prometheus / client_ruby / 517

100%

master: 100%

Pull #160

travis-ci

Reduce memory bloating in FileMappedDict when reading metrics.

During the read path (metrics export) we open all existing metric files
and read through them in order to aggregate metrics across different
processes. When reading non-empty files we end up parsing file content
twice: first during FileMappedDict initialisation, then again in the
caller site (`all_values`).

This commit refactors FileMappedDict so that while the `@positions` map
is populated at creation time, the actual metric values are read only
when explicitly requested. This avoids the memory bloat of unpacking
file content twice.

9 of 9 new or added lines in 1 file covered. (100.0%)

2958 of 2958 relevant lines covered (100.0%)

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