perf(shared-state): skip unchanged mutation notifications (#362)

Author: onmax

docs/content/1.guide/4.shared-state.md

@@ -72,7 +72,7 @@ state.mutate((draft) => {
 })
 ```
 
-Devframe applies the recipe to a draft, emits `updated` (with `SharedStatePatch[]` if enabled), and broadcasts to RPC clients; a `syncIds` set keeps mutations idempotent on replay.
+Devframe applies the recipe to a draft. When Immer returns a new state reference, Devframe emits `updated` and broadcasts it to RPC clients. Explicit replacement objects also notify. With patches enabled, `updated` carries `SharedStatePatch[]`. Sync IDs remain recorded for unchanged recipes, so replays stay idempotent.
 
 ## Patches (advanced)
 

packages/devframe/src/client/rpc-shared-state.test.ts

@@ -20,6 +20,22 @@ function makeFakeRpc() {
 }
 
 describe('client shared state', () => {
+  it('does not forward unchanged writes to the RPC server', async () => {
+    const { rpc, events, setCalls } = makeFakeRpc()
+    const state = await createRpcSharedStateClientHost(rpc).get('k', { initialValue: { count: 1 } })
+    events.emit('rpc:is-trusted:updated', true)
+
+    state.mutate((draft) => {
+      draft.count = 1
+    })
+    expect(setCalls).toHaveLength(0)
+    state.mutate((draft) => {
+      draft.count = 2
+    })
+    expect(setCalls).toHaveLength(1)
+    expect(setCalls[0]?.[1]).toEqual({ count: 2 })
+  })
+
   it('registers the server-sync bridge once across repeated trust flips', async () => {
     const { rpc, events, setCalls } = makeFakeRpc()
     const host = createRpcSharedStateClientHost(rpc)

packages/devframe/src/in-page-channel/in-page-channel.test.ts

@@ -325,6 +325,45 @@ describe('in-page channel over bring-your-own ports', () => {
 })
 
 describe('in-page channel shared state', () => {
+  it('seeds an equal snapshot and skips unchanged writes on both endpoints', async () => {
+    const { pageScript, panel, dispose } = createLinkedPair()
+    try {
+      const authority = await pageScript.sharedState.get('doc', { initialValue: { count: 1 } })
+      const mirror = await panel.sharedState.get('doc', { initialValue: { count: 1 } })
+      const initialMirror = mirror.value()
+      await until(() => mirror.value() !== initialMirror)
+      expect(mirror.value()).toEqual({ count: 1 })
+
+      const authorityUpdated = vi.fn()
+      const mirrorUpdated = vi.fn()
+      authority.on('updated', authorityUpdated)
+      mirror.on('updated', mirrorUpdated)
+      authority.mutate((draft) => {
+        draft.count = 1
+      })
+      mirror.mutate((draft) => {
+        draft.count = 1
+      })
+      await panel.call('echo', 'flushed')
+      expect(authorityUpdated).not.toHaveBeenCalled()
+      expect(mirrorUpdated).not.toHaveBeenCalled()
+
+      authority.mutate((draft) => {
+        draft.count = 2
+      })
+      await until(() => mirror.value().count === 2)
+      mirror.mutate((draft) => {
+        draft.count = 3
+      })
+      await until(() => authority.value().count === 3)
+      expect(authorityUpdated).toHaveBeenCalledTimes(2)
+      expect(mirrorUpdated).toHaveBeenCalledTimes(2)
+    }
+    finally {
+      dispose()
+    }
+  })
+
   it('replays the authority snapshot and streams patches to panels', async () => {
     const { pageScript, panel, dispose } = createLinkedPair()
     try {

packages/devframe/src/node/__tests__/rpc-shared-state.test.ts

@@ -0,0 +1,32 @@
+import type { DevframeNodeContext } from 'devframe/types'
+import { describe, expect, it, vi } from 'vitest'
+import { RpcFunctionsHostImpl } from '../host-functions'
+
+describe('node-side shared state', () => {
+  it('broadcasts the first RPC snapshot and deduplicates later echoes', async () => {
