SpinLock SpinLock SpinLock SpinLock Struct

定義

ロックが使用可能になるまで、ロックを取得しようとするスレッドがループの繰り返しチェック内で待機する相互排他ロック プリミティブを提供します。Provides a mutual exclusion lock primitive where a thread trying to acquire the lock waits in a loop repeatedly checking until the lock becomes available.

public value class SpinLock
[System.Runtime.InteropServices.ComVisible(false)]
public struct SpinLock
type SpinLock = struct
Public Structure SpinLock
継承
属性

次の例は、使用する方法を示します、 SpinLock:The following example shows how to use a SpinLock:

using System;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;


class SpinLockDemo
{


    // Demonstrates:
    //      Default SpinLock construction ()
    //      SpinLock.Enter(ref bool)
    //      SpinLock.Exit()
    static void SpinLockSample1()
    {
        SpinLock sl = new SpinLock();

        StringBuilder sb = new StringBuilder();

        // Action taken by each parallel job.
        // Append to the StringBuilder 10000 times, protecting
        // access to sb with a SpinLock.
        Action action = () =>
        {
            bool gotLock = false;
            for (int i = 0; i < 10000; i++)
            {
                gotLock = false;
                try
                {
                    sl.Enter(ref gotLock);
                    sb.Append((i % 10).ToString());
                }
                finally
                {
                    // Only give up the lock if you actually acquired it
                    if (gotLock) sl.Exit();
                }
            }
        };

        // Invoke 3 concurrent instances of the action above
        Parallel.Invoke(action, action, action);

        // Check/Show the results
        Console.WriteLine("sb.Length = {0} (should be 30000)", sb.Length);
        Console.WriteLine("number of occurrences of '5' in sb: {0} (should be 3000)",
            sb.ToString().Where(c => (c == '5')).Count());
    }

    // Demonstrates:
    //      Default SpinLock constructor (tracking thread owner)
    //      SpinLock.Enter(ref bool)
    //      SpinLock.Exit() throwing exception
    //      SpinLock.IsHeld
    //      SpinLock.IsHeldByCurrentThread
    //      SpinLock.IsThreadOwnerTrackingEnabled
    static void SpinLockSample2()
    {
        // Instantiate a SpinLock
        SpinLock sl = new SpinLock();

        // These MRESs help to sequence the two jobs below
        ManualResetEventSlim mre1 = new ManualResetEventSlim(false);
        ManualResetEventSlim mre2 = new ManualResetEventSlim(false);
        bool lockTaken = false;

        Task taskA = Task.Factory.StartNew(() =>
        {
            try
            {
                sl.Enter(ref lockTaken);
                Console.WriteLine("Task A: entered SpinLock");
                mre1.Set(); // Signal Task B to commence with its logic

                // Wait for Task B to complete its logic
                // (Normally, you would not want to perform such a potentially
                // heavyweight operation while holding a SpinLock, but we do it
                // here to more effectively show off SpinLock properties in
                // taskB.)
                mre2.Wait();
            }
            finally
            {
                if (lockTaken) sl.Exit();
            }
        });

        Task taskB = Task.Factory.StartNew(() =>
        {
            mre1.Wait(); // wait for Task A to signal me
            Console.WriteLine("Task B: sl.IsHeld = {0} (should be true)", sl.IsHeld);
            Console.WriteLine("Task B: sl.IsHeldByCurrentThread = {0} (should be false)", sl.IsHeldByCurrentThread);
            Console.WriteLine("Task B: sl.IsThreadOwnerTrackingEnabled = {0} (should be true)", sl.IsThreadOwnerTrackingEnabled);

            try
            {
                sl.Exit();
                Console.WriteLine("Task B: Released sl, should not have been able to!");
            }
            catch (Exception e)
            {
                Console.WriteLine("Task B: sl.Exit resulted in exception, as expected: {0}", e.Message);
            }

            mre2.Set(); // Signal Task A to exit the SpinLock
        });

        // Wait for task completion and clean up
        Task.WaitAll(taskA, taskB);
        mre1.Dispose();
        mre2.Dispose();
    }

    // Demonstrates:
    //      SpinLock constructor(false) -- thread ownership not tracked
    static void SpinLockSample3()
    {
        // Create SpinLock that does not track ownership/threadIDs
        SpinLock sl = new SpinLock(false);

        // Used to synchronize with the Task below
        ManualResetEventSlim mres = new ManualResetEventSlim(false);

