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try simplified event buffer with duration calculation on the fly instead

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This commit is contained in:
Carl-Gerhard Lindesvärd
2026-03-14 11:39:19 +01:00
parent 9c3c1458bb
commit 7a76b968ba
9 changed files with 269 additions and 789 deletions
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302
packages/db/src/buffers/event-buffer.ts
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@@ -5,32 +5,9 @@ import {
publishEvent,
} from '@openpanel/redis';
import { ch } from '../clickhouse/client';
import {
type IClickhouseEvent,
type IServiceEvent,
transformEvent,
} from '../services/event.service';
import { type IClickhouseEvent } from '../services/event.service';
import { BaseBuffer } from './base-buffer';
/**
* Event Buffer
*
* 1. All events go into a single list buffer (event_buffer:queue)
* 2. screen_view events are handled specially:
* - Store current screen_view as "last" for the session
* - When a new screen_view arrives, flush the previous one with calculated duration
* 3. session_end events:
* - Retrieve the last screen_view (don't modify it)
* - Push both screen_view and session_end to buffer
* 4. Flush: Process all events from the list buffer
*/
interface PendingEvent {
event: IClickhouseEvent;
eventJson: string;
eventWithTimestamp?: string;
type: 'regular' | 'screen_view' | 'session_end';
}
export class EventBuffer extends BaseBuffer {
private batchSize = process.env.EVENT_BUFFER_BATCH_SIZE
? Number.parseInt(process.env.EVENT_BUFFER_BATCH_SIZE, 10)
@@ -46,7 +23,7 @@ export class EventBuffer extends BaseBuffer {
? Number.parseInt(process.env.EVENT_BUFFER_MICRO_BATCH_SIZE, 10)
: 100;
private pendingEvents: PendingEvent[] = [];
private pendingEvents: IClickhouseEvent[] = [];
private flushTimer: ReturnType<typeof setTimeout> | null = null;
private isFlushing = false;
/** Tracks consecutive flush failures for observability; reset on success. */
@@ -59,100 +36,6 @@ export class EventBuffer extends BaseBuffer {
private queueKey = 'event_buffer:queue';
protected bufferCounterKey = 'event_buffer:total_count';
private scriptShas: {
addScreenView?: string;
addSessionEnd?: string;
} = {};
private getLastScreenViewKeyBySession(sessionId: string) {
return `event_buffer:last_screen_view:session:${sessionId}`;
}
private getLastScreenViewKeyByProfile(projectId: string, profileId: string) {
return `event_buffer:last_screen_view:profile:${projectId}:${profileId}`;
}
/**
* Lua script for screen_view addition.
* Uses GETDEL for atomic get-and-delete to prevent race conditions.
*
* KEYS[1] = last screen_view key (by session)
* KEYS[2] = last screen_view key (by profile, may be empty)
* KEYS[3] = queue key
* KEYS[4] = buffer counter key
* ARGV[1] = new event with timestamp as JSON: {"event": {...}, "ts": 123456}
* ARGV[2] = TTL for last screen_view (1 hour)
*/
private readonly addScreenViewScript = `
local sessionKey = KEYS[1]
local profileKey = KEYS[2]
local queueKey = KEYS[3]
local counterKey = KEYS[4]
local newEventData = ARGV[1]
local ttl = tonumber(ARGV[2])
local previousEventData = redis.call("GETDEL", sessionKey)
redis.call("SET", sessionKey, newEventData, "EX", ttl)
if profileKey and profileKey ~= "" then
redis.call("SET", profileKey, newEventData, "EX", ttl)
end
if previousEventData then
local prev = cjson.decode(previousEventData)
local curr = cjson.decode(newEventData)
if prev.ts and curr.ts then
prev.event.duration = math.max(0, curr.ts - prev.ts)
end
redis.call("RPUSH", queueKey, cjson.encode(prev.event))
redis.call("INCR", counterKey)
return 1
end
return 0
`;
/**
* Lua script for session_end.
* Uses GETDEL to atomically retrieve and delete the last screen_view.
