This checking is part one of trying to add some threading safety to our

internals. The first part of this is to use a new class:

lldb_private::ExecutionContextRef

This class holds onto weak pointers to the target, process, thread and frame
and it also contains the thread ID and frame Stack ID in case the thread and
frame objects go away and come back as new objects that represent the same
logical thread/frame. 

ExecutionContextRef objcets have accessors to access shared pointers for
the target, process, thread and frame which might return NULL if the backing
object is no longer available. This allows for references to persistent program
state without needing to hold a shared pointer to each object and potentially
keeping that object around for longer than it needs to be. 

You can also "Lock" and ExecutionContextRef (which contains weak pointers)
object into an ExecutionContext (which contains strong, or shared pointers)
with code like

ExecutionContext exe_ctx (my_obj->GetExectionContextRef().Lock());

llvm-svn: 150801

1 files changed, 427 insertions, 21 deletions

diff --git a/lldb/source/Target/ExecutionContext.cpp b/lldb/source/Target/ExecutionContext.cpp
index 8360d1addcf..6cce08a093b 100644
--- a/lldb/source/Target/ExecutionContext.cpp
+++ b/lldb/source/Target/ExecutionContext.cpp
@@ -25,24 +25,51 @@ ExecutionContext::ExecutionContext() :
 }
 
 ExecutionContext::ExecutionContext (const ExecutionContext &rhs) :
-    m_target_sp (rhs.m_target_sp),
+    m_target_sp(rhs.m_target_sp),
     m_process_sp(rhs.m_process_sp),
-    m_thread_sp (rhs.m_thread_sp),
-    m_frame_sp  (rhs.m_frame_sp)
+    m_thread_sp(rhs.m_thread_sp),
+    m_frame_sp(rhs.m_frame_sp)
 {
 }
 
-ExecutionContext &
-ExecutionContext::operator =(const ExecutionContext &rhs)
+ExecutionContext::ExecutionContext (const lldb::TargetSP &target_sp, bool get_process) :
+    m_target_sp (),
+    m_process_sp (),
+    m_thread_sp (),
+    m_frame_sp ()
 {
-    if (this != &rhs)
-    {
-        m_target_sp  = rhs.m_target_sp;
-        m_process_sp = rhs.m_process_sp;
-        m_thread_sp  = rhs.m_thread_sp;
-        m_frame_sp   = rhs.m_frame_sp;
-    }
-    return *this;
+    if (target_sp)
+        SetContext (target_sp, get_process);
+}
+
+ExecutionContext::ExecutionContext (const lldb::ProcessSP &process_sp) :
+    m_target_sp (),
+    m_process_sp (),
+    m_thread_sp (),
+    m_frame_sp ()
+{
+    if (process_sp)
+        SetContext (process_sp);
+}
+
+ExecutionContext::ExecutionContext (const lldb::ThreadSP &thread_sp) :
+    m_target_sp (),
+    m_process_sp (),
+    m_thread_sp (),
+    m_frame_sp ()
+{
+    if (thread_sp)
+        SetContext (thread_sp);
+}
+
+ExecutionContext::ExecutionContext (const lldb::StackFrameSP &frame_sp) :
+    m_target_sp (),
+    m_process_sp (),
+    m_thread_sp (),
+    m_frame_sp ()
+{
+    if (frame_sp)
+        SetContext (frame_sp);
 }
 
 ExecutionContext::ExecutionContext (Target* t, bool fill_current_process_thread_frame) :
@@ -73,19 +100,39 @@ ExecutionContext::ExecutionContext(Process* process, Thread *thread, StackFrame
         m_target_sp = process->GetTarget().shared_from_this();
 }
 
