perf(ssh): reuse streamed response idle timers (#18956)

src/main/ssh/ssh-git-stream-idle-timer.test.ts

@@ -0,0 +1,80 @@
+import { expect, it, vi } from 'vitest'
+import type { SshChannelMultiplexer } from './ssh-channel-multiplexer'
+import { requestGitStreamable } from './ssh-git-response-stream-reader'
+
+it.each(['end', 'abort', 'timeout'] as const)(
+  'reuses the idle deadline across 1000 chunks and cleans up on %s',
+  async (finish) => {
+    vi.useFakeTimers()
+    const setTimer = vi.spyOn(globalThis, 'setTimeout')
+    try {
+      const listeners = new Map<string, (params: Record<string, unknown>) => void>()
+      const controller = new AbortController()
+      const content = 'x'.repeat(998)
+      const encoded = Buffer.from(JSON.stringify(content))
+      const notify = vi.fn()
+      const mux = {
+        request: vi.fn(async () => ({
+          __orcaGitResponseStream: { streamId: 7, totalBytes: encoded.length, chunkCount: 1000 }
+        })),
+        isDisposed: () => false,
+        notify,
+        onDispose: () => () => {},
+        onNotificationByMethod: (
+          method: string,
+          callback: (params: Record<string, unknown>) => void
+        ) => {
+          listeners.set(method, callback)
+          return () => listeners.delete(method)
+        }
+      }
+      const promise = requestGitStreamable(
+        mux as unknown as SshChannelMultiplexer,
+        'git.diff',
+        {},
+        {
+          signal: controller.signal
+        }
+      )
+      const outcome = promise.then(
+        (value) => ({ value }),
+        (error: Error) => ({ error: error.message })
+      )
+      await vi.advanceTimersByTimeAsync(15_000)
+      for (let seq = 0; seq < encoded.length; seq++) {
+        listeners.get('git.responseChunk')!({
+          streamId: 7,
+          seq,
+          data: encoded.subarray(seq, seq + 1).toString('base64')
+        })
+      }
+      await vi.advanceTimersByTimeAsync(29_999)
+      expect(listeners.size).toBe(3)
+      expect(notify.mock.calls.filter(([method]) => method === 'git.responseAck')).toHaveLength(
+        1000
+      )
+      const allocations = setTimer.mock.calls.filter(([, delay]) => delay === 30_000).length
+      if (finish === 'end') {
+        listeners.get('git.responseEnd')!({ streamId: 7 })
+        expect(await outcome).toEqual({ value: content })
+      } else if (finish === 'abort') {
+        controller.abort()
+        expect(await outcome).toEqual({ error: 'Request was cancelled' })
+      } else {
+        await vi.advanceTimersByTimeAsync(1)
+        expect(await outcome).toEqual({
+          error: 'Git response stream stalled (>30000ms without data)'
+        })
+      }
+      expect(allocations).toBe(1)
+      expect(vi.getTimerCount()).toBe(0)
+      expect(listeners.size).toBe(0)
+      expect(
+        notify.mock.calls.filter(([method]) => method === 'git.cancelResponseStream')
+      ).toHaveLength(finish === 'end' ? 0 : 1)
+    } finally {
+      setTimer.mockRestore()
+      vi.useRealTimers()
+    }
+  }
+)