*
* KEYS[1] = last screen_view key (by session)
* KEYS[2] = last screen_view key (by profile, may be empty)
* KEYS[3] = queue key
* KEYS[4] = buffer counter key
* ARGV[1] = session_end event JSON
*/
private readonly addSessionEndScript = `
local sessionKey = KEYS[1]
local profileKey = KEYS[2]
local queueKey = KEYS[3]
local counterKey = KEYS[4]
local sessionEndJson = ARGV[1]
local previousEventData = redis.call("GETDEL", sessionKey)
local added = 0
if previousEventData then
local prev = cjson.decode(previousEventData)
redis.call("RPUSH", queueKey, cjson.encode(prev.event))
redis.call("INCR", counterKey)
added = added + 1
end
redis.call("RPUSH", queueKey, sessionEndJson)
redis.call("INCR", counterKey)
added = added + 1
if profileKey and profileKey ~= "" then
redis.call("DEL", profileKey)
end
return added
`;
constructor() {
super({
name: 'event',
@@ -160,27 +43,6 @@ return added
await this.processBuffer();
},
});
this.loadScripts();
}
private async loadScripts() {
try {
const redis = getRedisCache();
const [screenViewSha, sessionEndSha] = await Promise.all([
redis.script('LOAD', this.addScreenViewScript),
redis.script('LOAD', this.addSessionEndScript),
]);
this.scriptShas.addScreenView = screenViewSha as string;
this.scriptShas.addSessionEnd = sessionEndSha as string;
this.logger.info('Loaded Lua scripts into Redis', {
addScreenView: this.scriptShas.addScreenView,
addSessionEnd: this.scriptShas.addSessionEnd,
});
} catch (error) {
this.logger.error('Failed to load Lua scripts', { error });
}
}
bulkAdd(events: IClickhouseEvent[]) {
@@ -190,30 +52,7 @@ return added
}
add(event: IClickhouseEvent) {
const eventJson = JSON.stringify(event);
let type: PendingEvent['type'] = 'regular';
let eventWithTimestamp: string | undefined;
if (event.session_id && event.name === 'screen_view') {
type = 'screen_view';
const timestamp = new Date(event.created_at || Date.now()).getTime();
eventWithTimestamp = JSON.stringify({
event: event,
ts: timestamp,
});
} else if (event.session_id && event.name === 'session_end') {
type = 'session_end';
}
const pendingEvent: PendingEvent = {
event,
eventJson,
eventWithTimestamp,
type,
};
this.pendingEvents.push(pendingEvent);
this.pendingEvents.push(event);
if (this.pendingEvents.length >= this.microBatchMaxSize) {
this.flushLocalBuffer();
@@ -228,57 +67,6 @@ return added
}
}
private addToMulti(multi: ReturnType<Redis['multi']>, pending: PendingEvent) {
const { event, eventJson, eventWithTimestamp, type } = pending;
if (type === 'screen_view' && event.session_id) {
const sessionKey = this.getLastScreenViewKeyBySession(event.session_id);
const profileKey = event.profile_id
? this.getLastScreenViewKeyByProfile(event.project_id, event.profile_id)
: '';
this.evalScript(
multi,
'addScreenView',
this.addScreenViewScript,
4,
sessionKey,
profileKey,
this.queueKey,
this.bufferCounterKey,
eventWithTimestamp!,
'3600',
);
} else if (type === 'session_end' && event.session_id) {
const sessionKey = this.getLastScreenViewKeyBySession(event.session_id);
const profileKey = event.profile_id
? this.getLastScreenViewKeyByProfile(event.project_id, event.profile_id)
: '';
this.evalScript(
multi,
'addSessionEnd',
this.addSessionEndScript,
4,
sessionKey,
profileKey,
this.queueKey,
this.bufferCounterKey,
eventJson,
);
} else {
multi.rpush(this.queueKey, eventJson).incr(this.bufferCounterKey);
}
if (event.profile_id) {
this.incrementActiveVisitorCount(
multi,
event.project_id,
event.profile_id,
);
}
}
public async flush() {
if (this.flushTimer) {
clearTimeout(this.flushTimer);
@@ -301,9 +89,17 @@ return added
const redis = getRedisCache();
const multi = redis.multi();
for (const pending of eventsToFlush) {
this.addToMulti(multi, pending);
for (const event of eventsToFlush) {
multi.rpush(this.queueKey, JSON.stringify(event));
if (event.profile_id) {
this.incrementActiveVisitorCount(
multi,
event.project_id,
event.profile_id,
);
}
}
multi.incrby(this.bufferCounterKey, eventsToFlush.length);
await multi.exec();
@@ -314,11 +110,14 @@ return added
this.pendingEvents = eventsToFlush.concat(this.pendingEvents);
this.flushRetryCount += 1;
this.logger.warn('Failed to flush local buffer to Redis; events re-queued', {
error,
eventCount: eventsToFlush.length,
flushRetryCount: this.flushRetryCount,
});
this.logger.warn(
'Failed to flush local buffer to Redis; events re-queued',
{
error,
eventCount: eventsToFlush.length,
flushRetryCount: this.flushRetryCount,
},
);
} finally {
this.isFlushing = false;
// Events may have accumulated while we were flushing; schedule another flush if needed
@@ -331,24 +130,6 @@ return added
}
}
private evalScript(
multi: ReturnType<Redis['multi']>,
scriptName: keyof typeof this.scriptShas,
scriptContent: string,
numKeys: number,
...args: (string | number)[]
) {
const sha = this.scriptShas[scriptName];
if (sha) {
multi.evalsha(sha, numKeys, ...args);
} else {
multi.eval(scriptContent, numKeys, ...args);
this.logger.warn(`Script ${scriptName} not loaded, using EVAL fallback`);
this.loadScripts();
}
}
async processBuffer() {
const redis = getRedisCache();
@@ -398,7 +179,10 @@ return added
const countByProject = new Map<string, number>();
for (const event of eventsToClickhouse) {
countByProject.set(event.project_id, (countByProject.get(event.project_id) ?? 0) + 1);
countByProject.set(
event.project_id,
(countByProject.get(event.project_id) ?? 0) + 1,
);
}
for (const [projectId, count] of countByProject) {
publishEvent('events', 'batch', { projectId, count });
@@ -419,42 +203,6 @@ return added
}
}
public async getLastScreenView(
params:
| {
sessionId: string;
}
| {
projectId: string;
profileId: string;
},
): Promise<IServiceEvent | null> {
const redis = getRedisCache();
let lastScreenViewKey: string;
if ('sessionId' in params) {
lastScreenViewKey = this.getLastScreenViewKeyBySession(params.sessionId);
} else {
lastScreenViewKey = this.getLastScreenViewKeyByProfile(
params.projectId,
params.profileId,
);
}
const eventDataStr = await redis.get(lastScreenViewKey);
if (eventDataStr) {
const eventData = getSafeJson<{ event: IClickhouseEvent; ts: number }>(
eventDataStr,
);
if (eventData?.event) {
return transformEvent(eventData.event);
}
}
return null;
}
public async getBufferSize() {
return this.getBufferSizeWithCounter(async () => {
const redis = getRedisCache();