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llvm/lldb/source/Target/ThreadList.cpp
Greg Clayton e1cd1be6d6 Switching back to using std::tr1::shared_ptr. We originally switched away 
due to RTTI worries since llvm and clang don't use RTTI, but I was able to 
switch back with no issues as far as I can tell. Once the RTTI issue wasn't
an issue, we were looking for a way to properly track weak pointers to objects
to solve some of the threading issues we have been running into which naturally
led us back to std::tr1::weak_ptr. We also wanted the ability to make a shared 
pointer from just a pointer, which is also easily solved using the 
std::tr1::enable_shared_from_this class. 

The main reason for this move back is so we can start properly having weak
references to objects. Currently a lldb_private::Thread class has a refrence
to its parent lldb_private::Process. This doesn't work well when we now hand
out a SBThread object that contains a shared pointer to a lldb_private::Thread
as this SBThread can be held onto by external clients and if they end up
using one of these objects we can easily crash.

So the next task is to start adopting std::tr1::weak_ptr where ever it makes
sense which we can do with lldb_private::Debugger, lldb_private::Target,
lldb_private::Process, lldb_private::Thread, lldb_private::StackFrame, and
many more objects now that they are no longer using intrusive ref counted
pointer objects (you can't do std::tr1::weak_ptr functionality with intrusive
pointers).

llvm-svn: 149207
2012-01-29 20:56:30 +00:00

647 lines
19 KiB
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//===-- ThreadList.cpp ------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include <stdlib.h>
#include <algorithm>
#include "lldb/Core/Log.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/ThreadList.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlan.h"
#include "lldb/Target/Process.h"
using namespace lldb;
using namespace lldb_private;
ThreadList::ThreadList (Process *process) :
m_process (process),
m_stop_id (0),
m_threads(),
m_threads_mutex (Mutex::eMutexTypeRecursive),
m_selected_tid (LLDB_INVALID_THREAD_ID)
{
}
ThreadList::ThreadList (const ThreadList &rhs) :
m_process (),
m_stop_id (),
m_threads (),
m_threads_mutex (Mutex::eMutexTypeRecursive),
m_selected_tid ()
{
// Use the assignment operator since it uses the mutex
*this = rhs;
}
const ThreadList&
ThreadList::operator = (const ThreadList& rhs)
{
if (this != &rhs)
{
// Lock both mutexes to make sure neither side changes anyone on us
// while the assignement occurs
Mutex::Locker locker_lhs(m_threads_mutex);
Mutex::Locker locker_rhs(rhs.m_threads_mutex);
m_process = rhs.m_process;
m_stop_id = rhs.m_stop_id;
m_threads = rhs.m_threads;
m_selected_tid = rhs.m_selected_tid;
}
return *this;
}
ThreadList::~ThreadList()
{
}
uint32_t
ThreadList::GetStopID () const
{
return m_stop_id;
}
void
ThreadList::SetStopID (uint32_t stop_id)
{
m_stop_id = stop_id;
}
void
ThreadList::AddThread (ThreadSP &thread_sp)
{
Mutex::Locker locker(m_threads_mutex);
m_threads.push_back(thread_sp);
}
uint32_t
ThreadList::GetSize (bool can_update)
{
Mutex::Locker locker(m_threads_mutex);
if (can_update)
m_process->UpdateThreadListIfNeeded();
return m_threads.size();
}
ThreadSP
ThreadList::GetThreadAtIndex (uint32_t idx, bool can_update)
{
Mutex::Locker locker(m_threads_mutex);
if (can_update)
m_process->UpdateThreadListIfNeeded();
ThreadSP thread_sp;
if (idx < m_threads.size())
thread_sp = m_threads[idx];
return thread_sp;
}
ThreadSP
ThreadList::FindThreadByID (lldb::tid_t tid, bool can_update)
{
Mutex::Locker locker(m_threads_mutex);
if (can_update)
m_process->UpdateThreadListIfNeeded();
ThreadSP thread_sp;
uint32_t idx = 0;
const uint32_t num_threads = m_threads.size();
for (idx = 0; idx < num_threads; ++idx)
{
if (m_threads[idx]->GetID() == tid)
{
thread_sp = m_threads[idx];
break;
}
}
return thread_sp;
}
ThreadSP
ThreadList::GetThreadSPForThreadPtr (Thread *thread_ptr)
{
ThreadSP thread_sp;
if (thread_ptr)
{
Mutex::Locker locker(m_threads_mutex);
uint32_t idx = 0;
const uint32_t num_threads = m_threads.size();
for (idx = 0; idx < num_threads; ++idx)
{
if (m_threads[idx].get() == thread_ptr)
{
thread_sp = m_threads[idx];
break;
}
}
}
return thread_sp;
}
ThreadSP
ThreadList::FindThreadByIndexID (uint32_t index_id, bool can_update)
{
Mutex::Locker locker(m_threads_mutex);
if (can_update)
m_process->UpdateThreadListIfNeeded();
ThreadSP thread_sp;
const uint32_t num_threads = m_threads.size();
for (uint32_t idx = 0; idx < num_threads; ++idx)
{
if (m_threads[idx]->GetIndexID() == index_id)
{
thread_sp = m_threads[idx];
break;
}
}
return thread_sp;
}
bool
ThreadList::ShouldStop (Event *event_ptr)
{
Mutex::Locker locker(m_threads_mutex);
// Running events should never stop, obviously...
