blob: 9be103c69a0c986f3ed0ecdcb07f77a37d5f69b4 [file] [log] [blame] [edit]
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include <utility>
#include "vm/message_handler.h"
#include "vm/dart.h"
#include "vm/heap/safepoint.h"
#include "vm/isolate.h"
#include "vm/lockers.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/os.h"
#include "vm/port.h"
#include "vm/thread_interrupter.h"
namespace dart {
DECLARE_FLAG(bool, trace_service_pause_events);
class MessageHandlerTask : public ThreadPool::Task {
public:
explicit MessageHandlerTask(MessageHandler* handler) : handler_(handler) {
ASSERT(handler != nullptr);
}
virtual void Run() {
ASSERT(handler_ != nullptr);
handler_->TaskCallback();
}
private:
MessageHandler* handler_;
DISALLOW_COPY_AND_ASSIGN(MessageHandlerTask);
};
// static
const char* MessageHandler::MessageStatusString(MessageStatus status) {
switch (status) {
case kOK:
return "OK";
case kError:
return "Error";
case kShutdown:
return "Shutdown";
default:
UNREACHABLE();
return "Illegal";
}
}
MessageHandler::MessageHandler()
: queue_(new MessageQueue()),
oob_queue_(new MessageQueue()),
oob_message_handling_allowed_(true),
paused_for_messages_(false),
paused_(0),
#if !defined(PRODUCT)
should_pause_on_start_(false),
should_pause_on_exit_(false),
is_paused_on_start_(false),
is_paused_on_exit_(false),
remembered_paused_on_exit_status_(kOK),
paused_timestamp_(-1),
#endif
task_running_(false),
pool_(nullptr),
start_callback_(nullptr),
end_callback_(nullptr),
callback_data_(0) {
ASSERT(queue_ != nullptr);
ASSERT(oob_queue_ != nullptr);
}
MessageHandler::~MessageHandler() {
delete queue_;
delete oob_queue_;
queue_ = nullptr;
oob_queue_ = nullptr;
pool_ = nullptr;
}
const char* MessageHandler::name() const {
return "<unnamed>";
}
void MessageHandler::MessageNotify(Message::Priority priority) {
// By default, there is no custom message notification.
}
bool MessageHandler::Run(ThreadPool* pool,
StartCallback start_callback,
EndCallback end_callback,
CallbackData data) {
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
OS::PrintErr(
"[+] Starting message handler:\n"
"\thandler: %s\n",
name());
}
ASSERT(pool_ == nullptr);
pool_ = pool;
start_callback_ = start_callback;
end_callback_ = end_callback;
callback_data_ = data;
task_running_ = true;
bool result = pool_->Run<MessageHandlerTask>(this);
if (!result) {
pool_ = nullptr;
start_callback_ = nullptr;
end_callback_ = nullptr;
callback_data_ = 0;
task_running_ = false;
}
return result;
}
void MessageHandler::PostMessage(std::unique_ptr<Message> message,
bool before_events) {
Message::Priority saved_priority;
{
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
Isolate* source_isolate = Isolate::Current();
if (source_isolate != nullptr) {
OS::PrintErr(
"[>] Posting message:\n"
"\tlen: %" Pd "\n\tsource: (%" Pd64
") %s\n\tdest: %s\n"
"\tdest_port: %" Pd64 "\n",
message->Size(), static_cast<int64_t>(source_isolate->main_port()),
source_isolate->name(), name(), message->dest_port());
} else {
OS::PrintErr(
"[>] Posting message:\n"
"\tlen: %" Pd
"\n\tsource: <native code>\n"
"\tdest: %s\n"
"\tdest_port: %" Pd64 "\n",
message->Size(), name(), message->dest_port());
}
}
saved_priority = message->priority();
if (message->IsOOB()) {
oob_queue_->Enqueue(std::move(message), before_events);
} else {
queue_->Enqueue(std::move(message), before_events);
}
if (paused_for_messages_) {
ml.Notify();
}
if (pool_ != nullptr && !task_running_) {
task_running_ = true;
const bool launched_successfully = pool_->Run<MessageHandlerTask>(this);
ASSERT(launched_successfully);
}
}
// Invoke any custom message notification.
