From 90dfa437e024a0967557e31ccc4ff452a15cf691 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Thu, 11 Jul 2024 21:41:33 +0200
Subject: [PATCH] lib/alsa/NonBlock: use a persistent pollfd array

This implements the semantic API change introduced by commit
https://github.com/alsa-project/alsa-lib/commit/cd04da2bcfe147b08b8db2930b2294aead0a8968
---
 NEWS                      |  1 +
 src/lib/alsa/NonBlock.cxx | 34 ++++++++++++++--------------------
 src/lib/alsa/NonBlock.hxx | 10 +++++-----
 3 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/NEWS b/NEWS
index 433328caf..8eb412698 100644
--- a/NEWS
+++ b/NEWS
@@ -31,6 +31,7 @@ ver 0.24 (not yet released)
 * input
   - alsa: limit ALSA buffer time to 2 seconds
   - alsa: set up a channel map
+  - alsa: support the alsa-lib 1.2.11 API
   - curl: add "connect_timeout" configuration
 * decoder
   - ffmpeg: require FFmpeg 4.0 or later
diff --git a/src/lib/alsa/NonBlock.cxx b/src/lib/alsa/NonBlock.cxx
index a20255bcc..3e7c5f86c 100644
--- a/src/lib/alsa/NonBlock.cxx
+++ b/src/lib/alsa/NonBlock.cxx
@@ -8,21 +8,23 @@
 namespace Alsa {
 
 std::span<pollfd>
-NonBlock::CopyReturnedEvents(MultiSocketMonitor &m, std::size_t n) noexcept
+NonBlock::CopyReturnedEvents(MultiSocketMonitor &m) noexcept
 {
-	const auto pfds = buffer.Get(n), end = pfds + n;
+	const std::span<pollfd> pfds = buffer;
 
-	auto *i = pfds;
-	m.ForEachReturnedEvent([&i, end](SocketDescriptor s, unsigned events){
-		if (i >= end)
-			return;
+	for (auto &i : pfds)
+		i.revents = 0;
 
-		i->fd = s.Get();
-		i->events = i->revents = events;
-		++i;
+	m.ForEachReturnedEvent([pfds](SocketDescriptor s, unsigned events){
+		for (auto &i : pfds) {
+			if (i.fd == s.Get()) {
+				i.revents = events;
+				return;
+			}
+		}
 	});
 
-	return {pfds, static_cast<std::size_t>(i - pfds)};
+	return pfds;
 
 }
 
@@ -54,11 +56,7 @@ NonBlockPcm::PrepareSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
 void
 NonBlockPcm::DispatchSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
 {
-	int count = snd_pcm_poll_descriptors_count(pcm);
-	if (count <= 0)
-		return;
-
-	const auto pfds = base.CopyReturnedEvents(m, count);
+	const auto pfds = base.CopyReturnedEvents(m);
 
 	unsigned short dummy;
 	int err = snd_pcm_poll_descriptors_revents(pcm, pfds.data(), pfds.size(), &dummy);
@@ -88,11 +86,7 @@ NonBlockMixer::PrepareSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcep
 void
 NonBlockMixer::DispatchSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept
 {
-	int count = snd_mixer_poll_descriptors_count(mixer);
-	if (count <= 0)
-		return;
-
-	const auto pfds = base.CopyReturnedEvents(m, count);
+	const auto pfds = base.CopyReturnedEvents(m);
 
 	unsigned short dummy;
 	snd_mixer_poll_descriptors_revents(mixer, pfds.data(), pfds.size(), &dummy);
diff --git a/src/lib/alsa/NonBlock.hxx b/src/lib/alsa/NonBlock.hxx
index 16cfb3102..0b523f166 100644
--- a/src/lib/alsa/NonBlock.hxx
+++ b/src/lib/alsa/NonBlock.hxx
@@ -4,7 +4,7 @@
 #pragma once
 
 #include "event/Chrono.hxx"
-#include "util/ReusableArray.hxx"
+#include "util/AllocatedArray.hxx"
 
 #include <alsa/asoundlib.h>
 
@@ -15,15 +15,15 @@ class MultiSocketMonitor;
 namespace Alsa {
 
 class NonBlock {
-	ReusableArray<pollfd> buffer;
+	AllocatedArray<pollfd> buffer;
 
 public:
 	std::span<pollfd> Allocate(std::size_t n) noexcept {
-		return {buffer.Get(n), n};
+		buffer.ResizeDiscard(n);
+		return buffer;
 	}
 
-	std::span<pollfd> CopyReturnedEvents(MultiSocketMonitor &m,
-					     std::size_t n) noexcept;
+	std::span<pollfd> CopyReturnedEvents(MultiSocketMonitor &m) noexcept;
 };
 
 /**