Revert "Move mojo edk into mojo/edk"

mojo/edk/system/core.cc

Index: mojo/edk/system/core.cc
diff --git a/mojo/edk/system/core.cc b/mojo/edk/system/core.cc
deleted file mode 100644
index c67a6260fb33dd4d0c972f9bdd714ad10a31ac17..0000000000000000000000000000000000000000
--- a/mojo/edk/system/core.cc
+++ /dev/null
@@ -1,606 +0,0 @@
-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "mojo/edk/system/core.h"
-
-#include <vector>
-
-#include "base/logging.h"
-#include "base/time/time.h"
-#include "mojo/edk/embedder/platform_shared_buffer.h"
-#include "mojo/edk/embedder/platform_support.h"
-#include "mojo/edk/system/constants.h"
-#include "mojo/edk/system/data_pipe.h"
-#include "mojo/edk/system/data_pipe_consumer_dispatcher.h"
-#include "mojo/edk/system/data_pipe_producer_dispatcher.h"
-#include "mojo/edk/system/dispatcher.h"
-#include "mojo/edk/system/handle_signals_state.h"
-#include "mojo/edk/system/local_data_pipe.h"
-#include "mojo/edk/system/memory.h"
-#include "mojo/edk/system/message_pipe.h"
-#include "mojo/edk/system/message_pipe_dispatcher.h"
-#include "mojo/edk/system/shared_buffer_dispatcher.h"
-#include "mojo/edk/system/waiter.h"
-#include "mojo/public/c/system/macros.h"
-
-namespace mojo {
-namespace system {
-
-// Implementation notes
-//
-// Mojo primitives are implemented by the singleton |Core| object. Most calls
-// are for a "primary" handle (the first argument). |Core::GetDispatcher()| is
-// used to look up a |Dispatcher| object for a given handle. That object
-// implements most primitives for that object. The wait primitives are not
-// attached to objects and are implemented by |Core| itself.
-//
-// Some objects have multiple handles associated to them, e.g., message pipes
-// (which have two). In such a case, there is still a |Dispatcher| (e.g.,
-// |MessagePipeDispatcher|) for each handle, with each handle having a strong
-// reference to the common "secondary" object (e.g., |MessagePipe|). This
-// secondary object does NOT have any references to the |Dispatcher|s (even if
-// it did, it wouldn't be able to do anything with them due to lock order
-// requirements -- see below).
-//
-// Waiting is implemented by having the thread that wants to wait call the
-// |Dispatcher|s for the handles that it wants to wait on with a |Waiter|
-// object; this |Waiter| object may be created on the stack of that thread or be
-// kept in thread local storage for that thread (TODO(vtl): future improvement).
-// The |Dispatcher| then adds the |Waiter| to a |WaiterList| that's either owned
-// by that |Dispatcher| (see |SimpleDispatcher|) or by a secondary object (e.g.,
-// |MessagePipe|). To signal/wake a |Waiter|, the object in question -- either a
-// |SimpleDispatcher| or a secondary object -- talks to its |WaiterList|.
-
-// Thread-safety notes
-//
-// Mojo primitives calls are thread-safe. We achieve this with relatively
-// fine-grained locking. There is a global handle table lock. This lock should
-// be held as briefly as possible (TODO(vtl): a future improvement would be to
-// switch it to a reader-writer lock). Each |Dispatcher| object then has a lock
-// (which subclasses can use to protect their data).
-//
-// The lock ordering is as follows:
-//   1. global handle table lock, global mapping table lock
-//   2. |Dispatcher| locks
-//   3. secondary object locks
-//   ...
-//   INF. |Waiter| locks
-//
-// Notes:
-//    - While holding a |Dispatcher| lock, you may not unconditionally attempt
-//      to take another |Dispatcher| lock. (This has consequences on the
-//      concurrency semantics of |MojoWriteMessage()| when passing handles.)
-//      Doing so would lead to deadlock.
-//    - Locks at the "INF" level may not have any locks taken while they are
-//      held.
-
-// TODO(vtl): This should take a |scoped_ptr<PlatformSupport>| as a parameter.
