Remove static cache for generated names in SimpleNameFactory #149
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The `SimpleNameFactory` was using a static List in an attempt to improve performance, by avoiding the need to recreate the String name multiple times. The implementation was not thread-safe, and could result in invalid names being produced when Proguard was being run concurrently within the same classloader. When 2 threads entered `getName()` simultaneously, they could both construct the same name value for the same index, and both would then add these names to the static Map. This resulted in a name List like `['a', 'a', 'c', ...]. This bug would manifest itself with a `Duplicate Jar Entry` exception, due to the fact that `SimpleNameFactory` would return the same name value on subsequent calls. This commit merely removes the optimization. If name generation is demonstated to be a performance bottleneck, and safer optimization should be implemented, ensuring correct synchronization on shared resources.
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mrjameshamilton
approved these changes
Apr 26, 2021
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The
SimpleNameFactorywas using a static List in an attempt to improve performance,by avoiding the need to recreate the String name multiple times. The implementation
was not thread-safe, and could result in invalid names being produced when Proguard
was being run concurrently within the same classloader.
When 2 threads entered
getName()simultaneously, they could both construct the samename value for the same index, and both would then add these names to the static Map.
This resulted in a name List like `['a', 'a', 'c', ...].
This bug would manifest itself with a
Duplicate Jar Entryexception, due to the factthat
SimpleNameFactorywould return the same name value on subsequent calls.This fact was verified by logging the names produced by
SimpleNameFactory.This commit merely removes the questionable optimization. If name generation is demonstrated
to be a performance bottleneck a safer optimization should be implemented, ensuring
correct synchronization on shared resources.