// Copyright © 2020 The CefSharp Authors. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
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//
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using System;
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using System.Text;
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using System.Threading;
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namespace CefSharp.Internals
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{
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/// <summary>
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/// Tracks the number of browser instances currently open
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/// The cound will be incrmented and decremented each time a CefBrowser is created/closed.
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/// This includes CefBrowser popup instances.
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/// </summary>
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/// <remarks>
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/// Roughtly based on <see cref="CountdownEvent"/>, unforeunately <see cref="CountdownEvent.AddCount(int)"/>
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/// doesn't reset the internal <see cref="ManualResetEventSlim"/> when Count is aleady 0.
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/// In our case it's valid to increase the number of browsers and reset the event.
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/// </remarks>
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public sealed class BrowserRefCounter : IBrowserRefCounter
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{
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private volatile int count = 0;
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private ManualResetEventSlim manualResetEvent = new ManualResetEventSlim();
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private bool loggingEnabled = false;
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private StringBuilder logger = new StringBuilder();
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/// TODO: Refactor this so it's not static.
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public static IBrowserRefCounter Instance = new NoOpBrowserRefCounter();
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/// <summary>
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/// If logging is enabled the <paramref name="line"/> will be appended to
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/// the internal log.
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/// </summary>
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/// <param name="line">text to append to log if logging enabled.</param>
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public void AppendLineToLog(string line)
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{
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if(loggingEnabled)
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{
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logger.AppendLine(line);
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}
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}
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/// <inheritdoc/>
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void IBrowserRefCounter.Increment(Type type)
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{
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var newCount = Interlocked.Increment(ref count);
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if (newCount > 0)
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{
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manualResetEvent.Reset();
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AppendLineToLog($"{type} - Incremented (ManualResetEvent was reset)");
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}
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else if(loggingEnabled)
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{
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logger.AppendLine($"New Count <= 0 - {newCount} ");
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}
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}
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/// <inheritdoc/>
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bool IBrowserRefCounter.Decrement(Type type)
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{
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var newCount = Interlocked.Decrement(ref count);
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AppendLineToLog($"{type} - Decremented (Current Count {newCount})");
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if (newCount == 0)
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{
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manualResetEvent.Set();
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return true;
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}
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if (newCount < 0)
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{
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AppendLineToLog($"{type} - Decremented (Less than 0 : Current Count {newCount})");
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//If we went below 0 then reset to 0
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// TODO: something went wrong with our tracking
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Interlocked.Exchange(ref count, 0);
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manualResetEvent.Set();
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}
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return false;
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}
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/// <inheritdoc/>
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int IBrowserRefCounter.Count
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{
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get
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{
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int observedCount = count;
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return observedCount < 0 ? 0 : observedCount;
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}
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}
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/// <inheritdoc/>
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void IBrowserRefCounter.WaitForBrowsersToClose(int timeoutInMiliseconds)
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{
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AppendLineToLog($"WaitForBrowsersToClose - Current Count {count}");
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if (!manualResetEvent.IsSet)
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{
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manualResetEvent.Wait(timeoutInMiliseconds);
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}
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AppendLineToLog($"WaitForBrowsersToClose - Updated Count {count}");
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}
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/// <inheritdoc/>
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void IBrowserRefCounter.WaitForBrowsersToClose(int timeoutInMiliseconds, CancellationToken cancellationToken)
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{
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AppendLineToLog($"WaitForBrowsersToClose - Current Count {count}");
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if (!manualResetEvent.IsSet)
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{
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manualResetEvent.Wait(timeoutInMiliseconds, cancellationToken);
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}
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AppendLineToLog($"WaitForBrowsersToClose - Updated Count {count}");
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}
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/// <inheritdoc/>
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void IBrowserRefCounter.EnableLogging()
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{
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loggingEnabled = true;
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}
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/// <inheritdoc/>
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string IBrowserRefCounter.GetLog()
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{
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return logger.ToString();
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}
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public void Dispose()
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{
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manualResetEvent.Dispose();
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}
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}
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}
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