llvm-project/lldb/tools/lldb-mi/MIUtilThreadBaseStd.cpp

//===-- MIUtilThreadBaseStd.cpp ---------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

//++
// File:		MIUtilThreadBaseStd.cpp
//
// Overview:	CMIUtilThread implementation.
//				CMIUtilThreadActiveObjBase implementation.
//				CMIUtilThreadMutex implementation.
//
// Environment:	Compilers:	Visual C++ 12.
//							gcc (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1
//				Libraries:	See MIReadmetxt. 
//
// Copyright:	None.
//--

// Third Party Headers:
#include <assert.h>

// In-house headers:
#include "MIUtilThreadBaseStd.h"
#include "MICmnThreadMgrStd.h"

//++ ------------------------------------------------------------------------------------
// Details:	Constructor.
// Type:	None.
// Args:	None.
// Return:	None.
// Throws:	None.
//--
CMIUtilThreadActiveObjBase::CMIUtilThreadActiveObjBase( void )
:	m_references( 0 )
,	m_bHasBeenKilled( false )
{
}

//++ ------------------------------------------------------------------------------------
// Details:	Destructor.
// Type:	None.
// Args:	None.
// Return:	None.
// Throws:	None.
//--
CMIUtilThreadActiveObjBase::~CMIUtilThreadActiveObjBase( void )
{
	// Make sure our thread is not alive before we die
	m_thread.Join();
}

//++ ------------------------------------------------------------------------------------
// Details:	Check if an object is already running.
// Type:	Method.
// Args:	None.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThreadActiveObjBase::ThreadIsActive( void )
{
	// Create a new thread to occupy this threads Run() function
	return m_thread.IsActive();
}

//++ ------------------------------------------------------------------------------------
// Details:	Set up *this thread.
// Type:	Mrthod.
// Args:	None.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThreadActiveObjBase::ThreadExecute( void )
{
	// Create a new thread to occupy this threads Run() function
	return m_thread.Start( ThreadEntry, this );
}

//++ ------------------------------------------------------------------------------------
// Details:	Aquire a reference to CMIUtilThreadActiveObjBase.
// Type:	Method.
// Args:	None.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThreadActiveObjBase::Acquire( void )
{
	// Access to this function is serial
	CMIUtilThreadLock serial( m_mutex );

	// >0 == *this thread is alive
	m_references++;

	return MIstatus::success;
}

//++ ------------------------------------------------------------------------------------
// Details:	Release a reference to CMIUtilThreadActiveObjBase.
// Type:	Method.
// Args:	None.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThreadActiveObjBase::Release( void )
{
	// Access to this function is serial
	CMIUtilThreadLock serial( m_mutex );
		
	// 0 == kill off *this thread
	m_references--;

	return MIstatus::success;
}

//++ ------------------------------------------------------------------------------------
// Details:	Force this thread to stop, regardless of references
// Type:	Method.
// Args:	None.			
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThreadActiveObjBase::ThreadKill( void )
{
	// Access to this function is serial
	CMIUtilThreadLock serial( m_mutex );

	// Set this thread to killed status
	m_bHasBeenKilled = true;

	return MIstatus::success;
}

//++ ------------------------------------------------------------------------------------
// Details: Proxy to thread join.
// Type:	Method.
// Args:	None.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThreadActiveObjBase::ThreadJoin( void )
{
	return m_thread.Join();
}

//++ ------------------------------------------------------------------------------------
// Details:	This function is the entry point of this object thread.
//			It is a trampoline to an instances operation manager.
// Type:	Static method.
// Args:	vpThisClass	- (R) From the system (our CMIUtilThreadActiveObjBase from the ctor).
// Return:	MIuint - 0 = success.
// Throws:	None.
//--
MIuint CMIUtilThreadActiveObjBase::ThreadEntry( void * vpThisClass )
{
	// The argument is a pointer to a CMIUtilThreadActiveObjBase class
	// as passed from the initialize function, so we can safely cast it.
	assert( vpThisClass != nullptr );
	CMIUtilThreadActiveObjBase * pActive = reinterpret_cast< CMIUtilThreadActiveObjBase * >( vpThisClass );

