Use hash map for event handler file descriptor map

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 763b48e97258cfac5f21a3b7b142d476a09ca1f7..cb216927e99ed51ad131752f516f6ad43573887c 100644
--- a/runtime/bin/eventhandler_linux.h
+++ b/runtime/bin/eventhandler_linux.h
@@ -8,7 +8,7 @@
 #include <unistd.h>
 #include <sys/socket.h>
 
-#include "bin/thread_pool.h"
+#include "bin/hashmap.h"
 
 class InterruptMessage {
  public:
@@ -26,6 +26,10 @@ enum PortDataFlags {
 
 class SocketData {
  public:
+  SocketData(intptr_t fd) : fd_(fd), port_(0), mask_(0), flags_(0) {
+    ASSERT(fd_ != -1);
+  }
+
   intptr_t GetPollEvents();
 
   void Unregister() {
@@ -67,7 +71,6 @@ class SocketData {
   }
 
   intptr_t fd() { return fd_; }
-  void set_fd(intptr_t fd) { fd_ = fd; }
   Dart_Port port() { return port_; }
   intptr_t mask() { return mask_; }
 
@@ -99,9 +102,10 @@ class EventHandlerImplementation {
   void HandleInterruptFd();
   void SetPort(intptr_t fd, Dart_Port dart_port, intptr_t mask);
   intptr_t GetPollEvents(struct pollfd* pollfd);
+  static void* GetHashmapKeyFromFd(intptr_t fd);
+  static uint32_t GetHashmapHashFromFd(intptr_t fd);
 
-  SocketData* socket_map_;
-  intptr_t socket_map_size_;
+  HashMap socket_map_;
   int64_t timeout_;  // Time for next timeout.
   Dart_Port timeout_port_;
   int interrupt_fds_[2];