blob: 47ab4b9db7d4ef49dde0dc97e56e774319076820 [file] [log] [blame]
// 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 "vm/message_handler.h"
#include "vm/dart.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_isolates);
DECLARE_FLAG(bool, trace_service_pause_events);
class MessageHandlerTask : public ThreadPool::Task {
public:
explicit MessageHandlerTask(MessageHandler* handler)
: handler_(handler) {
ASSERT(handler != NULL);
}
virtual void Run() {
ASSERT(handler_ != NULL);
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 kRestart:
return "Restart";
case kShutdown:
return "Shutdown";
default:
UNREACHABLE();
return "Illegal";
}
}
MessageHandler::MessageHandler()
: queue_(new MessageQueue()),
oob_queue_(new MessageQueue()),
oob_message_handling_allowed_(true),
live_ports_(0),
paused_(0),
pause_on_start_(false),
pause_on_exit_(false),
paused_on_start_(false),
paused_on_exit_(false),
paused_timestamp_(-1),
pool_(NULL),
task_(NULL),
start_callback_(NULL),
end_callback_(NULL),
callback_data_(0) {
ASSERT(queue_ != NULL);
ASSERT(oob_queue_ != NULL);
}
MessageHandler::~MessageHandler() {
delete queue_;
delete oob_queue_;
}
const char* MessageHandler::name() const {
return "<unnamed>";
}
#if defined(DEBUG)
void MessageHandler::CheckAccess() {
// By default there is no checking.
}
#endif
void MessageHandler::MessageNotify(Message::Priority priority) {
// By default, there is no custom message notification.
}
void MessageHandler::Run(ThreadPool* pool,
StartCallback start_callback,
EndCallback end_callback,
CallbackData data) {
bool task_running;
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
OS::Print("[+] Starting message handler:\n"
"\thandler: %s\n",
name());
}
ASSERT(pool_ == NULL);
pool_ = pool;
start_callback_ = start_callback;
end_callback_ = end_callback;
callback_data_ = data;
task_ = new MessageHandlerTask(this);
task_running = pool_->Run(task_);
ASSERT(task_running);
}
void MessageHandler::PostMessage(Message* message, bool before_events) {
Message::Priority saved_priority;
bool task_running = true;
{
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
const char* source_name = "<native code>";
Isolate* source_isolate = Isolate::Current();
if (source_isolate) {
source_name = source_isolate->name();
}
OS::Print("[>] Posting message:\n"
"\tlen: %" Pd "\n"
"\tsource: %s\n"
"\tdest: %s\n"
"\tdest_port: %" Pd64 "\n",
message->len(), source_name, name(), message->dest_port());
}
saved_priority = message->priority();
if (message->IsOOB()) {
oob_queue_->Enqueue(message, before_events);
} else {
queue_->Enqueue(message, before_events);
}
message = NULL; // Do not access message. May have been deleted.
if ((pool_ != NULL) && (task_ == NULL)) {
task_ = new MessageHandlerTask(this);
task_running = pool_->Run(task_);
}
}
ASSERT(task_running);
// Invoke any custom message notification.
MessageNotify(saved_priority);
}
Message* MessageHandler::DequeueMessage(Message::Priority min_priority) {
// TODO(turnidge): Add assert that monitor_ is held here.
Message* message = oob_queue_->Dequeue();
if ((message == NULL) && (min_priority < Message::kOOBPriority)) {
message = queue_->Dequeue();
}
return message;
}
void MessageHandler::ClearOOBQueue() {
oob_queue_->Clear();
}
MessageHandler::MessageStatus MessageHandler::HandleMessages(
bool allow_normal_messages,
bool allow_multiple_normal_messages) {
// TODO(turnidge): Add assert that monitor_ is held here.
// If isolate() returns NULL StartIsolateScope does nothing.
StartIsolateScope start_isolate(isolate());
// ThreadInterrupter may have gone to sleep while waiting for
// an isolate to start handling messages.
ThreadInterrupter::WakeUp();
MessageStatus max_status = kOK;
Message::Priority min_priority = ((allow_normal_messages && !paused())
? Message::kNormalPriority
: Message::kOOBPriority);
Message* message = DequeueMessage(min_priority);
while (message != NULL) {
intptr_t message_len = message->len();
if (FLAG_trace_isolates) {
OS::Print("[<] 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().
monitor_.Exit();
Message::Priority saved_priority = message->priority();
Dart_Port saved_dest_port = message->dest_port();
MessageStatus status = HandleMessage(message);
if (status > max_status) {
max_status = status;
}
message = NULL; // May be deleted by now.
monitor_.Enter();
if (FLAG_trace_isolates) {
OS::Print("[.] 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;
}
// 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 processsing.
