llvm-project/lldb/source/Plugins/Process/Linux/ThreadStateCoordinator.cpp

722 lines
24 KiB
C++

//===-- ThreadStateCoordinator.cpp ------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#if !defined (__STDC_FORMAT_MACROS)
#define __STDC_FORMAT_MACROS 1
#endif
#include <inttypes.h>
#include "ThreadStateCoordinator.h"
#include <memory>
#include <cstdarg>
#include <sstream>
using namespace lldb_private;
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventBase : public std::enable_shared_from_this<ThreadStateCoordinator::EventBase>
{
public:
EventBase ()
{
}
virtual
~EventBase ()
{
}
// Return false if the coordinator should terminate running.
virtual EventLoopResult
ProcessEvent (ThreadStateCoordinator &coordinator) = 0;
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventStopCoordinator : public ThreadStateCoordinator::EventBase
{
public:
EventStopCoordinator ():
EventBase ()
{
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
return eventLoopResultStop;
}
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventCallAfterThreadsStop : public ThreadStateCoordinator::EventBase
{
public:
EventCallAfterThreadsStop (lldb::tid_t triggering_tid,
const ThreadIDSet &wait_for_stop_tids,
const ThreadIDFunction &request_thread_stop_function,
const ThreadIDFunction &call_after_function,
const ErrorFunction &error_function):
EventBase (),
m_triggering_tid (triggering_tid),
m_wait_for_stop_tids (wait_for_stop_tids),
m_original_wait_for_stop_tids (wait_for_stop_tids),
m_request_thread_stop_function (request_thread_stop_function),
m_call_after_function (call_after_function),
m_error_function (error_function),
m_request_stop_on_all_unstopped_threads (false)
{
}
EventCallAfterThreadsStop (lldb::tid_t triggering_tid,
const ThreadIDFunction &request_thread_stop_function,
const ThreadIDFunction &call_after_function,
const ErrorFunction &error_function) :
EventBase (),
m_triggering_tid (triggering_tid),
m_wait_for_stop_tids (),
m_original_wait_for_stop_tids (),
m_request_thread_stop_function (request_thread_stop_function),
m_call_after_function (call_after_function),
m_error_function (error_function),
m_request_stop_on_all_unstopped_threads (true)
{
}
lldb::tid_t GetTriggeringTID () const
{
return m_triggering_tid;
}
ThreadIDSet &
GetRemainingWaitTIDs ()
{
return m_wait_for_stop_tids;
}
const ThreadIDSet &
GetRemainingWaitTIDs () const
{
return m_wait_for_stop_tids;
}
const ThreadIDSet &
GetInitialWaitTIDs () const
{
return m_original_wait_for_stop_tids;
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
// Validate we know about the deferred trigger thread.
if (coordinator.m_tid_stop_map.find (m_triggering_tid) == coordinator.m_tid_stop_map.end ())
{
// We don't know about this thread. This is an error condition.
std::ostringstream error_message;
error_message << "error: deferred notification tid " << m_triggering_tid << " is unknown";
m_error_function (error_message.str ());
// We bail out here.
return eventLoopResultContinue;
}
if (m_request_stop_on_all_unstopped_threads)
{
RequestStopOnAllRunningThreads (coordinator);
}
else
{
if (!RequestStopOnAllSpecifiedThreads (coordinator))
return eventLoopResultContinue;
}
if (m_wait_for_stop_tids.empty ())
{
// We're not waiting for any threads. Fire off the deferred signal delivery event.
NotifyNow ();
}
else
{
// The real meat of this class: wait until all
// the thread stops (or thread deaths) come in
// before firing off that the triggering signal
// arrived.
coordinator.SetPendingNotification (shared_from_this ());
}
return eventLoopResultContinue;
}
// Return true if still pending thread stops waiting; false if no more stops.
// If no more pending stops, signal.
bool
RemoveThreadStopRequirementAndMaybeSignal (lldb::tid_t tid)
{
// Remove this tid if it was in it.
m_wait_for_stop_tids.erase (tid);
// Fire pending notification if no pending thread stops remain.
if (m_wait_for_stop_tids.empty ())
{
// Fire the pending notification now.
