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[debugserver] Migrate MachThreadList away from PThreadMutex (NFC) #137542

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Merged
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Apr 27, 2025
Merged

[debugserver] Migrate MachThreadList away from PThreadMutex (NFC) #137542

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38 changes: 18 additions & 20 deletions lldb/tools/debugserver/source/MacOSX/MachThreadList.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,7 @@
#include <memory>

MachThreadList::MachThreadList()
: m_threads(), m_threads_mutex(PTHREAD_MUTEX_RECURSIVE),
m_is_64_bit(false) {}
: m_threads(), m_threads_mutex(), m_is_64_bit(false) {}

MachThreadList::~MachThreadList() = default;

Expand Down Expand Up @@ -116,7 +115,7 @@ const char *MachThreadList::GetThreadInfo(nub_thread_t tid) const {
}

MachThreadSP MachThreadList::GetThreadByID(nub_thread_t tid) const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
MachThreadSP thread_sp;
const size_t num_threads = m_threads.size();
for (size_t idx = 0; idx < num_threads; ++idx) {
Expand All @@ -130,7 +129,7 @@ MachThreadSP MachThreadList::GetThreadByID(nub_thread_t tid) const {

MachThreadSP
MachThreadList::GetThreadByMachPortNumber(thread_t mach_port_number) const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
MachThreadSP thread_sp;
const size_t num_threads = m_threads.size();
for (size_t idx = 0; idx < num_threads; ++idx) {
Expand All @@ -144,7 +143,7 @@ MachThreadList::GetThreadByMachPortNumber(thread_t mach_port_number) const {

nub_thread_t
MachThreadList::GetThreadIDByMachPortNumber(thread_t mach_port_number) const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
MachThreadSP thread_sp;
const size_t num_threads = m_threads.size();
for (size_t idx = 0; idx < num_threads; ++idx) {
Expand All @@ -157,7 +156,7 @@ MachThreadList::GetThreadIDByMachPortNumber(thread_t mach_port_number) const {

thread_t MachThreadList::GetMachPortNumberByThreadID(
nub_thread_t globally_unique_id) const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
MachThreadSP thread_sp;
const size_t num_threads = m_threads.size();
for (size_t idx = 0; idx < num_threads; ++idx) {
Expand Down Expand Up @@ -219,12 +218,12 @@ bool MachThreadList::RestoreRegisterState(nub_thread_t tid, uint32_t save_id) {
}

nub_size_t MachThreadList::NumThreads() const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
return m_threads.size();
}

nub_thread_t MachThreadList::ThreadIDAtIndex(nub_size_t idx) const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
if (idx < m_threads.size())
return m_threads[idx]->ThreadID();
return INVALID_NUB_THREAD;
Expand All @@ -248,7 +247,7 @@ bool MachThreadList::NotifyException(MachException::Data &exc) {
}

void MachThreadList::Clear() {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
m_threads.clear();
}

Expand All @@ -259,7 +258,7 @@ MachThreadList::UpdateThreadList(MachProcess *process, bool update,
DNBLogThreadedIf(LOG_THREAD, "MachThreadList::UpdateThreadList (pid = %4.4x, "
"update = %u) process stop count = %u",
process->ProcessID(), update, process->StopCount());
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);

if (process->StopCount() == 0) {
int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PID, process->ProcessID()};
Expand Down Expand Up @@ -346,8 +345,7 @@ MachThreadList::UpdateThreadList(MachProcess *process, bool update,
}

void MachThreadList::CurrentThread(MachThreadSP &thread_sp) {
// locker will keep a mutex locked until it goes out of scope
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
if (m_current_thread.get() == NULL) {
// Figure out which thread is going to be our current thread.
// This is currently done by finding the first thread in the list
Expand All @@ -364,7 +362,7 @@ void MachThreadList::CurrentThread(MachThreadSP &thread_sp) {
}

void MachThreadList::Dump() const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
const size_t num_threads = m_threads.size();
for (uint32_t idx = 0; idx < num_threads; ++idx) {
m_threads[idx]->Dump(idx);
Expand All @@ -373,7 +371,7 @@ void MachThreadList::Dump() const {

void MachThreadList::ProcessWillResume(
MachProcess *process, const DNBThreadResumeActions &thread_actions) {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);

// Update our thread list, because sometimes libdispatch or the kernel
// will spawn threads while a task is suspended.
Expand Down Expand Up @@ -447,7 +445,7 @@ void MachThreadList::ProcessWillResume(
}

uint32_t MachThreadList::ProcessDidStop(MachProcess *process) {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
// Update our thread list
const uint32_t num_threads = UpdateThreadList(process, true);
for (uint32_t idx = 0; idx < num_threads; ++idx) {
Expand All @@ -466,7 +464,7 @@ uint32_t MachThreadList::ProcessDidStop(MachProcess *process) {
// true if we should stop and notify our clients
// false if we should resume our child process and skip notification
bool MachThreadList::ShouldStop(bool &step_more) {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
uint32_t should_stop = false;
const size_t num_threads = m_threads.size();
for (uint32_t idx = 0; !should_stop && idx < num_threads; ++idx) {
Expand All @@ -476,7 +474,7 @@ bool MachThreadList::ShouldStop(bool &step_more) {
}

void MachThreadList::NotifyBreakpointChanged(const DNBBreakpoint *bp) {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
const size_t num_threads = m_threads.size();
for (uint32_t idx = 0; idx < num_threads; ++idx) {
m_threads[idx]->NotifyBreakpointChanged(bp);
Expand All @@ -489,7 +487,7 @@ uint32_t MachThreadList::DoHardwareBreakpointAction(
return INVALID_NUB_HW_INDEX;

uint32_t hw_index = INVALID_NUB_HW_INDEX;
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
const size_t num_threads = m_threads.size();
// On Mac OS X we have to prime the control registers for new threads. We do
// this using the control register data for the first thread, for lack of a
Expand Down Expand Up @@ -555,7 +553,7 @@ bool MachThreadList::DisableHardwareBreakpoint(const DNBBreakpoint *bp) const {
}

uint32_t MachThreadList::NumSupportedHardwareWatchpoints() const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
const size_t num_threads = m_threads.size();
// Use an arbitrary thread to retrieve the number of supported hardware
// watchpoints.
Expand All @@ -566,7 +564,7 @@ uint32_t MachThreadList::NumSupportedHardwareWatchpoints() const {

uint32_t MachThreadList::GetThreadIndexForThreadStoppedWithSignal(
const int signo) const {
PTHREAD_MUTEX_LOCKER(locker, m_threads_mutex);
std::lock_guard<std::recursive_mutex> guard(m_threads_mutex);
uint32_t should_stop = false;
const size_t num_threads = m_threads.size();
for (uint32_t idx = 0; !should_stop && idx < num_threads; ++idx) {
Expand Down
2 changes: 1 addition & 1 deletion lldb/tools/debugserver/source/MacOSX/MachThreadList.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,7 +98,7 @@ class MachThreadList {
// const_iterator FindThreadByID (thread_t tid) const;

collection m_threads;
mutable PThreadMutex m_threads_mutex;
mutable std::recursive_mutex m_threads_mutex;
MachThreadSP m_current_thread;
bool m_is_64_bit;
};
Expand Down
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