From fb5d77158a183da47619db5a7885644fe8f6ccc3 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Sat, 12 Nov 2022 08:52:58 +0100
Subject: [PATCH] util/IntrusiveList: add enum LinkMode
Compile-time code simplification.
---
src/RemoteTagCache.hxx | 2 +-
src/client/Client.hxx | 2 +-
src/db/plugins/simple/Directory.hxx | 2 +-
src/db/plugins/simple/Song.hxx | 2 +-
src/event/SocketEvent.hxx | 4 +-
src/input/cache/Lease.hxx | 2 +-
src/io/uring/CancellableOperation.hxx | 3 +-
src/lib/nfs/Cancellable.hxx | 2 +-
src/lib/upnp/Discovery.hxx | 2 +-
src/output/plugins/httpd/HttpdClient.hxx | 2 +-
src/output/plugins/snapcast/Client.hxx | 2 +-
src/util/IntrusiveHookMode.hxx | 56 ++++++++++++
src/util/IntrusiveList.hxx | 104 +++++++++++------------
test/util/TestIntrusiveList.cxx | 28 +++---
14 files changed, 132 insertions(+), 81 deletions(-)
create mode 100644 src/util/IntrusiveHookMode.hxx
diff --git a/src/RemoteTagCache.hxx b/src/RemoteTagCache.hxx
index b99b7624c..a2051a575 100644
--- a/src/RemoteTagCache.hxx
+++ b/src/RemoteTagCache.hxx
@@ -46,7 +46,7 @@ class RemoteTagCache final {
struct Item final
: public boost::intrusive::unordered_set_base_hook<boost::intrusive::link_mode<boost::intrusive::normal_link>>,
- public IntrusiveListHook,
+ public IntrusiveListHook<>,
RemoteTagHandler
{
RemoteTagCache &parent;
diff --git a/src/client/Client.hxx b/src/client/Client.hxx
index 0ff71ae7f..a8770483c 100644
--- a/src/client/Client.hxx
+++ b/src/client/Client.hxx
@@ -53,7 +53,7 @@ class Client final
friend struct ClientPerPartitionListHook;
friend class ClientList;
- IntrusiveListHook list_siblings, partition_siblings;
+ IntrusiveListHook<> list_siblings, partition_siblings;
CoarseTimerEvent timeout_event;
diff --git a/src/db/plugins/simple/Directory.hxx b/src/db/plugins/simple/Directory.hxx
index 69a6b3195..00499cea6 100644
--- a/src/db/plugins/simple/Directory.hxx
+++ b/src/db/plugins/simple/Directory.hxx
@@ -51,7 +51,7 @@ static constexpr unsigned DEVICE_PLAYLIST = -3;
class SongFilter;
-struct Directory : IntrusiveListHook {
+struct Directory : IntrusiveListHook<> {
/* Note: the #IntrusiveListHook is protected with the global
#db_mutex. Read access in the update thread does not need
protection. */
diff --git a/src/db/plugins/simple/Song.hxx b/src/db/plugins/simple/Song.hxx
index 17b6b6a83..f575a6c9d 100644
--- a/src/db/plugins/simple/Song.hxx
+++ b/src/db/plugins/simple/Song.hxx
@@ -39,7 +39,7 @@ class ArchiveFile;
* A song file inside the configured music directory. Internal
* #SimpleDatabase class.
*/
-struct Song : IntrusiveListHook {
+struct Song : IntrusiveListHook<> {
/* Note: the #IntrusiveListHook is protected with the global
#db_mutex. Read access in the update thread does not need
protection. */
diff --git a/src/event/SocketEvent.hxx b/src/event/SocketEvent.hxx
index 0e8f95470..9603a1a1d 100644
--- a/src/event/SocketEvent.hxx
+++ b/src/event/SocketEvent.hxx
@@ -40,7 +40,9 @@ class EventLoop;
* thread that runs the #EventLoop, except where explicitly documented
* as thread-safe.
*/
-class SocketEvent final : IntrusiveListHook, public EventPollBackendEvents
+class SocketEvent final
+ : IntrusiveListHook<IntrusiveHookMode::NORMAL>,
+ public EventPollBackendEvents
{
friend class EventLoop;
friend struct IntrusiveListBaseHookTraits<SocketEvent>;
diff --git a/src/input/cache/Lease.hxx b/src/input/cache/Lease.hxx
index 833d7b601..55cfa1080 100644
--- a/src/input/cache/Lease.hxx
+++ b/src/input/cache/Lease.hxx
@@ -29,7 +29,7 @@
* A lease for an #InputCacheItem.
