Make all registry methods thread safe #201
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matthieuprat commented Aug 25, 2020
| | ||
| @mutex.synchronize do | ||
| if exist?(name.to_sym) | ||
| if @metrics.key?(name.to_sym) |
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I made this change because Mutex is not re-entrant. I guess we could use a Monitor instead but inlining the exist? method actually makes the code slightly more readable in my opinion.
The registry is backed by a Hash, which is not guaranteed to be thread safe on all interpreters. For peace of mind, this change synchronizes all accesses to the metrics hash. Another option would have been to use a [thread-safe Hash][1] instead of a Hash but this would have meant adding Ruby Concurrent as a dependency, which I'm assuming we don't want. Ref: prometheus#184 (comment) [1]: https://github.com/ruby-concurrency/concurrent-ruby/blob/v1.1.7/lib/concurrent-ruby/concurrent/hash.rb Signed-off-by: Matthieu Prat <matthieuprat@gocardless.com>
matthieuprat force-pushed the mprat/resgistry-thread-safety branch from e067f95 to c3836b2 Compare 
dmagliola approved these changes Oct 7, 2020
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| Sorry I somehow missed this for a month and a half! |
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The registry is backed by a Hash, which is not guaranteed to be thread
safe on all interpreters. For peace of mind, this change synchronizes
all accesses to the metrics hash.
Another option would have been to use a thread-safe Hash instead of
a Hash but this would have meant adding Ruby Concurrent as a
dependency, which I'm assuming we don't want.
Ref: #184 (comment)