-Core::Core(scoped_ptr<embedder::PlatformSupport> platform_support)
-    : platform_support_(platform_support.Pass()) {
-}
-
-Core::~Core() {
-}
-
-MojoHandle Core::AddDispatcher(const scoped_refptr<Dispatcher>& dispatcher) {
-  base::AutoLock locker(handle_table_lock_);
-  return handle_table_.AddDispatcher(dispatcher);
-}
-
-scoped_refptr<Dispatcher> Core::GetDispatcher(MojoHandle handle) {
-  if (handle == MOJO_HANDLE_INVALID)
-    return nullptr;
-
-  base::AutoLock locker(handle_table_lock_);
-  return handle_table_.GetDispatcher(handle);
-}
-
-MojoTimeTicks Core::GetTimeTicksNow() {
-  return base::TimeTicks::Now().ToInternalValue();
-}
-
-MojoResult Core::Close(MojoHandle handle) {
-  if (handle == MOJO_HANDLE_INVALID)
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  scoped_refptr<Dispatcher> dispatcher;
-  {
-    base::AutoLock locker(handle_table_lock_);
-    MojoResult result =
-        handle_table_.GetAndRemoveDispatcher(handle, &dispatcher);
-    if (result != MOJO_RESULT_OK)
-      return result;
-  }
-
-  // The dispatcher doesn't have a say in being closed, but gets notified of it.
-  // Note: This is done outside of |handle_table_lock_|. As a result, there's a
-  // race condition that the dispatcher must handle; see the comment in
-  // |Dispatcher| in dispatcher.h.
-  return dispatcher->Close();
-}
-
-MojoResult Core::Wait(MojoHandle handle,
-                      MojoHandleSignals signals,
-                      MojoDeadline deadline,
-                      UserPointer<MojoHandleSignalsState> signals_state) {
-  uint32_t unused = static_cast<uint32_t>(-1);
-  HandleSignalsState hss;
-  MojoResult rv = WaitManyInternal(&handle,
-                                   &signals,
-                                   1,
-                                   deadline,
-                                   &unused,
-                                   signals_state.IsNull() ? nullptr : &hss);
-  if (rv != MOJO_RESULT_INVALID_ARGUMENT && !signals_state.IsNull())
-    signals_state.Put(hss);
-  return rv;
-}
-
-MojoResult Core::WaitMany(UserPointer<const MojoHandle> handles,
-                          UserPointer<const MojoHandleSignals> signals,
-                          uint32_t num_handles,
-                          MojoDeadline deadline,
-                          UserPointer<uint32_t> result_index,
-                          UserPointer<MojoHandleSignalsState> signals_states) {
-  if (num_handles < 1)
-    return MOJO_RESULT_INVALID_ARGUMENT;
-  if (num_handles > kMaxWaitManyNumHandles)
-    return MOJO_RESULT_RESOURCE_EXHAUSTED;
-
-  UserPointer<const MojoHandle>::Reader handles_reader(handles, num_handles);
-  UserPointer<const MojoHandleSignals>::Reader signals_reader(signals,
-                                                              num_handles);
-  uint32_t index = static_cast<uint32_t>(-1);
-  MojoResult rv;
-  if (signals_states.IsNull()) {
-    rv = WaitManyInternal(handles_reader.GetPointer(),
-                          signals_reader.GetPointer(),
-                          num_handles,
-                          deadline,
-                          &index,
-                          nullptr);
-  } else {
-    UserPointer<MojoHandleSignalsState>::Writer signals_states_writer(
-        signals_states, num_handles);
-    // Note: The |reinterpret_cast| is safe, since |HandleSignalsState| is a
-    // subclass of |MojoHandleSignalsState| that doesn't add any data members.
