- Add an OSThread structure which is the generic TLS structure for all C++

runtime/vm/os_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/os_thread.h"
+
+#include "vm/atomic.h"
+#include "vm/lockers.h"
+#include "vm/log.h"
+#include "vm/thread_interrupter.h"
+
+namespace dart {
+
+// The single thread local key which stores all the thread local data
+// for a thread.
+ThreadLocalKey OSThread::thread_key_ = OSThread::kUnsetThreadLocalKey;
+OSThread* OSThread::thread_list_head_ = NULL;
+Mutex* OSThread::thread_list_lock_ = NULL;
+
+
+OSThread::OSThread() :
+    BaseThread(true),
+    id_(OSThread::GetCurrentThreadId()),
+    join_id_(OSThread::GetCurrentThreadJoinId()),
+    trace_id_(OSThread::GetCurrentThreadTraceId()),
+    name_(NULL),
+    timeline_block_lock_(new Mutex()),
+    timeline_block_(NULL),
+    thread_list_next_(NULL),
+    thread_interrupt_disabled_(1),  // Thread interrupts disabled by default.
+    log_(new class Log()),
+    stack_base_(0),
+    thread_(NULL) {
+  AddThreadToList(this);
+}
+
+
+OSThread::~OSThread() {
+  RemoveThreadFromList(this);
+  delete log_;
+  log_ = NULL;
+  if (Timeline::recorder() != NULL) {
+    Timeline::recorder()->FinishBlock(timeline_block_);
+  }
+  timeline_block_ = NULL;
+  delete timeline_block_lock_;

[Ivan Posva, 2015/11/19 06:23:23]

Who deletes name_? This also means that we have to strdup the name being passed
in.

[Cutch, 2015/11/19 15:12:21]

name_ must always be a statically allocated const char* and it isn't copied.

+}
+
+
+void OSThread::DisableThreadInterrupts() {
+  ASSERT(OSThread::Current() == this);
+  AtomicOperations::FetchAndIncrement(&thread_interrupt_disabled_);
+}
+
+
+void OSThread::EnableThreadInterrupts() {
+  ASSERT(OSThread::Current() == this);
+  uintptr_t old =
+      AtomicOperations::FetchAndDecrement(&thread_interrupt_disabled_);
+  if (old == 1) {
+    // We just decremented from 1 to 0.
+    // Make sure the thread interrupter is awake.
+    ThreadInterrupter::WakeUp();
+  }

[Ivan Posva, 2015/11/19 06:23:23]

} else if (old == 0) {

Should we FATAL out in all conditions or only in debug builds and otherwise just
limit to zero?

[Cutch, 2015/11/19 15:12:21]

I wrote this code so that it would FATAL in all configurations. The embedder or
the VM has a serious bug if they don't properly pair calls to
DisableThreadInterrupts with calls to EnableThreadInterrupts.

[siva, 2015/11/19 20:54:05]

I am going to leave it the way it is now, we can always revisit.

