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Rust:在catch_放松期间将回溯转换为字符串

backtrace error-handling rust

Bashir Abdelwahed · 技术社区 · 4 年前

我正在用Rust编写一个跨平台(Linux/iOS/Android)库。万一我的库陷入恐慌,我希望应用程序继续正常工作,而不是崩溃。为了做到这一点,我使用 catch_unwind ; 它的结果包含恐慌信息,并且没有包含足够的关于问题来源的信息,下面是一段代码,解释我在做什么:

fn calculate(json: &str) -> String {
    unimplemented!()
}

#[no_mangle]
pub fn rust_calculation(json: &str) -> String {
    let r = std::panic::catch_unwind(||{
        // rust calculation
        let calc: String = calculate(json).into();
        calc
    });
    let r_str = match r {
        Ok(v) => v,
        Err(e) => {
            let panic_information = match e.downcast::<String>() {
                Ok(v) => *v,
                _ => "Unknown Source of Error".to_owned()
            };
            panic_information
        }
    };
    return r_str;
}

fn main() {
    println!("{}", rust_calculation("test"));
}

Playground

如果发生错误,返回的消息是不够的,有时,它只包含消息

未知错误源

我想将回溯发送到调用源,这样它就可以记录它,然后我们就可以调试Rust库了。我该怎么做?

0 回复 | 直到 4 年前

Elias Holzmann 4 年前

有时,它会将信息计算在内:

未知错误源

这可能是因为 e 可能不仅仅是 String ,但也是一个 &str (嗯,它基本上可以是任何类型,但这两种类型是最常见的,使用时只能得到其他类型。) panic_any() ).打电话的时候 panic!() 在…内 catch_unwind() ,你只会得到一个 一串 如果你是 panic! “否则,恐慌信息就是一个错误。” &str (因为不需要分配 一串 ).

我想将回溯发送到调用源,这样他就可以记录它,然后我们可以在事后调试rust库,我该怎么做?

夜间生锈的解决方案

在夜间生锈时,你可以通过 std::backtrace::Backtrace :

#![feature(backtrace)]
use lazy_static::lazy_static;
use std::sync::{Arc, Mutex};

// on panic, save the backtrace here (as string)
lazy_static! {
    static ref BACKTRACE: Arc<Mutex<Option<String>>> = Arc::new(Mutex::new(None));
}

#[no_mangle]
pub fn rust_calculation(json: &str) -> String {
    let r = std::panic::catch_unwind(||{
        panic!("Panic");
    });
    let r_str = match r {
        Ok(v) => v,
        Err(e) => {
            let panic_information = match e.downcast::<String>() {
                Ok(v) => *v,
                Err(e) => match e.downcast::<&str>() {
                    Ok(v) => v.to_string(),
                    _ => "Unknown Source of Error".to_owned()
                }
            };
            format!("{}\nBacktrace:\n{}", panic_information, BACKTRACE.lock().unwrap().take().unwrap_or("<Backtrace not found>".to_string()))
        }
    };
    return r_str;
}

fn panic_hook(_: &std::panic::PanicInfo) {
    *BACKTRACE.lock().unwrap() = Some(std::backtrace::Backtrace::force_capture().to_string());
}

fn main() {
    std::panic::set_hook(Box::new(panic_hook));
    println!("{}", rust_calculation(""));
}

Playground link

输出:

