Only return eventhandler tokens in stacks of 8, to avoid runtime calls.

runtime/bin/eventhandler_linux.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_EVENTHANDLER_LINUX_H_
 #define BIN_EVENTHANDLER_LINUX_H_
 
 #if !defined(BIN_EVENTHANDLER_H_)
 #error Do not include eventhandler_linux.h directly; use eventhandler.h instead.
 #endif
@@ skipping 13 matching lines @@
 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) {
+  explicit SocketData(intptr_t fd) : fd_(fd), port_(0), mask_(0), tokens_(16) {
     ASSERT(fd_ != -1);
   }
 
   intptr_t GetPollEvents();
 
   void Close() {
     port_ = 0;
     mask_ = 0;
     VOID_TEMP_FAILURE_RETRY(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_; }
 
+  bool IsListeningSocket() { return (mask_ & (1 << kListeningSocket)) != 0; }
+
   // 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);
@@ skipping 36 matching lines @@
   bool shutdown_;
   int interrupt_fds_[2];
   int epoll_fd_;
   int timer_fd_;
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_EVENTHANDLER_LINUX_H_