From bc1e039ea1b28287b51327df6f61ccdb8a977d5c Mon Sep 17 00:00:00 2001
From: Bryce Curtis <curtis.bryce@gmail.com>
Date: Tue, 26 Oct 2010 15:09:54 -0500
Subject: [PATCH] Use polling instead of XHR for callbacks from Java to
 JavaScript when device has a proxy set.

---
 framework/assets/js/phonegap.js.base          | 40 ++++++++++++++++++-
 .../src/com/phonegap/CallbackServer.java      | 37 +++++++++++++++--
 framework/src/com/phonegap/api/Plugin.java    |  6 +--
 3 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/framework/assets/js/phonegap.js.base b/framework/assets/js/phonegap.js.base
index 4345e2f1..0ebc8383 100755
--- a/framework/assets/js/phonegap.js.base
+++ b/framework/assets/js/phonegap.js.base
@@ -238,7 +238,14 @@ PhoneGap.onDeviceReady = new PhoneGap.Channel('onDeviceReady');
 PhoneGap.Channel.join(function() {
 
     // Start listening for XHR callbacks
-    PhoneGap.JSCallback();
+    setTimeout(function() {
+            if (CallbackServer.usePolling()) {
+                PhoneGap.JSCallbackPolling();
+            }
+            else {
+                PhoneGap.JSCallback();
+            }
+        }, 1);
 
     // Run PhoneGap constructors
     PhoneGap.onPhoneGapInit.fire();
@@ -603,6 +610,37 @@ PhoneGap.JSCallback = function() {
     xmlhttp.send();
 };
 
+/**
+ * The polling period to use with JSCallbackPolling.
+ * This can be changed by the application.  The default is 50ms.
+ */
+PhoneGap.JSCallbackPollingPeriod = 50;
+
+/**
+ * This is only for Android.
+ *
+ * Internal function that uses polling to call into PhoneGap Java code and retrieve 
+ * any JavaScript code that needs to be run.  This is used for callbacks from
+ * Java to JavaScript.
+ */
+PhoneGap.JSCallbackPolling = function() {
+    var msg = CallbackServer.getJavascript();
+    if (msg) {
+        setTimeout(function() {
+            try {
+                var t = eval(""+msg);
+            }
+            catch (e) {
+                console.log("JSCallbackPolling Error: "+e);
+            }
+        }, 1);
+        setTimeout(PhoneGap.JSCallbackPolling, 1);
+    }
+    else {
+        setTimeout(PhoneGap.JSCallbackPolling, PhoneGap.JSCallbackPollingPeriod);
+    }
+};
+
 /**
  * Create a UUID
  *
diff --git a/framework/src/com/phonegap/CallbackServer.java b/framework/src/com/phonegap/CallbackServer.java
index 154c7b2f..6bf74c52 100755
--- a/framework/src/com/phonegap/CallbackServer.java
+++ b/framework/src/com/phonegap/CallbackServer.java
@@ -17,10 +17,10 @@ import java.util.LinkedList;
 
 /**
  * This class provides a way for Java to run JavaScript in the web page that has loaded PhoneGap.
- * The CallbackServer class implements an XHR server and a list of JavaScript statements
- * that are to be executed on the web page.
+ * The CallbackServer class implements an XHR server and a polling server with a list of JavaScript
+ * statements that are to be executed on the web page.
  * 
- * The process flow is:
+ * The process flow for XHR is:
  * 1. JavaScript makes an async XHR call. 
  * 2. The server holds the connection open until data is available. 
  * 3. The server writes the data to the client and closes the connection. 
@@ -30,6 +30,14 @@ import java.util.LinkedList;
  *
  * The CallbackServer class requires the following permission in Android manifest file
  * 		<uses-permission android:name="android.permission.INTERNET" />
+ * 
+ * If the device has a proxy set, then XHR cannot be used, so polling must be used instead.
+ * This can be determined by the client by calling CallbackServer.usePolling().  
+ * 
+ * The process flow for polling is:
+ * 1. The client calls CallbackServer.getJavascript() to retrieve next statement.
+ * 2. If statement available, then client processes it.
+ * 3. The client repeats #1 in loop. 
  */
 public class CallbackServer implements Runnable {
 	
@@ -58,6 +66,11 @@ public class CallbackServer implements Runnable {
 	 */
 	private boolean empty;
 	
+	/**
+	 * Indicates that polling should be used instead of XHR.
+	 */
+	private boolean usePolling;
+	
 	/**
 	 * Constructor.
 	 */
@@ -67,7 +80,23 @@ public class CallbackServer implements Runnable {
 		this.empty = true;
 		this.port = 0;
 		this.javascript = new LinkedList<String>();
-		this.startServer();
+		
+		if (android.net.Proxy.getDefaultHost() != null) {
+			this.usePolling = true;
+		}
+		else {
+			this.usePolling = false;
+			this.startServer();
+		}
+	}
+	
+	/**
+	 * Determine if polling should be used instead of XHR.
+	 * 
+	 * @return
+	 */
+	public boolean usePolling() {
+		return this.usePolling;
 	}
 	
 	/**
diff --git a/framework/src/com/phonegap/api/Plugin.java b/framework/src/com/phonegap/api/Plugin.java
index c16c6960..f22e4972 100755
--- a/framework/src/com/phonegap/api/Plugin.java
+++ b/framework/src/com/phonegap/api/Plugin.java
@@ -99,7 +99,7 @@ public abstract class Plugin implements IPlugin {
      * @param statement
      */
     public void sendJavascript(String statement) {
-    	this.ctx.callbackServer.sendJavascript(statement);
+    	this.ctx.sendJavascript(statement);
     }
 
     /**
@@ -113,7 +113,7 @@ public abstract class Plugin implements IPlugin {
 	 * @param callbackId		The callback id used when calling back into JavaScript.
      */
     public void success(PluginResult pluginResult, String callbackId) {
-    	this.ctx.callbackServer.sendJavascript(pluginResult.toSuccessCallbackString(callbackId));
+    	this.ctx.sendJavascript(pluginResult.toSuccessCallbackString(callbackId));
     }
 
     /**
@@ -123,6 +123,6 @@ public abstract class Plugin implements IPlugin {
 	 * @param callbackId		The callback id used when calling back into JavaScript.
      */
     public void error(PluginResult pluginResult, String callbackId) {
-    	this.ctx.callbackServer.sendJavascript(pluginResult.toErrorCallbackString(callbackId));
+    	this.ctx.sendJavascript(pluginResult.toErrorCallbackString(callbackId));
     }
 }