//
// 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_ == NULL);
#if defined(DEBUG)
CheckAccess();
#endif
return HandleMessages(true, false);
}
MessageHandler::MessageStatus MessageHandler::HandleOOBMessages() {
if (!oob_message_handling_allowed_) {
return kOK;
}
MonitorLocker ml(&monitor_);
#if defined(DEBUG)
CheckAccess();
#endif
return HandleMessages(false, false);
}
bool MessageHandler::HasOOBMessages() {
MonitorLocker ml(&monitor_);
return !oob_queue_->IsEmpty();
}
static bool ShouldPause(MessageHandler::MessageStatus status) {
// If we are restarting or shutting down, we do not want to honor
// pause_on_start or pause_on_exit.
return (status != MessageHandler::kRestart &&
status != MessageHandler::kShutdown);
}
void MessageHandler::TaskCallback() {
ASSERT(Isolate::Current() == NULL);
MessageStatus status = kOK;
bool run_end_callback = false;
{
// 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_);
if (pause_on_start()) {
if (!paused_on_start_) {
// 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.
paused_on_start_ = true;
paused_timestamp_ = OS::GetCurrentTimeMillis();
monitor_.Exit();
NotifyPauseOnStart();
monitor_.Enter();
}
// More messages may have come in before we (re)acquired the monitor.
status = HandleMessages(false, false);
if (ShouldPause(status) && pause_on_start()) {
// Still paused.
ASSERT(oob_queue_->IsEmpty());
task_ = NULL; // No task in queue.
return;
} else {
paused_on_start_ = false;
paused_timestamp_ = -1;
}
}
if (status == kOK) {
if (start_callback_) {
// 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.
monitor_.Exit();
status = start_callback_(callback_data_);
ASSERT(Isolate::Current() == NULL);
start_callback_ = NULL;
monitor_.Enter();
}
// Handle any pending messages for this message handler.
if (status != kShutdown) {
status = HandleMessages((status == kOK), true);
}
}
// The isolate exits when it encounters an error or when it no
// longer has live ports.
if (status != kOK || !HasLivePorts()) {
if (ShouldPause(status) && pause_on_exit()) {
if (!paused_on_exit_) {
if (FLAG_trace_service_pause_events) {
OS::PrintErr("Isolate %s paused before exiting. "
"Use the Observatory to release it.\n", name());
}
// 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.
paused_on_exit_ = true;
paused_timestamp_ = OS::GetCurrentTimeMillis();
monitor_.Exit();
NotifyPauseOnExit();
monitor_.Enter();
// More messages may have come in while we released the monitor.
HandleMessages(false, false);
}
if (ShouldPause(status) && pause_on_exit()) {
// Still paused.
ASSERT(oob_queue_->IsEmpty());
task_ = NULL; // No task in queue.
return;
} else {
paused_on_exit_ = false;
paused_timestamp_ = -1;
}
}
if (FLAG_trace_isolates) {
if (status != kOK && isolate() != NULL) {
const Error& error =
Error::Handle(isolate()->object_store()->sticky_error());
OS::Print("[-] Stopping message handler (%s):\n"
"\thandler: %s\n"
"\terror: %s\n",
MessageStatusString(status), name(), error.ToCString());
} else {
OS::Print("[-] Stopping message handler (%s):\n"
"\thandler: %s\n",
MessageStatusString(status), name());
}
}
pool_ = NULL;
run_end_callback = true;
}
// Clear the task_ last. This allows other tasks to potentially start
// for this message handler.
ASSERT(oob_queue_->IsEmpty());
task_ = NULL;
}
if (run_end_callback && end_callback_ != NULL) {
end_callback_(callback_data_);
// The handler may have been deleted after this point.
}
}
void MessageHandler::ClosePort(Dart_Port port) {
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
OS::Print("[-] Closing port:\n"
"\thandler: %s\n"
"\tport: %" Pd64 "\n"
"\tports: live(%" Pd ")\n",
name(), port, live_ports_);
}
}
void MessageHandler::CloseAllPorts() {
MonitorLocker ml(&monitor_);
if (FLAG_trace_isolates) {
OS::Print("[-] Closing all ports:\n"
"\thandler: %s\n",
name());
}
queue_->Clear();
oob_queue_->Clear();
}
void MessageHandler::increment_live_ports() {
MonitorLocker ml(&monitor_);
#if defined(DEBUG)
CheckAccess();
#endif
live_ports_++;
}
void MessageHandler::decrement_live_ports() {
MonitorLocker ml(&monitor_);
#if defined(DEBUG)
CheckAccess();
#endif
live_ports_--;
}
MessageHandler::AcquiredQueues::AcquiredQueues()
: handler_(NULL) {
}
MessageHandler::AcquiredQueues::~AcquiredQueues() {
Reset(NULL);
}
void MessageHandler::AcquiredQueues::Reset(MessageHandler* handler) {
if (handler_ != NULL) {
// Release ownership. The OOB flag is set without holding the monitor.
handler_->monitor_.Exit();
handler_->oob_message_handling_allowed_ = true;
}
handler_ = handler;
if (handler_ == NULL) {
return;
}
ASSERT(handler_ != NULL);
// Take ownership. The OOB flag is set without holding the monitor.
handler_->oob_message_handling_allowed_ = false;
handler_->monitor_.Enter();
}
void MessageHandler::AcquireQueues(AcquiredQueues* acquired_queues) {
ASSERT(acquired_queues != NULL);
// No double dipping.
ASSERT(acquired_queues->handler_ == NULL);
acquired_queues->Reset(this);
}
} // namespace dart