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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   // Iterate over in-use states.
     38   static ThreadState* FirstInUse();
     39   // Returns NULL after the last one.
     40   ThreadState* Next();
     41 
     42   enum List {FREE_LIST, IN_USE_LIST};
     43 
     44   void LinkInto(List list);
     45   void Unlink();
     46 
     47   static ThreadState* GetFree();
     48 
     49   // Id of thread.
     50   void set_id(int id) { id_ = id; }
     51   int id() { return id_; }
     52 
     53   // Should the thread be terminated when it is restored?
     54   bool terminate_on_restore() { return terminate_on_restore_; }
     55   void set_terminate_on_restore(bool terminate_on_restore) {
     56     terminate_on_restore_ = terminate_on_restore;
     57   }
     58 
     59   // Get data area for archiving a thread.
     60   char* data() { return data_; }
     61  private:
     62   ThreadState();
     63 
     64   void AllocateSpace();
     65 
     66   int id_;
     67   bool terminate_on_restore_;
     68   char* data_;
     69   ThreadState* next_;
     70   ThreadState* previous_;
     71 
     72   // In the following two lists there is always at least one object on the list.
     73   // The first object is a flying anchor that is only there to simplify linking
     74   // and unlinking.
     75   // Head of linked list of free states.
     76   static ThreadState* free_anchor_;
     77   // Head of linked list of states in use.
     78   static ThreadState* in_use_anchor_;
     79 };
     80 
     81 
     82 class ThreadManager : public AllStatic {
     83  public:
     84   static void Lock();
     85   static void Unlock();
     86 
     87   static void ArchiveThread();
     88   static bool RestoreThread();
     89   static void FreeThreadResources();
     90   static bool IsArchived();
     91 
     92   static void Iterate(ObjectVisitor* v);
     93   static void MarkCompactPrologue(bool is_compacting);
     94   static void MarkCompactEpilogue(bool is_compacting);
     95   static bool IsLockedByCurrentThread() { return mutex_owner_.IsSelf(); }
     96 
     97   static int CurrentId();
     98   static void AssignId();
     99   static bool HasId();
    100 
    101   static void TerminateExecution(int thread_id);
    102 
    103   static const int kInvalidId = -1;
    104  private:
    105   static void EagerlyArchiveThread();
    106 
    107   static int last_id_;  // V8 threads are identified through an integer.
    108   static Mutex* mutex_;
    109   static ThreadHandle mutex_owner_;
    110   static ThreadHandle lazily_archived_thread_;
    111   static ThreadState* lazily_archived_thread_state_;
    112 };
    113 
    114 
    115 // The ContextSwitcher thread is used to schedule regular preemptions to
    116 // multiple running V8 threads. Generally it is necessary to call
    117 // StartPreemption if there is more than one thread running. If not, a single
    118 // JavaScript can take full control of V8 and not allow other threads to run.
    119 class ContextSwitcher: public Thread {
    120  public:
    121   // Set the preemption interval for the ContextSwitcher thread.
    122   static void StartPreemption(int every_n_ms);
    123 
    124   // Stop sending preemption requests to threads.
    125   static void StopPreemption();
    126 
    127   // Preempted thread needs to call back to the ContextSwitcher to acknowledge
    128   // the handling of a preemption request.
    129   static void PreemptionReceived();
    130 
    131  private:
    132   explicit ContextSwitcher(int every_n_ms);
    133 
    134   void Run();
    135 
    136   bool keep_going_;
    137   int sleep_ms_;
    138 
    139   static ContextSwitcher* singleton_;
    140 };
    141 
    142 } }  // namespace v8::internal
    143 
    144 #endif  // V8_V8THREADS_H_
    145