Re: [POOL2] Pooling mutable objects
I'd think adding a UUID then overriding equals and hashCode would do the
trick. To aid you in doing this, commons-lang has EqualsBuilder [1] and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov 1983-01...@gmx.net wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is requested with
the fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and mutable
int might change.
Additionally, I did not implement any custom equals and hashCode methods.
I have searched the docs and the found and did not find any clear answer
which says
that pooled objects have to be immutable. Though, I have found POOL-283
and POOL-284 which
led me to the conclusion that this is a problem because the objects are
stored in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and hashCode and
provide some internal,
immutable value something like a UUID? Alternatively, I could retrieve the
JSESSIONID from the
cookie store and use this as a unique value.
Thanks,
Michael
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
Re: Re: [POOL2] Pooling mutable objects
This is what I did:
this.internalId = RandomStringUtils.randomAlphanumeric(8);
Some Eclipse magic:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((internalId == null) ? 0 :
internalId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
RawSession other = (RawSession) obj;
if (internalId == null) {
if (other.internalId != null)
return false;
} else if (!internalId.equals(other.internalId))
return false;
return true;
}
Gesendet: Freitag, 06. Februar 2015 um 16:47 Uhr
Von: James Carman ja...@carmanconsulting.com
An: Commons Users List user@commons.apache.org
Betreff: Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org wrote:
I'd think adding a UUID then overriding equals and hashCode would do the
trick. To aid you in doing this, commons-lang has EqualsBuilder [1] and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov 1983-01...@gmx.net wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is requested with
the fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and mutable
int might change.
Additionally, I did not implement any custom equals and hashCode methods.
I have searched the docs and the found and did not find any clear answer
which says
that pooled objects have to be immutable. Though, I have found POOL-283
and POOL-284 which
led me to the conclusion that this is a problem because the objects are
stored in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and hashCode and
provide some internal,
immutable value something like a UUID? Alternatively, I could retrieve the
JSESSIONID from the
cookie store and use this as a unique value.
Thanks,
Michael
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
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-
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Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org wrote:
I'd think adding a UUID then overriding equals and hashCode would do the
trick. To aid you in doing this, commons-lang has EqualsBuilder [1] and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov 1983-01...@gmx.net wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is requested with
the fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and mutable
int might change.
Additionally, I did not implement any custom equals and hashCode methods.
I have searched the docs and the found and did not find any clear answer
which says
that pooled objects have to be immutable. Though, I have found POOL-283
and POOL-284 which
led me to the conclusion that this is a problem because the objects are
stored in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and hashCode and
provide some internal,
immutable value something like a UUID? Alternatively, I could retrieve the
JSESSIONID from the
cookie store and use this as a unique value.
Thanks,
Michael
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
Re: Re: [POOL2] Pooling mutable objects
Try UUID.randomUUID().toString() rather than RandomStringUtils if you
really want unique keys.
On Fri, Feb 6, 2015 at 10:54 AM, Michael Osipov 1983-01...@gmx.net wrote:
This is what I did:
this.internalId = RandomStringUtils.randomAlphanumeric(8);
Some Eclipse magic:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((internalId == null) ? 0 :
internalId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
RawSession other = (RawSession) obj;
if (internalId == null) {
if (other.internalId != null)
return false;
} else if (!internalId.equals(other.internalId))
return false;
return true;
}
Gesendet: Freitag, 06. Februar 2015 um 16:47 Uhr
Von: James Carman ja...@carmanconsulting.com
An: Commons Users List user@commons.apache.org
Betreff: Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org wrote:
I'd think adding a UUID then overriding equals and hashCode would do the
trick. To aid you in doing this, commons-lang has EqualsBuilder [1] and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov 1983-01...@gmx.net wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is requested with
the fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and mutable
int might change.
Additionally, I did not implement any custom equals and hashCode methods.
I have searched the docs and the found and did not find any clear answer
which says
that pooled objects have to be immutable. Though, I have found POOL-283
and POOL-284 which
led me to the conclusion that this is a problem because the objects are
stored in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and hashCode and
provide some internal,
immutable value something like a UUID? Alternatively, I could retrieve the
JSESSIONID from the
cookie store and use this as a unique value.
Thanks,
Michael
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
-
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Re: Re: [POOL2] Pooling mutable objects
I'm not sure I understand your comment Mat. From what I can tell, Michael
made his own hash function. That's fine, but *might* have unexpected
collision issues. Might not too... I don't know. My guess though is that
he's not an expert (who is an expert on hash functions?) and might
unknowingly fall into a trap here.
For example, commons-lang HashBuilder uses 37 as the prime and 17 as the
initial result... Michael didn't. Maybe he's OK, maybe he's not... but why
risk it? Why not just use the library and not reinvent the wheel? (Most
valid reason would be not wanting to pull in a whole library for these two
functions/classes.)