*/
class InputCacheLease
- : public IntrusiveListHook
+ : public IntrusiveListHook<>
{
InputCacheItem *item = nullptr;
diff --git a/src/io/uring/CancellableOperation.hxx b/src/io/uring/CancellableOperation.hxx
index e495fefe1..5cd600e2e 100644
--- a/src/io/uring/CancellableOperation.hxx
+++ b/src/io/uring/CancellableOperation.hxx
@@ -40,7 +40,8 @@
namespace Uring {
-class CancellableOperation : public IntrusiveListHook
+class CancellableOperation
+ : public IntrusiveListHook<IntrusiveHookMode::NORMAL>
{
Operation *operation;
diff --git a/src/lib/nfs/Cancellable.hxx b/src/lib/nfs/Cancellable.hxx
index 3aa71bf4d..55276c8a4 100644
--- a/src/lib/nfs/Cancellable.hxx
+++ b/src/lib/nfs/Cancellable.hxx
@@ -27,7 +27,7 @@
template<typename T>
class CancellablePointer
- : public IntrusiveListHook
+ : public IntrusiveListHook<>
{
public:
typedef T *pointer;
diff --git a/src/lib/upnp/Discovery.hxx b/src/lib/upnp/Discovery.hxx
index c0cecadb2..02255f57d 100644
--- a/src/lib/upnp/Discovery.hxx
+++ b/src/lib/upnp/Discovery.hxx
@@ -79,7 +79,7 @@ class UPnPDeviceDirectory final : UpnpCallback {
};
class Downloader final
- : public IntrusiveListHook, CurlResponseHandler
+ : public IntrusiveListHook<>, CurlResponseHandler
{
InjectEvent defer_start_event;
diff --git a/src/output/plugins/httpd/HttpdClient.hxx b/src/output/plugins/httpd/HttpdClient.hxx
index 4ec01033a..95914211c 100644
--- a/src/output/plugins/httpd/HttpdClient.hxx
+++ b/src/output/plugins/httpd/HttpdClient.hxx
@@ -34,7 +34,7 @@ class HttpdOutput;
class HttpdClient final
: BufferedSocket,
- public IntrusiveListHook
+ public IntrusiveListHook<>
{
/**
* The httpd output object this client is connected to.
diff --git a/src/output/plugins/snapcast/Client.hxx b/src/output/plugins/snapcast/Client.hxx
index f06ea88f3..fef64eb31 100644
--- a/src/output/plugins/snapcast/Client.hxx
+++ b/src/output/plugins/snapcast/Client.hxx
@@ -33,7 +33,7 @@ struct SnapcastTime;
class SnapcastOutput;
class UniqueSocketDescriptor;
-class SnapcastClient final : BufferedSocket, public IntrusiveListHook
+class SnapcastClient final : BufferedSocket, public IntrusiveListHook<>
{
SnapcastOutput &output;
diff --git a/src/util/IntrusiveHookMode.hxx b/src/util/IntrusiveHookMode.hxx
new file mode 100644
index 000000000..238c68055
--- /dev/null
+++ b/src/util/IntrusiveHookMode.hxx
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2022 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+/**
+ * Specifies the mode in which a hook for intrusive containers
+ * operates. This is meant to be used as a template argument to the
+ * hook class (e.g. #IntrusiveListHook).
+ */
+enum class IntrusiveHookMode {
+ /**
+ * No implicit initialization.
+ */
+ NORMAL,
+
+ /**
+ * Keep track of whether the item is currently linked, allows
+ * using method is_linked(). This requires implicit
+ * initialization and requires iterating all items when
+ * deleting them which adds a considerable amount of overhead.
+ */
+ TRACK,
+
+ /**
+ * Automatically unlinks the item in the destructor. This
+ * implies #TRACK and adds code to the destructor.
+ */
+ AUTO_UNLINK,
+};
diff --git a/src/util/IntrusiveList.hxx b/src/util/IntrusiveList.hxx
index 570440b38..75c6cd0fa 100644
--- a/src/util/IntrusiveList.hxx
+++ b/src/util/IntrusiveList.hxx
@@ -30,6 +30,7 @@
#pragma once
#include "Cast.hxx"
+#include "IntrusiveHookMode.hxx"
#include "MemberPointer.hxx"
#include "OptionalCounter.hxx"
@@ -47,6 +48,7 @@ struct IntrusiveListNode {
}
};
+template<IntrusiveHookMode _mode=IntrusiveHookMode::NORMAL>
class IntrusiveListHook {
template<typename T> friend struct IntrusiveListBaseHookTraits;
template<auto member> friend struct IntrusiveListMemberHookTraits;
@@ -56,13 +58,33 @@ protected:
IntrusiveListNode siblings;
public:
- IntrusiveListHook() noexcept = default;
+ static constexpr IntrusiveHookMode mode = _mode;
+
+ IntrusiveListHook() noexcept {
+ if constexpr (mode >= IntrusiveHookMode::TRACK)
+ siblings.next = nullptr;
+ }
+
+ ~IntrusiveListHook() noexcept {
+ if constexpr (mode >= IntrusiveHookMode::AUTO_UNLINK)
+ if (is_linked())
+ unlink();
+ }
IntrusiveListHook(const IntrusiveListHook &) = delete;
IntrusiveListHook &operator=(const IntrusiveListHook &) = delete;
void unlink() noexcept {
IntrusiveListNode::Connect(*siblings.prev, *siblings.next);
+
+ if constexpr (mode >= IntrusiveHookMode::TRACK)
+ siblings.next = nullptr;
+ }
+
+ bool is_linked() const noexcept {
+ static_assert(mode >= IntrusiveHookMode::TRACK);
+
+ return siblings.next != nullptr;
}
private:
@@ -75,52 +97,27 @@ private:
}
};
-/**
- * A variant of #IntrusiveListHook which keeps track of whether it is
- * currently in a list.
