Refactor how padding is calculated.

webrtc/call/bitrate_allocator.cc

Index: webrtc/call/bitrate_allocator.cc
diff --git a/webrtc/call/bitrate_allocator.cc b/webrtc/call/bitrate_allocator.cc
index 3672ef520ca3422bc372d2108b75abf9b5390666..2d56ff80b399472d7650c3d53ad6c5f7f30db842 100644
--- a/webrtc/call/bitrate_allocator.cc
+++ b/webrtc/call/bitrate_allocator.cc
@@ -24,17 +24,18 @@ namespace webrtc {
 const int kTransmissionMaxBitrateMultiplier = 2;
 const int kDefaultBitrateBps = 300000;
 
-BitrateAllocator::BitrateAllocator()
-    : bitrate_observer_configs_(),
+BitrateAllocator::BitrateAllocator(LimitObserver* limit_observer)
+    : limit_observer_(limit_observer),
+      bitrate_observer_configs_(),
       enforce_min_bitrate_(true),
       last_bitrate_bps_(kDefaultBitrateBps),
       last_non_zero_bitrate_bps_(kDefaultBitrateBps),
       last_fraction_loss_(0),
       last_rtt_(0) {}
 
-uint32_t BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
-                                            uint8_t fraction_loss,
-                                            int64_t rtt) {
+void BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
+                                        uint8_t fraction_loss,
+                                        int64_t rtt) {
   rtc::CritScope lock(&crit_sect_);
   last_bitrate_bps_ = bitrate;
   last_non_zero_bitrate_bps_ =
@@ -42,67 +43,92 @@ uint32_t BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
   last_fraction_loss_ = fraction_loss;
   last_rtt_ = rtt;
 
-  uint32_t allocated_bitrate_bps = 0;
   ObserverAllocation allocation = AllocateBitrates(bitrate);
   for (const auto& kv : allocation) {
     kv.first->OnBitrateUpdated(kv.second, last_fraction_loss_, last_rtt_);
-    allocated_bitrate_bps += kv.second;
   }
-  return allocated_bitrate_bps;
 }
 
 int BitrateAllocator::AddObserver(BitrateAllocatorObserver* observer,
                                   uint32_t min_bitrate_bps,
                                   uint32_t max_bitrate_bps,
+                                  uint32_t pad_up_bitrate_bps,
                                   bool enforce_min_bitrate) {
+  int new_observer_bitrate_bps = 0;
   rtc::CritScope lock(&crit_sect_);
-  // TODO(mflodman): Enforce this per observer.
-  EnforceMinBitrate(enforce_min_bitrate);
-
-  auto it = FindObserverConfig(observer);
-
-  // Allow the max bitrate to be exceeded for FEC and retransmissions.
-  // TODO(holmer): We have to get rid of this hack as it makes it difficult to
-  // properly allocate bitrate. The allocator should instead distribute any
-  // extra bitrate after all streams have maxed out.
-  max_bitrate_bps *= kTransmissionMaxBitrateMultiplier;
-  if (it != bitrate_observer_configs_.end()) {
-    // Update current configuration.
-    it->min_bitrate_bps = min_bitrate_bps;
-    it->max_bitrate_bps = max_bitrate_bps;
-  } else {
-    // Add new settings.
-    bitrate_observer_configs_.push_back(ObserverConfig(
-        observer, min_bitrate_bps, max_bitrate_bps, enforce_min_bitrate));
-  }
+  {
+    // TODO(mflodman): Enforce this per observer.
+    EnforceMinBitrate(enforce_min_bitrate);
+
+    auto it = FindObserverConfig(observer);
+
+    // Allow the max bitrate to be exceeded for FEC and retransmissions.
+    // TODO(holmer): We have to get rid of this hack as it makes it difficult to
+    // properly allocate bitrate. The allocator should instead distribute any
+    // extra bitrate after all streams have maxed out.
+    max_bitrate_bps *= kTransmissionMaxBitrateMultiplier;
+    if (it != bitrate_observer_configs_.end()) {
+      // Update current configuration.
+      it->min_bitrate_bps = min_bitrate_bps;
+      it->max_bitrate_bps = max_bitrate_bps;
+      it->pad_up_bitrate_bps = pad_up_bitrate_bps;
+    } else {
+      // Add new settings.
+      bitrate_observer_configs_.push_back(
+          ObserverConfig(observer, min_bitrate_bps, max_bitrate_bps,
+                         pad_up_bitrate_bps, enforce_min_bitrate));
+    }
 
