Refactor of system/memory metricset (#26334)

* init commit

* start on linux implementation

* finish linux, start work on darwin

* fix build platform issues

* fix metrics on darwin

* add openbsd

* add freebsd

* add windows, aix

* fix aix build

* finish memory

* fix up opt changes

* cleanup metricset code

* fix up folder methods

* fix calculations, Opt API, gomod

* make notice

* go mod tidy, mage fmt

* fix up linux/memory

* update fields

* update system tests

* fix system tests, again

* fix extra print statements

* fix if block in fillPercentages

* vix Value API

* fix up tests, opt

go.mod

@@ -74,7 +74,7 @@ require (
 	github.com/elastic/go-sysinfo v1.7.0
 	github.com/elastic/go-txfile v0.0.7
 	github.com/elastic/go-ucfg v0.8.3
-	github.com/elastic/go-windows v1.0.1 // indirect
+	github.com/elastic/go-windows v1.0.1
 	github.com/elastic/gosigar v0.14.1
 	github.com/fatih/color v1.9.0
 	github.com/fsnotify/fsevents v0.1.1

libbeat/metric/system/process/process.go

@@ -32,7 +32,7 @@ import (
 	"github.com/elastic/beats/v7/libbeat/common"
 	"github.com/elastic/beats/v7/libbeat/common/match"
 	"github.com/elastic/beats/v7/libbeat/logp"
-	"github.com/elastic/beats/v7/libbeat/metric/system/memory"
+	sysinfo "github.com/elastic/go-sysinfo"
 	sigar "github.com/elastic/gosigar"
 	"github.com/elastic/gosigar/cgroup"
 )
@@ -288,12 +288,20 @@ func GetOwnResourceUsageTimeInMillis() (int64, int64, error) {
 
 func (procStats *Stats) getProcessEvent(process *Process) common.MapStr {
 
+	// This is a holdover until we migrate this library to metricbeat/internal
+	// At which point we'll use the memory code there.
 	var totalPhyMem uint64
-	baseMem, err := memory.Get()
+	host, err := sysinfo.Host()
 	if err != nil {
-		procStats.logger.Warnf("Getting memory details: %v", err)
+		procStats.logger.Warnf("Getting host details: %v", err)
 	} else {
-		totalPhyMem = baseMem.Mem.Total
+		memStats, err := host.Memory()
+		if err != nil {
+			procStats.logger.Warnf("Getting memory details: %v", err)
+		} else {
+			totalPhyMem = memStats.Total
+		}
+
 	}
 
 	proc := common.MapStr{

metricbeat/docs/fields.asciidoc

@@ -51614,6 +51614,18 @@ format: bytes
 The total amount of free memory in bytes. This value does not include memory consumed by system caches and buffers (see system.memory.actual.free).
 
 
+type: long
+
+format: bytes
+
+--
+
+*`system.memory.cached`*::
++
+--
+Total Cached memory on system.
+
+
 type: long
 
 format: bytes