NotifyNow ();
return false;
}
// Still have pending thread stops.
return true;
}
void
AddThreadStopRequirement (lldb::tid_t tid)
{
// Add this tid.
auto insert_result = m_wait_for_stop_tids.insert (tid);
// If it was really added, send the stop request to it.
if (insert_result.second)
m_request_thread_stop_function (tid);
}
private:
void
NotifyNow ()
{
m_call_after_function (m_triggering_tid);
}
bool
RequestStopOnAllSpecifiedThreads (const ThreadStateCoordinator &coordinator)
{
// Request a stop for all the thread stops that need to be stopped
// and are not already known to be stopped. Keep a list of all the
// threads from which we still need to hear a stop reply.
ThreadIDSet sent_tids;
for (auto tid : m_wait_for_stop_tids)
{
// Validate we know about all tids for which we must first receive a stop before
// triggering the deferred stop notification.
auto find_it = coordinator.m_tid_stop_map.find (tid);
if (find_it == coordinator.m_tid_stop_map.end ())
{
// This is an error. We shouldn't be asking for waiting pids that aren't known.
// NOTE: we may be stripping out the specification of wait tids and handle this
// automatically, in which case this state can never occur.
std::ostringstream error_message;
error_message << "error: deferred notification for tid " << m_triggering_tid << " specified an unknown/untracked pending stop tid " << m_triggering_tid;
m_error_function (error_message.str ());
// Bail out here.
return false;
}
// If the pending stop thread is currently running, we need to send it a stop request.
if (!find_it->second)
{
m_request_thread_stop_function (tid);
sent_tids.insert (tid);
}
}
// We only need to wait for the sent_tids - so swap our wait set
// to the sent tids. The rest are already stopped and we won't
// be receiving stop notifications for them.
m_wait_for_stop_tids.swap (sent_tids);
// Succeeded, keep running.
return true;
}
void
RequestStopOnAllRunningThreads (const ThreadStateCoordinator &coordinator)
{
// Request a stop for all the thread stops that need to be stopped
// and are not already known to be stopped. Keep a list of all the
// threads from which we still need to hear a stop reply.
ThreadIDSet sent_tids;
for (auto it = coordinator.m_tid_stop_map.begin(); it != coordinator.m_tid_stop_map.end(); ++it)
{
// We only care about threads not stopped.
const bool running = !it->second;
if (running)
{
// Request this thread stop.
const lldb::tid_t tid = it->first;
m_request_thread_stop_function (tid);
sent_tids.insert (tid);
}
}
// Set the wait list to the set of tids for which we requested stops.
m_wait_for_stop_tids.swap (sent_tids);
}
const lldb::tid_t m_triggering_tid;
ThreadIDSet m_wait_for_stop_tids;
const ThreadIDSet m_original_wait_for_stop_tids;
ThreadIDFunction m_request_thread_stop_function;
ThreadIDFunction m_call_after_function;
ErrorFunction m_error_function;
const bool m_request_stop_on_all_unstopped_threads;
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventReset : public ThreadStateCoordinator::EventBase
{
public:
EventReset ():
EventBase ()
{
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
coordinator.ResetNow ();
return eventLoopResultContinue;
}
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventThreadStopped : public ThreadStateCoordinator::EventBase
{
public:
EventThreadStopped (lldb::tid_t tid,
const ErrorFunction &error_function):
EventBase (),
m_tid (tid),
m_error_function (error_function)
{
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
coordinator.ThreadDidStop (m_tid, m_error_function);
return eventLoopResultContinue;
}
private:
const lldb::tid_t m_tid;
ErrorFunction m_error_function;
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventThreadCreate : public ThreadStateCoordinator::EventBase
{
public:
EventThreadCreate (lldb::tid_t tid,
bool is_stopped,
const ErrorFunction &error_function):
EventBase (),
m_tid (tid),
m_is_stopped (is_stopped),
m_error_function (error_function)
{
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
coordinator.ThreadWasCreated (m_tid, m_is_stopped, m_error_function);
return eventLoopResultContinue;
}
private:
const lldb::tid_t m_tid;
const bool m_is_stopped;
ErrorFunction m_error_function;
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventThreadDeath : public ThreadStateCoordinator::EventBase
{
public:
EventThreadDeath (lldb::tid_t tid,
const ErrorFunction &error_function):
EventBase (),
m_tid (tid),
m_error_function (error_function)
{
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
coordinator.ThreadDidDie (m_tid, m_error_function);
return eventLoopResultContinue;
}
private:
const lldb::tid_t m_tid;
ErrorFunction m_error_function;
};
//===----------------------------------------------------------------------===//
class ThreadStateCoordinator::EventRequestResume : public ThreadStateCoordinator::EventBase
{
public:
EventRequestResume (lldb::tid_t tid,
const ThreadIDFunction &request_thread_resume_function,
const ErrorFunction &error_function):
EventBase (),
m_tid (tid),
m_request_thread_resume_function (request_thread_resume_function),
m_error_function (error_function)
{
}
EventLoopResult
ProcessEvent(ThreadStateCoordinator &coordinator) override
{
// Ensure we know about the thread.
