I just found another bug of sync. Harmony throws SyncFailedException when fd
is read-only while RI returns silently. Spec doesn't explictly describe the
behaviour in such case[1]. But, it seems intended behaviour of RI, because
it requires additional check before invoke os sync. Following test
reproduces the bug:
public void testSyncReadOnly() throws Exception {
String TESTFILE = "tempFile";
try {
FileOutputStream fos = new FileOutputStream(TESTFILE);
fos.write("something".getBytes());
fos.close();
RandomAccessFile raf = new RandomAccessFile(TESTFILE, "rw");
raf.getFD().sync();
raf.close();
FileInputStream fis = new FileInputStream(TESTFILE);
fis.getFD().sync();
fis.close();
} finally {
new File(TESTFILE).delete();
}
}
I'll file a JIRA to record this bug soon!
[1] "SyncFailedException - Thrown when the buffers cannot be flushed, or
because the system cannot guarantee that all the buffers have been
synchronized with physical media."
On 9/19/06, Richard Liang <[EMAIL PROTECTED]> wrote:
On 9/18/06, Andrew Zhang <[EMAIL PROTECTED]> wrote:
> On 9/18/06, Richard Liang <[EMAIL PROTECTED]> wrote:
> >
> > Hello,
> >
> > One Apache Derby test[1] fails on Harmony. It seems that RI always
> > sync the FileOutputStream and FileChannel after each "write", which is
> > different from Harmony. But there is no explicit description in Java
> > Spec. Shall we follow RI? Thanks a lot.
> >
> > The following test cases could demonstrate this issue.
> >
> > public void testFile() {
> > File derbyLog = new File("d:\\", "derby1.log");
> >
> > try {
> > FileOutputStream fos = new FileOutputStream(derbyLog);
> > fos.write(0x41);
> > assertEquals(1, derbyLog.length());
> > } catch (Exception e) {
> > e.printStackTrace();
> > }
> > }
> >
> > public void testFileChannel() {
> > File derbyLog = new File("d:\\", "derby2.log");
> >
> > try {
> > FileOutputStream fos = new FileOutputStream(derbyLog);
> > FileChannel fc = fos.getChannel();
> > fc.write(ByteBuffer.wrap(new byte[]{0x41, 0x42}));
> > assertEquals(2, derbyLog.length());
> > } catch (Exception e) {
> > e.printStackTrace();
> > }
> > }
>
>
> Interesting. I think we'd better follow RI although it's implementation
> dependent. Otherwise, it breaks existing application.
>
> To make test more interesting, I wrote a similar test:
>
>
> public void testFile() throws Exception {
> File derbyLog = File.createTempFile("test", "log");
> derbyLog.deleteOnExit();
> RandomAccessFile fos = new RandomAccessFile(derbyLog, "rws");
> for (int i = 0; i < 1000; i++) {
> fos.write(0x41);
> assertEquals(1 + i, derbyLog.length());
> }
>
> }
>
> Run it and you'll be surprised. :-)
Wow! It tooks RI 0.381 seconds, while 21.761 seconds for Harmony. We
shall improve our performance!
Let's have a more further study about this issue.
>
> [1]
> >
http://svn.apache.org/viewvc/db/derby/code/trunk/java/testing/org/apache/derbyTesting/functionTests/tests/lang/logStream.java?view=co
> > --
> > Richard Liang
> > China Development Lab, IBM
> >
> > ---------------------------------------------------------------------
> > Terms of use : http://incubator.apache.org/harmony/mailing.html
> > To unsubscribe, e-mail: [EMAIL PROTECTED]
> > For additional commands, e-mail: [EMAIL PROTECTED]
> >
> >
>
>
> --
> Andrew Zhang
> China Software Development Lab, IBM
>
>
--
Richard Liang
China Development Lab, IBM
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