        // We will verify that the Task below runs on a separate thread
        Console.WriteLine("main thread id = {0}", Thread.CurrentThread.ManagedThreadId);

        // Now enter the SpinLock.  Ordinarily, you would not want to spend so
        // much time holding a SpinLock, but we do it here for the purpose of 
        // demonstrating that a non-ownership-tracking SpinLock can be exited 
        // by a different thread than that which was used to enter it.
        bool lockTaken = false;
        sl.Enter(ref lockTaken);

        // Create a separate Task from which to Exit() the SpinLock
        Task worker = Task.Factory.StartNew(() =>
        {
            Console.WriteLine("worker task thread id = {0} (should be different than main thread id)",
                Thread.CurrentThread.ManagedThreadId);

            // Now exit the SpinLock
            try
            {
                sl.Exit();
                Console.WriteLine("worker task: successfully exited SpinLock, as expected");
            }
            catch (Exception e)
            {
                Console.WriteLine("worker task: unexpected failure in exiting SpinLock: {0}", e.Message);
            }

            // Notify main thread to continue
            mres.Set();
        });

        // Do this instead of worker.Wait(), because worker.Wait() could inline the worker Task,
        // causing it to be run on the same thread.  The purpose of this example is to show that
        // a different thread can exit the SpinLock created (without thread tracking) on your thread.
        mres.Wait();

        // now Wait() on worker and clean up
        worker.Wait();
        mres.Dispose();
    }

}
Imports System.Text
Imports System.Threading
Imports System.Threading.Tasks


Module SpinLockDemo

    ' Demonstrates:
    ' Default SpinLock construction ()
    ' SpinLock.Enter(ref bool)
    ' SpinLock.Exit()
    Private Sub SpinLockSample1()
        Dim sl As New SpinLock()

        Dim sb As New StringBuilder()

        ' Action taken by each parallel job.
        ' Append to the StringBuilder 10000 times, protecting
        ' access to sb with a SpinLock.
        Dim action As Action =
            Sub()
                Dim gotLock As Boolean = False
                For i As Integer = 0 To 9999
                    gotLock = False
                    Try
                        sl.Enter(gotLock)
                        sb.Append((i Mod 10).ToString())
                    Finally
                        ' Only give up the lock if you actually acquired it
                        If gotLock Then
                            sl.[Exit]()
                        End If
                    End Try
                Next
            End Sub

        ' Invoke 3 concurrent instances of the action above
        Parallel.Invoke(action, action, action)

        ' Check/Show the results
        Console.WriteLine("sb.Length = {0} (should be 30000)", sb.Length)
        Console.WriteLine("number of occurrences of '5' in sb: {0} (should be 3000)", sb.ToString().Where(Function(c) (c = "5"c)).Count())
    End Sub

    ' Demonstrates:
    ' Default SpinLock constructor (tracking thread owner)
    ' SpinLock.Enter(ref bool)
    ' SpinLock.Exit() throwing exception
    ' SpinLock.IsHeld
    ' SpinLock.IsHeldByCurrentThread
    ' SpinLock.IsThreadOwnerTrackingEnabled
    Private Sub SpinLockSample2()
        ' Instantiate a SpinLock
        Dim sl As New SpinLock()

        ' These MRESs help to sequence the two jobs below
        Dim mre1 As New ManualResetEventSlim(False)
        Dim mre2 As New ManualResetEventSlim(False)
        Dim lockTaken As Boolean = False

        Dim taskA As Task = Task.Factory.StartNew(
            Sub()
                Try
                    sl.Enter(lockTaken)
                    Console.WriteLine("Task A: entered SpinLock")
                    mre1.[Set]()
                    ' Signal Task B to commence with its logic
                    ' Wait for Task B to complete its logic
                    ' (Normally, you would not want to perform such a potentially
                    ' heavyweight operation while holding a SpinLock, but we do it
                    ' here to more effectively show off SpinLock properties in
                    ' taskB.)
                    mre2.Wait()
                Finally
                    If lockTaken Then
                        sl.[Exit]()
                    End If
                End Try
            End Sub)

        Dim taskB As Task = Task.Factory.StartNew(
            Sub()
                mre1.Wait()
                ' wait for Task A to signal me
                Console.WriteLine("Task B: sl.IsHeld = {0} (should be true)", sl.IsHeld)
                Console.WriteLine("Task B: sl.IsHeldByCurrentThread = {0} (should be false)", sl.IsHeldByCurrentThread)
                Console.WriteLine("Task B: sl.IsThreadOwnerTrackingEnabled = {0} (should be true)", sl.IsThreadOwnerTrackingEnabled)

