Module counters 

Low-distortion performance instrumentation for fdu.

The subsystem has two complementary tiers:

• application counters attribute logical work to the filesystem, memory, and index layers;
• process samples kernel counters at phase boundaries and exposes only metrics supported by the current platform.

Recording is compiled in, off by default, and enabled with FDU_COUNTERS=1 by the shipped CLI and the repository performance probe. Per-event updates stay thread-local; workers fold their counts on exit, while a drop fallback preserves counts from callers that do not install an explicit worker guard.

Modules

alloc

A global allocator wrapper with certified, non-reentrant counter sinks.

process

Kernel-reported process counters sampled at phase boundaries.

Structs

Counts

Per-layer tallies for a walk, index build, and content pass.

Measurement

One opt-in instrumentation interval for a binary invocation.

Functions

bump

Add to one or more counters on the calling thread.

enable

Turn recording on or off for the whole process.

enable_from_env

Turn recording on when FDU_COUNTERS contains a truthy value.

enabled

Whether recording is currently on.

flush_thread

Fold this thread’s counts into the process total and clear them.

render

Render application counters followed by the supported kernel process counters.

reset

Clear process totals and the calling thread’s local counts.

snapshot

Process-wide totals, including the calling thread’s unflushed counts.

system_allocator

Create fdu’s certified system-allocator wrapper for a binary’s global allocator.

thread_snapshot

The calling thread’s unflushed counts, without consuming them.