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
bool should_stop = false;
m_process->UpdateThreadListIfNeeded();
collection::iterator pos, end = m_threads.end();
if (log)
{
log->PutCString("");
log->Printf ("ThreadList::%s: %zu threads", __FUNCTION__, m_threads.size());
}
// Run through the threads and ask whether we should stop. Don't ask
// suspended threads, however, it makes more sense for them to preserve their
// state across the times the process runs but they don't get a chance to.
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
if (thread_sp->GetResumeState () == eStateSuspended)
{
if (log)
log->Printf ("ThreadList::%s for tid = 0x%4.4llx, pc = 0x%16.16llx, should_stop = 0 (ignore since thread was suspended)",
__FUNCTION__,
thread_sp->GetID (),
thread_sp->GetRegisterContext()->GetPC());
continue;
}
if (thread_sp->ThreadStoppedForAReason() == false)
{
if (log)
log->Printf ("ThreadList::%s for tid = 0x%4.4llx, pc = 0x%16.16llx, should_stop = 0 (ignore since no stop reason)",
__FUNCTION__,
thread_sp->GetID (),
thread_sp->GetRegisterContext()->GetPC());
continue;
}
if (log)
log->Printf ("ThreadList::%s for tid = 0x%4.4llx, pc = 0x%16.16llx",
__FUNCTION__,
thread_sp->GetID (),
thread_sp->GetRegisterContext()->GetPC());
const bool thread_should_stop = thread_sp->ShouldStop(event_ptr);
if (thread_should_stop)
should_stop |= true;
}
if (log)
log->Printf ("ThreadList::%s overall should_stop = %i", __FUNCTION__, should_stop);
if (should_stop)
{
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
thread_sp->WillStop ();
}
}
return should_stop;
}
Vote
ThreadList::ShouldReportStop (Event *event_ptr)
{
Mutex::Locker locker(m_threads_mutex);
Vote result = eVoteNoOpinion;
m_process->UpdateThreadListIfNeeded();
collection::iterator pos, end = m_threads.end();
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
if (log)
log->Printf ("ThreadList::%s %zu threads", __FUNCTION__, m_threads.size());
// Run through the threads and ask whether we should report this event.
// For stopping, a YES vote wins over everything. A NO vote wins over NO opinion.
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
if (thread_sp->ThreadStoppedForAReason() && (thread_sp->GetResumeState () != eStateSuspended))
{
const Vote vote = thread_sp->ShouldReportStop (event_ptr);
if (log)
log->Printf ("ThreadList::%s thread 0x%4.4llx: pc = 0x%16.16llx, vote = %s",
__FUNCTION__,
thread_sp->GetID (),
thread_sp->GetRegisterContext()->GetPC(),
GetVoteAsCString (vote));
switch (vote)
{
case eVoteNoOpinion:
continue;
case eVoteYes:
result = eVoteYes;
break;
case eVoteNo:
if (result == eVoteNoOpinion)
{
result = eVoteNo;
}
else
{
if (log)
log->Printf ("ThreadList::%s thread 0x%4.4llx: pc = 0x%16.16llx voted %s, but lost out because result was %s",
__FUNCTION__,
thread_sp->GetID (),
thread_sp->GetRegisterContext()->GetPC(),
GetVoteAsCString (vote),
GetVoteAsCString (result));
}
break;
}
}
}
if (log)
log->Printf ("ThreadList::%s returning %s", __FUNCTION__, GetVoteAsCString (result));
return result;
}
Vote
ThreadList::ShouldReportRun (Event *event_ptr)
{
Mutex::Locker locker(m_threads_mutex);
Vote result = eVoteNoOpinion;
m_process->UpdateThreadListIfNeeded();
collection::iterator pos, end = m_threads.end();
// Run through the threads and ask whether we should report this event.