auto find_it = coordinator.m_tid_stop_map.find (m_tid);
if (find_it == coordinator.m_tid_stop_map.end ())
{
// We don't know about this thread. This is an error condition.
std::ostringstream error_message;
error_message << "error: tid " << m_tid << " asked to resume but tid is unknown";
m_error_function (error_message.str ());
return eventLoopResultContinue;
}
// Tell the thread to resume if we don't already think it is running.
const bool is_stopped = find_it->second;
if (!is_stopped)
{
// Skip the resume call - we have tracked it to be running.
std::ostringstream error_message;
error_message << "error: tid " << m_tid << " asked to resume but we think it is already running";
m_error_function (error_message.str ());
return eventLoopResultContinue;
}
// Before we do the resume below, first check if we have a pending
// stop notification this is currently or was previously waiting for
// this thread to stop. This is potentially a buggy situation since
// we're ostensibly waiting for threads to stop before we send out the
// pending notification, and here we are resuming one before we send
// out the pending stop notification.
const EventCallAfterThreadsStop *const pending_stop_notification = coordinator.GetPendingThreadStopNotification ();
if (pending_stop_notification)
{
if (pending_stop_notification->GetRemainingWaitTIDs ().count (m_tid) > 0)
{
coordinator.Log ("EventRequestResume::%s about to resume tid %" PRIu64 " per explicit request but we have a pending stop notification (tid %" PRIu64 ") that is actively waiting for this thread to stop. Valid sequence of events?", __FUNCTION__, m_tid, pending_stop_notification->GetTriggeringTID ());
}
else if (pending_stop_notification->GetInitialWaitTIDs ().count (m_tid) > 0)
{
coordinator.Log ("EventRequestResume::%s about to resume tid %" PRIu64 " per explicit request but we have a pending stop notification (tid %" PRIu64 ") that hasn't fired yet and this is one of the threads we had been waiting on (and already marked satisfied for this tid). Valid sequence of events?", __FUNCTION__, m_tid, pending_stop_notification->GetTriggeringTID ());
for (auto tid : pending_stop_notification->GetRemainingWaitTIDs ())
{
coordinator.Log ("EventRequestResume::%s tid %" PRIu64 " deferred stop notification still waiting on tid %" PRIu64,
__FUNCTION__,
pending_stop_notification->GetTriggeringTID (),
tid);
}
}
}
// Request a resume. We expect this to be synchronous and the system
// to reflect it is running after this completes.
m_request_thread_resume_function (m_tid);
// Now mark it is running.