                Try
                    sl.[Exit]()
                    Console.WriteLine("Task B: Released sl, should not have been able to!")
                Catch e As Exception
                    Console.WriteLine("Task B: sl.Exit resulted in exception, as expected: {0}", e.Message)
                End Try

                ' Signal Task A to exit the SpinLock
                mre2.[Set]()
            End Sub)

        ' Wait for task completion and clean up
        Task.WaitAll(taskA, taskB)
        mre1.Dispose()
        mre2.Dispose()
    End Sub

    ' Demonstrates:
    ' SpinLock constructor(false) -- thread ownership not tracked
    Private Sub SpinLockSample3()
        ' Create SpinLock that does not track ownership/threadIDs
        Dim sl As New SpinLock(False)

        ' Used to synchronize with the Task below
        Dim mres As New ManualResetEventSlim(False)

        ' We will verify that the Task below runs on a separate thread
        Console.WriteLine("main thread id = {0}", Thread.CurrentThread.ManagedThreadId)

        ' Now enter the SpinLock.  Ordinarily, you would not want to spend so
        ' much time holding a SpinLock, but we do it here for the purpose of 
        ' demonstrating that a non-ownership-tracking SpinLock can be exited 
        ' by a different thread than that which was used to enter it.
        Dim lockTaken As Boolean = False
        sl.Enter(lockTaken)

        ' Create a separate Task
        Dim worker As Task = Task.Factory.StartNew(
            Sub()
                Console.WriteLine("worker task thread id = {0} (should be different than main thread id)", Thread.CurrentThread.ManagedThreadId)

                ' Now exit the SpinLock
                Try
                    sl.[Exit]()
                    Console.WriteLine("worker task: successfully exited SpinLock, as expected")
                Catch e As Exception
                    Console.WriteLine("worker task: unexpected failure in exiting SpinLock: {0}", e.Message)
                End Try

                ' Notify main thread to continue
                mres.[Set]()
            End Sub)

        ' Do this instead of worker.Wait(), because worker.Wait() could inline the worker Task,
        ' causing it to be run on the same thread. The purpose of this example is to show that
        ' a different thread can exit the SpinLock created (without thread tracking) on your thread.
        mres.Wait()

        ' now Wait() on worker and clean up
        worker.Wait()
        mres.Dispose()
    End Sub


End Module

注釈

スピン ロックを使用する方法の例は、次を参照してください。方法。低レベルの同期に SpinLock を使用してします。For an example of how to use a Spin Lock, see How to: Use SpinLock for Low-Level Synchronization.

スピン ロック使用できるリーフ レベルのロックを使用してオブジェクトの割り当てが含まれる、Monitorサイズ、またはガベージ コレクションの不足のためコストが過度にします。Spin locks can be used for leaf-level locks where the object allocation implied by using a Monitor, in size or due to garbage collection pressure, is overly expensive. スピン ロックが; がブロックされないようにできます。ただし、大量のブロックしている場合は、過剰なスピンのためのスピン ロック使用していない可能性があります。A spin lock can be useful to avoid blocking; however, if you expect a significant amount of blocking, you should probably not use spin locks due to excessive spinning. 回転は、ロックが細かいと (たとえば、リンク リスト内のノードごとのロック) の数が多い場合、ロックの保持時間は常に非常に短いパフォーマンスを向上できます。Spinning can be beneficial when locks are fine-grained and large in number (for example, a lock per node in a linked list) and also when lock hold-times are always extremely short. 一般に、スピン ロックを保持しているときに 1 つ避ける必要があります、これらの操作。In general, while holding a spin lock, one should avoid any of these actions:

  • ブロックします。blocking,

  • 何かの呼び出しを妨げる可能性があります、calling anything that itself may block,

  • 一度に 1 つ以上のスピン ロックを保持しています。holding more than one spin lock at once,

  • 動的にディスパッチされる (インターフェイスと仮想メソッド) の呼び出しmaking dynamically dispatched calls (interface and virtuals),

  • 1 つ所有していない、すべてのコードに呼び出しをディスパッチする静的に行うか、making statically dispatched calls into any code one doesn't own, or

  • メモリを割り当てています。allocating memory.

