Files
ECC/scripts/lib/session-cost-snapshot.js
T
wellkilo 76329557c4 test(metrics): derive oversized fixture from scan cap
Export the internal scan budget for regression tests and size the oversized-line fixture as exactly two bounded passes.
2026-09-13 05:14:26 +08:00

514 lines
17 KiB
JavaScript

'use strict';
const crypto = require('crypto');
const fs = require('fs');
const os = require('os');
const path = require('path');
const { writeFileAtomic } = require('./atomic-write');
const { sanitizeSessionId } = require('./session-bridge');
const COST_SNAPSHOT_SCHEMA_VERSION = 'ecc.cost-snapshot.v1';
const COST_SNAPSHOT_DIRECTORY = 'cost-snapshots';
const COST_LOG_FILENAME = 'costs.jsonl';
const READ_CHUNK_BYTES = 64 * 1024;
const MAX_JSONL_LINE_BYTES = 1024 * 1024;
const MAX_SCAN_BYTES = 16 * 1024 * 1024;
const FINGERPRINT_WINDOW_BYTES = 256;
const PRUNE_INTERVAL_MS = 24 * 60 * 60 * 1000;
const SNAPSHOT_MAX_AGE_MS = 30 * 24 * 60 * 60 * 1000;
const MAX_SNAPSHOTS = 512;
const WARNING_CACHE_PREFIX = 'ecc-cost-snapshot-warnings-';
function assertSafeSessionId(sessionId) {
if (sanitizeSessionId(sessionId) !== sessionId) {
throw new Error('Cost snapshot requires a safe session ID');
}
}
function getSnapshotDirectory(metricsDir) {
return path.join(metricsDir, COST_SNAPSHOT_DIRECTORY);
}
function getCostSnapshotPath(metricsDir, sessionId) {
assertSafeSessionId(sessionId);
return path.join(getSnapshotDirectory(metricsDir), `session-${sessionId}.json`);
}
function isValidCostRow(row, sessionId) {
return row?.session_id === sessionId
&& typeof row.estimated_cost_usd === 'number'
&& Number.isFinite(row.estimated_cost_usd)
&& row.estimated_cost_usd >= 0
&& typeof row.input_tokens === 'number'
&& Number.isFinite(row.input_tokens)
&& row.input_tokens >= 0
&& typeof row.output_tokens === 'number'
&& Number.isFinite(row.output_tokens)
&& row.output_tokens >= 0;
}
function readJsonFile(filePath) {
try {
return JSON.parse(fs.readFileSync(filePath, 'utf8'));
} catch {
return null;
}
}
function chooseNewerCumulativeRow(currentRow, nextRow) {
if (!currentRow) return nextRow;
const nextDominates = nextRow.input_tokens >= currentRow.input_tokens
&& nextRow.output_tokens >= currentRow.output_tokens
&& nextRow.estimated_cost_usd >= currentRow.estimated_cost_usd;
const currentDominates = currentRow.input_tokens >= nextRow.input_tokens
&& currentRow.output_tokens >= nextRow.output_tokens
&& currentRow.estimated_cost_usd >= nextRow.estimated_cost_usd;
if (nextDominates && !currentDominates) return nextRow;
if (currentDominates && !nextDominates) return currentRow;
const nextTimestamp = Date.parse(nextRow.timestamp);
const currentTimestamp = Date.parse(currentRow.timestamp);
if (Number.isFinite(nextTimestamp) && Number.isFinite(currentTimestamp)) {
return nextTimestamp >= currentTimestamp ? nextRow : currentRow;
}
return nextRow;
}
function sourceIdentity(stat) {
return `${stat.dev}:${stat.ino}`;
}
function hashWindow(descriptor, position, length) {
const buffer = Buffer.alloc(length);
if (length > 0) fs.readSync(descriptor, buffer, 0, length, position);
return crypto.createHash('sha256').update(buffer).digest('hex');
}
function fingerprintProcessedPrefix(descriptor, offset) {
const windowLength = Math.min(FINGERPRINT_WINDOW_BYTES, offset);
const middleStart = Math.max(0, Math.floor((offset - windowLength) / 2));
return {
start: hashWindow(descriptor, 0, windowLength),
middle: hashWindow(descriptor, middleStart, windowLength),
end: hashWindow(descriptor, offset - windowLength, windowLength)
};
}
function fingerprintsMatch(left, right) {
return left?.start === right?.start
&& left?.middle === right?.middle
&& left?.end === right?.end;
}
function validSnapshotBase(snapshot, descriptor, stat, sessionId) {
if (snapshot?.schema_version !== COST_SNAPSHOT_SCHEMA_VERSION) return null;
if (snapshot.row !== null && !isValidCostRow(snapshot.row, sessionId)) return null;
const source = snapshot.source;
if (source?.identity !== sourceIdentity(stat)) return null;
if (!Number.isSafeInteger(source.offset_bytes) || source.offset_bytes < 0) return null;
if (source.offset_bytes > stat.size) return null;