find_it->second = false;
return eventLoopResultContinue;
}
private:
const lldb::tid_t m_tid;
ThreadIDFunction m_request_thread_resume_function;
ErrorFunction m_error_function;
};
//===----------------------------------------------------------------------===//
ThreadStateCoordinator::ThreadStateCoordinator (const LogFunction &log_function) :
m_log_function (log_function),
m_event_queue (),
m_queue_condition (),
m_queue_mutex (),
m_tid_stop_map ()
{
}
void
ThreadStateCoordinator::EnqueueEvent (EventBaseSP event_sp)
{
std::lock_guard<std::mutex> lock (m_queue_mutex);
m_event_queue.push (event_sp);
m_queue_condition.notify_one ();
}
ThreadStateCoordinator::EventBaseSP
ThreadStateCoordinator::DequeueEventWithWait ()
{
// Wait for an event to be present.
std::unique_lock<std::mutex> lock (m_queue_mutex);
m_queue_condition.wait (lock,
[this] { return !m_event_queue.empty (); });
// Grab the event and pop it off the queue.
EventBaseSP event_sp = m_event_queue.front ();
m_event_queue.pop ();
return event_sp;
}
void
ThreadStateCoordinator::SetPendingNotification (const EventBaseSP &event_sp)
{
assert (event_sp && "null event_sp");
if (!event_sp)
return;
const EventCallAfterThreadsStop *new_call_after_event = static_cast<EventCallAfterThreadsStop*> (event_sp.get ());
EventCallAfterThreadsStop *const prev_call_after_event = GetPendingThreadStopNotification ();
if (prev_call_after_event)
{
// Yikes - we've already got a pending signal notification in progress.
// Log this info. We lose the pending notification here.
Log ("ThreadStateCoordinator::%s dropping existing pending signal notification for tid %" PRIu64 ", to be replaced with signal for tid %" PRIu64,
__FUNCTION__,
prev_call_after_event->GetTriggeringTID (),
new_call_after_event->GetTriggeringTID ());
}
m_pending_notification_sp = event_sp;
}
void
ThreadStateCoordinator::CallAfterThreadsStop (const lldb::tid_t triggering_tid,
const ThreadIDSet &wait_for_stop_tids,
const ThreadIDFunction &request_thread_stop_function,
const ThreadIDFunction &call_after_function,
const ErrorFunction &error_function)
{
EnqueueEvent (EventBaseSP (new EventCallAfterThreadsStop (triggering_tid,
wait_for_stop_tids,
request_thread_stop_function,
call_after_function,
error_function)));
}
void
ThreadStateCoordinator::CallAfterRunningThreadsStop (const lldb::tid_t triggering_tid,
const ThreadIDFunction &request_thread_stop_function,
const ThreadIDFunction &call_after_function,
const ErrorFunction &error_function)
{
EnqueueEvent (EventBaseSP (new EventCallAfterThreadsStop (triggering_tid,
request_thread_stop_function,
call_after_function,
error_function)));
}
void
ThreadStateCoordinator::ThreadDidStop (lldb::tid_t tid, ErrorFunction &error_function)
{
// Ensure we know about the thread.
auto find_it = m_tid_stop_map.find (tid);
if (find_it == m_tid_stop_map.end ())
{
// We don't know about this thread. This is an error condition.
std::ostringstream error_message;
error_message << "error: tid " << tid << " asked to stop but tid is unknown";
error_function (error_message.str ());
return;
}
// Update the global list of known thread states. This one is definitely stopped.
find_it->second = true;
// If we have a pending notification, remove this from the set.
EventCallAfterThreadsStop *const call_after_event = GetPendingThreadStopNotification ();
if (call_after_event)
{
const bool pending_stops_remain = call_after_event->RemoveThreadStopRequirementAndMaybeSignal (tid);
if (!pending_stops_remain)
{
// Clear the pending notification now.
m_pending_notification_sp.reset ();
}
}
}
void
ThreadStateCoordinator::ThreadWasCreated (lldb::tid_t tid, bool is_stopped, ErrorFunction &error_function)
{
// Ensure we don't already know about the thread.
auto find_it = m_tid_stop_map.find (tid);
if (find_it != m_tid_stop_map.end ())
{
// We already know about this thread. This is an error condition.
std::ostringstream error_message;
error_message << "error: notified tid " << tid << " created but we already know about this thread";
error_function (error_message.str ());
return;
}
// Add the new thread to the stop map.
