From bafde1900b86c1ac82c129631701a8db151b0f0c Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Mon, 23 Jan 2023 14:55:04 +0100
Subject: [PATCH] lib/nfs/Manager: use IntrusiveList instead of
 boost::intrusive::set

MPD usually has only one NFS connection, maybe two, so managing them
in a tree seems like overkill, and since we want to get rid of Boost
anyway...
---
 src/lib/nfs/Manager.cxx | 59 +++++++----------------------------------
 src/lib/nfs/Manager.hxx | 38 ++++----------------------
 2 files changed, 15 insertions(+), 82 deletions(-)

diff --git a/src/lib/nfs/Manager.cxx b/src/lib/nfs/Manager.cxx
index 8d314429f..22b3c7775 100644
--- a/src/lib/nfs/Manager.cxx
+++ b/src/lib/nfs/Manager.cxx
@@ -22,10 +22,9 @@
 #include "event/Loop.hxx"
 #include "util/DeleteDisposer.hxx"
 #include "util/Domain.hxx"
+#include "util/StringAPI.hxx"
 #include "Log.hxx"
 
-#include <string.h>
-
 static constexpr Domain nfs_domain("nfs");
 
 void
@@ -40,42 +39,6 @@ NfsManager::ManagedConnection::OnNfsConnectionError(std::exception_ptr &&e) noex
 	manager.ScheduleDelete(*this);
 }
 
-inline bool
-NfsManager::Compare::operator()(const LookupKey a,
-				const ManagedConnection &b) const noexcept
-{
-	int result = strcmp(a.server, b.GetServer());
-	if (result != 0)
-		return result < 0;
-
-	result = strcmp(a.export_name, b.GetExportName());
-	return result < 0;
-}
-
-inline bool
-NfsManager::Compare::operator()(const ManagedConnection &a,
-				const LookupKey b) const noexcept
-{
-	int result = strcmp(a.GetServer(), b.server);
-	if (result != 0)
-		return result < 0;
-
-	result = strcmp(a.GetExportName(), b.export_name);
-	return result < 0;
-}
-
-inline bool
-NfsManager::Compare::operator()(const ManagedConnection &a,
-				const ManagedConnection &b) const noexcept
-{
-	int result = strcmp(a.GetServer(), b.GetServer());
-	if (result != 0)
-		return result < 0;
-
-	result = strcmp(a.GetExportName(), b.GetExportName());
-	return result < 0;
-}
-
 NfsManager::~NfsManager() noexcept
 {
 	assert(!GetEventLoop().IsAlive() || GetEventLoop().IsInside());
@@ -92,17 +55,15 @@ NfsManager::GetConnection(const char *server, const char *export_name) noexcept
 	assert(export_name != nullptr);
 	assert(GetEventLoop().IsInside());
 
-	Map::insert_commit_data hint;
-	auto result = connections.insert_check(LookupKey{server, export_name},
-					       Compare(), hint);
-	if (result.second) {
-		auto c = new ManagedConnection(*this, GetEventLoop(),
-					       server, export_name);
-		connections.insert_commit(*c, hint);
-		return *c;
-	} else {
-		return *result.first;
-	}
+	for (auto &c : connections)
+		if (StringIsEqual(server, c.GetServer()) &&
+		    StringIsEqual(export_name, c.GetExportName()))
+			return c;
+
+	auto c = new ManagedConnection(*this, GetEventLoop(),
+				       server, export_name);
+	connections.push_front(*c);
+	return *c;
 }
 
 void
diff --git a/src/lib/nfs/Manager.hxx b/src/lib/nfs/Manager.hxx
index b7983a9c0..cd5c1c62d 100644
--- a/src/lib/nfs/Manager.hxx
+++ b/src/lib/nfs/Manager.hxx
@@ -22,24 +22,17 @@
 
 #include "Connection.hxx"
 #include "event/IdleEvent.hxx"
-#include "util/IntrusiveForwardList.hxx"
-
-#include <boost/intrusive/set.hpp>
+#include "util/IntrusiveList.hxx"
 
 /**
  * A manager for NFS connections.  Handles multiple connections to
  * multiple NFS servers.
  */
 class NfsManager final {
-	struct LookupKey {
-		const char *server;
-		const char *export_name;
-	};
-
 	class ManagedConnection final
 		: public NfsConnection,
-		  public IntrusiveForwardListHook,
-		  public boost::intrusive::set_base_hook<boost::intrusive::link_mode<boost::intrusive::normal_link>> {
+		  public IntrusiveListHook<>
+	{
 		NfsManager &manager;
 
 	public:
@@ -54,30 +47,9 @@ class NfsManager final {
 		void OnNfsConnectionError(std::exception_ptr &&e) noexcept override;
 	};
 
-	struct Compare {
-		[[gnu::pure]]
-		bool operator()(const LookupKey a,
-				const ManagedConnection &b) const noexcept;
+	using List = IntrusiveList<ManagedConnection>;
 
-		[[gnu::pure]]
-		bool operator()(const ManagedConnection &a,
-				const LookupKey b) const noexcept;
-
-		[[gnu::pure]]
-		bool operator()(const ManagedConnection &a,
-				const ManagedConnection &b) const noexcept;
-	};
-
-	/**
-	 * Maps server and export_name to #ManagedConnection.
-	 */
-	typedef boost::intrusive::set<ManagedConnection,
-				      boost::intrusive::compare<Compare>,
-				      boost::intrusive::constant_time_size<false>> Map;
-
-	Map connections;
-
-	using List = IntrusiveForwardList<ManagedConnection>;
+	List connections;
 
 	/**
 	 * A list of "garbage" connection objects.  Their destruction