if (source.offset_bytes === stat.size && source.mtime_ms !== stat.mtimeMs) return null;
if (!fingerprintsMatch(
source.fingerprint,
fingerprintProcessedPrefix(descriptor, source.offset_bytes)
)) return null;
return {
row: snapshot.row,
offset: source.offset_bytes,
discardingLine: source.discarding_line === true
};
}
function createScanState(initialRow) {
return {
latestRow: initialRow,
committedRow: initialRow,
malformed: 0,
invalid: 0,
malformedHasher: crypto.createHash('sha256'),
invalidHasher: crypto.createHash('sha256')
};
}
function processCostLine(state, line, sessionId, committed = true) {
if (!line.trim()) return state;
try {
const row = JSON.parse(line);
if (row.session_id !== sessionId) return state;
if (!isValidCostRow(row, sessionId)) {
if (!committed) return state;
return {
...state,
invalid: state.invalid + 1,
invalidHasher: state.invalidHasher.copy().update(line).update('\0')
};
}
return {
...state,
latestRow: chooseNewerCumulativeRow(state.latestRow, row),
committedRow: committed
? chooseNewerCumulativeRow(state.committedRow, row)
: state.committedRow
};
} catch {
if (!committed) return state;
return {
...state,
malformed: state.malformed + 1,
malformedHasher: state.malformedHasher.copy().update(line).update('\0')
};
}
}
function markOversizedLine(state, pendingChunks, segment) {
const hasher = state.malformedHasher.copy();
for (const chunk of pendingChunks) hasher.update(chunk);
const remaining = Math.max(0, MAX_JSONL_LINE_BYTES - pendingChunks.reduce(
(total, chunk) => total + chunk.length,
0
));
hasher.update(segment.subarray(0, remaining)).update('\0<oversized>');
return { ...state, malformed: state.malformed + 1, malformedHasher: hasher };
}
function consumeLineSegment(scan, segment, terminated, sessionId) {
if (scan.discardingLine) {
return { ...scan, discardingLine: !terminated };
}
if (scan.pendingBytes + segment.length > MAX_JSONL_LINE_BYTES) {
return {
state: markOversizedLine(scan.state, scan.pendingChunks, segment),
pendingChunks: [],
pendingBytes: 0,
discardingLine: !terminated
};
}
const pendingChunks = segment.length > 0
? [...scan.pendingChunks, Buffer.from(segment)]
: scan.pendingChunks;
const pendingBytes = scan.pendingBytes + segment.length;
if (!terminated) return { ...scan, pendingChunks, pendingBytes };
const line = Buffer.concat(pendingChunks, pendingBytes).toString('utf8');
return {
state: processCostLine(scan.state, line, sessionId),
pendingChunks: [],
pendingBytes: 0,
discardingLine: false
};
}
function consumeJsonlChunk(scan, chunk, sessionId, absoluteStart, processedOffset) {
let nextScan = scan;
let nextOffset = processedOffset;
let segmentStart = 0;
for (;;) {
const newlineIndex = chunk.indexOf(0x0a, segmentStart);
if (newlineIndex < 0) break;
nextScan = consumeLineSegment(
nextScan, chunk.subarray(segmentStart, newlineIndex), true, sessionId
);
nextOffset = absoluteStart + newlineIndex + 1;
segmentStart = newlineIndex + 1;
}
nextScan = consumeLineSegment(
nextScan, chunk.subarray(segmentStart), false, sessionId
);
if (nextScan.discardingLine) nextOffset = absoluteStart + chunk.length;
return { scan: nextScan, processedOffset: nextOffset };
}
function scanJsonlRange(descriptor, start, end, sessionId, initialRow, initialDiscard = false) {
const buffer = Buffer.allocUnsafe(READ_CHUNK_BYTES);
let lineScan = {
state: createScanState(initialRow),
pendingChunks: [],
pendingBytes: 0,
discardingLine: initialDiscard
};
let position = start;
let processedOffset = start;
while (position < end) {
const bytesRead = fs.readSync(
descriptor,
buffer,
0,
Math.min(buffer.length, end - position),
position
);
if (bytesRead === 0) break;
const consumed = consumeJsonlChunk(
lineScan, buffer.subarray(0, bytesRead), sessionId, position, processedOffset
);
lineScan = consumed.scan;
processedOffset = consumed.processedOffset;
position += bytesRead;
}
if (lineScan.pendingBytes > 0) {
const line = Buffer.concat(lineScan.pendingChunks, lineScan.pendingBytes).toString('utf8');
lineScan = {
...lineScan,
state: processCostLine(lineScan.state, line, sessionId, false)
};
}
const { state } = lineScan;
return {
row: state.latestRow,
