29 lines
1.1 KiB
C#
29 lines
1.1 KiB
C#
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using System.Threading;
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namespace Pathfinding.Jobs {
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/// <summary>
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/// Spin lock which can be used in Burst.
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/// Good when the lock is generally uncontested.
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/// Very inefficient when the lock is contested.
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/// </summary>
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public struct SpinLock {
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private volatile int locked;
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public void Lock () {
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while (Interlocked.CompareExchange(ref locked, 1, 0) != 0)
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Unity.Burst.Intrinsics.Common.Pause(); // spin
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// We need to ensure that any optimizer does not reorder loads to before we aquire the lock.
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System.Threading.Thread.MemoryBarrier();
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}
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public void Unlock () {
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// We need a memory barrier to ensure that all writes are visible to other threads, before we unlock.
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// We also need to ensure that any optimizer does not reorder stores to after the unlock.
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System.Threading.Thread.MemoryBarrier();
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// Release the lock by writing 0 to it. Use atomics to make it immediately visible to other threads.
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if (Interlocked.Exchange(ref locked, 0) == 0) throw new System.InvalidOperationException("Trying to unlock a lock which is not locked");
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}
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}
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}
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