franz1981 commented on a change in pull request #2844: ARTEMIS-1811 NIO Seq
File should use RandomAccessFile with heap buffers
URL: https://github.com/apache/activemq-artemis/pull/2844#discussion_r327938663
##########
File path:
artemis-journal/src/main/java/org/apache/activemq/artemis/core/io/nio/NIOSequentialFile.java
##########
@@ -160,14 +173,63 @@ public int read(final ByteBuffer bytes) throws Exception
{
return read(bytes, null);
}
+ //This value has been tuned just to reduce the memory footprint
+ //of read/write of the whole file size: given that this value
+ //is > 8192, RandomAccessFile JNI code will use malloc/free instead
+ //of using a copy on the stack, but it has been proven to NOT be
+ //a bottleneck
+ private static final int BUF_SIZE = 2 * 1024 * 1024;
+
+ private static int readRaf(RandomAccessFile raf, byte[] b, int off, int
len, int ioSize) throws IOException {
+ int remaining = len;
+ int offset = off;
+ while (remaining > 0) {
+ final int chunkSize = Math.min(ioSize, remaining);
+ final int read = raf.read(b, offset, chunkSize);
+ assert read != 0;
+ if (read == -1) {
+ if (len == remaining) {
+ return -1;
+ }
+ break;
+ }
+ offset += read;
+ remaining -= read;
+ }
+ return len - remaining;
+ }
+
+ private static void writeRaf(RandomAccessFile raf, byte[] b, int off, int
len, int ioSize) throws IOException {
+ int remaining = len;
+ int offset = off;
+ while (remaining > 0) {
+ final int chunkSize = Math.min(ioSize, remaining);
+ raf.write(b, offset, chunkSize);
+ offset += chunkSize;
+ remaining -= chunkSize;
+ }
+ }
+
@Override
public synchronized int read(final ByteBuffer bytes,
final IOCallback callback) throws IOException,
ActiveMQIllegalStateException {
try {
if (channel == null) {
throw new ActiveMQIllegalStateException("File " +
this.getFileName() + " has a null channel");
}
- int bytesRead = channel.read(bytes);
+ final int bytesRead;
+ if (bytes.hasArray()) {
+ if (bytes.remaining() > BUF_SIZE) {
+ bytesRead = readRaf(rfile, bytes.array(), bytes.arrayOffset() +
bytes.position(), bytes.remaining(), BUF_SIZE);
+ } else {
+ bytesRead = rfile.read(bytes.array(), bytes.arrayOffset() +
bytes.position(), bytes.remaining());
Review comment:
to save inlining budget: for most of the cases where the first check will
save the call on the happy path
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