Web blocking API strategy

Web blocking API strategy

AI Markdown

Web blocking API strategy

Function

Describes the rules for operating slow I/O, blocking waits, and long-term background capabilities in the context of web requests.

The web request script will enter the BT process-level blocking pool for execution as a whole to avoid fs, short sleep(), template compilation, synchronization script logic, etc. from blocking Tokio Web workers. The number of threads, queue length, and default wait time of the blocking pool are controlled by the BT_IO_* configuration.

Syntax

Parameters

No parameters.

Return value

This page is a rule description and does not provide independent function return values.

Web request rules

APIBehavior in Web RequestsBoundaries
sleep(ms)Allow short sleep.ms cannot exceed BT_IO_TIMEOUT_MS, the default is 30000 milliseconds.
pause()Rejected.There is no interactive terminal for web requests.
fs.*Allowed.The entire request script runs in the blocking pool, subject to BT_IO_BLOCKING_WORKERS, BT_IO_BLOCKING_QUEUE, BT_IO_TIMEOUT_MS.
process.status() / process.output() / process.child() / process.wait()Rejected.These operations may wait synchronously on external processes or fork long-term child processes.
reqwest.send()Allowed.Using the shared I/O runtime, the default time for a single request is 30000 milliseconds; it can be set by timeout(ms), but the overall web request is still subject to BT_IO_TIMEOUT_MS.
mysql.all() / mysql.one() / mysql.exec()Allowed.Using the shared I/O runtime and MySQL query timeouts, web requests overall are still subject to BT_IO_TIMEOUT_MS.
task(fn, ...args)Allow background task submission.Task.on_done(), Task.await(), task_all(), task_race() rejected in web request.
device.*Allowed.Serial port opening, reading and writing must rely on the timeout in the device configuration, and the entire web request is subject to BT_IO_TIMEOUT_MS.

Code Example

Notes

  • BT_IO_TIMEOUT_MS Defaults to 30000 milliseconds and serves as the default upper limit for web request scripts to wait for results in the blocking pool.
  • If the blocking pool queue is full, the request will return an explicit Chinese error: I/O 阻塞任务队列已满.
  • Timeout will cause the current HTTP request to return an error, but the underlying operations that have entered the system blocking call cannot be safely forcibly interrupted by Rust; therefore, long-term external processes and non-timeout device operations should still be avoided in the Web.
  • When you need a verification example, run examples/web-blocking-policy/main.bt.