Make the event-handler handle backpreasure.

runtime/bin/eventhandler_linux.h

Index: runtime/bin/eventhandler_linux.h
diff --git a/runtime/bin/eventhandler_linux.h b/runtime/bin/eventhandler_linux.h
index f5386c34fbca8a1808a12ae8e5ace1899759f223..9341cd11f3ec30d9c7c5b13b1b4b60c33d764499 100644
--- a/runtime/bin/eventhandler_linux.h
+++ b/runtime/bin/eventhandler_linux.h
@@ -14,32 +14,93 @@
 #include <sys/socket.h>
 
 #include "platform/hashmap.h"
-#include "platform/thread.h"
 
 
 namespace dart {
 namespace bin {
 
+class InterruptMessage {
+ public:
+  intptr_t id;
+  Dart_Port dart_port;
+  int64_t data;
+};
+
+
+class SocketData {
+ public:
+  explicit SocketData(intptr_t fd) : fd_(fd), port_(0), mask_(0), tokens_(8) {
+    ASSERT(fd_ != -1);
+  }
+
+  intptr_t GetPollEvents();
+
+  void Close() {
+    port_ = 0;
+    mask_ = 0;
+    close(fd_);
+    fd_ = -1;
+  }
+
+  void SetPortAndMask(Dart_Port port, intptr_t mask) {
+    ASSERT(fd_ != -1);
+    port_ = port;
+    mask_ = mask;
+  }
+
+  intptr_t fd() { return fd_; }
+  Dart_Port port() { return port_; }
+
+  // Returns true if the last token was taken.
+  bool TakeToken() {
+    ASSERT(tokens_ > 0);
+    tokens_--;
+    return tokens_ == 0;
+  }
+
+  // Returns true if the tokens was 0 before adding.
+  bool ReturnToken() {
+    ASSERT(tokens_ >= 0);
+    tokens_++;
+    return tokens_ == 1;
+  }
+
+ private:
+  intptr_t fd_;
+  Dart_Port port_;
+  intptr_t mask_;
+  int tokens_;
+};
+
+
 class EventHandlerImplementation {
  public:
   EventHandlerImplementation();
   ~EventHandlerImplementation();
 
-  void Notify(intptr_t id, Dart_Port dart_port, int64_t data);
+  // Gets the socket data structure for a given file
+  // descriptor. Creates a new one if one is not found.
+  SocketData* GetSocketData(intptr_t fd);
+  void SendData(intptr_t id, Dart_Port dart_port, int64_t data);
   void Start(EventHandler* handler);
   void Shutdown();
 
  private:
   void HandleEvents(struct epoll_event* events, int size);
   static void Poll(uword args);
+  void WakeupHandler(intptr_t id, Dart_Port dart_port, int64_t data);
+  void HandleInterruptFd();
   void SetPort(intptr_t fd, Dart_Port dart_port, intptr_t mask);
-  intptr_t GetPollEvents(intptr_t events);
+  intptr_t GetPollEvents(intptr_t events, SocketData* sd);
+  static void* GetHashmapKeyFromFd(intptr_t fd);
+  static uint32_t GetHashmapHashFromFd(intptr_t fd);
 
+  HashMap socket_map_;
   TimeoutQueue timeout_queue_;
   bool shutdown_;
+  int interrupt_fds_[2];
   int epoll_fd_;
   int timer_fd_;
-  Mutex timer_mutex_;
 };
 
 }  // namespace bin