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ns3::SystemThread Class Reference

A class which provides a relatively platform-independent thread primitive. More...

#include <system-thread.h>

+ Inheritance diagram for ns3::SystemThread:

Public Member Functions

 SystemThread (Callback< void > callback)
 Create a SystemThread object. More...
 ~SystemThread ()
 Destroy a SystemThread object.
void Join (void)
 Suspend the caller until the thread of execution, running the provided callback, finishes.
void Start (void)
 Start a thread of execution, running the provided callback.
- Public Member Functions inherited from ns3::SimpleRefCount< SystemThread >
 SimpleRefCount (const SimpleRefCount &o)
uint32_t GetReferenceCount (void) const
SimpleRefCountoperator= (const SimpleRefCount &o)
void Ref (void) const
void Unref (void) const

Static Public Member Functions

static bool Equals (ThreadId id)
 Compares an TharedId with the current ThreadId . More...
static ThreadId Self (void)
 Returns the current thread Id. More...
- Static Public Member Functions inherited from ns3::SimpleRefCount< SystemThread >
static void Cleanup (void)

Detailed Description

A class which provides a relatively platform-independent thread primitive.

This class allows for creation of multiple threads of execution in a process. The exact implementation of the thread functionality is operating system dependent, but typically in ns-3 one is using an environment in which Posix Threads are supported (either navively or in the case of Windows via Cygwin's implementation of pthreads on the Win32 API. In either case we expect that these will be kernel-level threads and therefore a system with multiple CPUs will see truly concurrent execution.

Synchronization between threads is provided via the SystemMutex class.

Definition at line 47 of file system-thread.h.

Constructor & Destructor Documentation

ns3::SystemThread::SystemThread ( Callback< void >  callback)

Create a SystemThread object.

A system thread object is not created running. A thread of execution must be explicitly started by calling the Start method. When the Start method is called, it will spawn a thread of execution and cause that thread to call out into the callback function provided here as a parameter.

Like all ns-3 callbacks, the provided callback may refer to a function or a method of an object depending on how the MakeCallback function is used.

The most common use is expected to be creating a thread of execution in a method. In this case you would use code similar to,

MyClass myObject; Ptr<SystemThread> st = Create<SystemThread> ( MakeCallback (&MyClass::MyMethod, &myObject)); st->Start ();

The SystemThread is passed a callback that calls out to the function MyClass::MyMethod. When this function is called, it is called as an object method on the myObject object. Essentially what you are doing is asking the SystemThread to call object->MyMethod () in a new thread of execution.

If starting a thread in your currently executing object, you can use the "this" pointer:

Ptr<SystemThread> st = Create<SystemThread> ( MakeCallback (&MyClass::MyMethod, this)); st->Start ();

Object lifetime is always an issue with threads, so it is common to use smart pointers. If you are spinning up a thread in an object that is managed by a smart pointer, you can use that pointer directly:

Ptr<MyClass> myPtr = Create<MyClass> (); Ptr<SystemThread> st = Create<SystemThread> ( MakeCallback (&MyClass::MyMethod, myPtr)); st->Start ();

Just like any thread, you can synchronize with its termination. The method provided to do this is Join (). If you call Join() you will block until the SystemThread run method returns.

callbackentry point of the thread
I've made the system thread class look like a normal ns3 object with smart pointers, and living in the heap. This makes it very easy to manage threads from a single master thread context. You should be very aware though that I have not made Ptr multithread safe! This means that if you pass Ptr<SystemThread> around in a multithreaded environment, it is possible that the reference count will get messed up since it is not an atomic operation. CREATE AND MANAGE YOUR THREADS IN ONE PLACE – LEAVE THE PTR THERE.

Member Function Documentation

static bool ns3::SystemThread::Equals ( ThreadId  id)
static ThreadId ns3::SystemThread::Self ( void  )

Returns the current thread Id.

current thread Id.

Referenced by ns3::DefaultSimulatorImpl::Run(), and ns3::RealtimeSimulatorImpl::Run().

The documentation for this class was generated from the following file: