/**
* Reads data starting from {@code offsetToStartRead} of {@code segment} and matches it with
* {@code original}.
*
* @param segment the {@link LogSegment} to read from.
* @param offsetToStartRead the offset in {@code segment} to start reading from.
* @param original the byte array to compare against.
* @throws IOException
*/
private void readAndEnsureMatch(LogSegment segment, long offsetToStartRead, byte[] original)
throws IOException {
ByteBuffer readBuf = ByteBuffer.wrap(new byte[original.length]);
segment.readInto(readBuf, offsetToStartRead);
assertArrayEquals("Data read does not match data written", original, readBuf.array());
}
/**
* Tests {@link LogSegment#readInto(ByteBuffer, long)} for various cases.
*
* @throws IOException
*/
@Test
public void readTest() throws IOException {
Random random = new Random();
String segmentName = "log_current";
LogSegment segment = getSegment(segmentName, STANDARD_SEGMENT_SIZE, true);
try {
long writeStartOffset = segment.getStartOffset();
byte[] data = appendRandomData(segment, 2 * STANDARD_SEGMENT_SIZE / 3);
readAndEnsureMatch(segment, writeStartOffset, data);
int readCount = 10;
for (int i = 0; i < readCount; i++) {
int position = random.nextInt(data.length);
int size = random.nextInt(data.length - position);
readAndEnsureMatch(
segment,
writeStartOffset + position,
Arrays.copyOfRange(data, position, position + size));
}
// error scenarios
ByteBuffer readBuf = ByteBuffer.wrap(new byte[data.length]);
// data cannot be read at invalid offsets.
long[] invalidOffsets = {
writeStartOffset - 1, segment.getEndOffset(), segment.getEndOffset() + 1
};
ByteBuffer buffer = ByteBuffer.wrap(TestUtils.getRandomBytes(1));
for (long invalidOffset : invalidOffsets) {
try {
segment.readInto(readBuf, invalidOffset);
fail("Should have failed to read because position provided is invalid");
} catch (IndexOutOfBoundsException e) {
assertEquals("Position of buffer has changed", 0, buffer.position());
}
}
// position + buffer.remaining() > endOffset.
long readOverFlowCount = metrics.overflowReadError.getCount();
try {
segment.readInto(readBuf, writeStartOffset + 1);
fail("Should have failed to read because position + buffer.remaining() > endOffset");
} catch (IndexOutOfBoundsException e) {
assertEquals(
"Read overflow should have been reported",
readOverFlowCount + 1,
metrics.overflowReadError.getCount());
assertEquals("Position of buffer has changed", 0, readBuf.position());
}
segment.close();
// read after close
buffer = ByteBuffer.allocate(1);
try {
segment.readInto(buffer, writeStartOffset);
fail("Should have failed to read because segment is closed");
} catch (ClosedChannelException e) {
assertEquals("Position of buffer has changed", 0, buffer.position());
}
} finally {
closeSegmentAndDeleteFile(segment);
}
}