From 7cb0882c7339427ca95df6b70ea5a60f1fcfefd6 Mon Sep 17 00:00:00 2001
From: Winston Chang <winston@stdout.org>
Date: Mon, 28 Mar 2016 21:29:23 -0500
Subject: [PATCH] Add "force" option to allowReconnect

---
 R/shiny.R         | 21 ++++++++++++---------
 man/session.Rd    | 17 ++++++++++-------
 srcjs/shinyapp.js | 19 +++++++++----------
 3 files changed, 31 insertions(+), 26 deletions(-)

diff --git a/R/shiny.R b/R/shiny.R
index cc7f92d8a..e722ef9cc 100644
--- a/R/shiny.R
+++ b/R/shiny.R
@@ -242,13 +242,16 @@ workerId <- local({
 #'   (as opposed to the request that downloaded the web page for the app).
 #' }
 #' \item{allowReconnect(value)}{
-#'   If \code{value} is \code{TRUE}, this tells the browser that, if the
-#'   session ends due to the network connection closing, attempt to reconnect
-#'   to the server. If a reconnection is successful, the browser will send all
-#'   the current input values to the new session on the server, and the server
-#'   will recalculate any outputs and send them back to the client. If
-#'   \code{value} is \code{FALSE}, reconnections will be disabled (this is the
-#'   default state).
+#'   If \code{value} is \code{TRUE} and run in a hosting environment (Shiny
+#'   Server or Connect) with reconnections enabled,  then when the session ends
+#'   due to the network connection closing, the client will attempt to
+#'   reconnect to the server. If a reconnection is successful, the browser will
+#'   send all the current input values to the new session on the server, and
+#'   the server will recalculate any outputs and send them back to the client.
+#'   If \code{value} is \code{FALSE}, reconnections will be disabled (this is
+#'   the default state). If \code{"force"}, then the client browser will always
+#'   attempt to reconnect. The only reason to use \code{"force"} is for testing
+#'   on a local connection (without Shiny Server or Connect).
 #' }
 #' \item{sendCustomMessage(type, message)}{
 #'   Sends a custom message to the web page. \code{type} must be a
@@ -541,8 +544,8 @@ ShinySession <- R6Class(
     },
 
     allowReconnect = function(value) {
-      if (!(identical(value, TRUE) || identical(value, FALSE))) {
-        stop("value must be TRUE or FALSE")
+      if (!(identical(value, TRUE) || identical(value, FALSE) || identical(value, "force"))) {
+        stop('value must be TRUE, FALSE, or "force"')
       }
       private$write(toJSON(list(allowReconnect = value)))
     },
diff --git a/man/session.Rd b/man/session.Rd
index 145d8d28e..59bd79f06 100644
--- a/man/session.Rd
+++ b/man/session.Rd
@@ -86,13 +86,16 @@
   (as opposed to the request that downloaded the web page for the app).
 }
 \item{allowReconnect(value)}{
-  If \code{value} is \code{TRUE}, this tells the browser that, if the
-  session ends due to the network connection closing, attempt to reconnect
-  to the server. If a reconnection is successful, the browser will send all
-  the current input values to the new session on the server, and the server
-  will recalculate any outputs and send them back to the client. If
-  \code{value} is \code{FALSE}, reconnections will be disabled (this is the
-  default state).
+  If \code{value} is \code{TRUE} and run in a hosting environment (Shiny
+  Server or Connect) with reconnections enabled,  then when the session ends
+  due to the network connection closing, the client will attempt to
+  reconnect to the server. If a reconnection is successful, the browser will
+  send all the current input values to the new session on the server, and
+  the server will recalculate any outputs and send them back to the client.
+  If \code{value} is \code{FALSE}, reconnections will be disabled (this is
+  the default state). If \code{"force"}, then the client browser will always
+  attempt to reconnect. The only reason to use \code{"force"} is for testing
+  on a local connection (without Shiny Server or Connect).
 }
 \item{sendCustomMessage(type, message)}{
   Sends a custom message to the web page. \code{type} must be a
diff --git a/srcjs/shinyapp.js b/srcjs/shinyapp.js
index 70c58f630..4e6145007 100644
--- a/srcjs/shinyapp.js
+++ b/srcjs/shinyapp.js
@@ -82,12 +82,6 @@ var ShinyApp = function() {
       var ws = new WebSocket(protocol + '//' + window.location.host + defaultPath);
       ws.binaryType = 'arraybuffer';
 
-      // This flag indicates that reconnections are permitted by the server.
-      // When Shiny is running with Shiny Server, this flag will be present
-      // only on versions of SS that support reconnects. When running Shiny
-      // locally, this is set to true, because the "server" always permits
-      // reconnection.
-      ws.allowReconnect = true;
       return ws;
     };
 
@@ -225,8 +219,12 @@ var ShinyApp = function() {
     }
 
     // To try a reconnect, both the app (this.$allowReconnect) and the
-    // server (this.$socket.allowReconnect) must allow reconnections.
-    if (this.$allowReconnect === true && this.$socket.allowReconnect === true) {
+    // server (this.$socket.allowReconnect) must allow reconnections, or
+    // session$allowReconnect("force") was called. The "force" option should
+    // only be used for testing.
+    if ((this.$allowReconnect === true && this.$socket.allowReconnect === true) ||
+        this.$allowReconnect === "force")
+    {
       var delay = reconnectDelay.next();
       exports.showReconnectDialog(delay);
       this.$scheduleReconnect(delay);
@@ -591,10 +589,11 @@ var ShinyApp = function() {
   });
 
   addMessageHandler('allowReconnect', function(message) {
-    if (!(message === true || message === false)) {
+    if (message === true || message === false || message === "force") {
+      this.$allowReconnect = message;
+    } else {
       throw "Invalid value for allowReconnect: " + message;
     }
-    this.$allowReconnect = message;
   });
 
   addMessageHandler('custom', function(message) {