#Everywriter sync code

The following example builds on that in the section where the Order class contains a collection of Line objects which make up the order. Note that it is important that the writer methods leave the object in a consistent state before exiting, because other threads will be allowed to read the object. A method that holds an upgradeable reader lock can then invoke a method with the WriterAttribute attributes custom attribute. The UpgradeableReaderAttribute attribute ensures that no other thread than the current one will be able to acquire a writer lock on the object, so it gives the guarantee that the object is not going to be modified during the method’s execution. In this case, it is possible to use a combination of the UpgradeableReaderAttribute and WriterAttribute attributes. However, many write methods are actually composed of a lot of read operations but just a few write operations at the end. Some long-running write methods really do a lot of write operations (or rely on slow external services) which make them inappropriate for the reader-writer-synchronized model. Since write methods require exclusive access to the object, they should complete as quickly as possible. Likewise, invoking methods marked with WriterAttribute will lock the instance causing all reads and writes to block until the write has completed and the write lock has been released. Will be blocked until all reads are complete. While this lock is held, other threads can also read properties or invoke read-only methods of that instance, but calls to properties or methods marked with WriterAttribute The ReaderAttribute attribute causes PostSharp to acquire a lock on the instance whenever the method is invoked. Note that it is not necessary to put these attributes on property getters and setters or on events. So, not only the direct use of locks results in more lines of code, but it won’t reliably prevent nondeterministic data structure corruptions.Īdd the package your project.Īdd using namespace to your file.Īdd the custom attribute to the class.Īnnotate your object model for parent/child relationships as described in Annotating an Object Model for Parent/Child Relationships (Aggregatable).Īdd the custom attribute or It is unreliable because it is too easy to forget to acquire the right type of lock, and these errors are not detectable by the compiler or by unit tests.

#Everywriter sync code

It is cumbersome because a lot of code is required. However, working directly with the ReaderWriterLock and ReaderWriterLockSlim classes has disadvantages:

Public void Set( decimal amount, decimal discount) Public decimal Amount ĭecimal result = this.Amount - this.Discount Private ReaderWriterLockSlim orderLock = new ReaderWriterLockSlim()