#315: improve logger errors serialization

src/services/logger/abbreviate.js

@@ -0,0 +1,154 @@
+const STRING_MAX_LENGTH = 128*1024;
+
+/**
+ * Create a copy of any object without non-serializable elements to make result safe for JSON.stringify().
+ * Guaranteed to never throw.
+ *
+ * @param {any}    obj     Any data structure
+ * @param {object} options
+ * @param {function} options.filter - callback that is called on every object's key with (key,value) and should return
+ *        value to use (may return undefined to remove unwanted keys). See nodeFilter and browserFilter.
+ * @param {number} options.depth - maximum recursion depth. Elements deeper than that are stringified with util.inspect()
+ * @param {number} options.maxSize - roughly maximum allowed size of data after JSON serialisation (but it's not guaranteed
+ *        that it won't exceed the limit)
+ *
+ * @see https://github.com/ftlabs/js-abbreviate
+ */
+function abbreviate(obj, options) {
+    if (!options) options = {};
+
+    var filter = options.filter || function(k,v){return v;};
+    var maxDepth = options.depth || 10;
+    var maxSize = options.maxSize || 1*1024*1024;
+
+    return abbreviateRecursive(undefined, obj, filter, {sizeLeft: maxSize}, maxDepth);
+}
+
+function limitStringLength(str) {
+    if (str.length > STRING_MAX_LENGTH) {
+        return str.substring(0, STRING_MAX_LENGTH/2) + ' … ' + str.substring(str.length - STRING_MAX_LENGTH/2);
+    }
+    return str;
+}
+
+function abbreviateRecursive(key, obj, filter, state, maxDepth) {
+    if (state.sizeLeft < 0) {
+        return '**skipped**';
+    }
+
+    state.sizeLeft -= 5; // rough approximation of JSON overhead
+
+    obj = filter(key, obj);
+
+    try {
+        switch(typeof obj) {
+            case 'object':
+                if (null === obj) {
+                    return null;
+                }
+
+                if (maxDepth < 0) {
+                    break; // fall back to stringification
+                }
+
+                var newobj = Array.isArray(obj) ? [] : {};
+                for(var i in obj) {
+                    newobj[i] = abbreviateRecursive(i, obj[i], filter, state, maxDepth-1);
+                    if (state.sizeLeft < 0) break;
+                }
+                return newobj;
+
+            case 'string':
+                obj = limitStringLength(obj);
+                state.sizeLeft -= obj.length;
+                return obj;
+
+            case 'number':
+            case 'boolean':
+            case 'undefined':
+                return obj;
+        }
+    } catch(e) {/* fall back to inspect*/}
+
+    try {
+        obj = limitStringLength('' + obj);
+        state.sizeLeft -= obj.length;
+        return obj;
+    } catch(e) {
+        return "**non-serializable**";
+    }
+}
+
+function commonFilter(key, val) {
+    if ('function' === typeof val) {
+        return undefined;
+    }
+
+    if (val instanceof Date) {
+        return "**Date** " + val;
+    }
+
+    if (val instanceof Error) {
+        var err = {
+            // These properties are implemented as magical getters and don't show up in for in
+            stack: val.stack,
+            message: val.message,
+            name: val.name,
+        };
+        for(var i in val) {
+            err[i] = val[i];
+        }
+        return err;
+    }
+
+    return val;
+}
+
+function nodeFilter(key, val) {
+
+    // domain objects are huge and have circular references
+    if (key === 'domain' && 'object' === typeof val && val._events) {
+        return "**domain ignored**";
+    }
+    if (key === 'domainEmitter') {
+        return "**domainEmitter ignored**";
+    }
+
+    if (val === global) {
+        return "**global**";
+    }
+
+    return commonFilter(key, val);
+}
+
+function browserFilter(key, val) {
+    if (val === window) {
+        return "**window**";
+    }
+
+    if (val === document) {
+        return "**document**";
+    }
+
+    if (val instanceof HTMLElement) {
+        var outerHTML = val.outerHTML;
+        if ('undefined' != typeof outerHTML) {
+            return "**HTMLElement** " + outerHTML;
+        }
+    }
+
+    return commonFilter(key, val);
+}
+
+
+export {
+    abbreviate,
+    nodeFilter,
+    browserFilter
+};
+
+export default function(obj) {
+    return abbreviate(obj, {
+        filter: browserFilter
+    })
+};

src/services/logger/index.js

@@ -0,0 +1,3 @@
+import logger from './logger';
+
+export default logger;

src/services/logger/logger.js

@@ -1,5 +1,7 @@
 import Raven from 'raven-js';
 
+import abbreviate from './abbreviate';
+
 const isTest = process.env.__TEST__; // eslint-disable-line
 const isProduction = process.env.__PROD__; // eslint-disable-line
 
@@ -72,6 +74,8 @@ const logger = {
             };
         }
 
+        context = abbreviate(context); // prepare data for JSON.stringify
+
         console[method](message, context); // eslint-disable-line
 
         Raven.captureException(message, {