org.sonar.plugins.csharp.S2222.html Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of sonar-csharp-plugin Show documentation

Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
To prevent potential deadlocks in an application, it is crucial to release any locks that are
acquired within a method along all possible execution paths.
Failing to release locks properly can lead to potential deadlocks, where the lock might not be released, causing issues in the application.
This rule specifically focuses on tracking the following types from the System.Threading namespace:

   Monitor 
   Mutex 
   ReaderWriterLock 
   ReaderWriterLockSlim 
   SpinLock  

An issue is reported when a lock is acquired within a method but not released on all paths.
Exceptions
If the lock is never released within the method, no issue is raised, assuming that the callers will handle the release.
How to fix it
To make sure that a lock is always released correctly, you can follow one of these two methods:

   Use a lock statement with your
  lock object. 
   Use a try-finally statement and put the release of your lock object within the finally block. 

Code examples
Noncompliant code example
class MyClass
{
  private object obj = new object();

  public void DoSomethingWithMonitor()
  {
    Monitor.Enter(obj); // Noncompliant: not all paths release the lock
    if (IsInitialized())
    {
      // ...
      Monitor.Exit(obj);
    }
  }
}

class MyClass
{
  private ReaderWriterLockSlim lockObj = new ReaderWriterLockSlim();

  public void DoSomethingWithReaderWriteLockSlim()
  {
    lockObj.EnterReadLock(); // Noncompliant: not all paths release the lock
    if (IsInitialized())
    {
      // ...
      lockObj.ExitReadLock();
    }
  }
}

Compliant solution
class MyClass
{
  private object obj = new object();

  public void DoSomethingWithMonitor()
  {
    lock(obj) // Compliant: the lock will be released at the end of the lock block
    {
      if (IsInitialized())
      {
        // ...
      }
    }
  }
}

class MyClass
{
  private ReaderWriterLockSlim lockObj = new ReaderWriterLockSlim();

  public void DoSomethingWithReaderWriteLockSlim()
  {
    lockObj.EnterReadLock(); // Compliant: the lock will be released in the finally block
    try
    {
      if (IsInitialized())
      {
        // ...
      }
    }
    finally
    {
      lockObj.ExitReadLock();
    }
  }
}

Resources

   Synchronization of access to a shared resource 
   CWE - CWE-459 - Incomplete Cleanup 
   lock statement 
   The
  try-finally statement