SpinLock 行うのため、アプリケーション パフォーマンスが向上の決定された後にのみ使用される必要があります。SpinLock should only be used after you have been determined that doing so will improve an application's performance. 重要な点もSpinLockパフォーマンス上の理由から、値型であります。It is also important to note that SpinLock is a value type, for performance reasons. このために誤ってコピーしないは十分に注意する必要がある、SpinLockインスタンス、2 つのインスタンス (元およびコピー) の場合し、別の完全に独立して、アプリケーションのエラー動作につながる可能性があります。For this reason, you must be very careful not to accidentally copy a SpinLock instance, as the two instances (the original and the copy) would then be completely independent of one another, which would likely lead to erroneous behavior of the application. 場合、SpinLockインスタンスが渡される必要があります、値ではなく、参照渡しで渡す必要があります。If a SpinLock instance must be passed around, it should be passed by reference rather than by value.

保存しないSpinLock読み取り専用フィールド内のインスタンス。Do not store SpinLock instances in readonly fields.

コンストラクター

SpinLock(Boolean) SpinLock(Boolean) SpinLock(Boolean) SpinLock(Boolean)

デバッグを向上させるためにスレッド ID を追跡するオプションを使用して、SpinLock 構造体の新しいインスタンスを初期化します。Initializes a new instance of the SpinLock structure with the option to track thread IDs to improve debugging.

プロパティ

IsHeld IsHeld IsHeld IsHeld

ロックが現在いずれかのスレッドによって保持されているかどうかを取得します。Gets whether the lock is currently held by any thread.

IsHeldByCurrentThread IsHeldByCurrentThread IsHeldByCurrentThread IsHeldByCurrentThread

ロックが現在のスレッドによって保持されているかどうかを取得します。Gets whether the lock is held by the current thread.

IsThreadOwnerTrackingEnabled IsThreadOwnerTrackingEnabled IsThreadOwnerTrackingEnabled IsThreadOwnerTrackingEnabled

このインスタンスに対してスレッド所有権の追跡が有効になっているかどうかを取得します。Gets whether thread ownership tracking is enabled for this instance.

メソッド

Enter(Boolean) Enter(Boolean) Enter(Boolean) Enter(Boolean)

メソッド呼び出し内で例外が発生した場合でも、lockTaken を確実に確認して、ロックが取得されたかどうかを判断できるような信頼性の高い方法で、ロックを取得します。Acquires the lock in a reliable manner, such that even if an exception occurs within the method call, lockTaken can be examined reliably to determine whether the lock was acquired.

Exit() Exit() Exit() Exit()

ロックを解放します。Releases the lock.

Exit(Boolean) Exit(Boolean) Exit(Boolean) Exit(Boolean)

ロックを解放します。Releases the lock.

TryEnter(Boolean) TryEnter(Boolean) TryEnter(Boolean) TryEnter(Boolean)

メソッド呼び出し内で例外が発生した場合でも、lockTaken を確実に確認して、ロックが取得されたかどうかを判断できるような信頼性の高い方法で、ロックの取得を試みます。Attempts to acquire the lock in a reliable manner, such that even if an exception occurs within the method call, lockTaken can be examined reliably to determine whether the lock was acquired.

TryEnter(Int32, Boolean) TryEnter(Int32, Boolean) TryEnter(Int32, Boolean) TryEnter(Int32, Boolean)

メソッド呼び出し内で例外が発生した場合でも、lockTaken を確実に確認して、ロックが取得されたかどうかを判断できるような信頼性の高い方法で、ロックの取得を試みます。Attempts to acquire the lock in a reliable manner, such that even if an exception occurs within the method call, lockTaken can be examined reliably to determine whether the lock was acquired.

TryEnter(TimeSpan, Boolean) TryEnter(TimeSpan, Boolean) TryEnter(TimeSpan, Boolean) TryEnter(TimeSpan, Boolean)

メソッド呼び出し内で例外が発生した場合でも、lockTaken を確実に確認して、ロックが取得されたかどうかを判断できるような信頼性の高い方法で、ロックの取得を試みます。Attempts to acquire the lock in a reliable manner, such that even if an exception occurs within the method call, lockTaken can be examined reliably to determine whether the lock was acquired.

適用対象

スレッド セーフ

すべてのメンバーSpinLockはスレッド セーフであると同時に複数のスレッドから使用できます。All members of SpinLock are thread-safe and may be used from multiple threads concurrently.

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