RFR: 8247995: Avoid use of a mapping function in Permissions.getPermissionCollection
Claes Redestad
claes.redestad at oracle.com
Mon Jun 22 22:29:21 UTC 2020
Hi,
inlining the new method actually messed up microbenchmark scores a
lot (15-80% overhead). I settled for simplifying the duplicate
permsMap.get in the outer method in a way that keeps scores neutral:
http://cr.openjdk.java.net/~redestad/8247995/open.01/
Benchmark Mode Cnt Score Error
Units
PermissionsImplies.withPermission avgt 15 27.857 ± 0.137
ns/op
PermissionsImplies.withUnresolvedPermission avgt 15 27.918 ± 0.178
ns/op
PermissionsImplies.withoutPermission avgt 15 4.559 ± 0.115
ns/op
Thanks!
/Claes
On 2020-06-22 23:54, Claes Redestad wrote:
> Hi Roger,
>
> I prototyped it as such, and saw a 0.4ns/op overhead in the
> PermissionImplies.withoutPermission. Thinking about it a bit now, this
> should be the rare path taken, since it means the permission is not
> implied and the performance largely irrelevant. I'll simplify as you
> suggested.
>
> /Claes
>
> On 2020-06-22 23:03, Roger Riggs wrote:
>> Hi Claes,
>>
>> Its correct as is but I would have written it without duplicating the
>> 'permsMap.get(p.getClass())' invocation
>> and as a single method (unless the inlining of
>> getPermissionCollection(p,create)) is important.
>>
>> A patch on top of yours:
>>
>> diff --git
>> a/src/java.base/share/classes/java/security/Permissions.java
>> b/src/java.base/share/classes/java/security/Permissions.java
>> --- a/src/java.base/share/classes/java/security/Permissions.java
>> +++ b/src/java.base/share/classes/java/security/Permissions.java
>> @@ -229,20 +229,16 @@ implements Serializable
>> */
>> private PermissionCollection getPermissionCollection(Permission p,
>> boolean createEmpty) {
>> + PermissionCollection pc = permsMap.get(p.getClass());
>> if (!hasUnresolved && !createEmpty) {
>> // Collection not to be created
>> - return permsMap.get(p.getClass());
>> + return pc;
>> }
>> - PermissionCollection pc = permsMap.get(p.getClass());
>> if (pc != null) {
>> // Collection already created
>> return pc;
>> }
>> - return createPermissionCollection(p, createEmpty);
>> - }
>>
>> - private PermissionCollection
>> createPermissionCollection(Permission p,
>> - boolean createEmpty) {
>> synchronized (permsMap) {
>> Class<?> c = p.getClass();
>> PermissionCollection pc = permsMap.get(c);
>>
>> Thanks, Roger
>>
>>
>> On 6/22/20 11:04 AM, Claes Redestad wrote:
>>> Hi,
>>>
>>> this patch fixes a corner-case performance issue with
>>> Permissions.implies(Permission) by not needing to allocate a mapper
>>> function (or lambda) on each invocation of getPermissionCollection
>>> when there are unresolved permissions present.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8247995
>>> Patch: http://cr.openjdk.java.net/~redestad/8247995/open.00/
>>>
>>> Testing: tier1-2
>>>
>>> Thanks!
>>>
>>> /Claes
>>
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