MessageNotify(saved_priority);
}
std::unique_ptr<Message> MessageHandler::DequeueMessage(
Message::Priority min_priority) {
ASSERT(monitor_.IsOwnedByCurrentThread());
std::unique_ptr<Message> message = oob_queue_->Dequeue();
if ((message == nullptr) && (min_priority < Message::kOOBPriority)) {
message = queue_->Dequeue();
}
return message;
}
void MessageHandler::ClearOOBQueue() {
oob_queue_->Clear();
}
MessageHandler::MessageStatus MessageHandler::HandleMessages(
MonitorLocker* ml,
bool allow_normal_messages,
bool allow_multiple_normal_messages) {
ASSERT(monitor_.IsOwnedByCurrentThread());
// Scheduling of the mutator thread during the isolate start can cause this
// thread to safepoint.
// We want to avoid holding the message handler monitor during the safepoint
// operation to avoid possible deadlocks, which can occur if other threads are
// sending messages to this message handler.
//
// If isolate() returns nullptr [StartIsolateScope] does nothing.
ml->Exit();
StartIsolateScope start_isolate(isolate());
ml->Enter();
auto idle_time_handler =
isolate() != nullptr ? isolate()->group()->idle_time_handler() : nullptr;
MessageStatus max_status = kOK;
Message::Priority min_priority =
((allow_normal_messages && !paused()) ? Message::kNormalPriority
: Message::kOOBPriority);
std::unique_ptr<Message> message = DequeueMessage(min_priority);
while (message != nullptr) {
intptr_t message_len = message->Size();
if (FLAG_trace_isolates) {
OS::PrintErr(
"[<] Handling message:\n"
"\tlen: %" Pd
"\n"
"\thandler: %s\n"
"\tport: %" Pd64 "\n",
message_len, name(), message->dest_port());
}
// Release the monitor_ temporarily while we handle the message.
// The monitor was acquired in MessageHandler::TaskCallback().
ml->Exit();
Message::Priority saved_priority = message->priority();
Dart_Port saved_dest_port = message->dest_port();
MessageStatus status = kOK;
{
DisableIdleTimerScope disable_idle_timer(idle_time_handler);
status = HandleMessage(std::move(message));
}
if (status > max_status) {
max_status = status;
}
ml->Enter();
if (FLAG_trace_isolates) {
OS::PrintErr(
"[.] Message handled (%s):\n"
"\tlen: %" Pd
"\n"
"\thandler: %s\n"
"\tport: %" Pd64 "\n",
MessageStatusString(status), message_len, name(), saved_dest_port);
}
// If we are shutting down, do not process any more messages.
if (status == kShutdown) {
ClearOOBQueue();
break;
}
// Remember time since the last message. Don't consider OOB messages so
// using Observatory doesn't trigger additional idle tasks.
if ((FLAG_idle_timeout_micros != 0) &&
(saved_priority == Message::kNormalPriority)) {
if (idle_time_handler != nullptr) {
idle_time_handler->UpdateStartIdleTime();
}
}
// Some callers want to process only one normal message and then quit. At
// the same time it is OK to process multiple OOB messages.
if ((saved_priority == Message::kNormalPriority) &&
!allow_multiple_normal_messages) {
// We processed one normal message. Allow no more.
allow_normal_messages = false;
}
// Reevaluate the minimum allowable priority. The paused state
// may have changed as part of handling the message. We may also
// have encountered an error during message processing.
//
// Even if we encounter an error, we still process pending OOB
// messages so that we don't lose the message notification.
min_priority = (((max_status == kOK) && allow_normal_messages && !paused())
? Message::kNormalPriority
: Message::kOOBPriority);
message = DequeueMessage(min_priority);
}
return max_status;
}
MessageHandler::MessageStatus MessageHandler::HandleNextMessage() {
// We can only call HandleNextMessage when this handler is not
// assigned to a thread pool.
MonitorLocker ml(&monitor_);
ASSERT(pool_ == nullptr);
#if defined(DEBUG)
CheckAccess();
#endif
return HandleMessages(&ml, true, false);
}
MessageHandler::MessageStatus MessageHandler::PauseAndHandleAllMessages(
int64_t timeout_millis) {
MonitorLocker ml(&monitor_, /*no_safepoint_scope=*/false);
ASSERT(task_running_);
#if defined(DEBUG)
CheckAccess();
#endif
paused_for_messages_ = true;
while (queue_->IsEmpty() && oob_queue_->IsEmpty()) {
Monitor::WaitResult wr;
{
// Ensure this thread is at a safepoint while we wait for new messages to
// arrive.
TransitionVMToNative transition(Thread::Current());
wr = ml.Wait(timeout_millis);
}
ASSERT(task_running_);
if (wr == Monitor::kTimedOut) {
break;
}
if (queue_->IsEmpty()) {
// There are only OOB messages. Handle them and then continue waiting for
// normal messages unless there is an error.
