Add latency histogram

packages/client/lib/commands/LATENCY_HISTOGRAM.spec.ts

@@ -0,0 +1,44 @@
+import { strict as assert } from 'assert';
+import testUtils, { GLOBAL } from '../test-utils';
+import LATENCY_HISTOGRAM from './LATENCY_HISTOGRAM';
+import { parseArgs } from './generic-transformers';
+
+describe('LATENCY HISTOGRAM', () => {
+  describe('transformArguments', () => {
+    it('filtered by command set', () => {
+      assert.deepStrictEqual(
+        parseArgs(LATENCY_HISTOGRAM, 'set'),
+        ['LATENCY', 'HISTOGRAM', 'set'],
+      );
+    });
+
+    it('unfiltered', () => {
+      assert.deepStrictEqual(
+        parseArgs(LATENCY_HISTOGRAM),
+        ['LATENCY', 'HISTOGRAM'],
+      );
+    });
+  });
+
+  testUtils.testWithClient('unfiltered list', async client => {
+    await client.configResetStat();
+    await Promise.all([
+      client.lPush('push-key', 'hello '),
+      client.set('set-key', 'world!'),
+    ]);
+    const histogram = await client.latencyHistogram();
+    const commands = ['config|resetstat', 'set', 'lpush'];
+    for (const command of commands) {
+      assert.ok(typeof histogram[command]['calls'], 'number');
+      assert.ok(Array.isArray(histogram[command]['histogram_usec']));
+    }
+  }, GLOBAL.SERVERS.OPEN);
+
+  testUtils.testWithClient('filtered by a command list', async client => {
+    await client.configSet('latency-monitor-threshold', '100');
+    await client.set('set-key', 'hello');
+    const histogram = await client.latencyHistogram('set');
+    assert.ok(typeof histogram.set['calls'], 'number');
+    assert.ok(Array.isArray(histogram.set['histogram_usec']));
+  }, GLOBAL.SERVERS.OPEN);
+});

packages/client/lib/commands/LATENCY_HISTOGRAM.ts

@@ -0,0 +1,40 @@
+import { CommandParser } from '../client/parser';
+import { Command } from '../RESP/types';
+
+type RawHistogram = [string, number, string, number[]];
+
+type Histogram = Record<string, {
+  calls: number;
+  histogram_usec: number[];
+}>;
+
+export default {
+  CACHEABLE: false,
+  IS_READ_ONLY: true,
+  /**
+   * Constructs the LATENCY HISTOGRAM command
+   * 
+   * @param parser - The command parser
+   * @param commands - The list of redis commands to get histogram for
+   * @see https://redis.io/docs/latest/commands/latency-histogram/
+   */
+  parseCommand(parser: CommandParser, ...commands: string[]) {
+    const args = ['LATENCY', 'HISTOGRAM'];
+    if (commands.length !== 0) {
+      args.push(...commands);
+    }
+    parser.push(...args);
+  },
+  transformReply(reply: (string | RawHistogram)[]): Histogram {
+    const result: Histogram = {};
+    if (reply.length === 0) return result;
+    for (let i = 1; i < reply.length; i += 2) {
+      const histogram = reply[i] as RawHistogram;
+      result[reply[i - 1] as string] = {
+        calls: histogram[1],
+        histogram_usec: histogram[3],
+      };
+    }
+    return result;
+  }
+} as const satisfies Command;

packages/client/lib/commands/index.ts

@@ -361,6 +361,7 @@ import VREM from './VREM';
 import VSETATTR from './VSETATTR';
 import VSIM from './VSIM';
 import VSIM_WITHSCORES from './VSIM_WITHSCORES';
+import LATENCY_HISTOGRAM from './LATENCY_HISTOGRAM';
 
 export {
   CLIENT_KILL_FILTERS,
@@ -715,6 +716,8 @@ export default {
   latencyGraph: LATENCY_GRAPH,
   LATENCY_HISTORY,
   latencyHistory: LATENCY_HISTORY,
+  LATENCY_HISTOGRAM,
+  latencyHistogram: LATENCY_HISTOGRAM,
   LATENCY_LATEST,
   latencyLatest: LATENCY_LATEST,
   LATENCY_RESET,