-ExecutionContext::ExecutionContext (ExecutionContextScope *exe_scope_ptr)
+ExecutionContext::ExecutionContext (const ExecutionContextRef &exe_ctx_ref) :
+    m_target_sp (exe_ctx_ref.GetTargetSP()),
+    m_process_sp (exe_ctx_ref.GetProcessSP()),
+    m_thread_sp (exe_ctx_ref.GetThreadSP()),
+    m_frame_sp (exe_ctx_ref.GetFrameSP())
 {
-    if (exe_scope_ptr)
-        exe_scope_ptr->CalculateExecutionContext (*this);
-    else
+}
+
+ExecutionContext::ExecutionContext (const ExecutionContextRef *exe_ctx_ref_ptr) :
+    m_target_sp (),
+    m_process_sp (),
+    m_thread_sp (),
+    m_frame_sp ()
+{
+    if (exe_ctx_ref_ptr)
     {
-        m_target_sp.reset();
-        m_process_sp.reset();
-        m_thread_sp.reset();
-        m_frame_sp.reset();
+        m_target_sp  = exe_ctx_ref_ptr->GetTargetSP();
+        m_process_sp = exe_ctx_ref_ptr->GetProcessSP();
+        m_thread_sp = exe_ctx_ref_ptr->GetThreadSP();
+        m_frame_sp = exe_ctx_ref_ptr->GetFrameSP();
     }
 }
 
+ExecutionContext::ExecutionContext (ExecutionContextScope *exe_scope_ptr) :
+    m_target_sp (),
+    m_process_sp (),
+    m_thread_sp (),
+    m_frame_sp ()
+{
+    if (exe_scope_ptr)
+        exe_scope_ptr->CalculateExecutionContext (*this);
+}
+
 ExecutionContext::ExecutionContext (ExecutionContextScope &exe_scope_ref)
 {
     exe_scope_ref.CalculateExecutionContext (*this);
@@ -104,6 +151,17 @@ ExecutionContext::~ExecutionContext()
 {
 }
 
+uint32_t
+ExecutionContext::GetAddressByteSize() const
+{
+    if (m_target_sp && m_target_sp->GetArchitecture().IsValid())
+        m_target_sp->GetArchitecture().GetAddressByteSize();
+    if (m_process_sp)
+        m_process_sp->GetAddressByteSize();
+    return sizeof(void *);
+}
+
+
 
 RegisterContext *
 ExecutionContext::GetRegisterContext () const
@@ -235,3 +293,351 @@ ExecutionContext::SetFramePtr (StackFrame *frame)
         m_frame_sp.reset();
 }
 
