rspec/rules/S3078/java/rule.adoc

== Why is this an issue?

Using compound operators as well as increments and decrements (and toggling, in the case of ``++boolean++``s) on primitive fields are not atomic operations. That is, they don't happen in a single step. For instance, when a ``++volatile++`` primitive field is incremented or decremented you run the risk of data loss if threads interleave in the steps of the update. Instead, use a guaranteed-atomic class such as ``++AtomicInteger++``, or synchronize the access.


=== Noncompliant code example

[source,java]
----
private volatile int count = 0;
private volatile boolean boo = false;

public void incrementCount() {
  count++;  // Noncompliant
}

public void toggleBoo(){
  boo = !boo;  // Noncompliant
}
----


=== Compliant solution

[source,java]
----
private AtomicInteger count = 0;
private boolean boo = false;

public void incrementCount() {
  count.incrementAndGet(); 
}

public synchronized void toggleBoo() {
  boo = !boo;
}
----


== Resources

* https://wiki.sei.cmu.edu/confluence/x/SjdGBQ[CERT, VNA02-J.] - Ensure that compound operations on shared variables are atomic


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