	// Start the management routine of this object
	pActive->ThreadManage();

	// Thread death
    return 0;
}

//++ ------------------------------------------------------------------------------------
// Details:	This function forms a small management routine, to handle the thread's running.
// Type:	Method.
// Args:	None.
// Return:	None.
// Throws:	None.
//--
void CMIUtilThreadActiveObjBase::ThreadManage( void )
{
	bool bAlive = true;

	// Infinite loop
	while( bAlive )
	{
		// Scope the lock while we access m_isDying
		{
			// Lock down access to the interface
			CMIUtilThreadLock serial( m_mutex );

			// Quit the run loop if we are dying
			if( m_references == 0 )
				break;
		}
		// Execute the run routine
		if( !ThreadRun( bAlive ) )
			// Thread's run function failed (MIstatus::failure)
			break;

		// We will die if we have been signaled to die
		bAlive &= !m_bHasBeenKilled;
	}

	// Execute the finish routine just before we die
	// to give the object a chance to clean up
	ThreadFinish();
}

//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------

// 
CMIUtilThread::CMIUtilThread( void )
:	m_pThread( nullptr )
{
}

//++ ------------------------------------------------------------------------------------
// Details:	CMIUtilThread destructor.
// Type:	Method.
// Args:	None.
// Return:	None.
// Throws:	None.
//--
CMIUtilThread::~CMIUtilThread( void )
{
	Join();
}

//++ ------------------------------------------------------------------------------------
// Details:	Wait for thread to stop.
// Type:	Method.
// Args:	None.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThread::Join( void )
{
	if( m_pThread != nullptr )
	{
		// Wait for this thread to die
		m_pThread->join();
		
		// Scope the thread lock while we modify the pointer
		{
			CMIUtilThreadLock _lock( m_mutex );
			delete m_pThread;
			m_pThread = nullptr;
		}
	}

	return MIstatus::success;
}

//++ ------------------------------------------------------------------------------------
// Details:	Is the thread doing work.
// Type:	Method.
// Args:	None.
// Return:	bool - True = Yes active, false = not active.
// Throws:	None.
//--
bool CMIUtilThread::IsActive( void )
{
	// Lock while we access the thread pointer
	CMIUtilThreadLock _lock( m_mutex );
	if( m_pThread == nullptr )
		return false;
	else
		return true;
}

//++ ------------------------------------------------------------------------------------
// Details:	Set up *this thread.
// Type:	Method.
// Args:	vpFn	(R)	- Function pointer to thread's main function.
//			vpArg	(R) - Pointer arguments to pass to the thread.
// Return:	MIstatus::success - Functional succeeded.
//			MIstatus::failure - Functional failed.
// Throws:	None.
//--
bool CMIUtilThread::Start( FnThreadProc vpFn, void * vpArg )
{
	// Create the std thread, which starts immediately
	m_pThread = new std::thread( vpFn, vpArg );
	
	// We expect to always be able to create one
	assert( m_pThread != nullptr );
	
	return MIstatus::success;
}

//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------

//++ ------------------------------------------------------------------------------------
// Details:	Take resource.
// Type:	Method.
// Args:	None.
// Return:	None.
// Throws:	None.
//--
void CMIUtilThreadMutex::Lock( void )
{
	m_mutex.lock();
}
 
//++ ------------------------------------------------------------------------------------
// Details:	Release resource.
// Type:	Method.
// Args:	None.
// Return:	None.
// Throws:	None.
//--
void CMIUtilThreadMutex::Unlock( void )
{
	m_mutex.unlock();
}

//++ ------------------------------------------------------------------------------------
// Details:	Take resource if available. Immediately return in either case.
// Type:	Method.
// Args:	None.
// Return:	True	- mutex has been locked. 
//			False	- mutex could not be locked.
// Throws:	None.
//--
bool CMIUtilThreadMutex::TryLock( void )
{
	return m_mutex.try_lock();
}