fix(api): use array for channel queueing (#12069)

.changes/api-channel-miss-events.md

@@ -0,0 +1,5 @@
+---
+"@tauri-apps/api": "patch:bug"
+---
+
+Fix `Channel` never calls `onmessage` in some cases

examples/api/src-tauri/build.rs

@@ -17,6 +17,7 @@ fn main() {
         "log_operation",
         "perform_request",
         "echo",
+        "spam",
       ])),
   )
   .expect("failed to run tauri-build");

examples/api/src-tauri/capabilities/run-app.json

@@ -16,6 +16,7 @@
     },
     "allow-perform-request",
     "allow-echo",
+    "allow-spam",
     "app-menu:default",
     "sample:allow-ping-scoped",
     "sample:global-scope",

examples/api/src-tauri/permissions/autogenerated/spam.toml

@@ -0,0 +1,11 @@
+# Automatically generated - DO NOT EDIT!
+
+[[permission]]
+identifier = "allow-spam"
+description = "Enables the spam command without any pre-configured scope."
+commands.allow = ["spam"]
+
+[[permission]]
+identifier = "deny-spam"
+description = "Denies the spam command without any pre-configured scope."
+commands.deny = ["spam"]

examples/api/src-tauri/src/cmd.rs

@@ -3,7 +3,10 @@
 // SPDX-License-Identifier: MIT
 
 use serde::{Deserialize, Serialize};
-use tauri::{command, ipc::CommandScope};
+use tauri::{
+  command,
+  ipc::{Channel, CommandScope},
+};
 
 #[derive(Debug, Deserialize)]
 #[allow(unused)]
@@ -28,7 +31,7 @@ pub fn log_operation(
   } else if !command_scope.allows().iter().any(|s| s.event == event) {
     Err("not allowed")
   } else {
-    log::info!("{} {:?}", event, payload);
+    log::info!("{event} {payload:?}");
     Ok(())
   }
 }
@@ -40,7 +43,7 @@ pub struct ApiResponse {
 
 #[command]
 pub fn perform_request(endpoint: String, body: RequestBody) -> ApiResponse {
-  println!("{} {:?}", endpoint, body);
+  println!("{endpoint} {body:?}");
   ApiResponse {
     message: "message response".into(),
   }
@@ -50,3 +53,11 @@ pub fn perform_request(endpoint: String, body: RequestBody) -> ApiResponse {
 pub fn echo(request: tauri::ipc::Request<'_>) -> tauri::ipc::Response {
   tauri::ipc::Response::new(request.body().clone())
 }
+
+#[command]
+pub fn spam(channel: Channel<i32>) -> tauri::Result<()> {
+  for i in 1..=1_000 {
+    channel.send(i)?;
+  }
+  Ok(())
+}

examples/api/src-tauri/src/lib.rs

@@ -145,7 +145,8 @@ pub fn run_app<R: Runtime, F: FnOnce(&App<R>) + Send + 'static>(
     .invoke_handler(tauri::generate_handler![
       cmd::log_operation,
       cmd::perform_request,
-      cmd::echo
+      cmd::echo,
+      cmd::spam,
     ])
     .build(tauri::tauri_build_context!())
     .expect("error while building tauri application");

examples/api/src/views/Communication.svelte

@@ -1,6 +1,6 @@
 <script>
   import { getCurrentWebviewWindow } from '@tauri-apps/api/webviewWindow'
-  import { invoke } from '@tauri-apps/api/core'
+  import { Channel, invoke } from '@tauri-apps/api/core'
   import { onMount, onDestroy } from 'svelte'
 
   export let onMessage
@@ -46,6 +46,12 @@
     invoke('echo', [1, 2, 3]).then(onMessage).catch(onMessage)
   }
 
+  function spam() {
+    const channel = new Channel()
+    channel.onmessage = onMessage
+    invoke('spam', { channel })
+  }
+
   function emitEvent() {
     webviewWindow.emit('js-event', 'this is the payload string')
   }
@@ -60,4 +66,5 @@
     Send event to Rust
   </button>
   <button class="btn" id="request" on:click={echo}> Echo </button>
+  <button class="btn" id="request" on:click={spam}> Spam </button>
 </div>

packages/api/src/core.ts

@@ -81,42 +81,31 @@ class Channel<T = unknown> {
   #onmessage: (response: T) => void = () => {
     // no-op
   }
+  // the id is used as a mechanism to preserve message order
   #nextMessageId = 0
-  #pendingMessages: Record<string, T> = {}
+  #pendingMessages: T[] = []
 
   constructor() {
     this.id = transformCallback(
       ({ message, id }: { message: T; id: number }) => {
-        // the id is used as a mechanism to preserve message order
-        if (id === this.#nextMessageId) {
-          this.#nextMessageId = id + 1
+        // Process the message if we're at the right order
+        if (id == this.#nextMessageId) {
           this.#onmessage(message)
+          this.#nextMessageId += 1
 
           // process pending messages
-          const pendingMessageIds = Object.keys(this.#pendingMessages)
-          if (pendingMessageIds.length > 0) {
-            let nextId = id + 1
-            for (const pendingId of pendingMessageIds.sort()) {
-              // if we have the next message, process it
-              if (parseInt(pendingId) === nextId) {
-                // eslint-disable-next-line security/detect-object-injection
-                const message = this.#pendingMessages[pendingId]
-                // eslint-disable-next-line security/detect-object-injection
-                delete this.#pendingMessages[pendingId]
-
-                this.#onmessage(message)
-
-                // move the id counter to the next message to check
-                nextId += 1
-              } else {
-                // we do not have the next message, let's wait
-                break
-              }
-            }
-            this.#nextMessageId = nextId
+          while (this.#nextMessageId in this.#pendingMessages) {
+            const message = this.#pendingMessages[this.#nextMessageId]
+            this.#onmessage(message)
+            // eslint-disable-next-line @typescript-eslint/no-array-delete
+            delete this.#pendingMessages[this.#nextMessageId]
+            this.#nextMessageId += 1
           }
-        } else {
-          this.#pendingMessages[id.toString()] = message
+        }
+        // Queue the message if we're not
+        else {
+          // eslint-disable-next-line security/detect-object-injection
+          this.#pendingMessages[id] = message
         }
       }
     )