Use same key match for containsKey#9158
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headius merged 1 commit intojruby:masterfrom Jan 7, 2026
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The containsKey method was never modified to support identity mode and will inccorrectly return true for distinct object keys that are equals and have the same identity hashcode. This led to bugs in Marshal.dump when many of the same value occurred in an object graph. containsKey would report that such an object was already in the link map, but a subsequent get of that key would produce -1 to be written to the dump. Later loading of that dump would error due to the invalid link index. The fix here modifies containsKey to use the same matching logic as get, with awareness of identity comparison. A test is included that will usually exercise the given logic, if it can produce a duplicate key object within a 5s timeout. If it cannot do that, it will no-op and skip the test. On my MacBook Air M4 with 10ish cores, it finds such a duplicate about 90% of the time. Fixes jruby#9152
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The containsKey method was never modified to support identity mode and will inccorrectly return true for distinct object keys that are equals and have the same identity hashcode. This led to bugs in Marshal.dump when many of the same value occurred in an object graph. containsKey would report that such an object was already in the link map, but a subsequent get of that key would produce -1 to be written to the dump. Later loading of that dump would error due to the invalid link index.
The fix here modifies containsKey to use the same matching logic as get, with awareness of identity comparison.
A test is included that will usually exercise the given logic, if it can produce a duplicate key object within a 5s timeout. If it cannot do that, it will no-op and skip the test. On my MacBook Air M4 with 10ish cores, it finds such a duplicate about 90% of the time.
Fixes #9152