Sentry的异常数据处理流程
获取异常
在 Sentry的前端异常监控方案中之前我们说过，Sentry的全局异常获取方式有2种，window.onerror以及unhandledrejection。
异常数据的处理
以unhandledrejection为例 globalhandlers.ts中
addInstrumentationHandler({
// eslint-disable-next-line @typescript-eslint/no-explicit-any
callback: (e: any) => {
let error = e;
// dig the object of the rejection out of known event types
try {
// PromiseRejectionEvents store the object of the rejection under 'reason'
// see https://developer.mozilla.org/en-US/docs/Web/API/PromiseRejectionEvent
if ('reason' in e) {
error = e.reason;
}
// something, somewhere, (likely a browser extension) effectively casts PromiseRejectionEvents
// to CustomEvents, moving the `promise` and `reason` attributes of the PRE into
// the CustomEvent's `detail` attribute, since they're not part of CustomEvent's spec
// see https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent and
// https://github.com/getsentry/sentry-javascript/issues/2380
else if ('detail' in e && 'reason' in e.detail) {
error = e.detail.reason;
}
} catch (_oO) {
// no-empty
}
const currentHub = getCurrentHub();
const hasIntegration = currentHub.getIntegration(GlobalHandlers);
const isFailedOwnDelivery = error && error.__sentry_own_request__ === true;
// addEventListener的事件中直接throw Error的时候,shouldIgnoreOnError会为true.即不会上报
// 原因是在instrumentDOM方法中，用globalDOMEventHandler方法对监听事件包了一层,使得ignoreOnError>0
if (!hasIntegration || shouldIgnoreOnError() || isFailedOwnDelivery) {
return true;
}
const client = currentHub.getClient();
const event = isPrimitive(error)
? this._eventFromRejectionWithPrimitive(error)
: eventFromUnknownInput(error, undefined, {
attachStacktrace: client && client.getOptions().attachStacktrace,
rejection: true,
});
event.level = Severity.Error;
addExceptionMechanism(event, {
handled: false,
type: 'onunhandledrejection',
});
currentHub.captureEvent(event, {
originalException: error,
});
return;
},
type: 'unhandledrejection',
});
整体流程分为以下几个模块讲解
兼容处理
try {
// PromiseRejectionEvents store the object of the rejection under 'reason'
// see https://developer.mozilla.org/en-US/docs/Web/API/PromiseRejectionEvent
if ('reason' in e) {
error = e.reason;
}
// something, somewhere, (likely a browser extension) effectively casts PromiseRejectionEvents
// to CustomEvents, moving the `promise` and `reason` attributes of the PRE into
// the CustomEvent's `detail` attribute, since they're not part of CustomEvent's spec
// see https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent and
// https://github.com/getsentry/sentry-javascript/issues/2380
else if ('detail' in e && 'reason' in e.detail) {
error = e.detail.reason;
}
} catch (_oO) {
// no-empty
}
这一块都是在做兼容性处理，适配不同浏览器中的错误类型
过滤条件
const currentHub = getCurrentHub();
const hasIntegration = currentHub.getIntegration(GlobalHandlers);
const isFailedOwnDelivery = error && error.__sentry_own_request__ === true;
if (!hasIntegration || shouldIgnoreOnError() || isFailedOwnDelivery) {
return true;
}这里的hasIntergration是在判断是否安装了对应的全局监听函数的插件(初始化的时候就会默认加载)
shouldIgnoreOnError : addEventListener的事件中直接throw Error的时候,shouldIgnoreOnError会为true.即不会上报
原因是在instrumentDOM方法中，用globalDOMEventHandler方法对监听事件包了一层,使得ignoreOnError>0
isFailedOwnDelivery即判断是否为Sentry自身的请求错误，若是，则不上报。
核心处理逻辑
const client = currentHub.getClient();
const event = isPrimitive(error)
? this._eventFromRejectionWithPrimitive(error)
: eventFromUnknownInput(error, undefined, {
