public static void Spin_Locking()
{
var tasks = new List <Task>();
var ba = new BankAccountV3(0);
SpinLock sl = new SpinLock();
for (int i = 0; i < 10; i++)
{
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; j++)
{
// previous examples assumed that lock was always possible to take
var lockTaken = false;
try
{
sl.Enter(ref lockTaken);
ba.Deposit(100);
}
finally
{
if (lockTaken)
{
sl.Exit();
}
}
}
}));
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; j++)
{
var lockTaken = false;
try
{
sl.Enter(ref lockTaken);
ba.Withdraw(100);
}
finally
{
if (lockTaken)
{
sl.Exit();
}
}
}
}));
}
Task.WaitAll(tasks.ToArray());
Console.WriteLine($"Final balance is {ba.Balance}");
Console.ReadKey();
}
public void Transfer(BankAccountV3 where, int amount)
{
where.Balance += amount;
Balance -= amount;
}
public static void Local_Mutex()
{
var tasks = new List <Task>();
var ba = new BankAccountV3(0);
var ba2 = new BankAccountV3(0);
// many synchro types deriving from WaitHandle
// Mutex = mutual exclusion
// two types of mutexes
// this is a _local_ mutex
Mutex mutex = new Mutex();
Mutex mutex2 = new Mutex();
for (int i = 0; i < 10; ++i)
{
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
bool haveLock = mutex.WaitOne();
try
{
ba.Deposit(1); // deposit 10000 overall
}
finally
{
if (haveLock)
{
mutex.ReleaseMutex();
}
}
}
}));
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; ++j)
{
bool haveLock = mutex2.WaitOne();
try
{
ba2.Deposit(1); // deposit 10000
}
finally
{
if (haveLock)
{
mutex2.ReleaseMutex();
}
}
}
}));
// transfer needs to lock both accounts
tasks.Add(Task.Factory.StartNew(() =>
{
for (int j = 0; j < 1000; j++)
{
bool haveLock = Mutex.WaitAll(new[] { mutex, mutex2 });
try
{
ba.Transfer(ba2, 1); // transfer 10k from ba to ba2
}
finally
{
if (haveLock)
{
mutex.ReleaseMutex();
mutex2.ReleaseMutex();
}
}
}
}));
}
Task.WaitAll(tasks.ToArray());
Console.WriteLine($"Final balance is: ba={ba.Balance}, ba2={ba2.Balance}.");
}