// The rule is NO vote wins over everything, a YES vote wins over no opinion.
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
for (pos = m_threads.begin(); pos != end; ++pos)
{
if ((*pos)->GetResumeState () != eStateSuspended)
{
switch ((*pos)->ShouldReportRun (event_ptr))
{
case eVoteNoOpinion:
continue;
case eVoteYes:
if (result == eVoteNoOpinion)
result = eVoteYes;
break;
case eVoteNo:
if (log)
log->Printf ("ThreadList::ShouldReportRun() thread %d (0x%4.4llx) says don't report.",
(*pos)->GetIndexID(),
(*pos)->GetID());
result = eVoteNo;
break;
}
}
}
return result;
}
void
ThreadList::Clear()
{
Mutex::Locker locker(m_threads_mutex);
m_stop_id = 0;
m_threads.clear();
m_selected_tid = LLDB_INVALID_THREAD_ID;
}
void
ThreadList::Destroy()
{
Mutex::Locker locker(m_threads_mutex);
const uint32_t num_threads = m_threads.size();
for (uint32_t idx = 0; idx < num_threads; ++idx)
{
m_threads[idx]->DestroyThread();
}
}
void
ThreadList::RefreshStateAfterStop ()
{
Mutex::Locker locker(m_threads_mutex);
m_process->UpdateThreadListIfNeeded();
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
if (log && log->GetVerbose())
log->Printf ("Turning off notification of new threads while single stepping a thread.");
collection::iterator pos, end = m_threads.end();
for (pos = m_threads.begin(); pos != end; ++pos)
(*pos)->RefreshStateAfterStop ();
}
void
ThreadList::DiscardThreadPlans ()
{
// You don't need to update the thread list here, because only threads
// that you currently know about have any thread plans.
Mutex::Locker locker(m_threads_mutex);
collection::iterator pos, end = m_threads.end();
for (pos = m_threads.begin(); pos != end; ++pos)
(*pos)->DiscardThreadPlans (true);
}
bool
ThreadList::WillResume ()
{
// Run through the threads and perform their momentary actions.
// But we only do this for threads that are running, user suspended
// threads stay where they are.
bool success = true;
Mutex::Locker locker(m_threads_mutex);
m_process->UpdateThreadListIfNeeded();
collection::iterator pos, end = m_threads.end();
// See if any thread wants to run stopping others. If it does, then we won't
// setup the other threads for resume, since they aren't going to get a chance
// to run. This is necessary because the SetupForResume might add "StopOthers"
// plans which would then get to be part of the who-gets-to-run negotiation, but
// they're coming in after the fact, and the threads that are already set up should
// take priority.
bool wants_solo_run = false;
for (pos = m_threads.begin(); pos != end; ++pos)
{
if ((*pos)->GetResumeState() != eStateSuspended &&
(*pos)->GetCurrentPlan()->StopOthers())
{
wants_solo_run = true;
break;
}
}
if (wants_solo_run)
{
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
if (log && log->GetVerbose())
log->Printf ("Turning on notification of new threads while single stepping a thread.");
m_process->StartNoticingNewThreads();
}
else
{
LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
if (log && log->GetVerbose())
log->Printf ("Turning off notification of new threads while single stepping a thread.");
m_process->StopNoticingNewThreads();
}
// Give all the threads that are likely to run a last chance to set up their state before we
// negotiate who is actually going to get a chance to run...
// Don't set to resume suspended threads, and if any thread wanted to stop others, only
// call setup on the threads that request StopOthers...
for (pos = m_threads.begin(); pos != end; ++pos)
{
if ((*pos)->GetResumeState() != eStateSuspended
&& (!wants_solo_run || (*pos)->GetCurrentPlan()->StopOthers()))
{
(*pos)->SetupForResume ();
}
}
// Now go through the threads and see if any thread wants to run just itself.
// if so then pick one and run it.
