From af4ffa91fd1350b9cf6b30f7ce5384f92e5739c6 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Tue, 20 Aug 2019 19:23:44 +0200
Subject: [PATCH] decoder/Control: remove attribute `client_is_waiting`

This optimization is useless because sane pthread_cond_signal()
implementations check the number of waiters and do not invoke a system
call if there are none.
---
 src/decoder/Bridge.cxx  | 3 +--
 src/decoder/Control.cxx | 6 ------
 src/decoder/Control.hxx | 7 -------
 3 files changed, 1 insertion(+), 15 deletions(-)

diff --git a/src/decoder/Bridge.cxx b/src/decoder/Bridge.cxx
index 6d39efd7d..6fd2fbb23 100644
--- a/src/decoder/Bridge.cxx
+++ b/src/decoder/Bridge.cxx
@@ -145,8 +145,7 @@ DecoderBridge::FlushChunk() noexcept
 		dc.pipe->Push(std::move(chunk));
 
 	const std::lock_guard<Mutex> protect(dc.mutex);
-	if (dc.client_is_waiting)
-		dc.client_cond.notify_one();
+	dc.client_cond.notify_one();
 }
 
 bool
diff --git a/src/decoder/Control.cxx b/src/decoder/Control.cxx
index 6795fd01c..7d80d181f 100644
--- a/src/decoder/Control.cxx
+++ b/src/decoder/Control.cxx
@@ -43,13 +43,7 @@ DecoderControl::~DecoderControl() noexcept
 void
 DecoderControl::WaitForDecoder(std::unique_lock<Mutex> &lock) noexcept
 {
-	assert(!client_is_waiting);
-	client_is_waiting = true;
-
 	client_cond.wait(lock);
-
-	assert(client_is_waiting);
-	client_is_waiting = false;
 }
 
 void
diff --git a/src/decoder/Control.hxx b/src/decoder/Control.hxx
index ee9dde73b..363a77282 100644
--- a/src/decoder/Control.hxx
+++ b/src/decoder/Control.hxx
@@ -111,13 +111,6 @@ private:
 	bool quit;
 
 public:
-	/**
-	 * Is the client currently waiting for the DecoderThread?  If
-	 * false, the DecoderThread may omit invoking Cond::signal(),
-	 * reducing the number of system calls.
-	 */
-	bool client_is_waiting = false;
-
 	bool seek_error;
 	bool seekable;
 	SongTime seek_time;