committedRow: state.committedRow,
processedOffset,
malformed: state.malformed,
invalid: state.invalid,
malformedSignature: state.malformed > 0
? state.malformedHasher.digest('hex').slice(0, 16)
: null,
invalidSignature: state.invalid > 0
? state.invalidHasher.digest('hex').slice(0, 16)
: null,
discardingLine: lineScan.discardingLine
};
}
function writeSnapshotAtOffset(
metricsDir, sessionId, row, descriptor, stat, offset, discardingLine = false
) {
if (row !== null && !isValidCostRow(row, sessionId)) return false;
const snapshot = {
schema_version: COST_SNAPSHOT_SCHEMA_VERSION,
source: {
identity: sourceIdentity(stat),
offset_bytes: offset,
mtime_ms: stat.mtimeMs,
discarding_line: discardingLine,
fingerprint: fingerprintProcessedPrefix(descriptor, offset)
},
row
};
writeFileAtomic(
getCostSnapshotPath(metricsDir, sessionId),
JSON.stringify(snapshot),
{
beforeRename() {
const current = fs.fstatSync(descriptor);
if (current.size < offset) {
throw new Error('Cost log was truncated during snapshot publication');
}
if (current.size === offset && current.mtimeMs !== snapshot.source.mtime_ms) {
throw new Error('Cost log changed during snapshot publication');
}
if (!fingerprintsMatch(
fingerprintProcessedPrefix(descriptor, offset),
snapshot.source.fingerprint
)) {
throw new Error('Cost log prefix changed during snapshot publication');
}
}
}
);
return true;
}
function emptySnapshotResult(row) {
return {
row,
scannedBytes: 0,
malformed: 0,
invalid: 0,
malformedSignature: null,
invalidSignature: null,
snapshotError: null
};
}
function publishScanSnapshot(metricsDir, sessionId, scan, descriptor, stat) {
if (!scan.committedRow && scan.processedOffset === 0) return null;
try {
writeSnapshotAtOffset(
metricsDir,
sessionId,
scan.committedRow,
descriptor,
stat,
scan.processedOffset,
scan.discardingLine
);
return null;
} catch (error) {
return error;
}
}
function refreshSessionCostSnapshot(metricsDir, sessionId) {
assertSafeSessionId(sessionId);
const costsPath = path.join(metricsDir, COST_LOG_FILENAME);
const descriptor = fs.openSync(costsPath, 'r');
try {
const stat = fs.fstatSync(descriptor);
const snapshot = readJsonFile(getCostSnapshotPath(metricsDir, sessionId));
const base = validSnapshotBase(snapshot, descriptor, stat, sessionId);
if (base?.offset === stat.size) return emptySnapshotResult(base.row);
const scanEnd = Math.min(stat.size, (base?.offset || 0) + MAX_SCAN_BYTES);
const scan = scanJsonlRange(
descriptor,
base?.offset || 0,
scanEnd,
sessionId,
base?.row || null,
base?.discardingLine || false
);
const snapshotError = publishScanSnapshot(
metricsDir, sessionId, scan, descriptor, stat
);
return {
row: scan.row,
scannedBytes: scan.processedOffset - (base?.offset || 0),
malformed: scan.malformed,
invalid: scan.invalid,
malformedSignature: scan.malformedSignature,
invalidSignature: scan.invalidSignature,
snapshotError
};
} finally {
fs.closeSync(descriptor);
}
}
function costLogNeedsSeparator(metricsDir) {
const costsPath = path.join(metricsDir, COST_LOG_FILENAME);
let descriptor;
try {
descriptor = fs.openSync(costsPath, 'r');
const stat = fs.fstatSync(descriptor);
if (stat.size === 0) return false;
const lastByte = Buffer.alloc(1);
return fs.readSync(descriptor, lastByte, 0, 1, stat.size - 1) === 1
&& lastByte[0] !== 0x0a;
} catch (error) {
if (error.code === 'ENOENT') return false;
throw error;
} finally {
if (descriptor !== undefined) fs.closeSync(descriptor);
}
}
function appendSessionCostRow(metricsDir, sessionId, row) {
assertSafeSessionId(sessionId);
if (!isValidCostRow(row, sessionId)) {
throw new Error('Cost snapshot requires valid non-negative numeric totals for its session');
}
const prefix = costLogNeedsSeparator(metricsDir) ? '\n' : '';
fs.appendFileSync(
path.join(metricsDir, COST_LOG_FILENAME),
`${prefix}${JSON.stringify(row)}\n`,
'utf8'
);
const result = refreshSessionCostSnapshot(metricsDir, sessionId);
if (result.snapshotError) throw result.snapshotError;
try {
maybePruneSessionCostSnapshots(metricsDir);
} catch (error) {
// Retention is opportunistic and retried by a later update, but a
// persistent failure remains visible without rolling back the log append.
