From 4cd6221127fb5c1c7719be01162af1ed37d09d90 Mon Sep 17 00:00:00 2001
From: tkchin <tkchin@webrtc.org>
Date: Thu, 15 Dec 2016 13:17:54 -0800
Subject: [PATCH] iOS: Add trendline filter to field trials.

NOTRY=True
BUG=webrtc:6902

Review-Url: https://codereview.webrtc.org/2583643002
Cr-Commit-Position: refs/heads/master@{#15643}
---
 .../objc/AppRTCMobile/ios/ARDAppDelegate.m    |  5 ++-
 .../objc/Framework/Classes/RTCFieldTrials.mm  | 37 +++++++++++--------
 .../Framework/Headers/WebRTC/RTCFieldTrials.h | 25 +++++++++----
 3 files changed, 43 insertions(+), 24 deletions(-)

diff --git a/webrtc/examples/objc/AppRTCMobile/ios/ARDAppDelegate.m b/webrtc/examples/objc/AppRTCMobile/ios/ARDAppDelegate.m
index 6081d60c69..31f9fcd03a 100644
--- a/webrtc/examples/objc/AppRTCMobile/ios/ARDAppDelegate.m
+++ b/webrtc/examples/objc/AppRTCMobile/ios/ARDAppDelegate.m
@@ -25,7 +25,10 @@
 
 - (BOOL)application:(UIApplication *)application
     didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
-  RTCInitFieldTrials(RTCFieldTrialOptionsImprovedBitrateEstimate);
+  NSDictionary *fieldTrials = @{
+    kRTCFieldTrialImprovedBitrateEstimateKey: kRTCFieldTrialEnabledValue,
+  };
+  RTCInitFieldTrialDictionary(fieldTrials);
   RTCInitializeSSL();
   RTCSetupInternalTracer();
   _window =  [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCFieldTrials.mm b/webrtc/sdk/objc/Framework/Classes/RTCFieldTrials.mm
index 3057a17aed..224f7fd595 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCFieldTrials.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCFieldTrials.mm
@@ -16,24 +16,31 @@
 
 #include "webrtc/system_wrappers/include/field_trial_default.h"
 
-static NSString * const kRTCEnableImprovedBitrateEstimateString =
-    @"WebRTC-ImprovedBitrateEstimate/Enabled/";
-static NSString * const kRTCEnableAudioSendSideBweString =
-    @"WebRTC-Audio-SendSideBwe/Enabled/";
-static NSString * const kRTCEnableFlexFec03String =
-    @"WebRTC-FlexFEC-03/Enabled/";
+NSString * const kRTCFieldTrialAudioSendSideBweKey = @"WebRTC-Audio-SendSideBwe";
+NSString * const kRTCFieldTrialFlexFec03Key = @"WebRTC-FlexFEC-03";
+NSString * const kRTCFieldTrialImprovedBitrateEstimateKey = @"WebRTC-ImprovedBitrateEstimate";
+NSString * const kRTCFieldTrialTrendlineFilterKey = @"WebRTC-BweTrendlineFilter";
+NSString * const kRTCFieldTrialEnabledValue = @"Enabled";
+
 static std::unique_ptr<char[]> gFieldTrialInitString;
 
-void RTCInitFieldTrials(RTCFieldTrialOptions options) {
+NSString *RTCFieldTrialTrendlineFilterValue(
+    size_t windowSize, double smoothingCoeff, double thresholdGain) {
+  NSString *format = @"Enabled-%zu,%lf,%lf";
+  return [NSString stringWithFormat:format, windowSize, smoothingCoeff, thresholdGain];
+}
+
+void RTCInitFieldTrialDictionary(NSDictionary<NSString *, NSString *> *fieldTrials) {
+  if (!fieldTrials) {
+    RTCLogWarning(@"No fieldTrials provided.");
+    return;
+  }
+  // Assemble the keys and values into the field trial string.
+  // We don't perform any extra format checking. That should be done by the underlying WebRTC calls.
   NSMutableString *fieldTrialInitString = [NSMutableString string];
-  if (options & RTCFieldTrialOptionsImprovedBitrateEstimate) {
-    [fieldTrialInitString appendString:kRTCEnableImprovedBitrateEstimateString];
-  }
-  if (options & RTCFieldTrialOptionsAudioSendSideBwe) {
-    [fieldTrialInitString appendString:kRTCEnableAudioSendSideBweString];
-  }
-  if (options & RTCFieldTrialOptionsFlexFec03) {
-    [fieldTrialInitString appendString:kRTCEnableFlexFec03String];
+  for (NSString *key in fieldTrials) {
+    NSString *fieldTrialEntry = [NSString stringWithFormat:@"%@/%@/", key, fieldTrials[key]];
+    [fieldTrialInitString appendString:fieldTrialEntry];
   }
   size_t len = fieldTrialInitString.length + 1;
   gFieldTrialInitString.reset(new char[len]);
diff --git a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
index 504ff7a885..ee997888c1 100644
--- a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
+++ b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
@@ -12,14 +12,23 @@
 
 #import <WebRTC/RTCMacros.h>
 
-typedef NS_OPTIONS(NSUInteger, RTCFieldTrialOptions) {
-  RTCFieldTrialOptionsNone = 0,
-  RTCFieldTrialOptionsImprovedBitrateEstimate = 1 << 0,
-  RTCFieldTrialOptionsAudioSendSideBwe = 1 << 1,
-  RTCFieldTrialOptionsFlexFec03 = 1 << 2,
-};
+/** The only valid value for the following if set is kRTCFieldTrialEnabledValue. */
+RTC_EXTERN NSString * const kRTCFieldTrialAudioSendSideBweKey;
+RTC_EXTERN NSString * const kRTCFieldTrialFlexFec03Key;
+RTC_EXTERN NSString * const kRTCFieldTrialImprovedBitrateEstimateKey;
 
-/** Must be called before any other call into WebRTC. See:
+/** The valid value for field trials above. */
+RTC_EXTERN NSString * const kRTCFieldTrialEnabledValue;
+
+/** Use a string returned by RTCFieldTrialTrendlineFilterValue as the value. */
+RTC_EXTERN NSString * const kRTCFieldTrialTrendlineFilterKey;
+/** Returns a valid value for kRTCFieldTrialTrendlineFilterKey. */
+RTC_EXTERN NSString *RTCFieldTrialTrendlineFilterValue(
+    size_t windowSize, double smoothingCoeff, double thresholdGain);
+
+/** Initialize field trials using a dictionary mapping field trial keys to their values. See above
+ *  for valid keys and values.
+ *  Must be called before any other call into WebRTC. See:
  *  webrtc/system_wrappers/include/field_trial_default.h
  */
-RTC_EXTERN void RTCInitFieldTrials(RTCFieldTrialOptions options);
+RTC_EXTERN void RTCInitFieldTrialDictionary(NSDictionary<NSString *, NSString *> *fieldTrials);