blob: 276e39f167512bbf70d873ec0326761bc25c703e [file] [log] [blame]
// 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/edk/system/request_context.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/threading/thread_local.h"
namespace mojo {
namespace edk {
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);
MojoWatchNotificationFlags flags = MOJO_WATCH_NOTIFICATION_FLAG_NONE;
if (source_ == Source::SYSTEM)
flags |= MOJO_WATCH_NOTIFICATION_FLAG_FROM_SYSTEM;
// We run all cancellation finalizers first. This is necessary because it's
// possible that one of the cancelled watchers has other pending finalizers
// attached to this RequestContext.
//
// From the application's perspective the watch has already been cancelled,
// so we have to honor our contract which guarantees no more notifications.
for (const scoped_refptr<Watcher>& watcher :
watch_cancel_finalizers_.container())
watcher->Cancel();
for (const WatchNotifyFinalizer& watch :
watch_notify_finalizers_.container()) {
// Establish a new request context for the extent of each callback to
// ensure that they don't themselves invoke callbacks while holding a
// watcher lock.
RequestContext request_context(source_);
watch.watcher->MaybeInvokeCallback(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<Watcher> watcher,
MojoResult result,
const HandleSignalsState& state) {
DCHECK(IsCurrent());
watch_notify_finalizers_->push_back(
WatchNotifyFinalizer(watcher, result, state));
}
void RequestContext::AddWatchCancelFinalizer(scoped_refptr<Watcher> watcher) {
DCHECK(IsCurrent());
watch_cancel_finalizers_->push_back(watcher);
}
bool RequestContext::IsCurrent() const {
return tls_context_->Get() == this;
}
RequestContext::WatchNotifyFinalizer::WatchNotifyFinalizer(
scoped_refptr<Watcher> watcher,
MojoResult result,
const HandleSignalsState& state)
: watcher(watcher), result(result), state(state) {
}
RequestContext::WatchNotifyFinalizer::WatchNotifyFinalizer(
const WatchNotifyFinalizer& other) = default;
RequestContext::WatchNotifyFinalizer::~WatchNotifyFinalizer() {}
} // namespace edk
} // namespace mojo