static void Main(string[] args)
{
var tasks = new List <Task>();
var ba = new BankAccount();
for (int i = 0; i < 10; ++i)
{
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
ba.Deposit(100);
}
}));
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
ba.Withdraw(100);
}
}));
}
Task.WaitAll(tasks.ToArray());
Console.WriteLine($"Final balance is {ba.Balance}.");
// show interlocked methods here
// Interlocked.MemoryBarrier is a wrapper for Thread.MemoryBarrier
// only required on memory systems that have weak memory ordering (e.g., Itanium)
// prevents the CPU from reordering the instructions such that those before the barrier
// execute after those after
Console.WriteLine("All done here.");
}
public static void LocalMutex()
{
var tasks = new List <Task>();
var ba = new BankAccount(0);
var ba2 = new BankAccount(0);
// many synchro types deriving from WaitHandle
// Mutex = mutual exclusion
// two types of mutexes
// this is a _local_ mutex
Mutex mutex = new Mutex();
Mutex mutex2 = new Mutex();
for (int i = 0; i < 10; ++i)
{
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
bool haveLock = mutex.WaitOne();
try
{
ba.Deposit(1); // deposit 10000 overall
}
finally
{
if (haveLock)
{
mutex.ReleaseMutex();
}
}
}
}));
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
bool haveLock = mutex2.WaitOne();
try
{
ba2.Deposit(1); // deposit 10000
}
finally
{
if (haveLock)
{
mutex2.ReleaseMutex();
}
}
}
}));
// transfer needs to lock both accounts
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; j++)
{
bool haveLock = Mutex.WaitAll(new[] { mutex, mutex2 });
try
{
ba.Transfer(ba2, 1); // transfer 10k from ba to ba2
}
finally
{
if (haveLock)
{
mutex.ReleaseMutex();
mutex2.ReleaseMutex();
}
}
}
}));
}
Task.WaitAll(tasks.ToArray());
Console.WriteLine($"Final balance is: ba={ba.Balance}, ba2={ba2.Balance}.");
}
public static void SpinLockDemo()
{
var tasks = new List <Task>();
var ba = new BankAccount();
// spinning avoid overhead of resheduling
// useful if you expect the wait time to be very short
SpinLock sl = new SpinLock();
// owner tracking keeps a record of which thread acquired it to improve debugging
for (int i = 0; i < 10; ++i)
{
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
bool lockTaken = false;
try
{
// sl.IsHeld
// sl.IsHeldByCurrentThread
sl.Enter(ref lockTaken);
ba.Deposit(100);
}
finally
{
if (lockTaken)
{
sl.Exit();
}
}
}
}));
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
bool lockTaken = false;
try
{
sl.Enter(ref lockTaken);
ba.Withdraw(100);
}
finally
{
if (lockTaken)
{
sl.Exit();
}
}
}
}));
}
Task.WaitAll(tasks.ToArray());
Console.WriteLine($"Final balance is {ba.Balance}.");
}
