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Posted to dev@cayenne.apache.org by Tore Halset <ha...@pvv.ntnu.no> on 2008/01/02 22:51:01 UTC
Re: svn commit: r608235 - /cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/access/DataContext.java
Hello.
Interesting. Is it possible to use the "Making it work for static
singletons" variant to get rid of the synchronization?
Btw, this is also very well described in "Effective Java Programming
Language guide" by Joshua Bloch - a must-have book for me.
- Tore.
On Jan 2, 2008, at 22:26, mgentry@apache.org wrote:
> Author: mgentry
> Date: Wed Jan 2 13:26:15 2008
> New Revision: 608235
>
> URL: http://svn.apache.org/viewvc?rev=608235&view=rev
> Log:
> Removed double-checked locking of queryCache. See http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html
> for details.
>
> Modified:
> cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/
> java/org/apache/cayenne/access/DataContext.java
>
> Modified: cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/
> src/main/java/org/apache/cayenne/access/DataContext.java
> URL: http://svn.apache.org/viewvc/cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/access/DataContext.java?rev=608235&r1=608234&r2=608235&view=diff
> =
> =
> =
> =
> =
> =
> =
> =
> ======================================================================
> --- cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/
> java/org/apache/cayenne/access/DataContext.java (original)
> +++ cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/
> java/org/apache/cayenne/access/DataContext.java Wed Jan 2 13:26:15
> 2008
> @@ -257,16 +257,11 @@
> *
> * @since 3.0
> */
> - public QueryCache getQueryCache() {
> -
> + public synchronized QueryCache getQueryCache() {
> if (queryCache == null) {
> - synchronized (this) {
> - if (queryCache == null) {
> - queryCache = getParentDataDomain()
> - .getQueryCacheFactory()
> - .getQueryCache(Collections.EMPTY_MAP);
> - }
> - }
> + queryCache = getParentDataDomain()
> + .getQueryCacheFactory()
> + .getQueryCache(Collections.EMPTY_MAP);
> }
>
> return queryCache;
> @@ -277,7 +272,7 @@
> *
> * @since 3.0
> */
> - public void setQueryCache(QueryCache queryCache) {
> + public synchronized void setQueryCache(QueryCache queryCache) {
> this.queryCache = queryCache;
> }
>
>
>
>
Re: svn commit: r608235 - /cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/access/DataContext.java
Posted by Andrus Adamchik <an...@objectstyle.org>.
Also I think the article quoted predates java 5 which (I think) makes
double checked locking safe for "volatile" ivars??
Andrus
On Jan 2, 2008, at 11:51 PM, Tore Halset wrote:
> Hello.
>
> Interesting. Is it possible to use the "Making it work for static
> singletons" variant to get rid of the synchronization?
>
> Btw, this is also very well described in "Effective Java Programming
> Language guide" by Joshua Bloch - a must-have book for me.
>
> - Tore.
>
> On Jan 2, 2008, at 22:26, mgentry@apache.org wrote:
>
>> Author: mgentry
>> Date: Wed Jan 2 13:26:15 2008
>> New Revision: 608235
>>
>> URL: http://svn.apache.org/viewvc?rev=608235&view=rev
>> Log:
>> Removed double-checked locking of queryCache. See http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html
>> for details.
>>
>> Modified:
>> cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/
>> java/org/apache/cayenne/access/DataContext.java
>>
>> Modified: cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/
>> src/main/java/org/apache/cayenne/access/DataContext.java
>> URL: http://svn.apache.org/viewvc/cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/access/DataContext.java?rev=608235&r1=608234&r2=608235&view=diff
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =====================================================================
>> --- cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/
>> main/java/org/apache/cayenne/access/DataContext.java (original)
>> +++ cayenne/main/trunk/framework/cayenne-jdk1.5-unpublished/src/
>> main/java/org/apache/cayenne/access/DataContext.java Wed Jan 2
>> 13:26:15 2008
>> @@ -257,16 +257,11 @@
>> *
>> * @since 3.0
>> */
>> - public QueryCache getQueryCache() {
>> -
>> + public synchronized QueryCache getQueryCache() {
>> if (queryCache == null) {
>> - synchronized (this) {
>> - if (queryCache == null) {
>> - queryCache = getParentDataDomain()
>> - .getQueryCacheFactory()
>> - .getQueryCache(Collections.EMPTY_MAP);
>> - }
>> - }
>> + queryCache = getParentDataDomain()
>> + .getQueryCacheFactory()
>> + .getQueryCache(Collections.EMPTY_MAP);
>> }
>>
>> return queryCache;
>> @@ -277,7 +272,7 @@
>> *
>> * @since 3.0
>> */
>> - public void setQueryCache(QueryCache queryCache) {
>> + public synchronized void setQueryCache(QueryCache queryCache) {
>> this.queryCache = queryCache;
>> }
>>
>>
>>
>>
>
>