/**
* Gets a view of the given {@code segment} and verifies the ref count and the data obtained from
* the view against {@code expectedRefCount} and {@code dataInSegment} respectively.
*
* @param segment the {@link LogSegment} to get a view from.
* @param writeStartOffset the offset at which write was started on the segment.
* @param offset the offset for which a view is required.
* @param dataInSegment the entire data in the {@link LogSegment}.
* @param expectedRefCount the expected return value of {@link LogSegment#refCount()} once the
* view is obtained from the {@code segment}
* @throws IOException
*/
private void getAndVerifyView(
LogSegment segment,
long writeStartOffset,
int offset,
byte[] dataInSegment,
long expectedRefCount)
throws IOException {
Random random = new Random();
Pair<File, FileChannel> view = segment.getView();
assertNotNull("File object received in view is null", view.getFirst());
assertNotNull("FileChannel object received in view is null", view.getSecond());
assertEquals("Ref count is not as expected", expectedRefCount, segment.refCount());
int sizeToRead = random.nextInt(dataInSegment.length - offset + 1);
ByteBuffer buffer = ByteBuffer.wrap(new byte[sizeToRead]);
view.getSecond().read(buffer, writeStartOffset + offset);
assertArrayEquals(
"Data read from file does not match data written",
Arrays.copyOfRange(dataInSegment, offset, offset + sizeToRead),
buffer.array());
}
/**
* Verifies getting and closing views and makes sure that data and ref counts are consistent.
*
* @throws IOException
*/
@Test
public void viewAndRefCountTest() throws IOException {
String segmentName = "log_current";
LogSegment segment = getSegment(segmentName, STANDARD_SEGMENT_SIZE, true);
try {
long startOffset = segment.getStartOffset();
int readSize = 100;
int viewCount = 5;
byte[] data = appendRandomData(segment, readSize * viewCount);
for (int i = 0; i < viewCount; i++) {
getAndVerifyView(segment, startOffset, i * readSize, data, i + 1);
}
for (int i = 0; i < viewCount; i++) {
segment.closeView();
assertEquals("Ref count is not as expected", viewCount - i - 1, segment.refCount());
}
} finally {
closeSegmentAndDeleteFile(segment);
}
}