+  if (old == 0) {
+    // We just decremented from 0, this means we've got a mismatched pair
+    // of calls to EnableThreadInterrupts and DisableThreadInterrupts.
+    FATAL("Invalid call to OSThread::EnableThreadInterrupts()");
+  }
+}
+
+
+bool OSThread::ThreadInterruptsEnabled() {
+  return AtomicOperations::LoadRelaxed(&thread_interrupt_disabled_) == 0;
+}
+
+
+static void DeleteThread(void* thread) {
+  delete reinterpret_cast<OSThread*>(thread);
+}
+
+
+void OSThread::InitOnce() {
+  // Allocate the global OSThread lock.
+  ASSERT(thread_list_lock_ == NULL);
+  thread_list_lock_ = new Mutex();
+  ASSERT(thread_list_lock_ != NULL);
+
+  // Create the thread local key.
+  ASSERT(thread_key_ == kUnsetThreadLocalKey);
+  thread_key_ = CreateThreadLocal(DeleteThread);
+  ASSERT(thread_key_ != kUnsetThreadLocalKey);
+
+  // Create a new OSThread strcture and set it as the TLS.
+  OSThread* os_thread = new OSThread();
+  OSThread::SetCurrent(os_thread);
+  os_thread->set_name("Dart_Initialize");
+}
+
+
+void OSThread::Cleanup() {
+  if (thread_list_lock_ != NULL) {
+    // Delete the thread local key.
+    ASSERT(thread_key_ != kUnsetThreadLocalKey);
+    DeleteThreadLocal(thread_key_);
+    thread_key_ = kUnsetThreadLocalKey;
+
+    // Delete the global OSThread lock.
+    ASSERT(thread_list_lock_ != NULL);
+    delete thread_list_lock_;
+    thread_list_lock_ = NULL;
+  }
+}
+
+
+bool OSThread::IsThreadInList(ThreadId join_id) {
+  if (join_id == OSThread::kInvalidThreadJoinId) {
+    return false;
+  }
+  OSThreadIterator it;
+  while (it.HasNext()) {
+    ASSERT(OSThread::thread_list_lock_->IsOwnedByCurrentThread());
+    OSThread* t = it.Next();
+    // An address test is not sufficient because the allocator may recycle
+    // the address for another Thread. Test against the thread's join id.
+    if (t->join_id() == join_id) {
+      return true;
+    }
+  }
+  return false;
+}
+
+
+OSThread* OSThread::GetOSThreadFromThread(Thread* thread) {
+  ASSERT(thread->os_thread() != NULL);
+  return thread->os_thread();
+}
+
+
+void OSThread::AddThreadToList(OSThread* thread) {
+  ASSERT(thread != NULL);
+  ASSERT(thread_list_lock_ != NULL);
+  MutexLocker ml(thread_list_lock_);
+
+  ASSERT(thread->thread_list_next_ == NULL);
+
+#if defined(DEBUG)
+  {
+    // Ensure that we aren't already in the list.
+    OSThread* 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 OSThread::RemoveThreadFromList(OSThread* thread) {
+  {
+    ASSERT(thread != NULL);
+    ASSERT(thread_list_lock_ != NULL);
+    MutexLocker ml(thread_list_lock_);
+    OSThread* current = thread_list_head_;
+    OSThread* previous = NULL;
+
+    // Scan across list and remove |thread|.
+    while (current != NULL) {
+      if (current == thread) {
+        // We found |thread|, remove from list.
+        if (previous == NULL) {
+          thread_list_head_ = thread->thread_list_next_;
+        } else {
+          previous->thread_list_next_ = current->thread_list_next_;
+        }
+        thread->thread_list_next_ = NULL;
+        break;
+      }
+      previous = current;
+      current = current->thread_list_next_;
+    }
+  }
+  // Check if this is the last thread. The last thread does a cleanup
+  // which removes the thread local key and the associated mutex.
+  if (thread_list_head_ == NULL) {
+    Cleanup();
+  }
+}
+
+
+void OSThread::SetCurrent(OSThread* current) {
+  OSThread::SetThreadLocal(thread_key_, reinterpret_cast<uword>(current));
+}
+
+
+OSThreadIterator::OSThreadIterator() {
+  ASSERT(OSThread::thread_list_lock_ != NULL);
+  // Lock the thread list while iterating.
+  OSThread::thread_list_lock_->Lock();
+  next_ = OSThread::thread_list_head_;
+}
+
+
+OSThreadIterator::~OSThreadIterator() {
+  ASSERT(OSThread::thread_list_lock_ != NULL);
+  // Unlock the thread list when done.
+  OSThread::thread_list_lock_->Unlock();
+}
+
+
+bool OSThreadIterator::HasNext() const {
+  ASSERT(OSThread::thread_list_lock_ != NULL);
+  ASSERT(OSThread::thread_list_lock_->IsOwnedByCurrentThread());
+  return next_ != NULL;
+}
+
+
+OSThread* OSThreadIterator::Next() {
+  ASSERT(OSThread::thread_list_lock_ != NULL);
+  ASSERT(OSThread::thread_list_lock_->IsOwnedByCurrentThread());
+  OSThread* current = next_;
+  next_ = next_->thread_list_next_;
+  return current;
+}
+
+}  // namespace dart