[lldb-dap] Protect SetBreakpoint with the API mutex

[JDevlieghere]

Protect the various SetBreakpoint functions with the API mutex. This fixes a race condition between the breakpoint being created and the DAP label getting added. This was causing TestDAP_breakpointEvents.py to be flaky.

Fixes #131242.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Jonas Devlieghere (JDevlieghere)

Changes

Protect the various SetBreakpoint functions with the API mutex. This fixes a race condition between the breakpoint being created and the DAP label getting added. This was causing TestDAP_breakpointEvents.py to be flaky.

Fixes #131242.

---

Full diff: https://github.com/llvm/llvm-project/pull/134030.diff

5 Files Affected:

• (modified) lldb/tools/lldb-dap/Breakpoint.cpp (+6)
• (modified) lldb/tools/lldb-dap/DAP.h (+3)
• (modified) lldb/tools/lldb-dap/ExceptionBreakpoint.cpp (+5)
• (modified) lldb/tools/lldb-dap/FunctionBreakpoint.cpp (+5)
• (modified) lldb/tools/lldb-dap/SourceBreakpoint.cpp (+5)

diff --git a/lldb/tools/lldb-dap/Breakpoint.cpp b/lldb/tools/lldb-dap/Breakpoint.cpp
index e02f62076f935..5679fd545d53f 100644
--- a/lldb/tools/lldb-dap/Breakpoint.cpp
+++ b/lldb/tools/lldb-dap/Breakpoint.cpp
@@ -7,14 +7,17 @@
 //===----------------------------------------------------------------------===//
 
 #include "Breakpoint.h"
+#include "DAP.h"
 #include "JSONUtils.h"
 #include "lldb/API/SBAddress.h"
 #include "lldb/API/SBBreakpointLocation.h"
 #include "lldb/API/SBLineEntry.h"
+#include "lldb/API/SBMutex.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/JSON.h"
 #include <cstddef>
 #include <cstdint>
+#include <mutex>
 #include <string>
 
 using namespace lldb_dap;
@@ -74,6 +77,9 @@ bool Breakpoint::MatchesName(const char *name) {
 }
 
 void Breakpoint::SetBreakpoint() {
+  lldb::SBMutex lock = m_dap.GetAPIMutex();
+  std::lock_guard<lldb::SBMutex> guard(lock);
+
   m_bp.AddName(kDAPBreakpointLabel);
   if (!m_condition.empty())
     SetCondition();
diff --git a/lldb/tools/lldb-dap/DAP.h b/lldb/tools/lldb-dap/DAP.h
index 4357bdd5cc80f..3ce6498632479 100644
--- a/lldb/tools/lldb-dap/DAP.h
+++ b/lldb/tools/lldb-dap/DAP.h
@@ -27,6 +27,7 @@
 #include "lldb/API/SBFile.h"
 #include "lldb/API/SBFormat.h"
 #include "lldb/API/SBFrame.h"
+#include "lldb/API/SBMutex.h"
 #include "lldb/API/SBTarget.h"
 #include "lldb/API/SBThread.h"
 #include "lldb/API/SBValue.h"
@@ -404,6 +405,8 @@ struct DAP {
   InstructionBreakpoint *GetInstructionBreakpoint(const lldb::break_id_t bp_id);
 
   InstructionBreakpoint *GetInstructionBPFromStopReason(lldb::SBThread &thread);
+
+  lldb::SBMutex GetAPIMutex() const { return target.GetAPIMutex(); }
 };
 
 } // namespace lldb_dap
diff --git a/lldb/tools/lldb-dap/ExceptionBreakpoint.cpp b/lldb/tools/lldb-dap/ExceptionBreakpoint.cpp
index d8109daf89129..9772e7344ced6 100644
--- a/lldb/tools/lldb-dap/ExceptionBreakpoint.cpp
+++ b/lldb/tools/lldb-dap/ExceptionBreakpoint.cpp
@@ -9,11 +9,16 @@
 #include "ExceptionBreakpoint.h"
 #include "BreakpointBase.h"
 #include "DAP.h"
+#include "lldb/API/SBMutex.h"
 #include "lldb/API/SBTarget.h"
+#include <mutex>
 
 namespace lldb_dap {
 
 void ExceptionBreakpoint::SetBreakpoint() {
+  lldb::SBMutex lock = m_dap.GetAPIMutex();
+  std::lock_guard<lldb::SBMutex> guard(lock);
+
   if (m_bp.IsValid())
     return;
   bool catch_value = m_filter.find("_catch") != std::string::npos;
diff --git a/lldb/tools/lldb-dap/FunctionBreakpoint.cpp b/lldb/tools/lldb-dap/FunctionBreakpoint.cpp
index 2fb6e8fafc2fa..d87723f7557bd 100644
--- a/lldb/tools/lldb-dap/FunctionBreakpoint.cpp
+++ b/lldb/tools/lldb-dap/FunctionBreakpoint.cpp
@@ -9,6 +9,8 @@
 #include "FunctionBreakpoint.h"
 #include "DAP.h"
 #include "JSONUtils.h"
+#include "lldb/API/SBMutex.h"
+#include <mutex>
 
 namespace lldb_dap {
 
@@ -17,6 +19,9 @@ FunctionBreakpoint::FunctionBreakpoint(DAP &d, const llvm::json::Object &obj)
       m_function_name(std::string(GetString(obj, "name").value_or(""))) {}
 
 void FunctionBreakpoint::SetBreakpoint() {
+  lldb::SBMutex lock = m_dap.GetAPIMutex();
+  std::lock_guard<lldb::SBMutex> guard(lock);
+
   if (m_function_name.empty())
     return;
   m_bp = m_dap.target.BreakpointCreateByName(m_function_name.c_str());
diff --git a/lldb/tools/lldb-dap/SourceBreakpoint.cpp b/lldb/tools/lldb-dap/SourceBreakpoint.cpp
index 150fa6af44d3a..6d8d3470668c8 100644
--- a/lldb/tools/lldb-dap/SourceBreakpoint.cpp
+++ b/lldb/tools/lldb-dap/SourceBreakpoint.cpp
@@ -13,6 +13,7 @@
 #include "lldb/API/SBBreakpoint.h"
 #include "lldb/API/SBFileSpecList.h"
 #include "lldb/API/SBFrame.h"
+#include "lldb/API/SBMutex.h"
 #include "lldb/API/SBTarget.h"
 #include "lldb/API/SBThread.h"
 #include "lldb/API/SBValue.h"
@@ -20,6 +21,7 @@
 #include <cassert>
 #include <cctype>
 #include <cstdlib>
+#include <mutex>
 #include <utility>
 
 namespace lldb_dap {
@@ -33,6 +35,9 @@ SourceBreakpoint::SourceBreakpoint(DAP &dap, const llvm::json::Object &obj)
                    .value_or(LLDB_INVALID_COLUMN_NUMBER)) {}
 
 void SourceBreakpoint::SetBreakpoint(const llvm::StringRef source_path) {
+  lldb::SBMutex lock = m_dap.GetAPIMutex();
+  std::lock_guard<lldb::SBMutex> guard(lock);
+
   lldb::SBFileSpecList module_list;
   m_bp = m_dap.target.BreakpointCreateByLocation(
       source_path.str().c_str(), m_line, m_column, 0, module_list);

[ashgti]

Looks great!