From a6368d17c5ec52355f332d869996a1946535826f Mon Sep 17 00:00:00 2001
From: JT Teh <jtteh@webrtc.org>
Date: Thu, 28 Sep 2017 11:00:39 -0700
Subject: [PATCH] Fix occassional hang in iOS 11 when calling
 VTDecompressionSessionInvalidate.
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BUG=webrtc:8302

Change-Id: I426116c621c53a0300f87a2a5dc147578b559ed6
Reviewed-on: https://webrtc-review.googlesource.com/4520
Reviewed-by: Zeke Chin <tkchin@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: JT Teh <jtteh@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20026}
---
 sdk/objc/Framework/Classes/Common/UIDevice+RTCDevice.mm     | 4 ++++
 .../Framework/Classes/VideoToolbox/RTCVideoDecoderH264.mm   | 6 ++++++
 sdk/objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h      | 1 +
 3 files changed, 11 insertions(+)

diff --git a/sdk/objc/Framework/Classes/Common/UIDevice+RTCDevice.mm b/sdk/objc/Framework/Classes/Common/UIDevice+RTCDevice.mm
index 94faf53506..01905d99eb 100644
--- a/sdk/objc/Framework/Classes/Common/UIDevice+RTCDevice.mm
+++ b/sdk/objc/Framework/Classes/Common/UIDevice+RTCDevice.mm
@@ -173,4 +173,8 @@
   return [self currentDeviceSystemVersion] >= 9.0;
 }
 
++ (BOOL)isIOS11OrLater {
+  return [self currentDeviceSystemVersion] >= 11.0;
+}
+
 @end
diff --git a/sdk/objc/Framework/Classes/VideoToolbox/RTCVideoDecoderH264.mm b/sdk/objc/Framework/Classes/VideoToolbox/RTCVideoDecoderH264.mm
index 6e000ab747..4cf48bd9c4 100644
--- a/sdk/objc/Framework/Classes/VideoToolbox/RTCVideoDecoderH264.mm
+++ b/sdk/objc/Framework/Classes/VideoToolbox/RTCVideoDecoderH264.mm
@@ -25,6 +25,7 @@
 
 #if defined(WEBRTC_IOS)
 #import "Common/RTCUIApplicationStatusObserver.h"
+#import "WebRTC/UIDevice+RTCDevice.h"
 #endif
 
 // Struct that we pass to the decoder per frame to decode. We receive it again
@@ -236,6 +237,11 @@ void decompressionOutputCallback(void *decoder,
 
 - (void)destroyDecompressionSession {
   if (_decompressionSession) {
+#if defined(WEBRTC_IOS)
+    if ([UIDevice isIOS11OrLater]) {
+      VTDecompressionSessionWaitForAsynchronousFrames(_decompressionSession);
+    }
+#endif
     VTDecompressionSessionInvalidate(_decompressionSession);
     CFRelease(_decompressionSession);
     _decompressionSession = nullptr;
diff --git a/sdk/objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h b/sdk/objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h
index 29e4801b2e..7e01c47f39 100644
--- a/sdk/objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h
+++ b/sdk/objc/Framework/Headers/WebRTC/UIDevice+RTCDevice.h
@@ -60,5 +60,6 @@ typedef NS_ENUM(NSInteger, RTCDeviceType) {
 + (RTCDeviceType)deviceType;
 + (NSString *)stringForDeviceType:(RTCDeviceType)deviceType;
 + (BOOL)isIOS9OrLater;
++ (BOOL)isIOS11OrLater;
 
 @end