Again, take my advice for what you paid, nothing. :-)
Bill-
On Fri, Feb 6, 2015 at 11:06 AM, Mat Jaggard matt...@jaggard.org.uk wrote:
William - I'm not sure if you noticed, but they didn't hand-make anything.
On 6 February 2015 at 16:00, William Speirs wspe...@apache.org wrote:
Why wouldn't you use the HashCodeBuilder? Much simpler:
return new HashCodeBuilder().append(internalId).toHashCode();
Done in 1 line, and probably fewer collisions than your hand-made one.
Same
with the EqualsBuilder...
If you don't want the dep on commons-lang, then I can understand... but
I'd
just borrow their internal algo.
My $0.02...
Bill-
On Fri, Feb 6, 2015 at 10:54 AM, Michael Osipov 1983-01...@gmx.net
wrote:
This is what I did:
this.internalId = RandomStringUtils.randomAlphanumeric(8);
Some Eclipse magic:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((internalId == null) ? 0 :
internalId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
RawSession other = (RawSession) obj;
if (internalId == null) {
if (other.internalId != null)
return false;
} else if (!internalId.equals(other.internalId))
return false;
return true;
}
Gesendet: Freitag, 06. Februar 2015 um 16:47 Uhr
Von: James Carman ja...@carmanconsulting.com
An: Commons Users List user@commons.apache.org
Betreff: Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org
wrote:
I'd think adding a UUID then overriding equals and hashCode would
do
the
trick. To aid you in doing this, commons-lang has EqualsBuilder [1]
and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov 1983-01...@gmx.net
wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is
requested
with
the fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and
mutable
int might change.
Additionally, I did not implement any custom equals and hashCode
methods.
I have searched the docs and the found and did not find any clear
answer
which says
that pooled objects have to be immutable. Though, I have found
POOL-283
and POOL-284 which
led me to the conclusion that this is a problem because the
objects
are
stored in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and
hashCode
and
provide some internal,
immutable value something like a UUID? Alternatively, I could
retrieve the
JSESSIONID from the
cookie store and use this as a unique value.
Thanks,
Michael
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
-
To
Re: Re: [POOL2] Pooling mutable objects
He didn't create his own hash function, he generated it in eclipse. This is
better because you get all the testing of other eclipse users without any
runtime dependencies.
On 6 February 2015 at 16:16, William Speirs wspe...@apache.org wrote:
I'm not sure I understand your comment Mat. From what I can tell, Michael
made his own hash function. That's fine, but *might* have unexpected
collision issues. Might not too... I don't know. My guess though is that
he's not an expert (who is an expert on hash functions?) and might
unknowingly fall into a trap here.
For example, commons-lang HashBuilder uses 37 as the prime and 17 as the
initial result... Michael didn't. Maybe he's OK, maybe he's not... but why
risk it? Why not just use the library and not reinvent the wheel? (Most
valid reason would be not wanting to pull in a whole library for these two
functions/classes.)
Again, take my advice for what you paid, nothing. :-)
Bill-
On Fri, Feb 6, 2015 at 11:06 AM, Mat Jaggard matt...@jaggard.org.uk
wrote:
William - I'm not sure if you noticed, but they didn't hand-make
anything.
On 6 February 2015 at 16:00, William Speirs wspe...@apache.org wrote:
Why wouldn't you use the HashCodeBuilder? Much simpler:
return new HashCodeBuilder().append(internalId).toHashCode();
Done in 1 line, and probably fewer collisions than your hand-made one.
Same
with the EqualsBuilder...
If you don't want the dep on commons-lang, then I can understand... but
I'd
just borrow their internal algo.
My $0.02...
Bill-
On Fri, Feb 6, 2015 at 10:54 AM, Michael Osipov 1983-01...@gmx.net
wrote:
This is what I did:
this.internalId = RandomStringUtils.randomAlphanumeric(8);
Some Eclipse magic:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((internalId == null) ? 0 :
internalId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
RawSession other = (RawSession) obj;
if (internalId == null) {
if (other.internalId != null)
return false;
} else if (!internalId.equals(other.internalId))
return false;
return true;
}
Gesendet: Freitag, 06. Februar 2015 um 16:47 Uhr
Von: James Carman ja...@carmanconsulting.com
An: Commons Users List user@commons.apache.org
Betreff: Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org
wrote:
I'd think adding a UUID then overriding equals and hashCode would
do
the
trick. To aid you in doing this, commons-lang has EqualsBuilder
[1]
and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov
1983-01...@gmx.net
wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is
requested
with
the fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and
mutable
int might change.
Additionally, I did not implement any custom equals and hashCode
methods.
