Initial in-process implementation of some Mojo primitives.

mojo/system/dispatcher.cc

+// 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/system/dispatcher.h"
+
+#include "base/logging.h"
+
+namespace mojo {
+namespace system {
+
+MojoResult Dispatcher::Close() {
+  base::AutoLock locker(lock_);
+  if (is_closed_)
+    return MOJO_RESULT_INVALID_ARGUMENT;

[darin (slow to review), 2013/09/25 06:06:07]

Hmm, how do we ever reach this branch? it seems like CoreImpl::Close ensures
that Dispatcher::Close() can only ever be called once per Dispatcher. If so,
then we can just assert that is_closed_ is false on entry to this function,
right?

[viettrungluu, 2013/09/25 18:22:16]

You're right, thanks (Close() can't race with itself, but it can race with other
calls).

+
+  is_closed_ = true;
+  CancelAllWaitersNoLock();
+  return CloseImplNoLock();
+}
+
+MojoResult Dispatcher::WriteMessage(const void* bytes,
+                                    uint32_t num_bytes,
+                                    const MojoHandle* handles,
+                                    uint32_t num_handles,
+                                    MojoWriteMessageFlags flags) {
+  base::AutoLock locker(lock_);
+  if (is_closed_)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+
+  return WriteMessageImplNoLock(bytes, num_bytes, handles, num_handles, flags);
+}
+
+MojoResult Dispatcher::ReadMessage(void* bytes,
+                                   uint32_t* num_bytes,
+                                   MojoHandle* handles,
+                                   uint32_t* num_handles,
+                                   MojoReadMessageFlags flags) {
+  base::AutoLock locker(lock_);
+  if (is_closed_)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+
+  return ReadMessageImplNoLock(bytes, num_bytes, handles, num_handles, flags);
+}
+
+MojoResult Dispatcher::AddWaiter(Waiter* waiter,
+                                 MojoWaitFlags flags,
+                                 MojoResult wake_result) {
+  DCHECK_GE(wake_result, 0);
+
+  base::AutoLock locker(lock_);
+  if (is_closed_)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+
+  return AddWaiterImplNoLock(waiter, flags, wake_result);
+}
+
+void Dispatcher::RemoveWaiter(Waiter* waiter) {
+  base::AutoLock locker(lock_);
+  if (is_closed_)
+    return;
+  RemoveWaiterImplNoLock(waiter);
+}
+
+Dispatcher::Dispatcher()
+    : is_closed_(false) {
+}
+
+Dispatcher::~Dispatcher() {
+  // Make sure that |Close()| was called.
+  DCHECK(is_closed_);
+}
+
+void Dispatcher::CancelAllWaitersNoLock() {
+  lock_.AssertAcquired();
+  DCHECK(is_closed_);
+  // By default, waiting isn't supported. Only dispatchers that can be waited on
+  // will do something nontrivial.
+}
+
+MojoResult Dispatcher::CloseImplNoLock() {
+  lock_.AssertAcquired();
+  DCHECK(is_closed_);
+  // This may not need to do anything. Dispatchers should override this to do
+  // any actual close-time cleanup necessary.
+  return MOJO_RESULT_OK;
+}
+
+MojoResult Dispatcher::WriteMessageImplNoLock(const void* bytes,
+                                              uint32_t num_bytes,
+                                              const MojoHandle* handles,
+                                              uint32_t num_handles,
+                                              MojoWriteMessageFlags flags) {
+  lock_.AssertAcquired();
+  DCHECK(!is_closed_);
+  // By default, this isn't supported. Only dispatchers for message pipes (with
+  // whatever implementation, possibly a proxy) will do something nontrivial.
+  return MOJO_RESULT_INVALID_ARGUMENT;
+}
+
+MojoResult Dispatcher::ReadMessageImplNoLock(void* bytes,
+                                             uint32_t* num_bytes,
+                                             MojoHandle* handles,
+                                             uint32_t* num_handles,
+                                             MojoReadMessageFlags flags) {
+  lock_.AssertAcquired();
+  DCHECK(!is_closed_);
+  // By default, this isn't supported. Only dispatchers for message pipes (with
+  // whatever implementation, possibly a proxy) will do something nontrivial.
+  return MOJO_RESULT_INVALID_ARGUMENT;
+}
+
+MojoResult Dispatcher::AddWaiterImplNoLock(Waiter* waiter,
+                                           MojoWaitFlags flags,
+                                           MojoResult wake_result) {
+  lock_.AssertAcquired();
+  DCHECK(!is_closed_);
+  // By default, waiting isn't supported. Only dispatchers that can be waited on
+  // will do something nontrivial.
+  return MOJO_RESULT_FAILED_PRECONDITION;
+}
+
+void Dispatcher::RemoveWaiterImplNoLock(Waiter* waiter) {
+  lock_.AssertAcquired();
+  DCHECK(!is_closed_);
+  // By default, waiting isn't supported. Only dispatchers that can be waited on
+  // will do something nontrivial.
+}
+
+}  // namespace system
+}  // namespace mojo