- */
-class SafeLinkIntrusiveListHook : public IntrusiveListHook {
-public:
- SafeLinkIntrusiveListHook() noexcept {
- siblings.next = nullptr;
- }
-
- void unlink() noexcept {
- IntrusiveListHook::unlink();
- siblings.next = nullptr;
- }
-
- bool is_linked() const noexcept {
- return siblings.next != nullptr;
- }
-};
+using SafeLinkIntrusiveListHook =
+ IntrusiveListHook<IntrusiveHookMode::TRACK>;
+using AutoUnlinkIntrusiveListHook =
+ IntrusiveListHook<IntrusiveHookMode::AUTO_UNLINK>;
/**
- * A variant of #IntrusiveListHook which auto-unlinks itself from the
- * list upon destruction. As a side effect, it has an is_linked()
- * method.
- */
-class AutoUnlinkIntrusiveListHook : public SafeLinkIntrusiveListHook {
-public:
- ~AutoUnlinkIntrusiveListHook() noexcept {
- if (is_linked())
- unlink();
- }
-};
-
-/**
- * Detect the hook type; this is important because
- * SafeLinkIntrusiveListHook::unlink() needs to clear the "next"
- * pointer. This is a template to postpone the type checks, to allow
+ * Detect the hook type which is embedded in the given type as a base
+ * class. This is a template to postpone the type checks, to allow
* forward-declared types.
*/
template<typename U>
struct IntrusiveListHookDetection {
- static_assert(std::is_base_of_v<IntrusiveListHook, U>);
-
- using type = std::conditional_t<std::is_base_of_v<SafeLinkIntrusiveListHook, U>,
- SafeLinkIntrusiveListHook,
- IntrusiveListHook>;
+ /* TODO can this be simplified somehow, without checking for
+ all possible enum values? */
+ using type = std::conditional_t<std::is_base_of_v<IntrusiveListHook<IntrusiveHookMode::NORMAL>, U>,
+ IntrusiveListHook<IntrusiveHookMode::NORMAL>,
+ std::conditional_t<std::is_base_of_v<IntrusiveListHook<IntrusiveHookMode::TRACK>, U>,
+ IntrusiveListHook<IntrusiveHookMode::TRACK>,
+ std::conditional_t<std::is_base_of_v<IntrusiveListHook<IntrusiveHookMode::AUTO_UNLINK>, U>,
+ IntrusiveListHook<IntrusiveHookMode::AUTO_UNLINK>,
+ void>>>;
};
/**
@@ -131,10 +128,6 @@ struct IntrusiveListBaseHookTraits {
template<typename U>
using Hook = typename IntrusiveListHookDetection<U>::type;
- static constexpr bool IsAutoUnlink() noexcept {
- return std::is_base_of_v<AutoUnlinkIntrusiveListHook, T>;
- }
-
static constexpr T *Cast(IntrusiveListNode *node) noexcept {
auto *hook = &Hook<T>::Cast(*node);
return static_cast<T *>(hook);
@@ -152,14 +145,12 @@ template<auto member>
struct IntrusiveListMemberHookTraits {
using T = MemberPointerContainerType<decltype(member)>;
using _Hook = MemberPointerType<decltype(member)>;
- using Hook = typename IntrusiveListHookDetection<_Hook>::type;
- static constexpr bool IsAutoUnlink() noexcept {
- return std::is_base_of_v<AutoUnlinkIntrusiveListHook, _Hook>;
- }
+ template<typename Dummy>
+ using Hook = _Hook;
static constexpr T *Cast(IntrusiveListNode *node) noexcept {
- auto &hook = Hook::Cast(*node);
+ auto &hook = Hook<T>::Cast(*node);
return &ContainerCast(hook, member);
}
@@ -176,14 +167,15 @@ template<typename T,
typename HookTraits=IntrusiveListBaseHookTraits<T>,
bool constant_time_size=false>
class IntrusiveList {
- template<typename U>
- using Hook = typename IntrusiveListHookDetection<U>::type;
-
IntrusiveListNode head{&head, &head};
[[no_unique_address]]
OptionalCounter<constant_time_size> counter;
+ static constexpr auto GetHookMode() noexcept {
+ return HookTraits::template Hook<T>::mode;
