From 87bb570e2450549cc8b4c6b7669e3db574749346 Mon Sep 17 00:00:00 2001
From: Kirill Kirilenko <kirill@ultracoder.org>
Date: Fri, 13 Nov 2020 14:36:13 +0300
Subject: [PATCH] Use condition variable to suspend audio processing thread

---
 src/AudioProcessor.cpp | 10 +++++++++-
 src/AudioProcessor.h   |  4 ++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/AudioProcessor.cpp b/src/AudioProcessor.cpp
index a817bec..04cbd7e 100644
--- a/src/AudioProcessor.cpp
+++ b/src/AudioProcessor.cpp
@@ -70,8 +70,10 @@ qint64 AudioProcessor::readData(char* data, qint64 maxlen)
 
 qint64 AudioProcessor::writeData(const char* data, qint64 len)
 {
-	std::unique_lock<std::mutex> lock(inputMutex_);
+	std::unique_lock<std::mutex> lock1(inputMutex_);
+	std::unique_lock<std::mutex> lock2(inputEventMutex_);
 	inputBuffer_.append(data, len);
+	inputEvent_.notify_all();
 	return len;
 }
 
@@ -122,6 +124,12 @@ void AudioProcessor::process()
 				emit readyRead();
 			}
 		}
+		else
+		{
+			processLock.unlock();
+			std::unique_lock<std::mutex> lock(inputEventMutex_);
+			inputEvent_.wait(lock);
+		}
 	}
 }
 
diff --git a/src/AudioProcessor.h b/src/AudioProcessor.h
index ccbf5e9..afc176e 100644
--- a/src/AudioProcessor.h
+++ b/src/AudioProcessor.h
@@ -9,6 +9,7 @@
 #include <QIODevice>
 #include <QScopedPointer>
 
+#include <condition_variable>
 #include <mutex>
 #include <thread>
 
@@ -79,6 +80,9 @@ private:
 	std::thread worker_;
 	bool doWork_ = false;
 
+	std::condition_variable inputEvent_;
+	std::mutex inputEventMutex_;
+
 	QScopedPointer<WavFileWriter> sourceEncoder_;
 	QScopedPointer<WavFileWriter> processedEncoder_;
 };