+void
+ExecutionContext::SetContext (const lldb::TargetSP &target_sp, bool get_process)
+{
+    m_target_sp = target_sp;
+    if (get_process && target_sp)
+        m_process_sp = target_sp->GetProcessSP();
+    else
+        m_process_sp.reset();
+    m_thread_sp.reset();
+    m_frame_sp.reset();
+}
+
+void
+ExecutionContext::SetContext (const lldb::ProcessSP &process_sp)
+{
+    m_process_sp = process_sp;
+    if (process_sp)
+        m_target_sp = process_sp->GetTarget().shared_from_this();
+    else
+        m_target_sp.reset();
+    m_thread_sp.reset();
+    m_frame_sp.reset();
+}
+
+void
+ExecutionContext::SetContext (const lldb::ThreadSP &thread_sp)
+{
+    m_frame_sp.reset();
+    m_thread_sp = thread_sp;
+    if (thread_sp)
+    {
+        m_process_sp = thread_sp->GetProcess().shared_from_this();
+        if (m_process_sp)
+            m_target_sp = m_process_sp->GetTarget().shared_from_this();
+        else
+            m_target_sp.reset();
+    }
+    else
+    {
+        m_target_sp.reset();
+        m_process_sp.reset();
+    }
+}
+
+void
+ExecutionContext::SetContext (const lldb::StackFrameSP &frame_sp)
+{
+    m_frame_sp = frame_sp;
+    if (frame_sp)
+    {
+        m_thread_sp = frame_sp->GetThread().shared_from_this();
+        if (m_thread_sp)
+        {
+            m_process_sp = m_thread_sp->GetProcess().shared_from_this();
+            if (m_process_sp)
+                m_target_sp = m_process_sp->GetTarget().shared_from_this();
+            else
+                m_target_sp.reset();
+        }
+        else
+        {
+            m_target_sp.reset();
+            m_process_sp.reset();
+        }
+    }
+    else
+    {
+        m_target_sp.reset();
+        m_process_sp.reset();
+        m_thread_sp.reset();
+    }
+}
+
+ExecutionContext &
+ExecutionContext::operator =(const ExecutionContext &rhs)
+{
+    if (this != &rhs)
+    {
+        m_target_sp  = rhs.m_target_sp;
+        m_process_sp = rhs.m_process_sp;
+        m_thread_sp  = rhs.m_thread_sp;
+        m_frame_sp   = rhs.m_frame_sp;
+    }
+    return *this;
+}
+
+bool
+ExecutionContext::operator ==(const ExecutionContext &rhs) const
+{
+    // Check that the frame shared pointers match, or both are valid and their stack
+    // IDs match since sometimes we get new objects that represent the same 
+    // frame within a thread.
+    if ((m_frame_sp == rhs.m_frame_sp) || (m_frame_sp && rhs.m_frame_sp && m_frame_sp->GetStackID() == rhs.m_frame_sp->GetStackID()))
+    {
+        // Check that the thread shared pointers match, or both are valid and 
+        // their thread IDs match since sometimes we get new objects that 
+        // represent the same thread within a process.
+        if ((m_thread_sp == rhs.m_thread_sp) || (m_thread_sp && rhs.m_thread_sp && m_thread_sp->GetID() == rhs.m_thread_sp->GetID()))
+        {
+            // Processes and targets don't change much
+            return m_process_sp == rhs.m_process_sp && m_target_sp == rhs.m_target_sp;
+        }
+    }
+    return false;
+}
+
+bool
+ExecutionContext::operator !=(const ExecutionContext &rhs) const
+{
+    return !(*this == rhs);
+}
+
+
+ExecutionContextRef::ExecutionContextRef() :
+    m_target_wp (),
+    m_process_wp (),
+    m_thread_wp (),
+    m_frame_wp (),
+    m_tid(LLDB_INVALID_THREAD_ID),  
+    m_stack_id ()
+{
+}
+
+ExecutionContextRef::ExecutionContextRef (const ExecutionContext *exe_ctx) :
+    m_target_wp (),
+    m_process_wp (),
+    m_thread_wp (),
+    m_frame_wp (),
+    m_tid(LLDB_INVALID_THREAD_ID),  
+    m_stack_id ()
+{
+    if (exe_ctx)
+        *this = *exe_ctx;
+}
+
+ExecutionContextRef::ExecutionContextRef (const ExecutionContext &exe_ctx) :
+    m_target_wp (),
+    m_process_wp (),
+    m_thread_wp (),
+    m_frame_wp (),
+    m_tid(LLDB_INVALID_THREAD_ID),  
+    m_stack_id ()
+{
+    *this = exe_ctx;
+}
+
+
+ExecutionContextRef::ExecutionContextRef (Target *target, bool adopt_selected) :
+    m_target_wp(),
+    m_process_wp(),
+    m_thread_wp(),
+    m_frame_wp(),
+    m_tid(LLDB_INVALID_THREAD_ID),  
+    m_stack_id ()
+{
+    SetTargetPtr (target, adopt_selected);
+}
+
+
+
+
+ExecutionContextRef::ExecutionContextRef (const ExecutionContextRef &rhs) :
+    m_target_wp (rhs.m_target_wp),
+    m_process_wp(rhs.m_process_wp),
+    m_thread_wp (rhs.m_thread_wp),
+    m_frame_wp  (rhs.m_frame_wp),
+    m_tid       (rhs.m_tid),