+ }
+
static constexpr T *Cast(IntrusiveListNode *node) noexcept {
return HookTraits::Cast(node);
}
@@ -234,7 +226,7 @@ public:
}
~IntrusiveList() noexcept {
- if constexpr (std::is_base_of_v<SafeLinkIntrusiveListHook, T>)
+ if constexpr (GetHookMode() >= IntrusiveHookMode::TRACK)
clear();
}
@@ -283,7 +275,7 @@ public:
}
void clear() noexcept {
- if constexpr (std::is_base_of_v<SafeLinkIntrusiveListHook, T>) {
+ if constexpr (GetHookMode() >= IntrusiveHookMode::TRACK) {
/* for SafeLinkIntrusiveListHook, we need to
remove each item manually, or else its
is_linked() method will not work */
@@ -504,7 +496,7 @@ public:
void insert(iterator p, reference t) noexcept {
static_assert(!constant_time_size ||
- !HookTraits::IsAutoUnlink(),
+ GetHookMode() < IntrusiveHookMode::AUTO_UNLINK,
"Can't use auto-unlink hooks with constant_time_size");
auto &existing_node = ToNode(*p);
diff --git a/test/util/TestIntrusiveList.cxx b/test/util/TestIntrusiveList.cxx
index 1039324e6..a553c1979 100644
--- a/test/util/TestIntrusiveList.cxx
+++ b/test/util/TestIntrusiveList.cxx
@@ -36,17 +36,17 @@
namespace {
-template<typename Hook>
-struct CharItem final : Hook {
+template<IntrusiveHookMode mode>
+struct CharItem final : IntrusiveListHook<mode> {
char ch;
constexpr CharItem(char _ch) noexcept:ch(_ch) {}
};
-template<typename Hook>
+template<IntrusiveHookMode mode>
static std::string
-ToString(const IntrusiveList<CharItem<Hook>> &list,
- typename IntrusiveList<CharItem<Hook>>::const_iterator it,
+ToString(const IntrusiveList<CharItem<mode>> &list,
+ typename IntrusiveList<CharItem<mode>>::const_iterator it,
std::size_t n) noexcept
{
std::string result;
@@ -55,10 +55,10 @@ ToString(const IntrusiveList<CharItem<Hook>> &list,
return result;
}
-template<typename Hook>
+template<IntrusiveHookMode mode>
static std::string
-ToStringReverse(const IntrusiveList<CharItem<Hook>> &list,
- typename IntrusiveList<CharItem<Hook>>::const_iterator it,
+ToStringReverse(const IntrusiveList<CharItem<mode>> &list,
+ typename IntrusiveList<CharItem<mode>>::const_iterator it,
std::size_t n) noexcept
{
std::string result;
@@ -71,7 +71,7 @@ ToStringReverse(const IntrusiveList<CharItem<Hook>> &list,
TEST(IntrusiveList, Basic)
{
- using Item = CharItem<IntrusiveListHook>;
+ using Item = CharItem<IntrusiveHookMode::NORMAL>;
Item items[]{'a', 'b', 'c'};
@@ -103,9 +103,9 @@ TEST(IntrusiveList, Basic)
ASSERT_EQ(ToStringReverse(list, list.begin(), 6), "a_cfea");
}
-TEST(IntrusiveList, SafeLink)
+TEST(IntrusiveList, Track)
{
- using Item = CharItem<SafeLinkIntrusiveListHook>;
+ using Item = CharItem<IntrusiveHookMode::TRACK>;
Item items[]{'a', 'b', 'c'};
@@ -162,7 +162,7 @@ TEST(IntrusiveList, SafeLink)
TEST(IntrusiveList, AutoUnlink)
{
- using Item = CharItem<AutoUnlinkIntrusiveListHook>;
+ using Item = CharItem<IntrusiveHookMode::AUTO_UNLINK>;
Item a{'a'};
ASSERT_FALSE(a.is_linked());
@@ -194,7 +194,7 @@ TEST(IntrusiveList, AutoUnlink)
TEST(IntrusiveList, Merge)
{
- using Item = CharItem<IntrusiveListHook>;
+ using Item = CharItem<IntrusiveHookMode::NORMAL>;
const auto predicate = [](const Item &a, const Item &b){
return a.ch < b.ch;
@@ -229,7 +229,7 @@ TEST(IntrusiveList, Merge)
TEST(IntrusiveList, Sort)
{
- using Item = CharItem<IntrusiveListHook>;
+ using Item = CharItem<IntrusiveHookMode::NORMAL>;
const auto predicate = [](const Item &a, const Item &b){
return a.ch < b.ch;