m_tid_stop_map[tid] = is_stopped;
EventCallAfterThreadsStop *const call_after_event = GetPendingThreadStopNotification ();
if (call_after_event && !is_stopped)
{
// Tell the pending notification that we need to wait
// for this new thread to stop.
call_after_event->AddThreadStopRequirement (tid);
}
}
void
ThreadStateCoordinator::ThreadDidDie (lldb::tid_t tid, ErrorFunction &error_function)
{
// Ensure we know about the thread.
auto find_it = m_tid_stop_map.find (tid);
if (find_it == m_tid_stop_map.end ())
{
// We don't know about this thread. This is an error condition.
std::ostringstream error_message;
error_message << "error: notified tid " << tid << " died but tid is unknown";
error_function (error_message.str ());
return;
}
// Update the global list of known thread states. While this one is stopped, it is also dead.
// So stop tracking it. We assume the user of this coordinator will not keep trying to add
// dependencies on a thread after it is known to be dead.
m_tid_stop_map.erase (find_it);
// If we have a pending notification, remove this from the set.
EventCallAfterThreadsStop *const call_after_event = GetPendingThreadStopNotification ();
if (call_after_event)
{
const bool pending_stops_remain = call_after_event->RemoveThreadStopRequirementAndMaybeSignal (tid);
if (!pending_stops_remain)
{
// Clear the pending notification now.
m_pending_notification_sp.reset ();
}
}
}
void
ThreadStateCoordinator::ResetNow ()
{
// Clear the pending notification if there was one.
m_pending_notification_sp.reset ();
// Clear the stop map - we no longer know anything about any thread state.
// The caller is expected to reset thread states for all threads, and we
// will assume anything we haven't heard about is running and requires a
// stop.
m_tid_stop_map.clear ();
}
void
ThreadStateCoordinator::Log (const char *format, ...)
{
va_list args;
va_start (args, format);
m_log_function (format, args);
va_end (args);
}
void
ThreadStateCoordinator::NotifyThreadStop (lldb::tid_t tid,
const ErrorFunction &error_function)
{
EnqueueEvent (EventBaseSP (new EventThreadStopped (tid, error_function)));
}
void
ThreadStateCoordinator::RequestThreadResume (lldb::tid_t tid,
const ThreadIDFunction &request_thread_resume_function,
const ErrorFunction &error_function)
{
EnqueueEvent (EventBaseSP (new EventRequestResume (tid, request_thread_resume_function, error_function)));
}
void
ThreadStateCoordinator::NotifyThreadCreate (lldb::tid_t tid,
bool is_stopped,
const ErrorFunction &error_function)
{
EnqueueEvent (EventBaseSP (new EventThreadCreate (tid, is_stopped, error_function)));
}
void
ThreadStateCoordinator::NotifyThreadDeath (lldb::tid_t tid,
const ErrorFunction &error_function)
{
EnqueueEvent (EventBaseSP (new EventThreadDeath (tid, error_function)));
}
void
ThreadStateCoordinator::ResetForExec ()
{
std::lock_guard<std::mutex> lock (m_queue_mutex);
// Remove everything from the queue. This is the only
// state mutation that takes place outside the processing
// loop.
QueueType empty_queue;
m_event_queue.swap (empty_queue);
// Do the real clear behavior on the the queue to eliminate
// the chance that processing of a dequeued earlier event is
// overlapping with the clearing of state here. Push it
// directly because we need to have this happen with the lock,
// and so far I only have this one place that needs a no-lock
// variant.
m_event_queue.push (EventBaseSP (new EventReset ()));
}
void
ThreadStateCoordinator::StopCoordinator ()
{
EnqueueEvent (EventBaseSP (new EventStopCoordinator ()));
}
ThreadStateCoordinator::EventLoopResult
ThreadStateCoordinator::ProcessNextEvent ()
{
return DequeueEventWithWait()->ProcessEvent (*this);
}
ThreadStateCoordinator::EventCallAfterThreadsStop *
ThreadStateCoordinator::GetPendingThreadStopNotification ()
{
return static_cast<EventCallAfterThreadsStop*> (m_pending_notification_sp.get ());
}