Hi Staffan!
Isn't the second read in line# 268 erroneous?
267 while ((n = sis.read(b)) != -1) {
268 n = sis.read(b);
Sincerely yours,
Ivan
On 11.04.2014 11:16, Staffan Larsen wrote:
Here is a new version where the 200 char cap is removed:
http://cr.openjdk.java.net/~sla/8039173/webrev.02/
Thanks,
/Staffan
On 4 apr 2014, at 16:27, Staffan Larsen <staffan.lar...@oracle.com> wrote:
Thanks Ivan.
I’ve been thinking a bit more about this and discussing with people here. I’m
not sure anymore that it is a good idea to cap the error message. My original
thought was that it made sense to not overflow the client with tons of output
if something went wrong in the target. On the other hand, there is nothing that
says that the error message will be in the first 200 characters. It is
perfectly possible for an operation to successfully run for a while and only at
the end run into a problem. In that case the output will have the exception at
the end, following any amount of output. Capping the message in that case would
hide the error.
(My second thought was: let’s only take the last 200 chars, but there is no
guarantee that that will contain the complete error message either).
So the "keep it simple” principle here would be to remove the cap (which also
makes the code in getErrorMessage() simpler).
If someone has a better solution for propagating error messages from the
operations, I’m all ears.
Thanks,
/Staffan
On 4 apr 2014, at 14:41, Ivan Gerasimov <ivan.gerasi...@oracle.com> wrote:
An alternative, more compact variant might be
------------------------
String getErrorMessage(InputStream sis, int maxlen) throws IOException {
int n, off = 0, len = maxlen + 1;
byte b[] = new byte[len];
while ((n = sis.read(b, off, len - off)) > 0)
off += n;
return (off == 0) ? null
: (off < len)
? new String(b, 0, off, "UTF-8")
: new String(b, 0, maxlen, "UTF-8") + " ...";
}
------------------------
Not a big deal, of course.
Sincerely yours,
Ivan
On 04.04.2014 16:24, Ivan Gerasimov wrote:
Now you reintroduced the smallish issue, when the message is exactly 200
characters (or whatever maxlen is).
The dots will be appended to the message, even though it's not necessary.
I think the only reliable way to deal with it is to try to read one extra
character from sis.
Something like this should do:
------------------------
String getErrorMessage(InputStream sis, int maxlen) throws IOException {
byte b[] = new byte[maxlen + 1];
int n, off = 0, len = b.length;
do {
n = sis.read(b, off, len);
if (n == -1) {
break;
}
off += n;
len -= n;
} while (off < maxlen);
String message = null;
if (off > 0) {
message = (off > maxlen)
? new String(b, 0, maxlen, "UTF-8") + " ..."
: new String(b, 0, off, "UTF-8");
}
return message;
}
------------------------
Sincerely yours,
Ivan
On 04.04.2014 16:08, Staffan Larsen wrote:
I’m afraid you are right! Doh. Need to add more testing...
How about this change:
--- a/src/share/classes/sun/tools/attach/HotSpotVirtualMachine.java
+++ b/src/share/classes/sun/tools/attach/HotSpotVirtualMachine.java
@@ -267,9 +267,11 @@
String getErrorMessage(InputStream sis, int maxlen) throws IOException {
byte b[] = new byte[maxlen];
int n, off = 0, len = maxlen;
+ boolean complete = false;
do {
n = sis.read(b, off, len);
if (n == -1) {
+ complete = true;
break;
}
off += n;
@@ -280,7 +282,7 @@
if (off > 0) {
message = new String(b, 0, off, "UTF-8");
}
- if (off > b.length && message != null) {
+ if (!complete && message != null) {
message += " ...";
}
return message;
On 4 apr 2014, at 13:55, Ivan Gerasimov <ivan.gerasi...@oracle.com> wrote:
Thank you Staffan for fixing them!
But I'm afraid that now the function will never add ellipsis to the message,
even if it gets truncated.
Sincerely yours,
Ivan
On 04.04.2014 15:47, Staffan Larsen wrote:
Thanks for finding these bugs, Ivan!
I have updated the webrev at:
http://cr.openjdk.java.net/~sla/8039173/webrev.01/, and I have also included
the diff below.
The updated webrev also has some changes in the javadoc for VirtualMachine to
clarify that some methods can now throw AttachOperationFailedException.
Thanks,
/Staffan
diff --git a/src/share/classes/sun/tools/attach/HotSpotVirtualMachine.java
b/src/share/classes/sun/tools/attach/HotSpotVirtualMachine.java
--- a/src/share/classes/sun/tools/attach/HotSpotVirtualMachine.java
+++ b/src/share/classes/sun/tools/attach/HotSpotVirtualMachine.java
@@ -266,18 +266,21 @@
*/
String getErrorMessage(InputStream sis, int maxlen) throws IOException {
byte b[] = new byte[maxlen];
- int n, off = 0, len = b.length;
+ int n, off = 0, len = maxlen;
do {
n = sis.read(b, off, len);
+ if (n == -1) {
+ break;
+ }
off += n;
len -= n;
- } while (n >= 0 && off < b.length);
+ } while (off < maxlen);
String message = null;
if (off > 0) {
message = new String(b, 0, off, "UTF-8");
}
- if (off == b.length && message != null) {
+ if (off > b.length && message != null) {
message += " ...";
}
return message;
On 4 apr 2014, at 11:18, Ivan Gerasimov <ivan.gerasi...@oracle.com> wrote:
Hi Staffan!
I think there is a couple of minor bugs in getErrorMessage(InputStream sis, int
maxlen).
1) If maxlen is exactly the size of the message to read, the function will add
an ellipsis, even though the message isn't truncated,
2) If maxlen is greater than needed, then sis.read(b, off, len) at the line
#271 will eventually return -1, and it will cause the message to lose its last
character.
Sincerely yours,
Ivan
