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      1 // Copyright 2008 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_V8THREADS_H_
     29 #define V8_V8THREADS_H_
     30 
     31 namespace v8 {
     32 namespace internal {
     33 
     34 
     35 class ThreadState {
     36  public:
     37   // Returns NULL after the last one.
     38   ThreadState* Next();
     39 
     40   enum List {FREE_LIST, IN_USE_LIST};
     41 
     42   void LinkInto(List list);
     43   void Unlink();
     44 
     45   // Id of thread.
     46   void set_id(ThreadId id) { id_ = id; }
     47   ThreadId id() { return id_; }
     48 
     49   // Should the thread be terminated when it is restored?
     50   bool terminate_on_restore() { return terminate_on_restore_; }
     51   void set_terminate_on_restore(bool terminate_on_restore) {
     52     terminate_on_restore_ = terminate_on_restore;
     53   }
     54 
     55   // Get data area for archiving a thread.
     56   char* data() { return data_; }
     57 
     58  private:
     59   explicit ThreadState(ThreadManager* thread_manager);
     60 
     61   void AllocateSpace();
     62 
     63   ThreadId id_;
     64   bool terminate_on_restore_;
     65   char* data_;
     66   ThreadState* next_;
     67   ThreadState* previous_;
     68 
     69   ThreadManager* thread_manager_;
     70 
     71   friend class ThreadManager;
     72 };
     73 
     74 
     75 // Defined in isolate.h.
     76 class ThreadLocalTop;
     77 
     78 
     79 class ThreadVisitor {
     80  public:
     81   // ThreadLocalTop may be only available during this call.
     82   virtual void VisitThread(Isolate* isolate, ThreadLocalTop* top) = 0;
     83 
     84  protected:
     85   virtual ~ThreadVisitor() {}
     86 };
     87 
     88 
     89 class ThreadManager {
     90  public:
     91   void Lock();
     92   void Unlock();
     93 
     94   void ArchiveThread();
     95   bool RestoreThread();
     96   void FreeThreadResources();
     97   bool IsArchived();
     98 
     99   void Iterate(ObjectVisitor* v);
    100   void IterateArchivedThreads(ThreadVisitor* v);
    101   bool IsLockedByCurrentThread() {
    102     return mutex_owner_.Equals(ThreadId::Current());
    103   }
    104 
    105   ThreadId CurrentId();
    106 
    107   void TerminateExecution(ThreadId thread_id);
    108 
    109   // Iterate over in-use states.
    110   ThreadState* FirstThreadStateInUse();
    111   ThreadState* GetFreeThreadState();
    112 
    113  private:
    114   ThreadManager();
    115   ~ThreadManager();
    116 
    117   void EagerlyArchiveThread();
    118 
    119   Mutex* mutex_;
    120   ThreadId mutex_owner_;
    121   ThreadId lazily_archived_thread_;
    122   ThreadState* lazily_archived_thread_state_;
    123 
    124   // In the following two lists there is always at least one object on the list.
    125   // The first object is a flying anchor that is only there to simplify linking
    126   // and unlinking.
    127   // Head of linked list of free states.
    128   ThreadState* free_anchor_;
    129   // Head of linked list of states in use.
    130   ThreadState* in_use_anchor_;
    131 
    132   Isolate* isolate_;
    133 
    134   friend class Isolate;
    135   friend class ThreadState;
    136 };
    137 
    138 
    139 // The ContextSwitcher thread is used to schedule regular preemptions to
    140 // multiple running V8 threads. Generally it is necessary to call
    141 // StartPreemption if there is more than one thread running. If not, a single
    142 // JavaScript can take full control of V8 and not allow other threads to run.
    143 class ContextSwitcher: public Thread {
    144  public:
    145   // Set the preemption interval for the ContextSwitcher thread.
    146   static void StartPreemption(int every_n_ms);
    147 
    148   // Stop sending preemption requests to threads.
    149   static void StopPreemption();
    150 
    151   // Preempted thread needs to call back to the ContextSwitcher to acknowledge
    152   // the handling of a preemption request.
    153   static void PreemptionReceived();
    154 
    155  private:
    156   ContextSwitcher(Isolate* isolate, int every_n_ms);
    157 
    158   Isolate* isolate() const { return isolate_; }
    159 
    160   void Run();
    161 
    162   bool keep_going_;
    163   int sleep_ms_;
    164   Isolate* isolate_;
    165 };
    166 
    167 } }  // namespace v8::internal
    168 
    169 #endif  // V8_V8THREADS_H_
    170