Add ThreadIterator for iterating over all Threads

runtime/vm/thread.cc

 // Copyright (c) 2015, 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.
 
 #include "vm/thread.h"
 
 #include "vm/growable_array.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/log.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/os_thread.h"
 #include "vm/profiler.h"
 #include "vm/runtime_entry.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 #include "vm/thread_interrupter.h"
 #include "vm/thread_registry.h"
 
 namespace dart {
 
 // The single thread local key which stores all the thread local data
 // for a thread.
 ThreadLocalKey Thread::thread_key_ = OSThread::kUnsetThreadLocalKey;
-
+Thread* Thread::thread_list_head_ = NULL;
+Mutex Thread::thread_list_lock_;
 
 // Remove |thread| from each isolate's thread registry.
 class ThreadPruner : public IsolateVisitor {
  public:
   explicit ThreadPruner(Thread* thread)
       : thread_(thread) {
     ASSERT(thread_ != NULL);
   }
 
   void VisitIsolate(Isolate* isolate) {
     ThreadRegistry* registry = isolate->thread_registry();
     ASSERT(registry != NULL);
     registry->PruneThread(thread_);
   }
  private:
   Thread* thread_;
 };
 
 
+void Thread::AddThreadToList(Thread* thread) {
+  ASSERT(thread != NULL);
+  MutexLocker ml(&thread_list_lock_);
+  ASSERT(thread->thread_list_next_ == NULL);
+#if defined(DEBUG)
+  {
+    // Ensure that we aren't already in the list.
+    Thread* current = thread_list_head_;
+    while (current != NULL) {
+      ASSERT(current != thread);
+      current = current->thread_list_next_;
+    }
+  }
+#endif
+  // Insert at head of list.
+  thread->thread_list_next_ = thread_list_head_;
+  thread_list_head_ = thread;
+}
+
+
+void Thread::RemoveThreadFromList(Thread* thread) {
+  ASSERT(thread != NULL);
+  MutexLocker ml(&thread_list_lock_);
+
+  // Handle case where |thread| is head of list.
+  if (thread_list_head_ == thread) {
+    thread_list_head_ = thread->thread_list_next_;
+    thread->thread_list_next_ = NULL;
+    return;
+  }
+
+  Thread* current = thread_list_head_;
+  Thread* previous = NULL;
+
+#if defined(DEBUG)
+  bool found_in_list = false;
+#endif
+
+  // Scan across list and remove |thread|.
+  while (current != NULL) {
+    previous = current;
+    current = current->thread_list_next_;
+    if (current == thread) {
+      // We found |thread|, remove from list.
+      previous->thread_list_next_ = current->thread_list_next_;
+#if defined(DEBUG)
+      found_in_list = true;
+#endif

[siva, 2015/10/12 23:03:14]

missing 'break;' here?


Maybe you could restructure as
thread->thread_list_next_ = NULL;
return;

and add an UNREACHABLE(); at the end of the function.

[Cutch, 2015/10/13 16:41:23]

Done.

+    }
+  }
+
+#if defined(DEBUG)
+  ASSERT(found_in_list);
+#endif
+  thread->thread_list_next_ = NULL;
+}
+
+
 static void DeleteThread(void* thread) {
   delete reinterpret_cast<Thread*>(thread);
 }
 
 
 Thread::~Thread() {
   // We should cleanly exit any isolate before destruction.
   ASSERT(isolate_ == NULL);
   // Clear |this| from all isolate's thread registry.
   ThreadPruner pruner(this);
   Isolate::VisitIsolates(&pruner);
   delete log_;
   log_ = NULL;
+  RemoveThreadFromList(this);
 }
 
 
 void Thread::InitOnceBeforeIsolate() {
   ASSERT(thread_key_ == OSThread::kUnsetThreadLocalKey);
   thread_key_ = OSThread::CreateThreadLocal(DeleteThread);
   ASSERT(thread_key_ != OSThread::kUnsetThreadLocalKey);
   ASSERT(Thread::Current() == NULL);
   // Allocate a new Thread and postpone initialization of VM constants for
   // this first thread.
@@ skipping 51 matching lines @@
     : id_(OSThread::GetCurrentThreadId()),
       thread_interrupt_callback_(NULL),
       thread_interrupt_data_(NULL),
       isolate_(NULL),
       heap_(NULL),
       store_buffer_block_(NULL),
       log_(new class Log()),
       vm_tag_(0),
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_INITIALIZERS)
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_SCOPE_INIT)
-      reusable_handles_() {
+      reusable_handles_(),
+      thread_list_next_(NULL) {
   ClearState();
 
 #define DEFAULT_INIT(type_name, member_name, init_expr, default_init_value)    \
   member_name = default_init_value;
 CACHED_CONSTANTS_LIST(DEFAULT_INIT)
 #undef DEFAULT_INIT
 
 #define DEFAULT_INIT(name)                                                     \
   name##_entry_point_ = 0;
 RUNTIME_ENTRY_LIST(DEFAULT_INIT)
 #undef DEFAULT_INIT
 
 #define DEFAULT_INIT(returntype, name, ...)                                    \
   name##_entry_point_ = 0;
 LEAF_RUNTIME_ENTRY_LIST(DEFAULT_INIT)
 #undef DEFAULT_INIT
 
   if (init_vm_constants) {
     InitVMConstants();
   }
   SetCurrent(this);
+  AddThreadToList(this);
 }
 
 
 void Thread::InitVMConstants() {
 #define ASSERT_VM_HEAP(type_name, member_name, init_expr, default_init_value)  \
   ASSERT((init_expr)->IsOldObject());
 CACHED_VM_OBJECTS_LIST(ASSERT_VM_HEAP)
 #undef ASSERT_VM_HEAP
 
 #define INIT_VALUE(type_name, member_name, init_expr, default_init_value)      \
@@ skipping 262 matching lines @@
   if (runtime_entry->function() == k##name##RuntimeEntry.function())         { \
     return Thread::name##_entry_point_offset();                                \
   }
 LEAF_RUNTIME_ENTRY_LIST(COMPUTE_OFFSET)
 #undef COMPUTE_OFFSET
 
   UNREACHABLE();
   return -1;
 }
 
+
+ThreadIterator::ThreadIterator() {
+  // Lock the thread list while iterating.
+  Thread::thread_list_lock_.Lock();
+  next_ = Thread::thread_list_head_;
+}
+
+
+ThreadIterator::~ThreadIterator() {
+  // Unlock the thread list when done.
+  Thread::thread_list_lock_.Unlock();
+}
+
+
+bool ThreadIterator::HasNext() {

[siva, 2015/10/12 23:03:14]

ASSERT(Thread::thread_list_lock_->IsOwnedByCurrentThread());

[Cutch, 2015/10/13 16:41:23]

Done.

+  return next_ != NULL;
+}
+
+
+Thread* ThreadIterator::Next() {

[siva, 2015/10/12 23:03:14]

ASSERT(Thread::thread_list_lock_->IsOwnedByCurrentThread());

[Cutch, 2015/10/13 16:41:23]

Done.

+  Thread* current = next_;
+  next_ = next_->thread_list_next_;
+  return current;
+}
+
+
 }  // namespace dart