+    m_stack_id  (rhs.m_stack_id)
+{
+}
+
+ExecutionContextRef &
+ExecutionContextRef::operator =(const ExecutionContextRef &rhs)
+{
+    if (this != &rhs)
+    {
+        m_target_wp  = rhs.m_target_wp;
+        m_process_wp = rhs.m_process_wp;
+        m_thread_wp  = rhs.m_thread_wp;
+        m_frame_wp   = rhs.m_frame_wp;
+        m_tid        = rhs.m_tid;
+        m_stack_id   = rhs.m_stack_id;
+    }
+    return *this;
+}
+
+ExecutionContextRef &
+ExecutionContextRef::operator =(const ExecutionContext &exe_ctx)
+{
+    m_target_wp  = exe_ctx.GetTargetSP();
+    m_process_wp = exe_ctx.GetProcessSP();
+    SetThreadSP (exe_ctx.GetThreadSP());
+    SetFrameSP (exe_ctx.GetFrameSP());
+    return *this;
+}
+
+void
+ExecutionContextRef::Clear()
+{
+    m_target_wp.reset();
+    m_process_wp.reset();
+    m_thread_wp.reset();
+    m_frame_wp.reset();
+    m_tid = LLDB_INVALID_THREAD_ID;
+    m_stack_id.Clear();
+}
+
+ExecutionContextRef::~ExecutionContextRef()
+{
+}
+
+void
+ExecutionContextRef::SetTargetSP (const lldb::TargetSP &target_sp)
+{
+    m_target_wp = target_sp;
+}
+
+void
+ExecutionContextRef::SetProcessSP (const lldb::ProcessSP &process_sp)
+{
+    m_process_wp = process_sp;
+}
+
+void
+ExecutionContextRef::SetThreadSP (const lldb::ThreadSP &thread_sp)
+{
+    m_thread_wp = thread_sp;
+    if (thread_sp)
+        m_tid = thread_sp->GetID();
+    else
+        m_tid = LLDB_INVALID_THREAD_ID;
+}
+
+void
+ExecutionContextRef::SetFrameSP (const lldb::StackFrameSP &frame_sp)
+{
+    m_frame_wp = frame_sp;
+    if (frame_sp)
+        m_stack_id = frame_sp->GetStackID();
+    else
+        m_stack_id.Clear();
+}
+
+void
+ExecutionContextRef::SetTargetPtr (Target* target, bool adopt_selected)
+{
+    Clear();
+    if (target)
+    {
+        lldb::TargetSP target_sp (target->shared_from_this());
+        if (target_sp)
+        {
+            m_target_wp = target_sp;
+            if (adopt_selected)
+            {
+                lldb::ProcessSP process_sp (target_sp->GetProcessSP());
+                if (process_sp)
+                {
+                    m_process_wp = process_sp;
+                    if (process_sp)
+                    {
+                        lldb::ThreadSP thread_sp (process_sp->GetThreadList().GetSelectedThread());
+                        if (!thread_sp)
+                            thread_sp = process_sp->GetThreadList().GetThreadAtIndex(0);
+                        
+                        if (thread_sp)
+                        {
+                            SetThreadSP (thread_sp);
+                            lldb::StackFrameSP frame_sp (thread_sp->GetSelectedFrame());
+                            if (!frame_sp)
+                                frame_sp = thread_sp->GetStackFrameAtIndex(0);
+                            if (frame_sp)
+                                SetFrameSP (frame_sp);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+void
+ExecutionContextRef::SetProcessPtr (Process *process)
+{
+    if (process)
+        m_process_wp = process->shared_from_this();
+    else
+        m_process_wp.reset();
+}
+
+void
+ExecutionContextRef::SetThreadPtr (Thread *thread)
+{
+    if (thread)
+        m_thread_wp = thread->shared_from_this();
+    else
+        m_thread_wp.reset();
+}
+
+void
+ExecutionContextRef::SetFramePtr (StackFrame *frame)
+{
+    if (frame)
+        m_frame_wp = frame->shared_from_this();
+    else
+        m_frame_wp.reset();
+}
+
+
+lldb::ThreadSP
+ExecutionContextRef::GetThreadSP () const
+{
+    lldb::ThreadSP thread_sp (m_thread_wp.lock());
+    if (!thread_sp && m_tid != LLDB_INVALID_THREAD_ID)
+    {
+        lldb::ProcessSP process_sp(GetProcessSP());
+        if (process_sp)
+        {
+            thread_sp = process_sp->GetThreadList().FindThreadByID(m_tid);
+            m_thread_wp = thread_sp;
+        }
+    }
+    return thread_sp;
+}
+
+lldb::StackFrameSP
+ExecutionContextRef::GetFrameSP () const
+{
+    lldb::StackFrameSP frame_sp (m_frame_wp.lock());
+    if (!frame_sp && m_stack_id.IsValid())
+    {
+        lldb::ThreadSP thread_sp (GetThreadSP());
+        if (thread_sp)
+        {
+            frame_sp = thread_sp->GetFrameWithStackID (m_stack_id);
+            m_frame_wp = frame_sp;
+        }
+    }
+    return frame_sp;
+}
+
+ExecutionContext
+ExecutionContextRef::Lock () const
+{
+    return ExecutionContext(this);
+}
+
+