Refactoring day1

node_modules/mongodb/lib/utils.js

@@ -1,5 +1,6 @@
 'use strict';
 const MongoError = require('./core/error').MongoError;
+const ReadPreference = require('./core/topologies/read_preference');
 const WriteConcern = require('./write_concern');
 
 var shallowClone = function(obj) {
@@ -8,6 +9,31 @@ var shallowClone = function(obj) {
   return copy;
 };
 
+// Figure out the read preference
+var translateReadPreference = function(options) {
+  var r = null;
+  if (options.readPreference) {
+    r = options.readPreference;
+  } else {
+    return options;
+  }
+
+  if (typeof r === 'string') {
+    options.readPreference = new ReadPreference(r);
+  } else if (r && !(r instanceof ReadPreference) && typeof r === 'object') {
+    const mode = r.mode || r.preference;
+    if (mode && typeof mode === 'string') {
+      options.readPreference = new ReadPreference(mode, r.tags, {
+        maxStalenessSeconds: r.maxStalenessSeconds
+      });
+    }
+  } else if (!(r instanceof ReadPreference)) {
+    throw new TypeError('Invalid read preference: ' + r);
+  }
+
+  return options;
+};
+
 // Set simple property
 var getSingleProperty = function(obj, name, value) {
   Object.defineProperty(obj, name, {
@@ -464,6 +490,37 @@ function applyWriteConcern(target, sources, options) {
   return target;
 }
 
+/**
+ * Resolves a read preference based on well-defined inheritance rules. This method will not only
+ * determine the read preference (if there is one), but will also ensure the returned value is a
+ * properly constructed instance of `ReadPreference`.
+ *
+ * @param {Collection|Db|MongoClient} parent The parent of the operation on which to determine the read
+ * preference, used for determining the inherited read preference.
+ * @param {Object} options The options passed into the method, potentially containing a read preference
+ * @returns {(ReadPreference|null)} The resolved read preference
+ */
+function resolveReadPreference(parent, options) {
+  options = options || {};
+  const session = options.session;
+
+  const inheritedReadPreference = parent.readPreference;
+
+  let readPreference;
+  if (options.readPreference) {
+    readPreference = ReadPreference.fromOptions(options);
+  } else if (session && session.inTransaction() && session.transaction.options.readPreference) {
+    // The transaction’s read preference MUST override all other user configurable read preferences.
+    readPreference = session.transaction.options.readPreference;
+  } else if (inheritedReadPreference != null) {
+    readPreference = inheritedReadPreference;
+  } else {
+    throw new Error('No readPreference was provided or inherited.');
+  }
+
+  return typeof readPreference === 'string' ? new ReadPreference(readPreference) : readPreference;
+}
+
 /**
  * Checks if a given value is a Promise
  *
@@ -721,12 +778,6 @@ function makeInterruptableAsyncInterval(fn, options) {
     const timeUntilNextCall = Math.max(interval - timeSinceLastCall, 0);
     lastWakeTime = currentTime;
 
-    // For the streaming protocol: there is nothing obviously stopping this
-    // interval from being woken up again while we are waiting "infinitely"
-    // for `fn` to be called again`. Since the function effectively
-    // never completes, the `timeUntilNextCall` will continue to grow
-    // negatively unbounded, so it will never trigger a reschedule here.
-
     // debounce multiple calls to wake within the `minInterval`
     if (timeSinceLastWake < minInterval) {
       return;
@@ -759,7 +810,6 @@ function makeInterruptableAsyncInterval(fn, options) {
   function executeAndReschedule() {
     lastWakeTime = 0;
     lastCallTime = now();
-
     fn(err => {
       if (err) throw err;
       reschedule(interval);
@@ -776,15 +826,6 @@ function makeInterruptableAsyncInterval(fn, options) {
   return { wake, stop };
 }
 
-function hasAtomicOperators(doc) {
-  if (Array.isArray(doc)) {
-    return doc.reduce((err, u) => err || hasAtomicOperators(u), null);
-  }
-
-  const keys = Object.keys(doc);
-  return keys.length > 0 && keys[0][0] === '$';
-}
-
 module.exports = {
   filterOptions,
   mergeOptions,
@@ -802,6 +843,7 @@ module.exports = {
   debugOptions,
   MAX_JS_INT: Number.MAX_SAFE_INTEGER + 1,
   mergeOptionsAndWriteConcern,
+  translateReadPreference,
   executeLegacyOperation,
   applyRetryableWrites,
   applyWriteConcern,
@@ -811,11 +853,11 @@ module.exports = {
   deprecateOptions,
   SUPPORTS,
   MongoDBNamespace,
+  resolveReadPreference,
   emitDeprecationWarning,
   makeCounter,
   maybePromise,
   now,
   calculateDurationInMs,
-  makeInterruptableAsyncInterval,
-  hasAtomicOperators
+  makeInterruptableAsyncInterval
 };