Add cache_calls metric for persistent object cache integration

[Copilot]

Multiple persistent object cache plugins expose backend call counts, but wp profile had no way to surface this data.

Changes

• src/Logger.php — adds $cache_calls public property; adds get_object_cache_calls() static helper that reads from whichever backend is active; start() captures the offset, stop() computes and stores the delta. Gracefully no-ops (shows 0) when no supported backend is present.
• src/Profiler.php — adds $tick_cache_calls_offset for tick-based (function-level) profiling; mirrors the same offset/delta pattern in handle_function_tick() via the shared helper.
• src/Command.php — adds cache_calls to the $metrics fields for stage, hook, eval, and eval-file subcommands.
• features/profile-eval.feature — two new scenarios: one asserting cache_calls = 0 with the default cache; one using a minimal object-cache.php drop-in that mimics the cache_calls array format to assert the count is correct.

Supported backends

The get_object_cache_calls() helper checks each source in order:

Plugin	Property / Method
WP Redis	$wp_object_cache->redis_calls (array of command → count)
Redis Object Cache	$wp_object_cache->cache_calls (array of command → count)
Object Cache Pro	$wp_object_cache->metrics()->storeReads + storeWrites

Example output

$ wp profile eval 'wp_cache_set( "foo", "bar" ); wp_cache_get( "foo" ); wp_cache_get( "foo" );' \
    --fields=cache_hits,cache_misses,cache_calls
+------------+--------------+-------------+
| cache_hits | cache_misses | cache_calls |
+------------+--------------+-------------+
| 2          | 0            | 3           |
+------------+--------------+-------------+

[codecov]

Codecov Report

❌ Patch coverage is 58.13953% with 18 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/Profiler.php	0.00%	14 Missing ⚠️
src/Logger.php	84.00%	4 Missing ⚠️

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[swissspidy]

@copilot address the review comments

#219 (comment)

#219 (comment)

[Copilot]

@copilot address the review comments

#219 (comment)
...

Done in 20c95b9. Two changes made:

1. Renamed the metric from redis_calls to cache_calls across all files (Logger, Profiler, Command, and feature tests).

2. Added a Logger::get_object_cache_calls() static helper that checks all three backends in order:

   • WP Redis: $wp_object_cache->redis_calls (array)
   • Redis Object Cache: $wp_object_cache->cache_calls (array)
   • Object Cache Pro: $wp_object_cache->metrics()->storeReads + storeWrites

   Falls back to null (not tracked) when none of these are present, so the default WP object cache shows 0.

[swissspidy]

@copilot fix failing tests. apparently get_object_cache_calls() is being passed null as an argument

[Copilot]

@copilot fix failing tests. apparently get_object_cache_calls() is being passed null as an argument

Fixed in e13fa72. Added an is_object() guard at the top of get_object_cache_calls() — PHP 8 made method_exists(null, ...) throw a TypeError, so the function now returns null early when passed a non-object (including null).