attachStacktrace: client && client.getOptions().attachStacktrace,
rejection: true,
});
export function isPrimitive(wat: any): wat is Primitive {
return wat === null || (typeof wat !== 'object' && typeof wat !== 'function');
}isPrimitive(error)即在判断error是否为原始数据类型
若为原始数据类型，则处理比较简单
private _eventFromRejectionWithPrimitive(reason: Primitive): Event {
return {
exception: {
values: [
{
type: 'UnhandledRejection',
// String() is needed because the Primitive type includes symbols (which can't be automatically stringified)
value: `Non-Error promise rejection captured with value: ${String(reason)}`,
},
],
},
};
}
若为引用数据类型，核心处理函数在tracekit.ts为
stack = computeStackTraceFromStacktraceProp(ex);
if (stack) {
return popFrames(stack, popSize);
}具体就在computeStackTraceFromStacktraceProp，popFrames这2个函数中。
function computeStackTraceFromStackProp(ex: any): StackTrace | null {
if (!ex || !ex.stack) {
return null;
}
const stack = [];
const lines = ex.stack.split('\n');
let isEval;
let submatch;
let parts;
let element;
for (let i = 0; i < lines.length; ++i) {
if ((parts = chrome.exec(lines[i]))) {
const isNative = parts[2] && parts[2].indexOf('native') === 0; // start of line
isEval = parts[2] && parts[2].indexOf('eval') === 0; // start of line
if (isEval && (submatch = chromeEval.exec(parts[2]))) {
// throw out eval line/column and use top-most line/column number
parts[2] = submatch[1]; // url
parts[3] = submatch[2]; // line
parts[4] = submatch[3]; // column
}
element = {
// working with the regexp above is super painful. it is quite a hack, but just stripping the `address at `
// prefix here seems like the quickest solution for now.
url: parts[2] && parts[2].indexOf('address at ') === 0 ? parts[2].substr('address at '.length) : parts[2],
func: parts[1] || UNKNOWN_FUNCTION,
args: isNative ? [parts[2]] : [],
line: parts[3] ? +parts[3] : null,
column: parts[4] ? +parts[4] : null,
};
} else if ((parts = winjs.exec(lines[i]))) {
element = {
url: parts[2],
func: parts[1] || UNKNOWN_FUNCTION,
args: [],
line: +parts[3],
column: parts[4] ? +parts[4] : null,
};
} else if ((parts = gecko.exec(lines[i]))) {
isEval = parts[3] && parts[3].indexOf(' > eval') > -1;
if (isEval && (submatch = geckoEval.exec(parts[3]))) {
// throw out eval line/column and use top-most line number
parts[1] = parts[1] || `eval`;
parts[3] = submatch[1];
parts[4] = submatch[2];
parts[5] = ''; // no column when eval
} else if (i === 0 && !parts[5] && ex.columnNumber !== void 0) {
// FireFox uses this awesome columnNumber property for its top frame
// Also note, Firefox's column number is 0-based and everything else expects 1-based,
// so adding 1
// NOTE: this hack doesn't work if top-most frame is eval
stack[0].column = (ex.columnNumber as number) + 1;
}
element = {
url: parts[3],
func: parts[1] || UNKNOWN_FUNCTION,
args: parts[2] ? parts[2].split(',') : [],
line: parts[4] ? +parts[4] : null,
column: parts[5] ? +parts[5] : null,
};
} else {
continue;
}
if (!element.func && element.line) {
element.func = UNKNOWN_FUNCTION;
}
stack.push(element);
}
if (!stack.length) {
return null;
}
return {
message: extractMessage(ex),
name: ex.name,
stack,
};
}
可以看出，核心流程其实就是在对不同的浏览器做兼容处理，以及将数据组合成堆栈的形式
后续
将异常数据进行捕获以及处理之后，就是上报流程了。详情可以参看上一篇文档 Sentry的异常数据上报机制
currentHub.captureEvent(event, {
originalException: error,
});总结
在大致了解到了整个异常数据处理流程后，发现重点是在对于不同浏览器的兼容性处理上，整个链路比较清晰，中间很多繁琐的处理细节也都没有太多的去关注，毕竟时间和精力相对有限，想的是在对Sentry的整体脉络有了一定了解之后，对自己做监控能有很多启发，当然这也是研究Sentry源码的初衷。