-    rv = WaitManyInternal(handles_reader.GetPointer(),
-                          signals_reader.GetPointer(),
-                          num_handles,
-                          deadline,
-                          &index,
-                          reinterpret_cast<HandleSignalsState*>(
-                              signals_states_writer.GetPointer()));
-    if (rv != MOJO_RESULT_INVALID_ARGUMENT)
-      signals_states_writer.Commit();
-  }
-  if (index != static_cast<uint32_t>(-1) && !result_index.IsNull())
-    result_index.Put(index);
-  return rv;
-}
-
-MojoResult Core::CreateMessagePipe(
-    UserPointer<const MojoCreateMessagePipeOptions> options,
-    UserPointer<MojoHandle> message_pipe_handle0,
-    UserPointer<MojoHandle> message_pipe_handle1) {
-  MojoCreateMessagePipeOptions validated_options = {};
-  MojoResult result =
-      MessagePipeDispatcher::ValidateCreateOptions(options, &validated_options);
-  if (result != MOJO_RESULT_OK)
-    return result;
-
-  scoped_refptr<MessagePipeDispatcher> dispatcher0(
-      new MessagePipeDispatcher(validated_options));
-  scoped_refptr<MessagePipeDispatcher> dispatcher1(
-      new MessagePipeDispatcher(validated_options));
-
-  std::pair<MojoHandle, MojoHandle> handle_pair;
-  {
-    base::AutoLock locker(handle_table_lock_);
-    handle_pair = handle_table_.AddDispatcherPair(dispatcher0, dispatcher1);
-  }
-  if (handle_pair.first == MOJO_HANDLE_INVALID) {
-    DCHECK_EQ(handle_pair.second, MOJO_HANDLE_INVALID);
-    LOG(ERROR) << "Handle table full";
-    dispatcher0->Close();
-    dispatcher1->Close();
-    return MOJO_RESULT_RESOURCE_EXHAUSTED;
-  }
-
-  scoped_refptr<MessagePipe> message_pipe(MessagePipe::CreateLocalLocal());
-  dispatcher0->Init(message_pipe, 0);
-  dispatcher1->Init(message_pipe, 1);
-
-  message_pipe_handle0.Put(handle_pair.first);
-  message_pipe_handle1.Put(handle_pair.second);
-  return MOJO_RESULT_OK;
-}
-
-// Implementation note: To properly cancel waiters and avoid other races, this
-// does not transfer dispatchers from one handle to another, even when sending a
-// message in-process. Instead, it must transfer the "contents" of the
-// dispatcher to a new dispatcher, and then close the old dispatcher. If this
-// isn't done, in the in-process case, calls on the old handle may complete
-// after the the message has been received and a new handle created (and
-// possibly even after calls have been made on the new handle).
-MojoResult Core::WriteMessage(MojoHandle message_pipe_handle,
-                              UserPointer<const void> bytes,
-                              uint32_t num_bytes,
-                              UserPointer<const MojoHandle> handles,
-                              uint32_t num_handles,
-                              MojoWriteMessageFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  // Easy case: not sending any handles.
-  if (num_handles == 0)
-    return dispatcher->WriteMessage(bytes, num_bytes, nullptr, flags);
-
-  // We have to handle |handles| here, since we have to mark them busy in the
-  // global handle table. We can't delegate this to the dispatcher, since the
-  // handle table lock must be acquired before the dispatcher lock.
-  //
-  // (This leads to an oddity: |handles|/|num_handles| are always verified for
-  // validity, even for dispatchers that don't support |WriteMessage()| and will
-  // simply return failure unconditionally. It also breaks the usual
-  // left-to-right verification order of arguments.)
-  if (num_handles > kMaxMessageNumHandles)
-    return MOJO_RESULT_RESOURCE_EXHAUSTED;
-
-  UserPointer<const MojoHandle>::Reader handles_reader(handles, num_handles);
-
-  // We'll need to hold on to the dispatchers so that we can pass them on to
-  // |WriteMessage()| and also so that we can unlock their locks afterwards
-  // without accessing the handle table. These can be dumb pointers, since their
-  // entries in the handle table won't get removed (since they'll be marked as
-  // busy).
-  std::vector<DispatcherTransport> transports(num_handles);
-
-  // When we pass handles, we have to try to take all their dispatchers' locks
-  // and mark the handles as busy. If the call succeeds, we then remove the
-  // handles from the handle table.
-  {
-    base::AutoLock locker(handle_table_lock_);
-    MojoResult result =
-        handle_table_.MarkBusyAndStartTransport(message_pipe_handle,
-                                                handles_reader.GetPointer(),
-                                                num_handles,
-                                                &transports);
-    if (result != MOJO_RESULT_OK)
-      return result;
-  }
-
-  MojoResult rv =
-      dispatcher->WriteMessage(bytes, num_bytes, &transports, flags);
-
-  // We need to release the dispatcher locks before we take the handle table
-  // lock.