MessageStatus status = HandleMessages(&ml, false, false);
if (status != kOK) {
paused_for_messages_ = false;
return status;
}
}
}
paused_for_messages_ = false;
return HandleMessages(&ml, true, true);
}
MessageHandler::MessageStatus MessageHandler::HandleOOBMessages() {
if (!oob_message_handling_allowed_) {
return kOK;
}
MonitorLocker ml(&monitor_);
#if defined(DEBUG)
CheckAccess();
#endif
return HandleMessages(&ml, false, false);
}
#if !defined(PRODUCT)
bool MessageHandler::ShouldPauseOnStart(MessageStatus status) const {
Isolate* owning_isolate = isolate();
if (owning_isolate == nullptr) {
return false;
}
// If we are restarting or shutting down, we do not want to honor
// should_pause_on_start or should_pause_on_exit.
return (status != MessageHandler::kShutdown) && should_pause_on_start() &&
owning_isolate->is_runnable();
}
bool MessageHandler::ShouldPauseOnExit(MessageStatus status) const {
Isolate* owning_isolate = isolate();
if (owning_isolate == nullptr) {
return false;
}
return (status != MessageHandler::kShutdown) && should_pause_on_exit() &&
owning_isolate->is_runnable();
}
#endif
bool MessageHandler::HasOOBMessages() {
MonitorLocker ml(&monitor_);
return !oob_queue_->IsEmpty();
}
#if defined(TESTING)
std::unique_ptr<Message> MessageHandler::StealOOBMessage() {
MonitorLocker ml(&monitor_);
ASSERT(!oob_queue_->IsEmpty());
return oob_queue_->Dequeue();
}
#endif
bool MessageHandler::HasMessages() {
MonitorLocker ml(&monitor_);
return !queue_->IsEmpty();
}
void MessageHandler::TaskCallback() {
ASSERT(Isolate::Current() == nullptr);
MessageStatus status = kOK;
bool run_end_callback = false;
EndCallback end_callback = nullptr;
CallbackData callback_data = 0;
{
// We will occasionally release and reacquire this monitor in this
// function. Whenever we reacquire the monitor we *must* process
// all pending OOB messages, or we may miss a request for vm
// shutdown.
MonitorLocker ml(&monitor_);
// This method is running on the message handler task. Which means no
// other message handler tasks will be started until this one sets
// [task_running_] to false.
ASSERT(task_running_);
#if !defined(PRODUCT)
if (ShouldPauseOnStart(kOK)) {
if (!is_paused_on_start()) {
PausedOnStartLocked(&ml, true);
}
// More messages may have come in before we (re)acquired the monitor.
status = HandleMessages(&ml, false, false);
if (ShouldPauseOnStart(status)) {
// Still paused.
ASSERT(oob_queue_->IsEmpty());
task_running_ = false; // No task in queue.
return;
} else {
PausedOnStartLocked(&ml, false);
}
}
if (is_paused_on_exit()) {
status = HandleMessages(&ml, false, false);
if (ShouldPauseOnExit(status)) {
// Still paused.
ASSERT(oob_queue_->IsEmpty());
task_running_ = false; // No task in queue.
return;
} else {
PausedOnExitLocked(&ml, false);
if (status != kShutdown) {
status = remembered_paused_on_exit_status_;
}
}
}
#endif // !defined(PRODUCT)
if (status == kOK) {
if (start_callback_ != nullptr) {
// Initialize the message handler by running its start function,
// if we have one. For an isolate, this will run the isolate's
// main() function.
//
// Release the monitor_ temporarily while we call the start callback.
ml.Exit();
status = start_callback_(callback_data_);
ASSERT(Isolate::Current() == nullptr);
start_callback_ = nullptr;
ml.Enter();
}
// Handle any pending messages for this message handler.
if (status != kShutdown) {
status = HandleMessages(&ml, (status == kOK), true);
}
}
// The isolate exits when it encounters an error or when it no
// longer has live ports.
if (status != kOK || !KeepAliveLocked()) {
#if !defined(PRODUCT)
if (ShouldPauseOnExit(status)) {
if (FLAG_trace_service_pause_events) {
OS::PrintErr(
"Isolate %s paused before exiting. "
"Use the Observatory to release it.\n",
name());
}
remembered_paused_on_exit_status_ = status;
PausedOnExitLocked(&ml, true);
// More messages may have come in while we released the monitor.
status = HandleMessages(&ml, /*allow_normal_messages=*/false,
/*allow_multiple_normal_messagesfalse=*/false);
if (ShouldPauseOnExit(status)) {
// Still paused.
