linrongbin16L
Deno•17mo ago
linrongbin16

Is it possible to embed `deno_core` with a self-managed event loop?

And the 2nd question is: does the API 
deno_core::JsRuntime::run_event_loop
 only run 1 tick? or it try to wait everything inside its internal queue to complete?

Because after reading some tutorials and source code of 
deno_core
, I found there's already some queues inside 
deno_core
, I guess they're for the 
queueMicrotask
 and built-in 
async
/
await
 functions.

For example, if we have below sample code:

async function readFile(filename) {
   // Read a file in async mode
}

async function sleepFor(seconds) {
  // Sleep for seconds
}

const content = await readFile("README.md");
console.log(`We have read: ${content}`);
await sleepFor(10);
console.log(`We have sleep for 10s`);


Once the 
deno_core::JsRuntime
 execute it, I guess the 1st 
console.log
 will not be printed, instead it's been put in the internal queue and wait for the 
async readFile
 function done. Correct?

Then we call the 
js_runtime.run_event_loop().await
 , once it's completed, is the only 1st 
console.log
 been printed? Or both two 
console.log
 are been printed? i.e. the 
run_event_loop
 API runs for only 1 tick, or wait for all the tasks done?

If it only runs for 1 tick, then I can embed it into my command line TUI application. Because the TUI application is using tokio runtime with the crossterm library. I want to use 
tokio::select!
 on both the crossterm's 
EventStream
 (it receives terminal keyboard/mouse events, such as key pressed, mouse clicked, etc) and the 
deno_core::JsRuntime::run_event_loop
. Only 1 tick will never block the terminal events.

If it waits for all async tasks done, then it means it cannot work along with the tokio runtime managed by my TUI application. Because it will block the terminal.
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