Add support for cloning server-sockets.

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 10 matching lines @@
 namespace dart {
 namespace bin {
 
 class InterruptMessage {
  public:
   intptr_t id;
   Dart_Port dart_port;
   int64_t data;
 };
 
+template<typename T>
+class CircularLinkedList {
+ public:
+  CircularLinkedList() : head_(NULL) {}
 
+  // Returns true if the list was empty.
+  bool Add(T t) {
+    Entry* e = new Entry(t);
+    if (head_ == NULL) {
+      // Empty list, make e head, and point to itself.
+      e->next_ = e;
+      e->prev_ = e;
+      head_ = e;
+      return true;
+    } else {
+      // Insert e as the last element in the list.
+      e->prev_ = head_->prev_;
+      e->next_ = head_;
+      e->prev_->next_ = e;
+      head_->prev_ = e;
+      return false;
+    }
+  }
+
+  void RemoveHead() {
+    Entry* e = head_;
+    if (e->next_ == e) {
+      head_ = NULL;
+    } else {
+      e->prev_->next_ = e->next_;
+      e->next_->prev_ = e->prev_;
+      head_ = e->next_;
+    }
+    delete e;
+  }
+
+  T head() const { return head_->t; }
+
+  bool HasHead() {
+    return head_ != NULL;
+  }
+
+  void Rotate() {
+    head_ = head_->next_;
+  }
+
+ private:
+  struct Entry {
+    explicit Entry(const T& t) : t(t) {}
+    const T t;
+    Entry* next_;
+    Entry* prev_;
+  };
+
+  Entry* head_;
+};
+
+
+class ListeningSocketData;
 class SocketData {
  public:
-  explicit SocketData(intptr_t fd) : fd_(fd), port_(0), mask_(0), tokens_(16) {
+  explicit SocketData(intptr_t fd)
+      : fd_(fd), port_(0), mask_(0), tokens_(16) {
     ASSERT(fd_ != -1);
   }
 
+  virtual ~SocketData() {
+  }
+
   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) {
+  void SetMask(intptr_t mask) {
     ASSERT(fd_ != -1);
-    port_ = port;
     mask_ = mask;
   }
 
   intptr_t fd() { return fd_; }
-  Dart_Port port() { return port_; }
+  virtual Dart_Port port() { return port_; }
 
-  bool IsListeningSocket() { return (mask_ & (1 << kListeningSocket)) != 0; }
+  virtual bool IsListeningSocket() const { return false; }
+
+  virtual bool AddPort(Dart_Port port) {
+    ASSERT(port_ == 0);
+    port_ = port;
+    return true;
+  }
+
+  virtual bool RemovePort(Dart_Port port) {
+    ASSERT(port_ == 0 || port_ == port);
+    return true;
+  }
 
   // Returns true if the last token was taken.
-  bool TakeToken() {
+  virtual bool TakeToken() {
     ASSERT(tokens_ > 0);
     tokens_--;
     return tokens_ == 0;
   }
 
   // Returns true if the tokens was 0 before adding.
-  bool ReturnToken() {
+  virtual bool ReturnToken(Dart_Port port, int count) {
+    ASSERT(port_ == port);
     ASSERT(tokens_ >= 0);
-    tokens_++;
-    return tokens_ == 1;
+    bool was_empty = tokens_ == 0;
+    tokens_ += count;
+    return was_empty;
   }
 
- private:
+  bool HasTokens() const { return tokens_ > 0; }
+
+ protected:
   intptr_t fd_;
   Dart_Port port_;
   intptr_t mask_;
   int tokens_;
 };
 
