fix(config): guard NPE in getGrayLastModifiedTs and add volatile to DCL - #15669
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fix(config): guard NPE in getGrayLastModifiedTs and add volatile to DCL#15669srpatcha wants to merge 1 commit into
srpatcha wants to merge 1 commit into
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Two issues in the config module: 1. ConfigCacheService.getGrayLastModifiedTs dereferenced the CacheItem returned by CACHE.get(groupKey) without a null check, even though that map lookup can return null. Every sibling method (getContentGrayMd5, getGrayRule) already guards item == null. Added the missing guard so a non-existent group key returns 0 instead of throwing a NullPointerException. 2. ConfigDiskServiceFactory used double-checked locking on a non-volatile static field. Without volatile, the Java Memory Model allows a thread to observe a non-null reference to a partially-constructed object. Declared configDiskService volatile for safe publication. Also adds a regression assertion in ConfigCacheServiceTest covering the non-existent group key path for getGrayLastModifiedTs. Fixes alibaba#15625 Signed-off-by: Srikanth Patchava <spatchava@meta.com>
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Thanks for your this PR. 🙏 感谢您提交的PR。 🙏 |
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duplicated PR, reference：#15666 |
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What is the purpose of the change
Fixes #15625
Two targeted correctness fixes in the
configmodule.1. NPE in
ConfigCacheService.getGrayLastModifiedTsThe method dereferenced the
CacheItemreturned byCACHE.get(groupKey)without a null check, even though that lookup can returnnull. Every sibling method (getContentGrayMd5,getGrayRule) already guardsitem == null. A query for a non-existent group key would throw aNullPointerExceptioninstead of returning0.2. Broken double-checked locking in
ConfigDiskServiceFactoryThe singleton used double-checked locking but the static field was not
volatile. Withoutvolatile, the JMM permits a thread to observe a non-null reference to a partially-constructed object (classic broken DCL). Declared the fieldvolatilefor safe publication.Brief changelog
ConfigCacheService.getGrayLastModifiedTs: additem == nullguard consistent with sibling methods.ConfigDiskServiceFactory.configDiskService: markvolatile.ConfigCacheServiceTest.testGetGrayLastModifiedTs: add regression assertion for the non-existent group-key path.Verifying this change
testGetGrayLastModifiedTsextended to assertgetGrayLastModifiedTs("noKey", grayName) == 0(previously would NPE).