I have searched the docs and the found and did not find any
clear
answer
which says
that pooled objects have to be immutable. Though, I have found
POOL-283
and POOL-284 which
led me to the conclusion that this is a problem because the
objects
are
stored in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and
hashCode
and
provide some internal,
immutable value something like a UUID? Alternatively, I could
retrieve the
JSESSIONID from the
Re: Re: [POOL2] Pooling mutable objects
The existing Pool2 implementations use equals() to decide if two
objects are the same.
You have to make sure that your equals() implementation returns true
if and only if the objects being compared are the same as far as your
use of them is concerned.
So for example two Integers are equal if they have the same integral
value, but two different StringBuffer instances are never equal.
Once you have determined what constitutes equality for your instances,
make sure that the hash code is coded accordingly, i.e. two objects
that are equal() must have the same hash code.
If this requirment is not met, then the HashMap used internally by
Pool2 will behave unpredictably.
If all RawSession instances are to be regarded as unique (which seems
likely), then define equals and hash code as noted in POOL-283:
https://issues.apache.org/jira/browse/POOL-283?focusedCommentId=14307637page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14307637
On 6 February 2015 at 16:34, Mat Jaggard matt...@jaggard.org.uk wrote:
He didn't create his own hash function, he generated it in eclipse. This is
better because you get all the testing of other eclipse users without any
runtime dependencies.
On 6 February 2015 at 16:16, William Speirs wspe...@apache.org wrote:
I'm not sure I understand your comment Mat. From what I can tell, Michael
made his own hash function. That's fine, but *might* have unexpected
collision issues. Might not too... I don't know. My guess though is that
he's not an expert (who is an expert on hash functions?) and might
unknowingly fall into a trap here.
For example, commons-lang HashBuilder uses 37 as the prime and 17 as the
initial result... Michael didn't. Maybe he's OK, maybe he's not... but why
risk it? Why not just use the library and not reinvent the wheel? (Most
valid reason would be not wanting to pull in a whole library for these two
functions/classes.)
Again, take my advice for what you paid, nothing. :-)
Bill-
On Fri, Feb 6, 2015 at 11:06 AM, Mat Jaggard matt...@jaggard.org.uk
wrote:
William - I'm not sure if you noticed, but they didn't hand-make
anything.
On 6 February 2015 at 16:00, William Speirs wspe...@apache.org wrote:
Why wouldn't you use the HashCodeBuilder? Much simpler:
return new HashCodeBuilder().append(internalId).toHashCode();
Done in 1 line, and probably fewer collisions than your hand-made one.
Same
with the EqualsBuilder...
If you don't want the dep on commons-lang, then I can understand... but
I'd
just borrow their internal algo.
My $0.02...
Bill-
On Fri, Feb 6, 2015 at 10:54 AM, Michael Osipov 1983-01...@gmx.net
wrote:
This is what I did:
this.internalId = RandomStringUtils.randomAlphanumeric(8);
Some Eclipse magic:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((internalId == null) ? 0 :
internalId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
RawSession other = (RawSession) obj;
if (internalId == null) {
if (other.internalId != null)
return false;
} else if (!internalId.equals(other.internalId))
return false;
return true;
}
Gesendet: Freitag, 06. Februar 2015 um 16:47 Uhr
Von: James Carman ja...@carmanconsulting.com
An: Commons Users List user@commons.apache.org
Betreff: Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org
wrote:
I'd think adding a UUID then overriding equals and hashCode would
do
the
trick. To aid you in doing this, commons-lang has EqualsBuilder
[1]
and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael Osipov
1983-01...@gmx.net
wrote:
Hi folks,
I am developing a session pool for an HTTP backend which is
requested
with
the fabulous HttpClient.
The session object is this:
[POOL2] Pooling mutable objects
Hi folks,
I am developing a session pool for an HTTP backend which is requested with the
fabulous HttpClient.
The session object is this:
public class RawSession {
private CookieStore cookieStore;
private String logId;
private MutableInt requestId;
private String clientId;
private String serverId;
}
There won't be any setters but as you see, the cookie store and mutable int
might change.
Additionally, I did not implement any custom equals and hashCode methods.
I have searched the docs and the found and did not find any clear answer which
says
that pooled objects have to be immutable. Though, I have found POOL-283 and
POOL-284 which
led me to the conclusion that this is a problem because the objects are stored
in a map
which relies on equals and hashCode.
Does this ultimately mean that I have to override equals and hashCode and
provide some internal,
immutable value something like a UUID? Alternatively, I could retrieve the
JSESSIONID from the
cookie store and use this as a unique value.
