[
https://issues.apache.org/jira/browse/DERBY-2686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12498624
]
Kristian Waagan commented on DERBY-2686:
----------------------------------------
FYI, from this years JavaOne, session TS-2707 - "Java Puzzlers Episode VI: The
Phantom-Reference Menace/Attack of the Clone/Revenge of the Shift" by Joshua
Bloch, Google, Inc.; William Pugh, Univ. of Maryland, pdf page 35 and 36:
"static void skipFully(InputStream in, long nBytes)
throws IOException {
long remaining = nBytes;
while (remaining != 0) {
long skipped = in.skip(remaining);
if (skipped == 0)
throw new EOFException();
remaining -= skipped;
}
}"
And the following statements:
"Moral
• The skip method is hard to use and error prone
• Use your skipFully instead of skip
• There is an RFE to add it to InputStream
• More generally, if an API is broken, wrap it
• For API designers
• Don't violate the principle of least astonishment
• Make it easy to do simple things"
Again, this does not necessarily justify a specific solution/implementation, it
is just another data point.
> The skip method for some InputStreams and Readers return invalid values
> -----------------------------------------------------------------------
>
> Key: DERBY-2686
> URL: https://issues.apache.org/jira/browse/DERBY-2686
> Project: Derby
> Issue Type: Bug
> Components: JDBC, Store
> Affects Versions: 10.3.0.0
> Reporter: Kristian Waagan
> Assigned To: Kristian Waagan
> Attachments: derby-2686-1a.diff, derby-2686-1a.stat
>
>
> The Java API docs for InputStream.skip and Reader.skip seem to indicate that
> returning a negative value is breaking the contract.
> The contract for Reader.skip is the more clear one, while I have taken the
> assumption that all Derby InputStreams will return 0 only when EOF has been
> reached or 0 is passed in as the amount of bytes to skip.
> Bad checking in a skip method also caused Derby to enter an infinite loop in
> a skip method.
> It should also be noted that skipping bytes/characters should be done in a
> loop, as skip is free to skip a smaller amount of bytes than requested. This
> is true even if EOF is not reached.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