Panic
Backtrace:
   0: playground::panic_hook
             at ./src/main.rs:32:39
   1: core::ops::function::Fn::call
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/core/src/ops/function.rs:70:5
   2: std::panicking::rust_panic_with_hook
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:626:17
   3: std::panicking::begin_panic::{{closure}}
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:542:9
   4: std::sys_common::backtrace::__rust_end_short_backtrace
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/sys_common/backtrace.rs:141:18
   5: std::panicking::begin_panic
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:541:12
   6: playground::rust_calculation::{{closure}}
             at ./src/main.rs:13:9
   7: std::panicking::try::do_call
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:401:40
   8: __rust_try
   9: std::panicking::try
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:365:19
  10: std::panic::catch_unwind
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panic.rs:434:14
  11: rust_calculation
             at ./src/main.rs:12:13
  12: playground::main
             at ./src/main.rs:37:20
  13: core::ops::function::FnOnce::call_once
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/core/src/ops/function.rs:227:5
  14: std::sys_common::backtrace::__rust_begin_short_backtrace
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/sys_common/backtrace.rs:125:18
  15: std::rt::lang_start::{{closure}}
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/rt.rs:63:18
  16: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/core/src/ops/function.rs:259:13
  17: std::panicking::try::do_call
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:401:40
  18: std::panicking::try
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:365:19
  19: std::panic::catch_unwind
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panic.rs:434:14
  20: std::rt::lang_start_internal::{{closure}}
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/rt.rs:45:48
  21: std::panicking::try::do_call
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:401:40
  22: std::panicking::try
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panicking.rs:365:19
  23: std::panic::catch_unwind
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/panic.rs:434:14
  24: std::rt::lang_start_internal
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/rt.rs:45:20
  25: std::rt::lang_start
             at /rustc/2faabf579323f5252329264cc53ba9ff803429a3/library/std/src/rt.rs:62:5
  26: main
  27: __libc_start_main
  28: _start

请注意,在调用 惊恐 这是因为Rust的内部紧急处理代码。

具有依赖关系的解决方案

如果你愿意在夜间使用相同的依赖项,则可以在夜间使用相同的依赖项 backtrace crate (感谢@BashirAbdelwahed提醒我注意这一点):

use lazy_static::lazy_static;
use std::sync::{Arc, Mutex};

// on panic, save the backtrace here (as string)
lazy_static! {
    static ref BACKTRACE: Arc<Mutex<Option<String>>> = Arc::new(Mutex::new(None));
}

#[no_mangle]
pub fn rust_calculation(json: &str) -> String {
    let r = std::panic::catch_unwind(||{
        panic!("Panic");
    });
    let r_str = match r {
        Ok(v) => v,
        Err(e) => {
            let panic_information = match e.downcast::<String>() {
                Ok(v) => *v,
                Err(e) => match e.downcast::<&str>() {
                    Ok(v) => v.to_string(),
                    _ => "Unknown Source of Error".to_owned()
                }
            };
            format!("{}\nBacktrace:\n{}", panic_information, BACKTRACE.lock().unwrap().take().unwrap_or("<Backtrace not found>".to_string()))
        }
    };
    return r_str;
}

fn panic_hook(_: &std::panic::PanicInfo) {
    *BACKTRACE.lock().unwrap() = Some(format!("{:?}", backtrace::Backtrace::new()));
}

fn main() {
    std::panic::set_hook(Box::new(panic_hook));
    println!("{}", rust_calculation(""));
}

Playground link

输出:

Panic
Backtrace:
   0: playground::panic_hook
             at src/main.rs:31:55
   1: core::ops::function::Fn::call
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/core/src/ops/function.rs:70:5
   2: std::panicking::rust_panic_with_hook
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:595:17
   3: std::panicking::begin_panic::{{closure}}
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:520:9
   4: std::sys_common::backtrace::__rust_end_short_backtrace
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/sys_common/backtrace.rs:141:18
   5: std::panicking::begin_panic
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:519:12
   6: playground::rust_calculation::{{closure}}
             at src/main.rs:12:9
   7: std::panicking::try::do_call
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:379:40
   8: __rust_try
   9: std::panicking::try
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:343:19
  10: std::panic::catch_unwind
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panic.rs:431:14
  11: rust_calculation
             at src/main.rs:11:13
  12: playground::main
             at src/main.rs:36:20
  13: core::ops::function::FnOnce::call_once
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/core/src/ops/function.rs:227:5
  14: std::sys_common::backtrace::__rust_begin_short_backtrace
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/sys_common/backtrace.rs:125:18
  15: std::rt::lang_start::{{closure}}
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/rt.rs:49:18
  16: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/core/src/ops/function.rs:259:13
      std::panicking::try::do_call
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:379:40
      std::panicking::try
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panicking.rs:343:19
      std::panic::catch_unwind
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/panic.rs:431:14
      std::rt::lang_start_internal
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/rt.rs:34:21
  17: std::rt::lang_start
             at /rustc/53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b/library/std/src/rt.rs:48:5
  18: main
  19: __libc_start_main
  20: _start