warnSessionCostSnapshotFailure('retention', metricsDir, sessionId, error);
}
return JSON.stringify(result.row) === JSON.stringify(row);
}
function readSessionCostSnapshot(metricsDir, sessionId) {
try {
return refreshSessionCostSnapshot(metricsDir, sessionId);
} catch (error) {
if (error.code === 'ENOENT') {
return { row: null, scannedBytes: 0, malformed: 0, invalid: 0, snapshotError: null };
}
throw error;
}
}
function maybePruneSessionCostSnapshots(metricsDir, options = {}) {
const snapshotDir = getSnapshotDirectory(metricsDir);
const now = Number.isFinite(options.now) ? options.now : Date.now();
const maxAgeMs = Number.isFinite(options.maxAgeMs) ? options.maxAgeMs : SNAPSHOT_MAX_AGE_MS;
const maxSnapshots = Number.isSafeInteger(options.maxSnapshots)
? Math.max(0, options.maxSnapshots)
: MAX_SNAPSHOTS;
const markerPath = path.join(snapshotDir, '.last-prune');
fs.mkdirSync(snapshotDir, { recursive: true });
const snapshotEntries = fs.readdirSync(snapshotDir, { withFileTypes: true })
.filter(entry => entry.isFile() && /^session-.+\.json$/.test(entry.name));
if (!options.force) {
try {
const intervalIsFresh = now - fs.statSync(markerPath).mtimeMs < PRUNE_INTERVAL_MS;
if (intervalIsFresh && snapshotEntries.length <= maxSnapshots) return 0;
} catch (error) {
if (error.code !== 'ENOENT') throw error;
}
}
const snapshots = snapshotEntries
.map(entry => {
const filePath = path.join(snapshotDir, entry.name);
return { filePath, mtimeMs: fs.statSync(filePath).mtimeMs };
})
.sort((left, right) => right.mtimeMs - left.mtimeMs);
const removals = snapshots.filter((entry, index) => (
index >= maxSnapshots || now - entry.mtimeMs > maxAgeMs
));
let removed = 0;
for (const entry of removals) {
try {
if (fs.statSync(entry.filePath).mtimeMs <= entry.mtimeMs) {
fs.rmSync(entry.filePath, { force: true });
removed += 1;
}
} catch (error) {
if (error.code !== 'ENOENT') throw error;
}
}
fs.writeFileSync(markerPath, String(now), { encoding: 'utf8', mode: 0o600 });
return removed;
}
function warningClaimPath(kind, metricsDir, sessionId, signature) {
const key = crypto.createHash('sha256')
.update(`${path.resolve(metricsDir)}\0${sessionId}\0${kind}\0${signature}`)
.digest('hex')
.slice(0, 16);
return path.join(os.tmpdir(), `${WARNING_CACHE_PREFIX}${key}.claim`);
}
function warnSessionCostSnapshotFailure(kind, metricsDir, sessionId, error) {
const targetPath = getCostSnapshotPath(metricsDir, sessionId);
const errorCode = error?.code || error?.name || 'error';
const signature = `${kind}:${targetPath}:${errorCode}`;
const claimPath = warningClaimPath(kind, metricsDir, sessionId, signature);
let claimDescriptor;
try {
claimDescriptor = fs.openSync(claimPath, 'wx', 0o600);
fs.closeSync(claimDescriptor);
claimDescriptor = undefined;
} catch (claimError) {
if (claimDescriptor !== undefined) fs.closeSync(claimDescriptor);
if (claimError.code === 'EEXIST') return;
// Warning persistence is best effort. If the claim cannot be created,
// still surface the underlying snapshot failure.
}
process.stderr.write(
`[cost-snapshot] ${kind} failed for session ${sessionId}: ${error?.message || String(error)}\n`
);
}
module.exports = {
COST_SNAPSHOT_SCHEMA_VERSION,
COST_SNAPSHOT_DIRECTORY,
COST_LOG_FILENAME,
MAX_SCAN_BYTES,
getCostSnapshotPath,
isValidCostRow,
chooseNewerCumulativeRow,
appendSessionCostRow,
readSessionCostSnapshot,
refreshSessionCostSnapshot,
costLogNeedsSeparator,
maybePruneSessionCostSnapshots,
warnSessionCostSnapshotFailure
};