rule version 1

rules/S7131/csharp/rule.adoc

@@ -1,44 +1,53 @@
-FIXME: add a description
 
-// If you want to factorize the description uncomment the following line and create the file.
-//include::../description.adoc[]
+When using https://learn.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlock[ReaderWriterLock] and https://learn.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlockslim[ReaderWriterLockSlim] for managing read and write locks, you should not exit a read lock while holding a write lock otherwise you might have unexpected behavior.
 
-== Why is this an issue?
-
-FIXME: remove the unused optional headers (that are commented out)
 
-//=== What is the potential impact?
+== Why is this an issue?
 
-== How to fix it
-//== How to fix it in FRAMEWORK NAME
+When you acquire a write lock using, for example, `EnterWriteLock`, you indicate that you need exclusive access to the resource, meaning no other thread should be able to read or write to the resource. If you exit a read lock while holding a write lock, you might inadvertently allow other threads to acquire a read lock, leading to race conditions and data corruption.
+Additionally, it can lead to deadlocks (a situation where two or more threads are waiting indefinitely for each other to release locks) and runtime exceptions (unexpected errors that occur during the execution of a program), as the lock state becomes inconsistent.
+Finally, correctly matching lock acquisition and release calls (for example, `EnterWriteLock` with `ExitWriteLock` and `EnterReadLock` with `ExitReadLock`) makes the code more transparent and easier to maintain. It ensures that the locking logic is straightforward and less prone to errors.
 
 === Code examples
 
 ==== Noncompliant code example
 
 [source,csharp,diff-id=1,diff-type=noncompliant]
 ----
-FIXME
+var lock = new ReaderWriterLock();
+
+lock.EnterWriteLock();
+try
+{
+    // Write resources
+}
+finally
+{
+    Lock.ExitReadLock(); // Noncompliant
+}
 ----
 
 ==== Compliant solution
 
 [source,csharp,diff-id=1,diff-type=compliant]
 ----
-FIXME
+var lock = new ReaderWriterLock();
+
+lock.EnterWriteLock();
+try
+{
+    // Write resources
+}
+finally
+{
+    lock.ExitWriterLock(); // Release the writerlock first
+}
 ----
 
-//=== How does this work?
-
-//=== Pitfalls
-
-//=== Going the extra mile
+== Resources
 
+=== Documentation
 
-//== Resources
-//=== Documentation
-//=== Articles & blog posts
-//=== Conference presentations
-//=== Standards
-//=== External coding guidelines
-//=== Benchmarks
+* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/lock[The lock statement - ensure exclusive access to a shared resource]
+* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlock[ReaderWriterLock Class]
+* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlockslim[ReaderWriterLockSlim]