Sentry的異常數據處理流程

Sentry的異常數據處理流程

獲取異常

在 Sentry的前端異常監控方案中以前咱們說過，Sentry的全局異常獲取方式有2種，window.onerror以及unhandledrejection。

異常數據的處理

以unhandledrejection爲例 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的時候,shouldIgnoreOnError會爲true.即不會上報
        // 緣由是在instrumentDOM方法中，用globalDOMEventHandler方法對監聽事件包了一層,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',
    });

總體流程分爲如下幾個模塊講解

兼容處理

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
        }

這一塊都是在作兼容性處理，適配不一樣瀏覽器中的錯誤類型

過濾條件

const currentHub = getCurrentHub();
        const hasIntegration = currentHub.getIntegration(GlobalHandlers);
        const isFailedOwnDelivery = error && error.__sentry_own_request__ === true;

        if (!hasIntegration || shouldIgnoreOnError() || isFailedOwnDelivery) {
          return true;
        }

這裏的hasIntergration是在判斷是否安裝了對應的全局監聽函數的插件(初始化的時候就會默認加載)
shouldIgnoreOnError : addEventListener的事件中直接throw Error的時候,shouldIgnoreOnError會爲true.即不會上報
緣由是在instrumentDOM方法中，用globalDOMEventHandler方法對監聽事件包了一層,使得ignoreOnError>0
isFailedOwnDelivery即判斷是否爲Sentry自身的請求錯誤，如果，則不上報。

核心處理邏輯

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)即在判斷error是否爲原始數據類型
若爲原始數據類型，則處理比較簡單

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)}`,
          },
        ],
      },
    };
  }

若爲引用數據類型，核心處理函數在tracekit.ts爲

stack = computeStackTraceFromStacktraceProp(ex);
    if (stack) {
      return popFrames(stack, popSize);
    }

具體就在computeStackTraceFromStacktraceProp，popFrames這2個函數中。

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,
  };
}

能夠看出，核心流程其實就是在對不一樣的瀏覽器作兼容處理，以及將數據組合成堆棧的形式

後續

將異常數據進行捕獲以及處理以後，就是上報流程了。詳情能夠參看上一篇文檔 Sentry的異常數據上報機制

currentHub.captureEvent(event, {
          originalException: error,
        });

總結

在大體瞭解到了整個異常數據處理流程後，發現重點是在對於不一樣瀏覽器的兼容性處理上，整個鏈路比較清晰，中間不少繁瑣的處理細節也都沒有太多的去關注，畢竟時間和精力相對有限，想的是在對Sentry的總體脈絡有了必定了解以後，對本身作監控能有不少啓發，固然這也是研究Sentry源碼的初衷。