Ensure conflict resolution in keyspace

TODO

@@ -1,4 +1,4 @@
-cache headers for static assets
+cache headers for static assets (and on document GET)
 tests
 fix any annoying visual quirks
 add FAVICON
@@ -6,7 +6,7 @@ cache static in memory
 add feedback for errors to UI - esp. too long
 copy URL to clipboard button
 add about page
-add conflict resolution for keys when creating a post
+support built-in expiration
 
 # shared version only
 some way to do announcements easily (and use for ads)

lib/document_handler.js

@@ -29,7 +29,6 @@ DocumentHandler.prototype.handleGet = function(key, response) {
 // Handle adding a new Document
 DocumentHandler.prototype.handlePost = function(request, response) {
   var _this = this;
-  var key = this.randomKey();
   var buffer = '';
   request.on('data', function(data) {
     if (!buffer) {
@@ -38,23 +37,25 @@ DocumentHandler.prototype.handlePost = function(request, response) {
     buffer += data.toString();
     if (_this.maxLength && buffer.length > _this.maxLength) {
       _this.cancelled = true;
-      winston.warn('attempted to upload a document >maxLength', { maxLength: _this.maxLength });
+      winston.warn('document >maxLength', { maxLength: _this.maxLength });
       response.writeHead(400, { 'content-type': 'application/json' });
       response.end(JSON.stringify({ message: 'document exceeds maximum length' }));
     }
   });
   request.on('end', function(end) {
     if (_this.cancelled) return;
-    _this.store.set(key, buffer, function(res) {
-      if (res) {
-        winston.verbose('added document', { key: key });
-        response.end(JSON.stringify({ key: key }));
-      }
-      else {
-        winston.verbose('error adding document');
-        response.writeHead(500, { 'content-type': 'application/json' });
-        response.end(JSON.stringify({ message: 'error adding document' }));
-      }
+    _this.chooseKey(function(key) {
+      _this.store.set(key, buffer, function(res) {
+        if (res) {
+          winston.verbose('added document', { key: key });
+          response.end(JSON.stringify({ key: key }));
+        }
+        else {
+          winston.verbose('error adding document');
+          response.writeHead(500, { 'content-type': 'application/json' });
+          response.end(JSON.stringify({ message: 'error adding document' }));
+        }
+      });
     });
   });
   request.on('error', function(error) {
@@ -64,6 +65,19 @@ DocumentHandler.prototype.handlePost = function(request, response) {
   });
 };
 
+// Get a random key that hasn't been already used
+DocumentHandler.prototype.chooseKey = function(callback) {
+  var key = this.randomKey();
+  var _this = this;
+  this.store.get(key, function(ret) {
+    if (ret) {
+      _this.chooseKey(callback);
+    } else {
+      callback(key);
+    }
+  }); 
+};
+
 // Generate a random key
 DocumentHandler.prototype.randomKey = function() {
   var text = '';