Re: Immutable SyntexCheckers

2017-03-20 Thread Emmanuel Lécharny 


Le 20/03/2017 à 08:20, Stefan Seelmann a écrit :
> On 03/20/2017 08:12 AM, Emmanuel Lécharny wrote:
>>
>> Le 20/03/2017 à 07:37, Stefan Seelmann a écrit :
>>> On 03/20/2017 02:10 AM, Emmanuel Lécharny wrote:
 public class BooleanSyntaxChecker extends SyntaxChecker
 {
 /**
  * A static instance of BooleanSyntaxChecker
  */
 public static final BooleanSyntaxChecker INSTANCE = new
 BooleanSyntaxChecker( SchemaConstants.BOOLEAN_SYNTAX );

 /** A static instance of the builder */
 private static final Builder BUILDER_INSTANCE = new Builder();
 /**
  * @return An instance of the Builder for this class
  */
 public static Builder builder()
 {
 return BUILDER_INSTANCE;
 }
>>> Hm, why a static builder? As it is not immutable there's a chance of
>>> race condition in case two threads use it concurrently.
>> That can't happen, because we have :
>>
>> private static final Builder BUILDER_INSTANCE = new Builder();
>>
>> that is guaranteed to be built during the class loading.
> I agree about the creation of the builder instance.
>
> But if two threads *use* it:
> 1. thread 1 calls builder()
> 2. thread 2 calls builder() and gets the same builder instance
> 3. thread 1 calls setOid("1.1.1")
> 4. thread 2 calls setOid("2.2.2")
> 5. thread 1 calls build() and may get an SC with OID "2.2.2"!

Good catch...

/**
 * @return An instance of the Builder for this class
 */
public static Builder builder()
{
return new Builder();
}

would solve the issue, correct ?

(somtime, trying to verdue is wrong).


>
>

-- 
Emmanuel Lecharny

Symas.com
directory.apache.org

Re: Immutable SyntexCheckers

2017-03-20 Thread Stefan Seelmann 
On 03/20/2017 08:12 AM, Emmanuel Lécharny wrote:
> 
> 
> Le 20/03/2017 à 07:37, Stefan Seelmann a écrit :
>> On 03/20/2017 02:10 AM, Emmanuel Lécharny wrote:
>>> public class BooleanSyntaxChecker extends SyntaxChecker
>>> {
>>> /**
>>>  * A static instance of BooleanSyntaxChecker
>>>  */
>>> public static final BooleanSyntaxChecker INSTANCE = new
>>> BooleanSyntaxChecker( SchemaConstants.BOOLEAN_SYNTAX );
>>>
>>> /** A static instance of the builder */
>>> private static final Builder BUILDER_INSTANCE = new Builder();
>>> /**
>>>  * @return An instance of the Builder for this class
>>>  */
>>> public static Builder builder()
>>> {
>>> return BUILDER_INSTANCE;
>>> }
>> Hm, why a static builder? As it is not immutable there's a chance of
>> race condition in case two threads use it concurrently.
> 
> That can't happen, because we have :
> 
> private static final Builder BUILDER_INSTANCE = new Builder();
> 
> that is guaranteed to be built during the class loading.

I agree about the creation of the builder instance.

But if two threads *use* it:
1. thread 1 calls builder()
2. thread 2 calls builder() and gets the same builder instance
3. thread 1 calls setOid("1.1.1")
4. thread 2 calls setOid("2.2.2")
5. thread 1 calls build() and may get an SC with OID "2.2.2"!

Re: Immutable SyntexCheckers

2017-03-20 Thread Emmanuel Lécharny 


Le 20/03/2017 à 07:37, Stefan Seelmann a écrit :
> On 03/20/2017 02:10 AM, Emmanuel Lécharny wrote:
>> public class BooleanSyntaxChecker extends SyntaxChecker
>> {
>> /**
>>  * A static instance of BooleanSyntaxChecker
>>  */
>> public static final BooleanSyntaxChecker INSTANCE = new
>> BooleanSyntaxChecker( SchemaConstants.BOOLEAN_SYNTAX );
>>
>> /** A static instance of the builder */
>> private static final Builder BUILDER_INSTANCE = new Builder();
>> /**
>>  * @return An instance of the Builder for this class
>>  */
>> public static Builder builder()
>> {
>> return BUILDER_INSTANCE;
>> }
> Hm, why a static builder? As it is not immutable there's a chance of
> race condition in case two threads use it concurrently.

That can't happen, because we have :

private static final Builder BUILDER_INSTANCE = new Builder();

that is guaranteed to be built during the class loading.

-- 
Emmanuel Lecharny

Symas.com
directory.apache.org