This reverts commit 55d5027c97e2484d3e2b63ec6eb54845a8f69227.
Reason for revert: the process_resident_memory_anonymous_bytes and process_resident_memory_pagecache_bytes metrics have been substituted
by more complete set of metrics in the commit 5a49bb8e88e070e43cbffaa68776259f11f6c053:
* process_resident_memory_anon_bytes
* process_resident_memory_file_bytes
* process_resident_memory_shared_bytes
Metrics are:
process_io_read_bytes_total - the number of bytes read via io syscalls such as read and pread
process_io_written_bytes_total - the number of bytes written via io syscalls such as write and pwrite
process_io_read_syscalls_total - the number of read syscalls such as read and pread
process_io_write_syscalls_total - the number of write syscalls such as write and pwrite
process_io_storage_read_bytes_total - the number of bytes read from storage layer
process_io_storage_written_bytes_total - the number of bytes written to storage layer
Log-based histograms provide lower estimation error for the same number of buckets compared to log-linear histograms.
For example, the current Histogram implementation splits each decimal range (10^n .. 10^(n+1)] into 18 buckets.
These buckets have the following bounds:
- for log-linear histogram: (1 .. 1.5], (1.5 .. 2], (2 .. 2.5], ... (9.5 .. 10]
- for log-based histogram: (1 .. 1.136], (1.136 .. 1.292], ... (8.799 ... 10]
The maximum estimated error for log-linear histogram is reached in the first bucket per each decimal range and equals to 1.5-1=0.5 or 50%.
The maximum estimated error for log-based histogram is constant across buckets and equals to 1.136-1=0.136 or 13.6%.
This means that log-based histogram improves histogram accuracy by up to 50%/13.6% = 3.6 times when using the same number of buckets.
Further reading - https://linuxczar.net/blog/2020/08/13/histogram-error/
The change covers two things:
1. Cleanup of Set.a metrics list from per-quantile metrics
for summary.
2. Register summary metric and per-quantile metrics in one take.
This prevents registry corruption when Unregister called in the
middle of metric register process.
* Allow unregistration of metrics
* Provide metrics.WritePrometheusSet to write using a dedicated metric set
* Cleanup unregister metrics patch, add generic WriteProcessMetrics
* Add new type of counter: FloatCounter
* sometimes you need to count things with more precision than uint64
* FloatCounter also usefull if you need setable Gauge w/o callback func
* Fix PR review:
* sync.RWMutex -> sync.Mutex
* more idiomatic add/sub
