123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116 |
- // Copyright 2016 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/core/request_context.h"
- #include "base/check.h"
- #include "base/lazy_instance.h"
- #include "base/threading/thread_local.h"
- namespace mojo {
- namespace core {
- namespace {
- base::LazyInstance<base::ThreadLocalPointer<RequestContext>>::Leaky
- g_current_context = LAZY_INSTANCE_INITIALIZER;
- } // namespace
- RequestContext::RequestContext() : RequestContext(Source::LOCAL_API_CALL) {}
- RequestContext::RequestContext(Source source)
- : source_(source), tls_context_(g_current_context.Pointer()) {
- // We allow nested RequestContexts to exist as long as they aren't actually
- // used for anything.
- if (!tls_context_->Get())
- tls_context_->Set(this);
- }
- RequestContext::~RequestContext() {
- if (IsCurrent()) {
- // NOTE: Callbacks invoked by this destructor are allowed to initiate new
- // EDK requests on this thread, so we need to reset the thread-local context
- // pointer before calling them. We persist the original notification source
- // since we're starting over at the bottom of the stack.
- tls_context_->Set(nullptr);
- MojoTrapEventFlags flags = MOJO_TRAP_EVENT_FLAG_NONE;
- if (source_ == Source::LOCAL_API_CALL)
- flags |= MOJO_TRAP_EVENT_FLAG_WITHIN_API_CALL;
- // We send all cancellation notifications first. This is necessary because
- // it's possible that cancelled watches have other pending notifications
- // attached to this RequestContext.
- //
- // From the application's perspective the watch is cancelled as soon as this
- // notification is received, and dispatching the cancellation notification
- // updates some internal Watch state to ensure no further notifications
- // fire. Because notifications on a single Watch are mutually exclusive,
- // this is sufficient to guarantee that MOJO_RESULT_CANCELLED is the last
- // notification received; which is the guarantee the API makes.
- for (const scoped_refptr<Watch>& watch :
- watch_cancel_finalizers_.container()) {
- static const HandleSignalsState closed_state = {0, 0};
- // Establish a new RequestContext to capture and run any new notifications
- // triggered by the callback invocation. Note that while it would be safe
- // to inherit |source_| from the perspective of Mojo core re-entrancy,
- // upper application layers may use the flag as a signal to allow
- // synchronous event dispatch and in turn shoot themselves in the foot
- // with e.g. mutually recursive event handlers. We avoid that by
- // treating all nested trap events as if they originated from a local API
- // call even if this is a system RequestContext.
- RequestContext inner_context(Source::LOCAL_API_CALL);
- watch->InvokeCallback(MOJO_RESULT_CANCELLED, closed_state, flags);
- }
- for (const WatchNotifyFinalizer& watch :
- watch_notify_finalizers_.container()) {
- RequestContext inner_context(source_);
- watch.watch->InvokeCallback(watch.result, watch.state, flags);
- }
- } else {
- // It should be impossible for nested contexts to have finalizers.
- DCHECK(watch_notify_finalizers_.container().empty());
- DCHECK(watch_cancel_finalizers_.container().empty());
- }
- }
- // static
- RequestContext* RequestContext::current() {
- DCHECK(g_current_context.Pointer()->Get());
- return g_current_context.Pointer()->Get();
- }
- void RequestContext::AddWatchNotifyFinalizer(scoped_refptr<Watch> watch,
- MojoResult result,
- const HandleSignalsState& state) {
- DCHECK(IsCurrent());
- watch_notify_finalizers_->push_back(
- WatchNotifyFinalizer(std::move(watch), result, state));
- }
- void RequestContext::AddWatchCancelFinalizer(scoped_refptr<Watch> watch) {
- DCHECK(IsCurrent());
- watch_cancel_finalizers_->push_back(std::move(watch));
- }
- bool RequestContext::IsCurrent() const {
- return tls_context_->Get() == this;
- }
- RequestContext::WatchNotifyFinalizer::WatchNotifyFinalizer(
- scoped_refptr<Watch> watch,
- MojoResult result,
- const HandleSignalsState& state)
- : watch(std::move(watch)), result(result), state(state) {}
- RequestContext::WatchNotifyFinalizer::WatchNotifyFinalizer(
- const WatchNotifyFinalizer& other) = default;
- RequestContext::WatchNotifyFinalizer::~WatchNotifyFinalizer() = default;
- } // namespace core
- } // namespace mojo
|