adds ability to set cache expiration from pulsed cli

control/control.go

@@ -98,6 +98,12 @@ func MaxRunningPlugins(m int) controlOpt {
 	}
 }
 
+func CacheExpiration(t time.Duration) controlOpt {
+	return func(c *pluginControl) {
+		client.CacheExpiration = t
+	}
+}
+
 // New returns a new pluginControl instance
 func New(opts ...controlOpt) *pluginControl {
 

control/plugin/client/cache.go

@@ -8,9 +8,11 @@ import (
 	"github.com/intelsdi-x/pulse/core"
 )
 
+// the time limit for which a cache entry is valid.
+var CacheExpiration time.Duration
+
 var (
-	cacheExpiration = time.Duration(500 * time.Millisecond)
-	metricCache     = cache{
+	metricCache = cache{
 		table: make(map[string]*cachecell),
 	}
 	cacheLog = log.WithField("_module", "client-cache")
@@ -32,7 +34,7 @@ func (c *cache) get(key string) core.Metric {
 		cell *cachecell
 		ok   bool
 	)
-	if cell, ok = c.table[key]; ok && time.Since(cell.time) < cacheExpiration {
+	if cell, ok = c.table[key]; ok && time.Since(cell.time) < CacheExpiration {
 		cell.hits++
 		cacheLog.WithFields(log.Fields{
 			"namespace": key,

control/plugin/client/cache_test.go

@@ -10,6 +10,7 @@ import (
 )
 
 func TestCache(t *testing.T) {
+	CacheExpiration = time.Duration(500 * time.Millisecond)
 	Convey("puts and gets a metric", t, func() {
 		mc := &cache{
 			table: make(map[string]*cachecell),

pulse.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"syscall"
+	"time"
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
@@ -56,6 +57,12 @@ var (
 		Usage:  "Auto discover paths separated by colons.",
 		EnvVar: "PULSE_AUTOLOAD_PATH",
 	}
+	flCache = cli.StringFlag{
+		Name:   "cache-expiration",
+		Usage:  "The time limit for which a metric cache entry is valid",
+		EnvVar: "PULSE_CACHE_EXPIRATION",
+		Value:  "500ms",
+	}
 	gitversion string
 )
 
@@ -80,7 +87,7 @@ func main() {
 	app.Name = "pulsed"
 	app.Version = gitversion
 	app.Usage = "A powerful telemetry agent framework"
-	app.Flags = []cli.Flag{flAPIDisabled, flAPIPort, flLogLevel, flLogPath, flMaxProcs, flPluginVersion, flNumberOfPLs}
+	app.Flags = []cli.Flag{flAPIDisabled, flAPIPort, flLogLevel, flLogPath, flMaxProcs, flPluginVersion, flNumberOfPLs, flCache}
 
 	app.Action = action
 	app.Run(os.Args)
@@ -102,6 +109,11 @@ func action(ctx *cli.Context) {
 	apiPort := ctx.Int("api-port")
 	autodiscoverPath := ctx.String("auto-discover")
 	maxRunning := ctx.Int("max-running-plugins")
+	cachestr := ctx.String("cache-expiration")
+	cache, err := time.ParseDuration(cachestr)
+	if err != nil {
+		log.Fatal(fmt.Sprintf("invalid cache-expiration format: %s", cachestr))
+	}
 
 	log.Info("Starting pulsed (version: ", gitversion, ")")
 
@@ -161,6 +173,7 @@ func action(ctx *cli.Context) {
 
 	c := control.New(
 		control.MaxRunningPlugins(maxRunning),
+		control.CacheExpiration(cache),
 	)
 	s := scheduler.New(
 		scheduler.CollectQSizeOption(defaultQueueSize),