LibIPC: Use AllocatingMemoryStream in TransportSocket send queue

Memory stream is a more suitable container for the socket send queue,
as using it results in fewer allocations than trying to emulate a stream
using a Vector.

Libraries/LibIPC/TransportSocket.cpp

@@ -16,7 +16,7 @@ namespace IPC {
 void SendQueue::enqueue_message(Vector<u8>&& bytes, Vector<int>&& fds)
 {
     Threading::MutexLocker locker(m_mutex);
-    m_bytes.append(bytes.data(), bytes.size());
+    VERIFY(MUST(m_stream.write_some(bytes.span())) == bytes.size());
     m_fds.append(fds.data(), fds.size());
     m_condition.signal();
 }
@@ -24,26 +24,27 @@ void SendQueue::enqueue_message(Vector<u8>&& bytes, Vector<int>&& fds)
 SendQueue::Running SendQueue::block_until_message_enqueued()
 {
     Threading::MutexLocker locker(m_mutex);
-    while (m_bytes.is_empty() && m_fds.is_empty() && m_running)
+    while (m_stream.is_eof() && m_fds.is_empty() && m_running)
         m_condition.wait();
     return m_running ? Running::Yes : Running::No;
 }
 
-SendQueue::BytesAndFds SendQueue::dequeue(size_t max_bytes)
+SendQueue::BytesAndFds SendQueue::peek(size_t max_bytes)
 {
     Threading::MutexLocker locker(m_mutex);
-    auto bytes_to_send = min(max_bytes, m_bytes.size());
-    Vector<u8> bytes;
-    bytes.append(m_bytes.data(), bytes_to_send);
-    m_bytes.remove(0, bytes_to_send);
-    return { move(bytes), move(m_fds) };
+    BytesAndFds result;
+    auto bytes_to_send = min(max_bytes, m_stream.used_buffer_size());
+    result.bytes.resize(bytes_to_send);
+    m_stream.peek_some(result.bytes);
+    result.fds = m_fds;
+    return result;
 }
 
-void SendQueue::return_unsent_data_to_front_of_queue(ReadonlyBytes const& bytes, Vector<int> const& fds)
+void SendQueue::discard(size_t bytes_count, size_t fds_count)
 {
     Threading::MutexLocker locker(m_mutex);
-    m_bytes.prepend(bytes.data(), bytes.size());
-    m_fds.prepend(fds.data(), fds.size());
+    MUST(m_stream.discard(bytes_count));
+    m_fds.remove(0, fds_count);
 }
 
 void SendQueue::stop()
@@ -62,7 +63,8 @@ TransportSocket::TransportSocket(NonnullOwnPtr<Core::LocalSocket> socket)
             if (send_queue->block_until_message_enqueued() == SendQueue::Running::No)
                 break;
 
-            auto [bytes, fds] = send_queue->dequeue(4096);
+            auto [bytes, fds] = send_queue->peek(4096);
+            auto fds_count = fds.size();
             ReadonlyBytes remaining_to_send_bytes = bytes;
 
             Threading::RWLockLocker<Threading::LockMode::Read> lock(m_socket_rw_lock);
@@ -72,8 +74,10 @@ TransportSocket::TransportSocket(NonnullOwnPtr<Core::LocalSocket> socket)
                 VERIFY_NOT_REACHED();
             }
 
-            if (!remaining_to_send_bytes.is_empty() || !fds.is_empty()) {
-                send_queue->return_unsent_data_to_front_of_queue(remaining_to_send_bytes, fds);
+            auto written_bytes_count = bytes.size() - remaining_to_send_bytes.size();
+            auto written_fds_count = fds_count - fds.size();
+            if (written_bytes_count > 0 || written_fds_count > 0) {
+                send_queue->discard(written_bytes_count, written_fds_count);
             }
 
             if (!m_socket->is_open())

Libraries/LibIPC/TransportSocket.h

@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <AK/MemoryStream.h>
 #include <AK/Queue.h>
 #include <LibCore/Socket.h>
 #include <LibThreading/ConditionVariable.h>
@@ -56,11 +57,11 @@ public:
         Vector<u8> bytes;
         Vector<int> fds;
     };
-    BytesAndFds dequeue(size_t max_bytes);
-    void return_unsent_data_to_front_of_queue(ReadonlyBytes const& bytes, Vector<int> const& fds);
+    BytesAndFds peek(size_t max_bytes);
+    void discard(size_t bytes_count, size_t fds_count);
 
 private:
-    Vector<u8> m_bytes;
+    AllocatingMemoryStream m_stream;
     Vector<int> m_fds;
     Threading::Mutex m_mutex;
     Threading::ConditionVariable m_condition { m_mutex };