Thanks,
Michael
-
To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
For additional commands, e-mail: user-h...@commons.apache.org
Re: Re: [POOL2] Pooling mutable objects
Hi William, William Speirs wrote: I'm not sure I understand your comment Mat. From what I can tell, Michael made his own hash function. That's fine, but *might* have unexpected collision issues. Might not too... I don't know. My guess though is that he's not an expert (who is an expert on hash functions?) and might unknowingly fall into a trap here. For example, commons-lang HashBuilder uses 37 as the prime and 17 as the initial result... Michael didn't. Maybe he's OK, maybe he's not... but why risk it? Why not just use the library and not reinvent the wheel? (Most valid reason would be not wanting to pull in a whole library for these two functions/classes.) Maybe because it can be dead-slow? https://www.mail-archive.com/user@xstream.codehaus.org/msg00677.html I use HashCodeBuilder and EqualsBilder for Mock objects only ... for good reason. Cheers, Jörg - To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
Re: [POOL2] Pooling mutable objects
On 2/6/15 10:16 AM, sebb wrote:
The existing Pool2 implementations use equals() to decide if two
objects are the same.
As of pool 2.3.
You have to make sure that your equals() implementation returns true
if and only if the objects being compared are the same as far as your
use of them is concerned.
So for example two Integers are equal if they have the same integral
value, but two different StringBuffer instances are never equal.
Once you have determined what constitutes equality for your instances,
make sure that the hash code is coded accordingly, i.e. two objects
that are equal() must have the same hash code.
If this requirment is not met, then the HashMap used internally by
Pool2 will behave unpredictably.
Also, hash codes should not change between the time that an object
is borrowed from the pool and subsequently returned. Again, for
pool 2.0-2.3 (latest as of this post), objects under management by
the pool are kept in a hashmap keyed on the objects themselves, so
mutability that changes hashcodes (and / or equality) can cause
problems. See the discussion on POOL-284.
These problems do not impact earlier (1.x) versions of Commons Pool.
If all RawSession instances are to be regarded as unique (which seems
likely), then define equals and hash code as noted in POOL-283:
https://issues.apache.org/jira/browse/POOL-283?focusedCommentId=14307637page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14307637
On 6 February 2015 at 16:34, Mat Jaggard matt...@jaggard.org.uk wrote:
He didn't create his own hash function, he generated it in eclipse. This is
better because you get all the testing of other eclipse users without any
runtime dependencies.
On 6 February 2015 at 16:16, William Speirs wspe...@apache.org wrote:
I'm not sure I understand your comment Mat. From what I can tell, Michael
made his own hash function. That's fine, but *might* have unexpected
collision issues. Might not too... I don't know. My guess though is that
he's not an expert (who is an expert on hash functions?) and might
unknowingly fall into a trap here.
For example, commons-lang HashBuilder uses 37 as the prime and 17 as the
initial result... Michael didn't. Maybe he's OK, maybe he's not... but why
risk it? Why not just use the library and not reinvent the wheel? (Most
valid reason would be not wanting to pull in a whole library for these two
functions/classes.)
Again, take my advice for what you paid, nothing. :-)
Bill-
On Fri, Feb 6, 2015 at 11:06 AM, Mat Jaggard matt...@jaggard.org.uk
wrote:
William - I'm not sure if you noticed, but they didn't hand-make
anything.
On 6 February 2015 at 16:00, William Speirs wspe...@apache.org wrote:
Why wouldn't you use the HashCodeBuilder? Much simpler:
return new HashCodeBuilder().append(internalId).toHashCode();
Done in 1 line, and probably fewer collisions than your hand-made one.
Same
with the EqualsBuilder...
If you don't want the dep on commons-lang, then I can understand... but
I'd
just borrow their internal algo.
My $0.02...
Bill-
On Fri, Feb 6, 2015 at 10:54 AM, Michael Osipov 1983-01...@gmx.net
wrote:
This is what I did:
this.internalId = RandomStringUtils.randomAlphanumeric(8);
Some Eclipse magic:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((internalId == null) ? 0 :
internalId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
RawSession other = (RawSession) obj;
if (internalId == null) {
if (other.internalId != null)
return false;
} else if (!internalId.equals(other.internalId))
return false;
return true;
}
Gesendet: Freitag, 06. Februar 2015 um 16:47 Uhr
Von: James Carman ja...@carmanconsulting.com
An: Commons Users List user@commons.apache.org
Betreff: Re: [POOL2] Pooling mutable objects
Or just let your IDE generate the methods.
On Fri, Feb 6, 2015 at 9:05 AM, William Speirs wspe...@apache.org
wrote:
I'd think adding a UUID then overriding equals and hashCode would
do
the
trick. To aid you in doing this, commons-lang has EqualsBuilder
[1]
and
HashCodeBuilder [2], I highly recommend using them.
Bill-
[1]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/EqualsBuilder.html
[2]
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/org/apache/commons/lang3/builder/HashCodeBuilder.html
On Fri, Feb 6, 2015 at 9:00 AM, Michael
