105 lines
3.5 KiB
C++
105 lines
3.5 KiB
C++
// Copyright 2016 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "mojo/edk/system/request_context.h"
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#include "base/lazy_instance.h"
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#include "base/logging.h"
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#include "base/threading/thread_local.h"
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namespace mojo {
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namespace edk {
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namespace {
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base::LazyInstance<base::ThreadLocalPointer<RequestContext>>::Leaky
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g_current_context = LAZY_INSTANCE_INITIALIZER;
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} // namespace
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RequestContext::RequestContext() : RequestContext(Source::LOCAL_API_CALL) {}
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RequestContext::RequestContext(Source source)
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: source_(source), tls_context_(g_current_context.Pointer()) {
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// We allow nested RequestContexts to exist as long as they aren't actually
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// used for anything.
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if (!tls_context_->Get())
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tls_context_->Set(this);
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}
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RequestContext::~RequestContext() {
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if (IsCurrent()) {
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// NOTE: Callbacks invoked by this destructor are allowed to initiate new
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// EDK requests on this thread, so we need to reset the thread-local context
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// pointer before calling them. We persist the original notification source
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// since we're starting over at the bottom of the stack.
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tls_context_->Set(nullptr);
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MojoWatchNotificationFlags flags = MOJO_WATCH_NOTIFICATION_FLAG_NONE;
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if (source_ == Source::SYSTEM)
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flags |= MOJO_WATCH_NOTIFICATION_FLAG_FROM_SYSTEM;
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// We run all cancellation finalizers first. This is necessary because it's
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// possible that one of the cancelled watchers has other pending finalizers
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// attached to this RequestContext.
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//
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// From the application's perspective the watch has already been cancelled,
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// so we have to honor our contract which guarantees no more notifications.
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for (const scoped_refptr<Watcher>& watcher :
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watch_cancel_finalizers_.container())
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watcher->Cancel();
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for (const WatchNotifyFinalizer& watch :
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watch_notify_finalizers_.container()) {
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// Establish a new request context for the extent of each callback to
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// ensure that they don't themselves invoke callbacks while holding a
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// watcher lock.
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RequestContext request_context(source_);
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watch.watcher->MaybeInvokeCallback(watch.result, watch.state, flags);
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}
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} else {
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// It should be impossible for nested contexts to have finalizers.
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DCHECK(watch_notify_finalizers_.container().empty());
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DCHECK(watch_cancel_finalizers_.container().empty());
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}
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}
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// static
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RequestContext* RequestContext::current() {
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DCHECK(g_current_context.Pointer()->Get());
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return g_current_context.Pointer()->Get();
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}
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void RequestContext::AddWatchNotifyFinalizer(
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scoped_refptr<Watcher> watcher,
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MojoResult result,
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const HandleSignalsState& state) {
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DCHECK(IsCurrent());
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watch_notify_finalizers_->push_back(
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WatchNotifyFinalizer(watcher, result, state));
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}
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void RequestContext::AddWatchCancelFinalizer(scoped_refptr<Watcher> watcher) {
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DCHECK(IsCurrent());
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watch_cancel_finalizers_->push_back(watcher);
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}
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bool RequestContext::IsCurrent() const {
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return tls_context_->Get() == this;
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}
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RequestContext::WatchNotifyFinalizer::WatchNotifyFinalizer(
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scoped_refptr<Watcher> watcher,
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MojoResult result,
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const HandleSignalsState& state)
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: watcher(watcher), result(result), state(state) {
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}
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RequestContext::WatchNotifyFinalizer::WatchNotifyFinalizer(
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const WatchNotifyFinalizer& other) = default;
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RequestContext::WatchNotifyFinalizer::~WatchNotifyFinalizer() {}
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} // namespace edk
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} // namespace mojo
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