 
+class ListeningSocketData : public SocketData {
+ private:
+  static const int kTokenCount = 4;
+
+  static bool SamePortValue(void* key1, void* key2) {
+    return reinterpret_cast<Dart_Port>(key1) ==
+        reinterpret_cast<Dart_Port>(key2);
+  }
+
+  static uint32_t GetHashmapHashFromPort(Dart_Port port) {
+    return static_cast<uint32_t>(port & 0xFFFFFFFF);
+  }
+
+  static void* GetHashmapKeyFromPort(Dart_Port port) {
+    return reinterpret_cast<void*>(port);
+  }
+
+ public:
+  explicit ListeningSocketData(intptr_t fd)
+      : SocketData(fd),
+        tokens_map_(&SamePortValue, 4) {}
+
+  bool IsListeningSocket() const { return true; }
+
+  bool AddPort(Dart_Port port) {
+    HashMap::Entry* entry = tokens_map_.Lookup(
+        GetHashmapKeyFromPort(port), GetHashmapHashFromPort(port), true);
+    entry->value = reinterpret_cast<void*>(kTokenCount);
+    return live_ports_.Add(port);
+  }
+
+  virtual bool RemovePort(Dart_Port port) {
+    HashMap::Entry* entry = tokens_map_.Lookup(
+        GetHashmapKeyFromPort(port), GetHashmapHashFromPort(port), false);
+    ASSERT(entry != NULL);
+    intptr_t tokens = reinterpret_cast<intptr_t>(entry->value);
+    if (tokens == 0) {
+      while (idle_ports_.head() != port) {
+        idle_ports_.Rotate();
+      }
+      idle_ports_.RemoveHead();
+    } else {
+      while (live_ports_.head() != port) {
+        live_ports_.Rotate();
+      }
+      live_ports_.RemoveHead();
+    }
+    tokens_map_.Remove(
+        GetHashmapKeyFromPort(port), GetHashmapHashFromPort(port));
+    return !live_ports_.HasHead();
+  }
+
+  bool TakeToken() {
+    ASSERT(live_ports_.HasHead());
+    Dart_Port port = live_ports_.head();
+    HashMap::Entry* entry = tokens_map_.Lookup(
+        GetHashmapKeyFromPort(port), GetHashmapHashFromPort(port), false);
+    ASSERT(entry != NULL);
+    intptr_t tokens = reinterpret_cast<intptr_t>(entry->value);
+    tokens--;
+    entry->value = reinterpret_cast<void*>(tokens);
+    if (tokens == 0) {
+      live_ports_.RemoveHead();
+      idle_ports_.Add(port);
+      if (!live_ports_.HasHead()) {
+        return true;
+      }
+    } else {
+      live_ports_.Rotate();
+    }
+    return false;
+  }
+
+  Dart_Port port() { return live_ports_.head(); }
+
+  bool ReturnToken(Dart_Port port, int count) {
+    HashMap::Entry* entry = tokens_map_.Lookup(
+        GetHashmapKeyFromPort(port), GetHashmapHashFromPort(port), false);
+    ASSERT(entry != NULL);
+    intptr_t tokens = reinterpret_cast<intptr_t>(entry->value);
+    tokens += count;
+    entry->value = reinterpret_cast<void*>(tokens);
+    if (tokens == count) {
+      // Return to live_ports_.
+      while (idle_ports_.head() != port) {
+        idle_ports_.Rotate();
+      }
+      idle_ports_.RemoveHead();
+      bool was_empty = !live_ports_.HasHead();
+      live_ports_.Add(port);
+      return was_empty;
+    }
+    return false;
+  }
+
+ private:
+  CircularLinkedList<Dart_Port> live_ports_;
+  CircularLinkedList<Dart_Port> idle_ports_;
+  HashMap tokens_map_;
+};
+
+
 class EventHandlerImplementation {
  public:
   EventHandlerImplementation();
   ~EventHandlerImplementation();
 
   // Gets the socket data structure for a given file
   // descriptor. Creates a new one if one is not found.
-  SocketData* GetSocketData(intptr_t fd);
+  SocketData* GetSocketData(intptr_t fd, bool is_listening);
   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, 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_;
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_EVENTHANDLER_LINUX_H_