-  for (uint32_t i = 0; i < num_handles; i++)
-    transports[i].End();
-
-  {
-    base::AutoLock locker(handle_table_lock_);
-    if (rv == MOJO_RESULT_OK) {
-      handle_table_.RemoveBusyHandles(handles_reader.GetPointer(), num_handles);
-    } else {
-      handle_table_.RestoreBusyHandles(handles_reader.GetPointer(),
-                                       num_handles);
-    }
-  }
-
-  return rv;
-}
-
-MojoResult Core::ReadMessage(MojoHandle message_pipe_handle,
-                             UserPointer<void> bytes,
-                             UserPointer<uint32_t> num_bytes,
-                             UserPointer<MojoHandle> handles,
-                             UserPointer<uint32_t> num_handles,
-                             MojoReadMessageFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  uint32_t num_handles_value = num_handles.IsNull() ? 0 : num_handles.Get();
-
-  MojoResult rv;
-  if (num_handles_value == 0) {
-    // Easy case: won't receive any handles.
-    rv = dispatcher->ReadMessage(
-        bytes, num_bytes, nullptr, &num_handles_value, flags);
-  } else {
-    DispatcherVector dispatchers;
-    rv = dispatcher->ReadMessage(
-        bytes, num_bytes, &dispatchers, &num_handles_value, flags);
-    if (!dispatchers.empty()) {
-      DCHECK_EQ(rv, MOJO_RESULT_OK);
-      DCHECK(!num_handles.IsNull());
-      DCHECK_LE(dispatchers.size(), static_cast<size_t>(num_handles_value));
-
-      bool success;
-      UserPointer<MojoHandle>::Writer handles_writer(handles,
-                                                     dispatchers.size());
-      {
-        base::AutoLock locker(handle_table_lock_);
-        success = handle_table_.AddDispatcherVector(
-            dispatchers, handles_writer.GetPointer());
-      }
-      if (success) {
-        handles_writer.Commit();
-      } else {
-        LOG(ERROR) << "Received message with " << dispatchers.size()
-                   << " handles, but handle table full";
-        // Close dispatchers (outside the lock).
-        for (size_t i = 0; i < dispatchers.size(); i++) {
-          if (dispatchers[i].get())
-            dispatchers[i]->Close();
-        }
-        if (rv == MOJO_RESULT_OK)
-          rv = MOJO_RESULT_RESOURCE_EXHAUSTED;
-      }
-    }
-  }
-
-  if (!num_handles.IsNull())
-    num_handles.Put(num_handles_value);
-  return rv;
-}
-
-MojoResult Core::CreateDataPipe(
-    UserPointer<const MojoCreateDataPipeOptions> options,
-    UserPointer<MojoHandle> data_pipe_producer_handle,
-    UserPointer<MojoHandle> data_pipe_consumer_handle) {
-  MojoCreateDataPipeOptions validated_options = {};
-  MojoResult result =
-      DataPipe::ValidateCreateOptions(options, &validated_options);
-  if (result != MOJO_RESULT_OK)
-    return result;
-
-  scoped_refptr<DataPipeProducerDispatcher> producer_dispatcher(
-      new DataPipeProducerDispatcher());
-  scoped_refptr<DataPipeConsumerDispatcher> consumer_dispatcher(
-      new DataPipeConsumerDispatcher());
-
-  std::pair<MojoHandle, MojoHandle> handle_pair;
-  {
-    base::AutoLock locker(handle_table_lock_);
-    handle_pair = handle_table_.AddDispatcherPair(producer_dispatcher,
-                                                  consumer_dispatcher);
-  }
-  if (handle_pair.first == MOJO_HANDLE_INVALID) {
-    DCHECK_EQ(handle_pair.second, MOJO_HANDLE_INVALID);
-    LOG(ERROR) << "Handle table full";
-    producer_dispatcher->Close();
-    consumer_dispatcher->Close();
-    return MOJO_RESULT_RESOURCE_EXHAUSTED;
-  }
-  DCHECK_NE(handle_pair.second, MOJO_HANDLE_INVALID);
-
-  scoped_refptr<DataPipe> data_pipe(new LocalDataPipe(validated_options));
-  producer_dispatcher->Init(data_pipe);
-  consumer_dispatcher->Init(data_pipe);
-
-  data_pipe_producer_handle.Put(handle_pair.first);