ASSERT(oob_queue_->IsEmpty());
task_running_ = false; // No task in queue.
return;
} else {
PausedOnExitLocked(&ml, false);
}
}
#endif // !defined(PRODUCT)
if (FLAG_trace_isolates) {
if (status != kOK && thread() != nullptr) {
const Error& error = Error::Handle(thread()->sticky_error());
OS::PrintErr(
"[-] Stopping message handler (%s):\n"
"\thandler: %s\n"
"\terror: %s\n",
MessageStatusString(status), name(), error.ToCString());
} else {
OS::PrintErr(
"[-] Stopping message handler (%s):\n"
"\thandler: %s\n",
MessageStatusString(status), name());
}
}
pool_ = nullptr;
// Decide if we have a callback before releasing the monitor.
end_callback = end_callback_;
callback_data = callback_data_;
run_end_callback = end_callback_ != nullptr;
}
// Clear task_running_ last. This allows other tasks to potentially start
// for this message handler.
ASSERT(oob_queue_->IsEmpty());
task_running_ = false;
}
// The handler may have been deleted by another thread here if it is a native
// message handler.
if (run_end_callback) {
ASSERT(end_callback != nullptr);
end_callback(callback_data);
// The handler may have been deleted after this point.
}
}
void MessageHandler::OnPortClosed(Dart_Port port) {
if (FLAG_trace_isolates) {
MonitorLocker ml(&monitor_);
OS::PrintErr(
"[-] Closing port:\n"
"\thandler: %s\n"
"\tport: %" Pd64 "\n",
name(), port);
}
}
void MessageHandler::OnAllPortsClosed() {
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
OS::PrintErr(
"[-] Closing all ports:\n"
"\thandler: %s\n",
name());
}
queue_->Clear();
oob_queue_->Clear();
}
#if !defined(PRODUCT)
void MessageHandler::DebugDump() {
PortMap::DebugDumpForMessageHandler(this);
}
void MessageHandler::PausedOnStart(bool paused) {
MonitorLocker ml(&monitor_);
PausedOnStartLocked(&ml, paused);
}
void MessageHandler::PausedOnStartLocked(MonitorLocker* ml, bool paused) {
if (paused) {
ASSERT(!is_paused_on_start_);
ASSERT(paused_timestamp_ == -1);
paused_timestamp_ = OS::GetCurrentTimeMillis();
// Temporarily release the monitor when calling out to
// NotifyPauseOnStart. This avoids a dead lock that can occur
// when this message handler tries to post a message while a
// message is being posted to it.
ml->Exit();
NotifyPauseOnStart();
ml->Enter();
is_paused_on_start_ = true;
} else {
ASSERT(is_paused_on_start_);
ASSERT(paused_timestamp_ != -1);
paused_timestamp_ = -1;
// Resumed. Clear the resume request of the owning isolate.
Isolate* owning_isolate = isolate();
if (owning_isolate != nullptr) {
owning_isolate->GetAndClearResumeRequest();
}
is_paused_on_start_ = false;
}
}
void MessageHandler::PausedOnExit(bool paused) {
MonitorLocker ml(&monitor_);
PausedOnExitLocked(&ml, paused);
}
void MessageHandler::PausedOnExitLocked(MonitorLocker* ml, bool paused) {
if (paused) {
ASSERT(!is_paused_on_exit_);
ASSERT(paused_timestamp_ == -1);
paused_timestamp_ = OS::GetCurrentTimeMillis();
// Temporarily release the monitor when calling out to
// NotifyPauseOnExit. This avoids a dead lock that can
// occur when this message handler tries to post a message
// while a message is being posted to it.
ml->Exit();
NotifyPauseOnExit();
ml->Enter();
is_paused_on_exit_ = true;
} else {
ASSERT(is_paused_on_exit_);
ASSERT(paused_timestamp_ != -1);
paused_timestamp_ = -1;
// Resumed. Clear the resume request of the owning isolate.
Isolate* owning_isolate = isolate();
if (owning_isolate != nullptr) {
owning_isolate->GetAndClearResumeRequest();
}
is_paused_on_exit_ = false;
}
}
#endif // !defined(PRODUCT)
MessageHandler::AcquiredQueues::AcquiredQueues(MessageHandler* handler)
: handler_(handler), ml_(&handler->monitor_) {
ASSERT(handler != nullptr);
handler_->oob_message_handling_allowed_ = false;
}
MessageHandler::AcquiredQueues::~AcquiredQueues() {
ASSERT(handler_ != nullptr);
handler_->oob_message_handling_allowed_ = true;
}
} // namespace dart