java / expert
Snippet
Fine-grained Memory Barriers with VarHandles
VarHandles provide a standard way to perform atomic operations and memory fencing. 'setRelease' ensures that all prior writes in the current thread are visible to other threads performing an 'acquire' load, providing higher performance than 'volatile' for specific synchronization patterns.
snippet.java
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private static final VarHandle STATE_VH;static {try {STATE_VH = MethodHandles.lookup().findVarHandle(Node.class, "state", int.class);} catch (Exception e) { throw new Error(e); }}public void releaseState() {STATE_VH.setRelease(this, 1);}
Breakdown
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findVarHandle(Node.class, "state", int.class)
Dynamically links a handle to a specific field for low-level access.
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STATE_VH.setRelease(this, 1)
Writes the value with 'release' semantics, acting as a one-way memory barrier.