || job.completed || currentTtsJob !== job) {
continue;
}
if (typeof job.results[index] !== 'undefined') {
scheduleMoreTtsFetches(job);
continue;
}
if (!job.groups || !job.groups[index]) {
scheduleMoreTtsFetches(job);
continue;
}

const wait = Math.max(0, (lastTtsFetchEndedAt + ttsFetchCooldownMs) - Date.now());
if (wait > 0) {
await sleep(wait);
}

job.inflight += 1;
setTtsChunkState(job, index, 'sent');
const fetchStart = Date.now();
let url = null;
let error = null;
try {
url = await fetchTtsAudioUrl(job.groups[index], job.voice);
} catch (err) {
error = err;
}
const duration = Date.now() - fetchStart;
job.inflight = Math.max(0, job.inflight - 1);
lastTtsFetchEndedAt = Date.now();

if (job.cancelled || job.completed || currentTtsJob !== job) {
continue;
}

if (!error && url) {
job.results[index] = url;
setTtsChunkState(job, index, 'received');
adjustTtsCooldownOnSuccess(duration);
tryStartPlayback(job);
} else {
console.warn('TTS fetch failed', error);
adjustTtsCooldownOnError();
if (attempt + 1 < TTS_FETCH_MAX_RETRIES) {
const retryDelay = Math.min(4000, Math.round((attempt + 1) * 900 + Math.random() * 250));
queueTtsFetch(job, index, attempt + 1, retryDelay);
} else {
job.results[index] = TTS_CHUNK_ERROR;
setTtsChunkState(job, index, 'error');
tryStartPlayback(job);
}
}

scheduleMoreTtsFetches(job);
}
} finally {
ttsFetchWorkerActive = false;
if (ttsFetchQueue.length) {
runTtsFetchQueue();
}
}
})();
}

function isMessageInTtsPipeline(messageId) {
if (messageId == null) return false;
if (currentTtsJob && !currentTtsJob.cancelled && currentTtsJob.messageId === messageId) return true;
Expand Down Expand Up @@ -1070,6 +1229,7 @@ function ensureTtsStatusElement(job) {

function cancelTtsJob(job, { resetPending = false } = {}) {
if (!job) return;
removeQueuedFetchesForJob(job);
job.cancelled = true;
for (const t of job.timers) clearTimeout(t);
job.timers.length = 0;
Expand All @@ -1079,6 +1239,7 @@ function cancelTtsJob(job, { resetPending = false } = {}) {
job.audio = null;
job.activeIndex = null;
job.inflight = 0;
job.nextFetchIndex = job.groups.length;
if (resetPending && Array.isArray(job.status)) {
for (let i = 0; i < job.status.length; i += 1) {
if (job.status[i] !== 'done' && job.status[i] !== 'error') {
Expand Down Expand Up @@ -1125,6 +1286,7 @@ function createTtsJob(message, voice) {
status: new Array(chunks.length).fill('pending'),
statusEl: null,
started: false,
pendingFetches: new Set(),
};
}

Expand All @@ -1147,59 +1309,13 @@ function beginTtsJob(job) {
job.completed = false;
ensureTtsStatusElement(job);
renderTtsStatus(job);

const scheduleNextFetch = () => {
if (job.cancelled || job.completed || currentTtsJob !== job) return;
if (job.nextFetchIndex >= job.groups.length) return;
if (job.inflight >= 2) {
const wait = setTimeout(scheduleNextFetch, 250);
job.timers.push(wait);
return;
}
const index = job.nextFetchIndex++;
const fetchChunk = (attempt = 0) => {
if (job.cancelled || job.completed || currentTtsJob !== job) return;
job.inflight += 1;
setTtsChunkState(job, index, 'sent');
(async () => {
try {
const url = await fetchTtsAudioUrl(job.groups[index], job.voice);
if (!job.cancelled && !job.completed && currentTtsJob === job) {
job.results[index] = url;
setTtsChunkState(job, index, 'received');
tryStartPlayback(job);
}
} catch (e) {
if (!job.cancelled && !job.completed && currentTtsJob === job) {
console.warn('TTS fetch failed', e);
const maxRetries = 3;
if (attempt + 1 < maxRetries) {
const delay = [750, 1500, 3000][Math.min(attempt, 2)];
const timer = setTimeout(() => fetchChunk(attempt + 1), delay);
job.timers.push(timer);
} else {
job.results[index] = TTS_CHUNK_ERROR;
setTtsChunkState(job, index, 'error');
tryStartPlayback(job);
}
}
} finally {
job.inflight = Math.max(0, job.inflight - 1);
}
})();
};
fetchChunk(0);
if (job.nextFetchIndex < job.groups.length) {
const t = setTimeout(scheduleNextFetch, 3000);
job.timers.push(t);
}
};
scheduleNextFetch();
scheduleMoreTtsFetches(job);
}

function completeTtsJob(job) {
if (!job || job.completed) return;
job.completed = true;
removeQueuedFetchesForJob(job);
for (const t of job.timers) clearTimeout(t);
job.timers.length = 0;
if (job.audio) {
Expand Down Expand Up @@ -1253,11 +1369,13 @@ function tryStartPlayback(job) {
if (typeof result === 'undefined') return; // not ready yet
if (result === TTS_CHUNK_ERROR) {
job.playIndex += 1;
scheduleMoreTtsFetches(job);
continue;
}
const url = result;
if (!url) {
job.playIndex += 1;
scheduleMoreTtsFetches(job);
continue;
}
const audio = new Audio(url);
Expand Down Expand Up @@ -1330,6 +1448,7 @@ function tryStartPlayback(job) {
job.activeIndex = null;
job.audio = null;
job.playIndex += 1;
scheduleMoreTtsFetches(job);
tryStartPlayback(job);
});
audio.addEventListener('error', () => {
Expand All @@ -1338,6 +1457,7 @@ function tryStartPlayback(job) {
job.activeIndex = null;
job.audio = null;
job.playIndex += 1; // skip broken chunk
scheduleMoreTtsFetches(job);
tryStartPlayback(job);
});
return;
Expand Down