sort documents within batch to prevent deadlock #535

Author: ehennum

lib/documents.js

@@ -41,6 +41,25 @@ function getDocumentUris(documents) {
   return documents.reduce(addDocumentUri, []);
 }
 
+/** @ignore */
+function compareDocuments(firstDoc, secondDoc) {
+  const hasFirstDoc  = (firstDoc  !== null);
+  const hasSecondDoc = (secondDoc !== null);
+  if (!hasFirstDoc && !hasSecondDoc) return  0;
+  if (!hasFirstDoc && hasSecondDoc)  return -1;
+  if (hasFirstDoc  && !hasSecondDoc) return  1;
+  const firstUri  = firstDoc.uri;
+  const secondUri = secondDoc.uri;
+  const hasFirstUri  = ((typeof firstUri  === 'string' || firstUri  instanceof String) && firstUri.length  > 0);
+  const hasSecondUri = ((typeof secondUri === 'string' || secondUri instanceof String) && secondUri.length > 0);
+  if (!hasFirstUri && !hasSecondUri) return  0;
+  if (!hasFirstUri && hasSecondUri)  return -1;
+  if (hasFirstUri  && !hasSecondUri) return  1;
+  if (firstUri < secondUri) return -1;
+  if (firstUri > secondUri) return  1;
+  return 0;
+}
+
 /** @ignore */
 function uriErrorTransform(message) {
   /*jshint validthis:true */
@@ -1206,6 +1225,10 @@ function writeContent(contentOnly, document, requestParams, categories, requestT
 /** @ignore */
 function writeDocumentList(contentOnly, documents, requestParams, categories) {
   /*jshint validthis:true */
+  if (documents.length > 1) {
+    documents = documents.sort(compareDocuments);
+  }
+
   var requestPartList = [];
   for (var i=0; i < documents.length; i++) {
     addDocumentParts(requestPartList, documents[i], false);