fix: use monotonic clock for elapsed time and handle nil max_elapsed_time

[kamui]

Summary

• Monotonic clock: Replace Time.now with Process.clock_gettime(CLOCK_MONOTONIC) for elapsed-time tracking in the retry loop. Wall-clock time (Time.now) is susceptible to NTP adjustments and manual system clock changes, which can cause retries to stop early or run too long. Monotonic clock is the correct primitive for measuring durations.

• Nil-safe max_elapsed_time: Guard can_retry? so that max_elapsed_time: nil means "no time limit" instead of raising NoMethodError on the <= comparison. This is a runtime crash that only manifests after a failure+retry, making it easy to miss in testing.

• Remove dead * 1.0: The randomize method in ExponentialBackoff multiplied by 1.0 unnecessarily — rand_factor is already a float.

Testing

• Two new regression specs: one verifying max_elapsed_time: nil retries up to tries limit, one verifying Process.clock_gettime(CLOCK_MONOTONIC) is called during retries.
• All 59 specs pass. No RuboCop offenses on changed files.

[Copilot]

Pull request overview

This PR improves the reliability and configurability of Retriable’s retry loop by switching elapsed-time tracking to a monotonic clock and making max_elapsed_time nil-safe to avoid runtime crashes during retries.

Changes:

• Use Process.clock_gettime(Process::CLOCK_MONOTONIC) instead of Time.now for elapsed-time measurement.
• Treat max_elapsed_time: nil as “no elapsed-time limit” in retry eligibility checks.
• Simplify exponential backoff randomization math by removing a float-coercion multiplier.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
spec/retriable_spec.rb	Adds regression specs for max_elapsed_time: nil and monotonic clock usage.
lib/retriable/exponential_backoff.rb	Removes * 1.0 from randomization calculation and minor expression tweak.
lib/retriable.rb	Switches elapsed-time tracking to monotonic clock; makes can_retry? nil-safe for max_elapsed_time.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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