Make interval budget use ratio instead of percent

All usages compare the budget usage to ratios, so we can skip a few
multiplications.

Bug: webrtc:10719
Change-Id: I0205d74762043d972c087c152915e4fdd9510057
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/140289
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28190}

modules/congestion_controller/goog_cc/alr_detector.cc

@@ -92,12 +92,11 @@ void AlrDetector::OnBytesSent(size_t bytes_sent, int64_t send_time_ms) {
   alr_budget_.UseBudget(bytes_sent);
   alr_budget_.IncreaseBudget(delta_time_ms);
   bool state_changed = false;
-  if (alr_budget_.budget_level_percent() > start_budget_level_ratio_ * 100 &&
+  if (alr_budget_.budget_ratio() > start_budget_level_ratio_ &&
       !alr_started_time_ms_) {
     alr_started_time_ms_.emplace(rtc::TimeMillis());
     state_changed = true;
-  } else if (alr_budget_.budget_level_percent() <
-                 stop_budget_level_ratio_ * 100 &&
+  } else if (alr_budget_.budget_ratio() < stop_budget_level_ratio_ &&
              alr_started_time_ms_) {
     state_changed = true;
     alr_started_time_ms_.reset();

modules/pacing/interval_budget.cc

@@ -8,9 +8,10 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include "modules/pacing/interval_budget.h"
+
 #include <algorithm>
 
-#include "modules/pacing/interval_budget.h"
 #include "rtc_base/numerics/safe_conversions.h"
 
 namespace webrtc {
@@ -54,11 +55,10 @@ size_t IntervalBudget::bytes_remaining() const {
   return static_cast<size_t>(std::max(0, bytes_remaining_));
 }
 
-int IntervalBudget::budget_level_percent() const {
+double IntervalBudget::budget_ratio() const {
   if (max_bytes_in_budget_ == 0)
-    return 0;
-  return rtc::dchecked_cast<int>(int64_t{bytes_remaining_} * 100 /
-                                 max_bytes_in_budget_);
+    return 0.0;
+  return static_cast<double>(bytes_remaining_) / max_bytes_in_budget_;
 }
 
 int IntervalBudget::target_rate_kbps() const {

modules/pacing/interval_budget.h

@@ -29,7 +29,7 @@ class IntervalBudget {
   void UseBudget(size_t bytes);
 
   size_t bytes_remaining() const;
-  int budget_level_percent() const;
+  double budget_ratio() const;
   int target_rate_kbps() const;
 
  private:

modules/pacing/interval_budget_unittest.cc

@@ -26,7 +26,7 @@ size_t TimeToBytes(int bitrate_kbps, int time_ms) {
 
 TEST(IntervalBudgetTest, InitailState) {
   IntervalBudget interval_budget(kBitrateKbps);
-  EXPECT_EQ(interval_budget.budget_level_percent(), 0);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(), 0.0);
   EXPECT_EQ(interval_budget.bytes_remaining(), 0u);
 }
 
@@ -34,7 +34,8 @@ TEST(IntervalBudgetTest, Underuse) {
   IntervalBudget interval_budget(kBitrateKbps);
   int delta_time_ms = 50;
   interval_budget.IncreaseBudget(delta_time_ms);
-  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(),
+                   kWindowMs / static_cast<double>(100 * delta_time_ms));
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, delta_time_ms));
 }
@@ -43,7 +44,7 @@ TEST(IntervalBudgetTest, DontUnderuseMoreThanMaxWindow) {
   IntervalBudget interval_budget(kBitrateKbps);
   int delta_time_ms = 1000;
   interval_budget.IncreaseBudget(delta_time_ms);
-  EXPECT_EQ(interval_budget.budget_level_percent(), 100);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(), 1.0);
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, kWindowMs));
 }
@@ -53,7 +54,7 @@ TEST(IntervalBudgetTest, DontUnderuseMoreThanMaxWindowWhenChangeBitrate) {
   int delta_time_ms = kWindowMs / 2;
   interval_budget.IncreaseBudget(delta_time_ms);
   interval_budget.set_target_rate_kbps(kBitrateKbps / 10);
-  EXPECT_EQ(interval_budget.budget_level_percent(), 100);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(), 1.0);
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps / 10, kWindowMs));
 }
@@ -63,7 +64,7 @@ TEST(IntervalBudgetTest, BalanceChangeOnBitrateChange) {
   int delta_time_ms = kWindowMs;
   interval_budget.IncreaseBudget(delta_time_ms);
   interval_budget.set_target_rate_kbps(kBitrateKbps * 2);
-  EXPECT_EQ(interval_budget.budget_level_percent(), 50);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(), 0.5);
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, kWindowMs));
 }
@@ -73,8 +74,8 @@ TEST(IntervalBudgetTest, Overuse) {
   int overuse_time_ms = 50;
   int used_bytes = TimeToBytes(kBitrateKbps, overuse_time_ms);
   interval_budget.UseBudget(used_bytes);
-  EXPECT_EQ(interval_budget.budget_level_percent(),
-            -kWindowMs / overuse_time_ms);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(),
+                   -kWindowMs / static_cast<double>(100 * overuse_time_ms));
   EXPECT_EQ(interval_budget.bytes_remaining(), 0u);
 }
 
@@ -83,7 +84,7 @@ TEST(IntervalBudgetTest, DontOveruseMoreThanMaxWindow) {
   int overuse_time_ms = 1000;
   int used_bytes = TimeToBytes(kBitrateKbps, overuse_time_ms);
   interval_budget.UseBudget(used_bytes);
-  EXPECT_EQ(interval_budget.budget_level_percent(), -100);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(), -1.0);
   EXPECT_EQ(interval_budget.bytes_remaining(), 0u);
 }
 
@@ -91,13 +92,14 @@ TEST(IntervalBudgetTest, CanBuildUpUnderuseWhenConfigured) {
   IntervalBudget interval_budget(kBitrateKbps, kCanBuildUpUnderuse);
   int delta_time_ms = 50;
   interval_budget.IncreaseBudget(delta_time_ms);
-  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(),
+                   kWindowMs / static_cast<double>(100 * delta_time_ms));
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, delta_time_ms));
 
   interval_budget.IncreaseBudget(delta_time_ms);
-  EXPECT_EQ(interval_budget.budget_level_percent(),
-            2 * kWindowMs / delta_time_ms);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(),
+                   2 * kWindowMs / static_cast<double>(100 * delta_time_ms));
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, 2 * delta_time_ms));
 }
@@ -106,12 +108,14 @@ TEST(IntervalBudgetTest, CanNotBuildUpUnderuseWhenConfigured) {
   IntervalBudget interval_budget(kBitrateKbps, kCanNotBuildUpUnderuse);
   int delta_time_ms = 50;
   interval_budget.IncreaseBudget(delta_time_ms);
-  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(),
+                   kWindowMs / static_cast<double>(100 * delta_time_ms));
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, delta_time_ms));
 
   interval_budget.IncreaseBudget(delta_time_ms);
-  EXPECT_EQ(interval_budget.budget_level_percent(), kWindowMs / delta_time_ms);
+  EXPECT_DOUBLE_EQ(interval_budget.budget_ratio(),
+                   kWindowMs / static_cast<double>(100 * delta_time_ms));
   EXPECT_EQ(interval_budget.bytes_remaining(),
             TimeToBytes(kBitrateKbps, delta_time_ms));
 }