From 3fdb3cbc6aeed9d2598f076a6740374c11d4c06f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Per=20=C3=85hgren?= <peah@webrtc.org>
Date: Wed, 11 Dec 2019 10:57:13 +0100
Subject: [PATCH] Remove potential real-time reallocation in PushResampler
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This CL removes the use of absl::InlineVector in the PushResampler which
causes real-time reallocations for setups with more than 8 channels.

As part of the CL, it also removes one dependency on absl for the
common_audio module.

Bug: webrtc:11197
Change-Id: I0788ee9a0f3d08b91bb18caa65f660fb52368a97
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/161729
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30059}
---
 common_audio/BUILD.gn                           |  1 -
 common_audio/resampler/include/push_resampler.h |  5 +++++
 common_audio/resampler/push_resampler.cc        | 17 ++++++++---------
 3 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/common_audio/BUILD.gn b/common_audio/BUILD.gn
index 7170000740..8b18fcbf92 100644
--- a/common_audio/BUILD.gn
+++ b/common_audio/BUILD.gn
@@ -58,7 +58,6 @@ rtc_library("common_audio") {
     "../system_wrappers",
     "../system_wrappers:cpu_features_api",
     "third_party/fft4g",
-    "//third_party/abseil-cpp/absl/container:inlined_vector",
     "//third_party/abseil-cpp/absl/types:optional",
   ]
 
diff --git a/common_audio/resampler/include/push_resampler.h b/common_audio/resampler/include/push_resampler.h
index 232ad2a79f..3da67120f0 100644
--- a/common_audio/resampler/include/push_resampler.h
+++ b/common_audio/resampler/include/push_resampler.h
@@ -40,6 +40,11 @@ class PushResampler {
   int src_sample_rate_hz_;
   int dst_sample_rate_hz_;
   size_t num_channels_;
+  // Vector that is needed to provide the proper inputs and outputs to the
+  // interleave/de-interleave methods used in Resample. This needs to be
+  // heap-allocated on the state to support an arbitrary number of channels
+  // without doing run-time heap-allocations in the Resample method.
+  std::vector<T*> channel_data_array_;
 
   struct ChannelResampler {
     std::unique_ptr<PushSincResampler> resampler;
diff --git a/common_audio/resampler/push_resampler.cc b/common_audio/resampler/push_resampler.cc
index 17b876b6b2..d7aa8d7613 100644
--- a/common_audio/resampler/push_resampler.cc
+++ b/common_audio/resampler/push_resampler.cc
@@ -15,7 +15,6 @@
 
 #include <memory>
 
-#include "absl/container/inlined_vector.h"
 #include "common_audio/include/audio_util.h"
 #include "common_audio/resampler/push_sinc_resampler.h"
 #include "rtc_base/checks.h"
@@ -100,6 +99,8 @@ int PushResampler<T>::InitializeIfNeeded(int src_sample_rate_hz,
     channel_resampler->destination.resize(dst_size_10ms_mono);
   }
 
+  channel_data_array_.resize(num_channels_);
+
   return 0;
 }
 
@@ -121,12 +122,11 @@ int PushResampler<T>::Resample(const T* src,
   const size_t src_length_mono = src_length / num_channels_;
   const size_t dst_capacity_mono = dst_capacity / num_channels_;
 
-  absl::InlinedVector<T*, 8> source_pointers;
-  for (auto& resampler : channel_resamplers_) {
-    source_pointers.push_back(resampler.source.data());
+  for (size_t ch = 0; ch < num_channels_; ++ch) {
+    channel_data_array_[ch] = channel_resamplers_[ch].source.data();
   }
 
-  Deinterleave(src, src_length_mono, num_channels_, source_pointers.data());
+  Deinterleave(src, src_length_mono, num_channels_, channel_data_array_.data());
 
   size_t dst_length_mono = 0;
 
@@ -136,12 +136,11 @@ int PushResampler<T>::Resample(const T* src,
         dst_capacity_mono);
   }
 
-  absl::InlinedVector<T*, 8> destination_pointers;
-  for (auto& resampler : channel_resamplers_) {
-    destination_pointers.push_back(resampler.destination.data());
+  for (size_t ch = 0; ch < num_channels_; ++ch) {
+    channel_data_array_[ch] = channel_resamplers_[ch].destination.data();
   }
 
-  Interleave(destination_pointers.data(), dst_length_mono, num_channels_, dst);
+  Interleave(channel_data_array_.data(), dst_length_mono, num_channels_, dst);
   return static_cast<int>(dst_length_mono * num_channels_);
 }