From 7269f69aa7b4fd74906f13f03b3d92131872eac0 Mon Sep 17 00:00:00 2001
From: SotaSato-stst <sota.sato@plaid.co.jp>
Date: Mon, 19 Aug 2024 00:57:38 +0900
Subject: [PATCH] Add support for LATENCY HISTOGRAM

---
 packages/client/lib/client/commands.ts        |  3 ++
 .../lib/commands/LATENCY_HISTOGRAM.spec.ts    | 28 +++++++++++++++
 .../client/lib/commands/LATENCY_HISTOGRAM.ts  | 34 +++++++++++++++++++
 3 files changed, 65 insertions(+)
 create mode 100644 packages/client/lib/commands/LATENCY_HISTOGRAM.spec.ts
 create mode 100644 packages/client/lib/commands/LATENCY_HISTOGRAM.ts

diff --git a/packages/client/lib/client/commands.ts b/packages/client/lib/client/commands.ts
index 76ae5d73735..6ee0b0be775 100644
--- a/packages/client/lib/client/commands.ts
+++ b/packages/client/lib/client/commands.ts
@@ -86,6 +86,7 @@ import * as KEYS from '../commands/KEYS';
 import * as LASTSAVE from '../commands/LASTSAVE';
 import * as LATENCY_DOCTOR from '../commands/LATENCY_DOCTOR';
 import * as LATENCY_GRAPH from '../commands/LATENCY_GRAPH';
+import * as LATENCY_HISTOGRAM from '../commands/LATENCY_HISTOGRAM';
 import * as LATENCY_HISTORY from '../commands/LATENCY_HISTORY';
 import * as LATENCY_LATEST from '../commands/LATENCY_LATEST';
 import * as LOLWUT from '../commands/LOLWUT';
@@ -299,6 +300,8 @@ export default {
     latencyDoctor: LATENCY_DOCTOR,
     LATENCY_GRAPH,
     latencyGraph: LATENCY_GRAPH,
+    LATENCY_HISTOGRAM,
+    latencyHistogram: LATENCY_HISTOGRAM,
     LATENCY_HISTORY,
     latencyHistory: LATENCY_HISTORY,
     LATENCY_LATEST,
diff --git a/packages/client/lib/commands/LATENCY_HISTOGRAM.spec.ts b/packages/client/lib/commands/LATENCY_HISTOGRAM.spec.ts
new file mode 100644
index 00000000000..9c66f581fb7
--- /dev/null
+++ b/packages/client/lib/commands/LATENCY_HISTOGRAM.spec.ts
@@ -0,0 +1,28 @@
+import {strict as assert} from 'assert';
+import testUtils, {GLOBAL} from '../test-utils';
+import { transformArguments } from './LATENCY_HISTOGRAM';
+
+describe('LATENCY HISTOGRAM', () => {
+    it('transformArguments', () => {
+        assert.deepEqual(
+            transformArguments('command'),
+            ['LATENCY', 'HISTOGRAM', 'command']
+        );
+    });
+
+    testUtils.testWithClient('client.latencyHistory', async client => {
+        await Promise.all([
+            client.set('sample-key', 'sample-value'),
+            client.get('sample-key')
+        ]);
+
+        const commandNames = ['set', 'get'];
+        const latencyHistograms = await client.latencyHistogram(...commandNames);
+
+        for (const commandName of commandNames) {
+            const commandInfo = latencyHistograms[commandName];
+            assert.ok(Number.isInteger(commandInfo['calls']));
+            assert.ok(Array.isArray(commandInfo['histogram_usec']));
+        }
+    }, GLOBAL.SERVERS.OPEN);
+});
diff --git a/packages/client/lib/commands/LATENCY_HISTOGRAM.ts b/packages/client/lib/commands/LATENCY_HISTOGRAM.ts
new file mode 100644
index 00000000000..446fb867ff4
--- /dev/null
+++ b/packages/client/lib/commands/LATENCY_HISTOGRAM.ts
@@ -0,0 +1,34 @@
+import { RedisCommandArgument, RedisCommandArguments } from '.';
+
+export type LatencyHistogram = Record<string, {
+    calls: number;
+    histogram_usec: HistogramData;
+}>;
+
+export type HistogramData = number[];
+
+export type CommandInfo = [
+    string,
+    number,
+    string,
+    HistogramData
+]
+
+export type RawReply = (string | CommandInfo)[];
+
+export function transformArguments(...commands: RedisCommandArgument[]): RedisCommandArguments {
+    return ['LATENCY', 'HISTOGRAM', ...commands];
+}
+
+export  function transformReply(rawReply: RawReply): LatencyHistogram {
+    const result: LatencyHistogram = {};
+    
+    for (let i = 0; i < rawReply.length; i += 2) {
+        const [command, [_, calls, __, histogram]] = [rawReply[i] as string, rawReply[i + 1] as CommandInfo];
+        result[command] = {
+            calls,
+            histogram_usec: histogram
+        };
+    }
+    return result;
+};