Changeset 28223 in webkit for trunk/JavaScriptCore/kjs/collector.cpp

Timestamp:

Nov 29, 2007, 7:02:08 PM (18 years ago)

Author:

[email protected]

Message:

Make the JS collector work with multiple threads

Reviewed by Maciej and Darin.

Under heavy contention it was possible the GC to suspend other
threads inside the pthread spinlock, which could lead to the GC
thread blocking on the pthread spinlock itself.

We now determine and store each thread's stack base when it is
registered, thus removing the need for any calls to pthread_get_stackaddr_np
that needed the pthread spinlock.

File:

• trunk/JavaScriptCore/kjs/collector.cpp (modified) (4 diffs)

trunk/JavaScriptCore/kjs/collector.cpp

@@ -409 +409 @@
 class Collector::Thread {
 public:
-  Thread(pthread_t pthread, const PlatformThread& platThread) : posixThread(pthread), platformThread(platThread) {}
+  Thread(pthread_t pthread, const PlatformThread& platThread, void* base) 
+  : posixThread(pthread), platformThread(platThread), stackBase(base) {}
   Thread* next;
   pthread_t posixThread;
   PlatformThread platformThread;
+  void* stackBase;
 };
 
@@ -465 +467 @@
 #endif
 
-    Collector::Thread *thread = new Collector::Thread(pthread_self(), getCurrentPlatformThread());
+    Collector::Thread *thread = new Collector::Thread(pthread_self(), getCurrentPlatformThread(), currentThreadStackBase());
 
     thread->next = registeredThreads;
@@ -676 +678 @@
 }
 
-static inline void* otherThreadStackBase(const PlatformThreadRegisters& regs, Collector::Thread* thread)
-{
-#if PLATFORM(DARWIN)
-  (void)regs;
-  return pthread_get_stackaddr_np(thread->posixThread);
-// end PLATFORM(DARWIN);
-#elif PLATFORM(X86) && PLATFORM(WIN_OS)
-  LDT_ENTRY desc;
-  NT_TIB* tib;
-  GetThreadSelectorEntry(thread->platformThread.handle, regs.SegFs, &desc);
-  tib = (NT_TIB*)(uintptr_t)(desc.BaseLow | desc.HighWord.Bytes.BaseMid << 16 | desc.HighWord.Bytes.BaseHi << 24);
-  ASSERT(tib == tib->Self);
-  return tib->StackBase;
-#else
-#error Need a way to get the stack pointer for another thread on this platform
-#endif
-}
-
 void Collector::markOtherThreadConservatively(Thread* thread)
 {
@@ -705 +689 @@
  
   void* stackPointer = otherThreadStackPointer(regs);
-  void* stackBase = otherThreadStackBase(regs, thread);
-  markStackObjectsConservatively(stackPointer, stackBase);
+  markStackObjectsConservatively(stackPointer, thread->stackBase);
 
   resumeThread(thread->platformThread);