From 2fd5b206ff9d981ff63265678a60735781b0c0d8 Mon Sep 17 00:00:00 2001
From: Chris Schechter <schechte@adobe.com>
Date: Mon, 24 Feb 2020 17:11:11 -0800
Subject: [PATCH] okhttp: unit testing sending initialWindowSize in settings

---
 .../io/grpc/okhttp/OkHttpClientTransport.java | 28 ++++++++++-------
 .../okhttp/OkHttpClientTransportTest.java     | 30 +++++++++++++++++++
 2 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/okhttp/src/main/java/io/grpc/okhttp/OkHttpClientTransport.java b/okhttp/src/main/java/io/grpc/okhttp/OkHttpClientTransport.java
index bde9b010543c..8bfd50a2c2f4 100644
--- a/okhttp/src/main/java/io/grpc/okhttp/OkHttpClientTransport.java
+++ b/okhttp/src/main/java/io/grpc/okhttp/OkHttpClientTransport.java
@@ -605,16 +605,7 @@ sslSocketFactory, hostnameVerifier, sock, getOverridenHost(), getOverridenPort()
     });
     // Schedule to send connection preface & settings before any other write.
     try {
-      synchronized (lock) {
-        frameWriter.connectionPreface();
-        Settings settings = new Settings();
-        OkHttpSettingsUtil.set(settings, OkHttpSettingsUtil.INITIAL_WINDOW_SIZE, initialWindowSize);
-        frameWriter.settings(settings);
-        if (initialWindowSize > DEFAULT_WINDOW_SIZE) {
-          frameWriter.windowUpdate(
-              Utils.CONNECTION_STREAM_ID, initialWindowSize - DEFAULT_WINDOW_SIZE);
-        }
-      }
+      sendConnectionPrefaceAndSettings();
     } finally {
       latch.countDown();
     }
@@ -634,6 +625,23 @@ public void run() {
     return null;
   }
 
+  /**
+   * Should only be called once when the transport is first established.
+   */
+  @VisibleForTesting
+  void sendConnectionPrefaceAndSettings() {
+    synchronized (lock) {
+      frameWriter.connectionPreface();
+      Settings settings = new Settings();
+      OkHttpSettingsUtil.set(settings, OkHttpSettingsUtil.INITIAL_WINDOW_SIZE, initialWindowSize);
+      frameWriter.settings(settings);
+      if (initialWindowSize > DEFAULT_WINDOW_SIZE) {
+        frameWriter.windowUpdate(
+                Utils.CONNECTION_STREAM_ID, initialWindowSize - DEFAULT_WINDOW_SIZE);
+      }
+    }
+  }
+
   private Socket createHttpProxySocket(InetSocketAddress address, InetSocketAddress proxyAddress,
       String proxyUsername, String proxyPassword) throws StatusException {
     try {
diff --git a/okhttp/src/test/java/io/grpc/okhttp/OkHttpClientTransportTest.java b/okhttp/src/test/java/io/grpc/okhttp/OkHttpClientTransportTest.java
index 3b4b9bcfdf7a..091105efdd25 100644
--- a/okhttp/src/test/java/io/grpc/okhttp/OkHttpClientTransportTest.java
+++ b/okhttp/src/test/java/io/grpc/okhttp/OkHttpClientTransportTest.java
@@ -404,6 +404,36 @@ public void maxMessageSizeShouldBeEnforced() throws Exception {
     shutdownAndVerify();
   }
 
+  @Test
+  public void includeInitialWindowSizeInFirstSettings() throws Exception {
+    int initialWindowSize = 65535;
+    startTransport(
+            DEFAULT_START_STREAM_ID, null, true, DEFAULT_MAX_MESSAGE_SIZE, initialWindowSize, null);
+    clientTransport.sendConnectionPrefaceAndSettings();
+
+    ArgumentCaptor<Settings> settings = ArgumentCaptor.forClass(Settings.class);
+    verify(frameWriter, timeout(TIME_OUT_MS)).settings(settings.capture());
+    assertEquals(65535, settings.getValue().get(7));
+  }
+
+  /**
+   * A "large" window size is anything over 65535 (the starting size for any connection-level
+   * flow control value).
+   */
+  @Test
+  public void includeInitialWindowSizeInFirstSettings_largeWindowSize() throws Exception {
+    int initialWindowSize = 75535; // 65535 + 10000
+    startTransport(
+            DEFAULT_START_STREAM_ID, null, true, DEFAULT_MAX_MESSAGE_SIZE, initialWindowSize, null);
+    clientTransport.sendConnectionPrefaceAndSettings();
+
+    ArgumentCaptor<Settings> settings = ArgumentCaptor.forClass(Settings.class);
+    verify(frameWriter, timeout(TIME_OUT_MS)).settings(settings.capture());
+    assertEquals(75535, settings.getValue().get(7));
+
+    verify(frameWriter, timeout(TIME_OUT_MS)).windowUpdate(0, 10000);
+  }
+
   /**
    * When nextFrame throws IOException, the transport should be aborted.
    */