-  int new_observer_bitrate_bps = 0;
-  if (last_bitrate_bps_ > 0) {  // We have a bitrate to allocate.
-    ObserverAllocation allocation = AllocateBitrates(last_bitrate_bps_);
-    for (auto& kv : allocation) {
-      // Update all observers with the new allocation.
-      kv.first->OnBitrateUpdated(kv.second, last_fraction_loss_, last_rtt_);
-      if (kv.first == observer)
-        new_observer_bitrate_bps = kv.second;
+    if (last_bitrate_bps_ > 0) {  // We have a bitrate to allocate.
+      ObserverAllocation allocation = AllocateBitrates(last_bitrate_bps_);
+      for (auto& kv : allocation) {
+        // Update all observers with the new allocation.
+        kv.first->OnBitrateUpdated(kv.second, last_fraction_loss_, last_rtt_);
+        if (kv.first == observer)
+          new_observer_bitrate_bps = kv.second;
+      }
+    } else {
+      // Currently, an encoder is not allowed to produce frames.
+      // But we still have to return the initial config bitrate + let the
+      // observer know that it can not produce frames.
+      ObserverAllocation allocation =
+          AllocateBitrates(last_non_zero_bitrate_bps_);
+      observer->OnBitrateUpdated(0, last_fraction_loss_, last_rtt_);
+      new_observer_bitrate_bps = allocation[observer];
     }
-  } else {
-    // Currently, an encoder is not allowed to produce frames.
-    // But we still have to return the initial config bitrate + let the
-    // observer know that it can not produce frames.
-    ObserverAllocation allocation =
-        AllocateBitrates(last_non_zero_bitrate_bps_);
-    observer->OnBitrateUpdated(0, last_fraction_loss_, last_rtt_);
-    new_observer_bitrate_bps = allocation[observer];
   }
+  UpdateAllocationLimits();
+
   return new_observer_bitrate_bps;
 }
 
+void BitrateAllocator::UpdateAllocationLimits() {
+  uint32_t total_requested_padding_bitrate = 0;
+  uint32_t total_requested_min_bitrate = 0;
+
+  {
+    rtc::CritScope lock(&crit_sect_);
+    for (const auto& config : bitrate_observer_configs_) {
+      if (enforce_min_bitrate_) {
+        total_requested_min_bitrate += config.min_bitrate_bps;
+      }
+      total_requested_padding_bitrate += config.pad_up_bitrate_bps;
+    }
+  }
+
+  limit_observer_->OnAllocationLimitsChanged(total_requested_min_bitrate,
+                                             total_requested_padding_bitrate);
+}
+
 void BitrateAllocator::RemoveObserver(BitrateAllocatorObserver* observer) {
-  rtc::CritScope lock(&crit_sect_);
-  auto it = FindObserverConfig(observer);
-  if (it != bitrate_observer_configs_.end()) {
-    bitrate_observer_configs_.erase(it);
+  {
+    rtc::CritScope lock(&crit_sect_);
+    auto it = FindObserverConfig(observer);
+    if (it != bitrate_observer_configs_.end()) {
+      bitrate_observer_configs_.erase(it);
+    }
   }
+  UpdateAllocationLimits();
 }
 
 void BitrateAllocator::EnforceMinBitrate(bool enforce_min_bitrate) {