+    const rpc = new RpcFunctionsHostImpl({} as DevframeNodeContext)
+    const broadcast = vi.spyOn(rpc, 'broadcast').mockResolvedValue()
+
+    await rpc.invokeLocal('devframe:rpc:server-state:set', 'counter', { count: 1 }, 'first')
+    expect(broadcast).toHaveBeenCalledTimes(1)
+    expect(broadcast).toHaveBeenLastCalledWith({
+      method: 'devframe:rpc:client-state:updated',
+      args: ['counter', { count: 1 }, 'first'],
+      filter: expect.any(Function),
+    })
+
+    const state = await rpc.sharedState.get<{ count: number }>('counter')
+    await rpc.invokeLocal('devframe:rpc:server-state:set', 'counter', { count: 2 }, 'first')
+    expect(state.value()).toEqual({ count: 1 })
+    expect(broadcast).toHaveBeenCalledTimes(1)
+
+    await rpc.invokeLocal('devframe:rpc:server-state:set', 'counter', { count: 2 }, 'second')
+    expect(state.value()).toEqual({ count: 2 })
+    expect(broadcast).toHaveBeenCalledTimes(2)
+
+    state.mutate((draft) => {
+      draft.count = 2
+    })
+    expect(broadcast).toHaveBeenCalledTimes(2)
+  })
+})

packages/devframe/src/node/rpc-shared-state.ts

@@ -130,7 +130,8 @@ export function createRpcSharedStateServerHost(
       const state = await host.get(key, {
         initialValue: value,
       })
-      state.mutate(() => value, syncId)
+      // Publish the snapshot even when get() just created the state with this value.
+      state.patch([{ op: 'replace', path: [], value }], syncId)
     },
   })
 

packages/devframe/src/utils/shared-state.test.ts

@@ -3,6 +3,40 @@ import { describe, expect, it, vi } from 'vitest'
 import { createSharedState } from './shared-state'
 
 describe('shared-state', () => {
+  it.each([false, true])('skips unchanged recipes and keeps sync IDs with patches enabled: %s', (enablePatches) => {
+    const initialValue = { count: 0 }
+    const state = createSharedState({ initialValue, enablePatches })
+    const updated = vi.fn()
+    state.on('updated', updated)
+
+    state.mutate(() => {}, 'empty')
+    state.mutate((draft) => {
+      draft.count = 0
+    }, 'same-value')
+    state.mutate(() => initialValue, 'same-reference')
+    expect(state.value()).toBe(initialValue)
+    expect(updated).not.toHaveBeenCalled()
+    expect([...state.syncIds]).toEqual(['empty', 'same-value', 'same-reference'])
+
+    state.mutate((draft) => {
+      draft.count = 99
+    }, 'same-value')
+    expect(state.value().count).toBe(0)
+    state.mutate((draft) => {
+      draft.count = 1
+    }, 'changed')
+    expect(state.value().count).toBe(1)
+    expect(updated).toHaveBeenCalledTimes(1)
+
+    state.mutate(() => ({ count: 1 }), 'replacement')
+    expect(updated).toHaveBeenCalledTimes(2)
+    expect(() => state.mutate(() => {
+      throw new Error('recipe failed')
+    })).toThrow('recipe failed')
+    expect(state.value().count).toBe(1)
+    expect(updated).toHaveBeenCalledTimes(2)
+  })
+
   describe('immutability', () => {
     it('should return immutable state from get()', () => {
       const state = createSharedState({

packages/devframe/src/utils/shared-state.ts

@@ -126,11 +126,16 @@ export function createSharedState<T extends object>(
           state as Objectish,
           fn as (draft: any) => void,
         )
+        if (nextState === state)
+          return
         state = nextState as T
         events.emit('updated', state, patches as SharedStatePatch[], syncId)
       }
       else {
-        state = produce(state as Objectish, fn as (draft: any) => void) as T
+        const nextState = produce(state as Objectish, fn as (draft: any) => void) as T
+        if (nextState === state)
+          return
+        state = nextState
         events.emit('updated', state, undefined, syncId)
       }
     },