Unused Field

[QiAnXinCodeSafe]

HaloDB/src/main/java/com/oath/halodb/Segment.java

Line 22 in 741b4f7

private volatile long lock;

This field is never used.

[tuannh982]

The lock field is used for re-entrance lock. lock value is the the thread_id that currently acquire the current Segment instance, which is updated by the lockFieldUpdater

HaloDB/src/main/java/com/oath/halodb/Segment.java

Lines 23 to 24 in 741b4f7

	private static final AtomicLongFieldUpdater<Segment> lockFieldUpdater =
	AtomicLongFieldUpdater.newUpdater(Segment.class, "lock");

HaloDB/src/main/java/com/oath/halodb/Segment.java

Lines 39 to 65 in 741b4f7

	boolean lock() {
	long t = Thread.currentThread().getId();
	if (t == lockFieldUpdater.get(this)) {
	return false;
	}
	while (true) {
	if (lockFieldUpdater.compareAndSet(this, 0L, t)) {
	return true;
	}
	// yield control to other thread.
	// Note: we cannot use LockSupport.parkNanos() as that does not
	// provide nanosecond resolution on Windows.
	Thread.yield();
	}
	}
	void unlock(boolean wasFirst) {
	if (!wasFirst) {
	return;
	}
	long t = Thread.currentThread().getId();
	boolean r = lockFieldUpdater.compareAndSet(this, t, 0L);
	assert r;
	}