ThreadList run_me_only_list (m_process);
run_me_only_list.SetStopID(m_process->GetStopID());
ThreadSP immediate_thread_sp;
bool run_only_current_thread = false;
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
if (thread_sp->GetResumeState() != eStateSuspended &&
thread_sp->GetCurrentPlan()->StopOthers())
{
// You can't say "stop others" and also want yourself to be suspended.
assert (thread_sp->GetCurrentPlan()->RunState() != eStateSuspended);
if (thread_sp == GetSelectedThread())
{
run_only_current_thread = true;
run_me_only_list.Clear();
run_me_only_list.AddThread (thread_sp);
break;
}
run_me_only_list.AddThread (thread_sp);
}
}
if (immediate_thread_sp)
{
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
if (thread_sp.get() == immediate_thread_sp.get())
thread_sp->WillResume(thread_sp->GetCurrentPlan()->RunState());
else
thread_sp->WillResume (eStateSuspended);
}
}
else if (run_me_only_list.GetSize (false) == 0)
{
// Everybody runs as they wish:
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
thread_sp->WillResume(thread_sp->GetCurrentPlan()->RunState());
}
}
else
{
ThreadSP thread_to_run;
if (run_only_current_thread)
{
thread_to_run = GetSelectedThread();
}
else if (run_me_only_list.GetSize (false) == 1)
{
thread_to_run = run_me_only_list.GetThreadAtIndex (0);
}
else
{
int random_thread = (int)
((run_me_only_list.GetSize (false) * (double) rand ()) / (RAND_MAX + 1.0));
thread_to_run = run_me_only_list.GetThreadAtIndex (random_thread);
}
for (pos = m_threads.begin(); pos != end; ++pos)
{
ThreadSP thread_sp(*pos);
if (thread_sp == thread_to_run)
thread_sp->WillResume(thread_sp->GetCurrentPlan()->RunState());
else
thread_sp->WillResume (eStateSuspended);
}
}
return success;
}
void
ThreadList::DidResume ()
{
Mutex::Locker locker(m_threads_mutex);
collection::iterator pos, end = m_threads.end();
for (pos = m_threads.begin(); pos != end; ++pos)
{
// Don't clear out threads that aren't going to get a chance to run, rather
// leave their state for the next time around.
ThreadSP thread_sp(*pos);
if (thread_sp->GetResumeState() != eStateSuspended)
thread_sp->DidResume ();
}
}
ThreadSP
ThreadList::GetSelectedThread ()
{
Mutex::Locker locker(m_threads_mutex);
ThreadSP thread_sp = FindThreadByID(m_selected_tid);
if (!thread_sp.get())
{
if (m_threads.size() == 0)
return thread_sp;
m_selected_tid = m_threads[0]->GetID();
thread_sp = m_threads[0];
}
return thread_sp;
}
bool
ThreadList::SetSelectedThreadByID (lldb::tid_t tid)
{
Mutex::Locker locker(m_threads_mutex);
ThreadSP selected_thread_sp(FindThreadByID(tid));
if (selected_thread_sp)
{
m_selected_tid = tid;
selected_thread_sp->SetDefaultFileAndLineToSelectedFrame();
}
else
m_selected_tid = LLDB_INVALID_THREAD_ID;
return m_selected_tid != LLDB_INVALID_THREAD_ID;
}
bool
ThreadList::SetSelectedThreadByIndexID (uint32_t index_id)
{
Mutex::Locker locker(m_threads_mutex);
ThreadSP selected_thread_sp (FindThreadByIndexID(index_id));
if (selected_thread_sp.get())
{
m_selected_tid = selected_thread_sp->GetID();
selected_thread_sp->SetDefaultFileAndLineToSelectedFrame();
}
else
m_selected_tid = LLDB_INVALID_THREAD_ID;
return m_selected_tid != LLDB_INVALID_THREAD_ID;
}
void
ThreadList::Update (ThreadList &rhs)
{
if (this != &rhs)
{
// Lock both mutexes to make sure neither side changes anyone on us
// while the assignement occurs
Mutex::Locker locker_lhs(m_threads_mutex);
Mutex::Locker locker_rhs(rhs.m_threads_mutex);
m_process = rhs.m_process;
m_stop_id = rhs.m_stop_id;
m_threads.swap(rhs.m_threads);
m_selected_tid = rhs.m_selected_tid;
// Now we look for threads that we are done with and
// make sure to clear them up as much as possible so
// anyone with a shared pointer will still have a reference,
// but the thread won't be of much use. Using std::weak_ptr
// for all backward references (such as a thread to a process)
// will eventually solve this issue for us, but for now, we
// need to work around the issue
collection::iterator rhs_pos, rhs_end = rhs.m_threads.end();
for (rhs_pos = rhs.m_threads.begin(); rhs_pos != rhs_end; ++rhs_pos)
{
const lldb::tid_t tid = (*rhs_pos)->GetID();
bool thread_is_alive = false;
const uint32_t num_threads = m_threads.size();
for (uint32_t idx = 0; idx < num_threads; ++idx)
{
if (m_threads[idx]->GetID() == tid)
{
thread_is_alive = true;
break;
}
}
if (!thread_is_alive)
(*rhs_pos)->DestroyThread();
}
}
}
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