-  data_pipe_consumer_handle.Put(handle_pair.second);
-  return MOJO_RESULT_OK;
-}
-
-MojoResult Core::WriteData(MojoHandle data_pipe_producer_handle,
-                           UserPointer<const void> elements,
-                           UserPointer<uint32_t> num_bytes,
-                           MojoWriteDataFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(
-      GetDispatcher(data_pipe_producer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return dispatcher->WriteData(elements, num_bytes, flags);
-}
-
-MojoResult Core::BeginWriteData(MojoHandle data_pipe_producer_handle,
-                                UserPointer<void*> buffer,
-                                UserPointer<uint32_t> buffer_num_bytes,
-                                MojoWriteDataFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(
-      GetDispatcher(data_pipe_producer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return dispatcher->BeginWriteData(buffer, buffer_num_bytes, flags);
-}
-
-MojoResult Core::EndWriteData(MojoHandle data_pipe_producer_handle,
-                              uint32_t num_bytes_written) {
-  scoped_refptr<Dispatcher> dispatcher(
-      GetDispatcher(data_pipe_producer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return dispatcher->EndWriteData(num_bytes_written);
-}
-
-MojoResult Core::ReadData(MojoHandle data_pipe_consumer_handle,
-                          UserPointer<void> elements,
-                          UserPointer<uint32_t> num_bytes,
-                          MojoReadDataFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(
-      GetDispatcher(data_pipe_consumer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return dispatcher->ReadData(elements, num_bytes, flags);
-}
-
-MojoResult Core::BeginReadData(MojoHandle data_pipe_consumer_handle,
-                               UserPointer<const void*> buffer,
-                               UserPointer<uint32_t> buffer_num_bytes,
-                               MojoReadDataFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(
-      GetDispatcher(data_pipe_consumer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return dispatcher->BeginReadData(buffer, buffer_num_bytes, flags);
-}
-
-MojoResult Core::EndReadData(MojoHandle data_pipe_consumer_handle,
-                             uint32_t num_bytes_read) {
-  scoped_refptr<Dispatcher> dispatcher(
-      GetDispatcher(data_pipe_consumer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return dispatcher->EndReadData(num_bytes_read);
-}
-
-MojoResult Core::CreateSharedBuffer(
-    UserPointer<const MojoCreateSharedBufferOptions> options,
-    uint64_t num_bytes,
-    UserPointer<MojoHandle> shared_buffer_handle) {
-  MojoCreateSharedBufferOptions validated_options = {};
-  MojoResult result = SharedBufferDispatcher::ValidateCreateOptions(
-      options, &validated_options);
-  if (result != MOJO_RESULT_OK)
-    return result;
-
-  scoped_refptr<SharedBufferDispatcher> dispatcher;
-  result = SharedBufferDispatcher::Create(
-      platform_support(), validated_options, num_bytes, &dispatcher);
-  if (result != MOJO_RESULT_OK) {
-    DCHECK(!dispatcher.get());
-    return result;
-  }
-
-  MojoHandle h = AddDispatcher(dispatcher);
-  if (h == MOJO_HANDLE_INVALID) {
-    LOG(ERROR) << "Handle table full";
-    dispatcher->Close();
-    return MOJO_RESULT_RESOURCE_EXHAUSTED;
-  }
-
-  shared_buffer_handle.Put(h);
-  return MOJO_RESULT_OK;
-}
-
-MojoResult Core::DuplicateBufferHandle(
-    MojoHandle buffer_handle,
-    UserPointer<const MojoDuplicateBufferHandleOptions> options,
-    UserPointer<MojoHandle> new_buffer_handle) {
-  scoped_refptr<Dispatcher> dispatcher(GetDispatcher(buffer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  // Don't verify |options| here; that's the dispatcher's job.
