path: root/metrics/metrics.go

// Package metrics provides general system and process level metrics collection.
package metrics

import (
    "os"
    "runtime"
    "strings"
    "time"

    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/rcrowley/go-metrics"
)

// MetricsEnabledFlag is the CLI flag name to use to enable metrics collections.
var MetricsEnabledFlag = "metrics"

// enabled is the flag specifying if metrics are enable or not.
var enabled = false

// Init enables or disables the metrics system. Since we need this to run before
// any other code gets to create meters and timers, we'll actually do an ugly hack
// and peek into the command line args for the metrics flag.
func init() {
    for _, arg := range os.Args {
        if strings.TrimLeft(arg, "-") == MetricsEnabledFlag {
            glog.V(logger.Info).Infof("Enabling metrics collection")
            enabled = true
        }
    }
}

// NewMeter create a new metrics Meter, either a real one of a NOP stub depending
// on the metrics flag.
func NewMeter(name string) metrics.Meter {
    if !enabled {
        return new(metrics.NilMeter)
    }
    return metrics.GetOrRegisterMeter(name, metrics.DefaultRegistry)
}

// NewTimer create a new metrics Timer, either a real one of a NOP stub depending
// on the metrics flag.
func NewTimer(name string) metrics.Timer {
    if !enabled {
        return new(metrics.NilTimer)
    }
    return metrics.GetOrRegisterTimer(name, metrics.DefaultRegistry)
}

// CollectProcessMetrics periodically collects various metrics about the running
// process.
func CollectProcessMetrics(refresh time.Duration) {
    // Short circuit if the metrics system is disabled
    if !enabled {
        return
    }
    // Create the various data collectors
    memstats := make([]*runtime.MemStats, 2)
    diskstats := make([]*DiskStats, 2)
    for i := 0; i < len(memstats); i++ {
        memstats[i] = new(runtime.MemStats)
        diskstats[i] = new(DiskStats)
    }
    // Define the various metrics to collect
    memAllocs := metrics.GetOrRegisterMeter("system/memory/allocs", metrics.DefaultRegistry)
    memFrees := metrics.GetOrRegisterMeter("system/memory/frees", metrics.DefaultRegistry)
    memInuse := metrics.GetOrRegisterMeter("system/memory/inuse", metrics.DefaultRegistry)
    memPauses := metrics.GetOrRegisterMeter("system/memory/pauses", metrics.DefaultRegistry)

    var diskReads, diskReadBytes, diskWrites, diskWriteBytes metrics.Meter
    if err := ReadDiskStats(diskstats[0]); err == nil {
        diskReads = metrics.GetOrRegisterMeter("system/disk/readcount", metrics.DefaultRegistry)
        diskReadBytes = metrics.GetOrRegisterMeter("system/disk/readdata", metrics.DefaultRegistry)
        diskWrites = metrics.GetOrRegisterMeter("system/disk/writecount", metrics.DefaultRegistry)
        diskWriteBytes = metrics.GetOrRegisterMeter("system/disk/writedata", metrics.DefaultRegistry)
    } else {
        glog.V(logger.Debug).Infof("failed to read disk metrics: %v", err)
    }
    // Iterate loading the different stats and updating the meters
    for i := 1; ; i++ {
        runtime.ReadMemStats(memstats[i%2])
        memAllocs.Mark(int64(memstats[i%2].Mallocs - memstats[(i-1)%2].Mallocs))
        memFrees.Mark(int64(memstats[i%2].Frees - memstats[(i-1)%2].Frees))
        memInuse.Mark(int64(memstats[i%2].Alloc - memstats[(i-1)%2].Alloc))
        memPauses.Mark(int64(memstats[i%2].PauseTotalNs - memstats[(i-1)%2].PauseTotalNs))

        if ReadDiskStats(diskstats[i%2]) == nil {
            diskReads.Mark(int64(diskstats[i%2].ReadCount - diskstats[(i-1)%2].ReadCount))
            diskReadBytes.Mark(int64(diskstats[i%2].ReadBytes - diskstats[(i-1)%2].ReadBytes))
            diskWrites.Mark(int64(diskstats[i%2].WriteCount - diskstats[(i-1)%2].WriteCount))
            diskWriteBytes.Mark(int64(diskstats[i%2].WriteBytes - diskstats[(i-1)%2].WriteBytes))
        }
        time.Sleep(refresh)
    }
}