output/httpd: use boost::intrusive::list instead of std::forward_list

src/output/plugins/httpd/HttpdClient.hxx

@@ -23,6 +23,8 @@
 #include "event/BufferedSocket.hxx"
 #include "Compiler.h"
 
+#include <boost/intrusive/list.hpp>
+
 #include <queue>
 #include <list>
 
@@ -31,7 +33,9 @@
 class HttpdOutput;
 class Page;
 
-class HttpdClient final : BufferedSocket {
+class HttpdClient final
+	: BufferedSocket,
+	  public boost::intrusive::list_base_hook<boost::intrusive::link_mode<boost::intrusive::normal_link>> {
 	/**
 	 * The httpd output object this client is connected to.
 	 */

src/output/plugins/httpd/HttpdInternal.hxx

@@ -25,6 +25,7 @@
 #ifndef MPD_OUTPUT_HTTPD_INTERNAL_H
 #define MPD_OUTPUT_HTTPD_INTERNAL_H
 
+#include "HttpdClient.hxx"
 #include "output/Internal.hxx"
 #include "output/Timer.hxx"
 #include "thread/Mutex.hxx"
@@ -33,12 +34,6 @@
 #include "util/Cast.hxx"
 #include "Compiler.h"
 
-#ifdef _LIBCPP_VERSION
-/* can't use incomplete template arguments with libc++ */
-#include "HttpdClient.hxx"
-#endif
-
-#include <forward_list>
 #include <queue>
 #include <list>
 
@@ -135,7 +130,8 @@ private:
 	 * A linked list containing all clients which are currently
 	 * connected.
 	 */
-	std::forward_list<HttpdClient> clients;
+	boost::intrusive::list<HttpdClient,
+			       boost::intrusive::constant_time_size<true>> clients;
 
 	/**
 	 * A temporary buffer for the httpd_output_read_page()
@@ -147,7 +143,7 @@ private:
 	 * The maximum and current number of clients connected
 	 * at the same time.
 	 */
-	unsigned clients_max, clients_cnt;
+	unsigned clients_max;
 
 public:
 	HttpdOutput(EventLoop &_loop);

src/output/plugins/httpd/HttpdOutputPlugin.cxx

@@ -34,6 +34,7 @@
 #include "event/Call.hxx"
 #include "util/Error.hxx"
 #include "util/Domain.hxx"
+#include "util/DeleteDisposer.hxx"
 #include "Log.hxx"
 
 #include <assert.h>
@@ -169,9 +170,9 @@ httpd_output_finish(AudioOutput *ao)
 inline void
 HttpdOutput::AddClient(int fd)
 {
-	clients.emplace_front(*this, fd, GetEventLoop(),
-			      encoder->plugin.tag == nullptr);
-	++clients_cnt;
+	auto *client = new HttpdClient(*this, fd, GetEventLoop(),
+				       encoder->plugin.tag == nullptr);
+	clients.push_front(*client);
 
 	/* pass metadata to client */
 	if (metadata != nullptr)
@@ -235,7 +236,7 @@ HttpdOutput::OnAccept(int fd, SocketAddress address, gcc_unused int uid)
 
 	if (fd >= 0) {
 		/* can we allow additional client */
-		if (open && (clients_max == 0 ||  clients_cnt < clients_max))
+		if (open && (clients_max == 0 || clients.size() < clients_max))
 			AddClient(fd);
 		else
 			close_socket(fd);
@@ -319,7 +320,6 @@ HttpdOutput::Open(AudioFormat &audio_format, Error &error)
 
 	/* initialize other attributes */
 
-	clients_cnt = 0;
 	timer = new Timer(audio_format);
 
 	open = true;
@@ -347,7 +347,7 @@ HttpdOutput::Close()
 	delete timer;
 
 	BlockingCall(GetEventLoop(), [this](){
-			clients.clear();
+			clients.clear_and_dispose(DeleteDisposer());
 		});
 
 	if (header != nullptr)
@@ -368,17 +368,10 @@ httpd_output_close(AudioOutput *ao)
 void
 HttpdOutput::RemoveClient(HttpdClient &client)
 {
-	assert(clients_cnt > 0);
+	assert(!clients.empty());
 
-	for (auto prev = clients.before_begin(), i = std::next(prev);;
-	     prev = i, i = std::next(prev)) {
-		assert(i != clients.end());
-		if (&*i == &client) {
-			clients.erase_after(prev);
-			clients_cnt--;
-			break;
-		}
-	}
+	clients.erase_and_dispose(clients.iterator_to(client),
+				  DeleteDisposer());
 }
 
 void