WindowServer: Slurp all available client messages when checking them.

We were reading one client message per client per event loop iteration.
That was not very snappy. Make the sockets non-blocking and read() until
there are no messages left.

It would be even better to make as few calls to read() as possible to
reduce context switching, but this is already a huge improvement.

1 files changed, 18 insertions, 15 deletions

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 39ce65120a..2b80a64180 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -2304,7 +2304,7 @@ int Process::sys$listen(int sockfd, int backlog)
     return 0;
 }
 
-int Process::sys$accept(int sockfd, sockaddr* address, socklen_t* address_size)
+int Process::sys$accept(int accepting_socket_fd, sockaddr* address, socklen_t* address_size)
 {
     if (!validate_write_typed(address_size))
         return -EFAULT;
@@ -2312,28 +2312,31 @@ int Process::sys$accept(int sockfd, sockaddr* address, socklen_t* address_size)
         return -EFAULT;
     if (number_of_open_file_descriptors() >= m_max_open_file_descriptors)
         return -EMFILE;
-    int fd = 0;
-    for (; fd < (int)m_max_open_file_descriptors; ++fd) {
-        if (!m_fds[fd])
+    int accepted_socket_fd = 0;
+    for (; accepted_socket_fd < (int)m_max_open_file_descriptors; ++accepted_socket_fd) {
+        if (!m_fds[accepted_socket_fd])
             break;
     }
-    auto* descriptor = file_descriptor(sockfd);
-    if (!descriptor)
+    auto* accepting_socket_descriptor = file_descriptor(accepting_socket_fd);
+    if (!accepting_socket_descriptor)
         return -EBADF;
-    if (!descriptor->is_socket())
+    if (!accepting_socket_descriptor->is_socket())
         return -ENOTSOCK;
-    auto& socket = *descriptor->socket();
+    auto& socket = *accepting_socket_descriptor->socket();
     if (!socket.can_accept()) {
-        ASSERT(!descriptor->is_blocking());
+        ASSERT(!accepting_socket_descriptor->is_blocking());
         return -EAGAIN;
     }
-    auto client = socket.accept();
-    ASSERT(client);
-    bool success = client->get_address(address, address_size);
+    auto accepted_socket = socket.accept();
+    ASSERT(accepted_socket);
+    bool success = accepted_socket->get_address(address, address_size);
     ASSERT(success);
-    auto client_descriptor = FileDescriptor::create(move(client), SocketRole::Accepted);
-    m_fds[fd].set(move(client_descriptor));
-    return fd;
+    auto accepted_socket_descriptor = FileDescriptor::create(move(accepted_socket), SocketRole::Accepted);
+    // NOTE: The accepted socket inherits fd flags from the accepting socket.
+    //       I'm not sure if this matches other systems but it makes sense to me.
+    accepted_socket_descriptor->set_blocking(accepting_socket_descriptor->is_blocking());
+    m_fds[accepted_socket_fd].set(move(accepted_socket_descriptor), m_fds[accepting_socket_fd].flags);
+    return accepted_socket_fd;
 }
 
 int Process::sys$connect(int sockfd, const sockaddr* address, socklen_t address_size)