-  scoped_refptr<Dispatcher> new_dispatcher;
-  MojoResult result =
-      dispatcher->DuplicateBufferHandle(options, &new_dispatcher);
-  if (result != MOJO_RESULT_OK)
-    return result;
-
-  MojoHandle new_handle = AddDispatcher(new_dispatcher);
-  if (new_handle == MOJO_HANDLE_INVALID) {
-    LOG(ERROR) << "Handle table full";
-    dispatcher->Close();
-    return MOJO_RESULT_RESOURCE_EXHAUSTED;
-  }
-
-  new_buffer_handle.Put(new_handle);
-  return MOJO_RESULT_OK;
-}
-
-MojoResult Core::MapBuffer(MojoHandle buffer_handle,
-                           uint64_t offset,
-                           uint64_t num_bytes,
-                           UserPointer<void*> buffer,
-                           MojoMapBufferFlags flags) {
-  scoped_refptr<Dispatcher> dispatcher(GetDispatcher(buffer_handle));
-  if (!dispatcher.get())
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  scoped_ptr<embedder::PlatformSharedBufferMapping> mapping;
-  MojoResult result = dispatcher->MapBuffer(offset, num_bytes, flags, &mapping);
-  if (result != MOJO_RESULT_OK)
-    return result;
-
-  DCHECK(mapping);
-  void* address = mapping->GetBase();
-  {
-    base::AutoLock locker(mapping_table_lock_);
-    result = mapping_table_.AddMapping(mapping.Pass());
-  }
-  if (result != MOJO_RESULT_OK)
-    return result;
-
-  buffer.Put(address);
-  return MOJO_RESULT_OK;
-}
-
-MojoResult Core::UnmapBuffer(UserPointer<void> buffer) {
-  base::AutoLock locker(mapping_table_lock_);
-  return mapping_table_.RemoveMapping(buffer.GetPointerValue());
-}
-
-// Note: We allow |handles| to repeat the same handle multiple times, since
-// different flags may be specified.
-// TODO(vtl): This incurs a performance cost in |RemoveWaiter()|. Analyze this
-// more carefully and address it if necessary.
-MojoResult Core::WaitManyInternal(const MojoHandle* handles,
-                                  const MojoHandleSignals* signals,
-                                  uint32_t num_handles,
-                                  MojoDeadline deadline,
-                                  uint32_t* result_index,
-                                  HandleSignalsState* signals_states) {
-  DCHECK_GT(num_handles, 0u);
-  DCHECK_EQ(*result_index, static_cast<uint32_t>(-1));
-
-  DispatcherVector dispatchers;
-  dispatchers.reserve(num_handles);
-  for (uint32_t i = 0; i < num_handles; i++) {
-    scoped_refptr<Dispatcher> dispatcher = GetDispatcher(handles[i]);
-    if (!dispatcher.get()) {
-      *result_index = i;
-      return MOJO_RESULT_INVALID_ARGUMENT;
-    }
-    dispatchers.push_back(dispatcher);
-  }
-
-  // TODO(vtl): Should make the waiter live (permanently) in TLS.
-  Waiter waiter;
-  waiter.Init();
-
-  uint32_t i;
-  MojoResult rv = MOJO_RESULT_OK;
-  for (i = 0; i < num_handles; i++) {
-    rv = dispatchers[i]->AddWaiter(
-        &waiter, signals[i], i, signals_states ? &signals_states[i] : nullptr);
-    if (rv != MOJO_RESULT_OK) {
-      *result_index = i;
-      break;
-    }
-  }
-  uint32_t num_added = i;
-
-  if (rv == MOJO_RESULT_ALREADY_EXISTS)
-    rv = MOJO_RESULT_OK;  // The i-th one is already "triggered".
-  else if (rv == MOJO_RESULT_OK)
-    rv = waiter.Wait(deadline, result_index);
-
-  // Make sure no other dispatchers try to wake |waiter| for the current
-  // |Wait()|/|WaitMany()| call. (Only after doing this can |waiter| be
-  // destroyed, but this would still be required if the waiter were in TLS.)
-  for (i = 0; i < num_added; i++) {
-    dispatchers[i]->RemoveWaiter(&waiter,
-                                 signals_states ? &signals_states[i] : nullptr);
-  }
-  if (signals_states) {
-    for (; i < num_handles; i++)
-      signals_states[i] = dispatchers[i]->GetHandleSignalsState();
-  }
-
-  return rv;
-}
-
-}  // namespace system
-}  // namespace mojo