Implement the linux debugger wire protocol.

runtime/bin/dbg_connection_linux.cc

Index: runtime/bin/dbg_connection_linux.cc
===================================================================
--- runtime/bin/dbg_connection_linux.cc	(revision 8867)
+++ runtime/bin/dbg_connection_linux.cc	(working copy)
@@ -5,14 +5,102 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
+#include <sys/epoll.h>
 
 #include "bin/dbg_connection.h"
 #include "bin/fdutils.h"
 #include "bin/socket.h"
 
+int DebuggerConnectionImpl::epoll_fd_ = -1;
+int DebuggerConnectionImpl::wakeup_fds_[2] = {-1, -1};

[siva, 2012/06/20 00:53:31]

It is not clear when epoll_fd_, wakeup_fds_ and listener_fd_ is closed.

[hausner, 2012/06/20 16:05:58]

They are currently never closed. The Socket class does not have a close
function. I'm adding a todo and will add a Socket::Close function later. It is
also needed in the platform-independent code in dbg_connection.cc.

 
+
+void DebuggerConnectionImpl::HandleEvent(struct epoll_event* event) {
+  if (event->data.fd == DebuggerConnectionHandler::listener_fd_) {
+    if (DebuggerConnectionHandler::IsConnected()) {
+      FATAL("Cannot connect to more than one debugger.\n");
+    }
+    int fd = ServerSocket::Accept(event->data.fd);
+    if (fd < 0) {
+      FATAL("Accepting new debugger connection failed.\n");
+    }
+    FDUtils::SetBlocking(fd);
+    DebuggerConnectionHandler::AcceptDbgConnection(fd);
+    // TODO(hausner): add the debugger wire socket fd to the event poll queue
+    // once we poll the debugger connection.
+  } else if (event->data.fd == DebuggerConnectionHandler::debugger_fd_) {
+    printf("unexpected: receiving debugger connection event.\n");
+    UNIMPLEMENTED();
+  } else {
+    // Sync message. Not yet implemented.
+    UNIMPLEMENTED();
+  }
+}
+
+
+void DebuggerConnectionImpl::Handler(uword args) {
+  static const intptr_t kMaxEvents = 4;
+  struct epoll_event events[kMaxEvents];
+  while (1) {
+    const int no_timeout = -1;
+    intptr_t result = TEMP_FAILURE_RETRY(
+        epoll_wait(epoll_fd_, events, kMaxEvents, no_timeout));
+    ASSERT(EAGAIN == EWOULDBLOCK);
+    if (result == -1) {
+      if (errno != EWOULDBLOCK) {
+        perror("epoll_wait failed");
+      }
+    } else {
+      ASSERT(result <= kMaxEvents);
+      for (int i = 0; i < result; i++) {
+        HandleEvent(&events[i]);
+      }
+    }
+  }
+}
+
+
+void DebuggerConnectionImpl::SetupPollQueue() {
+  int result;
+  result = TEMP_FAILURE_RETRY(pipe(wakeup_fds_));

[siva, 2012/06/20 00:53:31]

int result = TEMP....
instead of two lines.

[hausner, 2012/06/20 16:05:58]

Done.

+  if (result != 0) {
+    FATAL1("Pipe creation failed with error %d\n", result);
+  }
+  FDUtils::SetNonBlocking(wakeup_fds_[0]);
+
+  static const int kEpollInitialSize = 16;
+  epoll_fd_ = TEMP_FAILURE_RETRY(epoll_create(kEpollInitialSize));
+  if (epoll_fd_ == -1) {
+    FATAL("Failed creating epoll file descriptor");
+  }
+
+  // Register the wakeup _fd with the epoll instance.
+  struct epoll_event event;
+  event.events = EPOLLIN;
+  event.data.fd = wakeup_fds_[0];
+  int status = TEMP_FAILURE_RETRY(epoll_ctl(
+                   epoll_fd_, EPOLL_CTL_ADD, wakeup_fds_[0], &event));
+  if (status == -1) {
+    FATAL("Failed adding wakeup fd to epoll instance");
+  }
+
+  // Register the wakeup_fd with the epoll instance.

[siva, 2012/06/20 00:53:31]

Register the listener_fd_ with the epoll instance.

[hausner, 2012/06/20 16:05:58]

Done.

+  event.events = EPOLLIN;
+  event.data.fd = DebuggerConnectionHandler::listener_fd_;
+  status = TEMP_FAILURE_RETRY(epoll_ctl(epoll_fd_, EPOLL_CTL_ADD,
+               DebuggerConnectionHandler::listener_fd_, &event));
+  if (status == -1) {
+    FATAL("Failed adding listener fd to epoll instance");
+  }
+}
+
+
 void DebuggerConnectionImpl::StartHandler(int port_number) {
-  FATAL("Debugger wire protocol not yet implemented on Linux\n");
+  ASSERT(DebuggerConnectionHandler::listener_fd_ != -1);
+  SetupPollQueue();
+  int result = dart::Thread::Start(&DebuggerConnectionImpl::Handler, 0);
+  if (result != 0) {
+    FATAL1("Failed to start debugger connection handler thread: %d\n", result);
+  }
 }
+

[siva, 2012/06/20 00:53:31]

wasted space.

[hausner, 2012/06/20 16:05:58]

What, the empty line after the }  ?

I'll add a TODO to remove the empty line :)