Minor cleanup in perf collector (#1616)

* Use `strconv.Itoa()` instead of `fmt.Sprintf()` for simple conversion.
* Eliminate copy-paste in collector setup.

Signed-off-by: Ben Kochie <superq@gmail.com>

1 files changed, 28 insertions, 38 deletions

diff --git a/collector/perf_linux.go b/collector/perf_linux.go
index b67f970..bb8716a 100644
--- a/collector/perf_linux.go
+++ b/collector/perf_linux.go
@@ -111,52 +111,42 @@ func NewPerfCollector(logger log.Logger) (Collector, error) {
                 logger:              logger,
         }
 
+        var (
+                cpus []int
+                err  error
+        )
         if perfCPUsFlag != nil && *perfCPUsFlag != "" {
-                cpus, err := perfCPUFlagToCPUs(*perfCPUsFlag)
+                cpus, err = perfCPUFlagToCPUs(*perfCPUsFlag)
                 if err != nil {
                         return nil, err
                 }
-                for _, cpu := range cpus {
-                        // Use -1 to profile all processes on the CPU, see:
-                        // man perf_event_open
-                        hwProf := perf.NewHardwareProfiler(-1, cpu)
-                        if err := hwProf.Start(); err != nil {
-                                return nil, err
-                        }
-                        collector.perfHwProfilers[cpu] = &hwProf
-
-                        swProf := perf.NewSoftwareProfiler(-1, cpu)
-                        if err := swProf.Start(); err != nil {
-                                return nil, err
-                        }
-                        collector.perfSwProfilers[cpu] = &swProf
+        } else {
+                cpus = make([]int, runtime.NumCPU())
+                for i := range cpus {
+                        cpus[i] = i
+                }
+        }
 
-                        cacheProf := perf.NewCacheProfiler(-1, cpu)
-                        if err := cacheProf.Start(); err != nil {
-                                return nil, err
-                        }
-                        collector.perfCacheProfilers[cpu] = &cacheProf
+        for _, cpu := range cpus {
+                // Use -1 to profile all processes on the CPU, see:
+                // man perf_event_open
+                hwProf := perf.NewHardwareProfiler(-1, cpu)
+                if err := hwProf.Start(); err != nil {
+                        return nil, err
                 }
-        } else {
-                for i := 0; i < runtime.NumCPU(); i++ {
-                        hwProf := perf.NewHardwareProfiler(-1, i)
-                        if err := hwProf.Start(); err != nil {
-                                return nil, err
-                        }
-                        collector.perfHwProfilers[i] = &hwProf
+                collector.perfHwProfilers[cpu] = &hwProf
 
-                        swProf := perf.NewSoftwareProfiler(-1, i)
-                        if err := swProf.Start(); err != nil {
-                                return nil, err
-                        }
-                        collector.perfSwProfilers[i] = &swProf
+                swProf := perf.NewSoftwareProfiler(-1, cpu)
+                if err := swProf.Start(); err != nil {
+                        return nil, err
+                }
+                collector.perfSwProfilers[cpu] = &swProf
 
-                        cacheProf := perf.NewCacheProfiler(-1, i)
-                        if err := cacheProf.Start(); err != nil {
-                                return nil, err
-                        }
-                        collector.perfCacheProfilers[i] = &cacheProf
+                cacheProf := perf.NewCacheProfiler(-1, cpu)
+                if err := cacheProf.Start(); err != nil {
+                        return nil, err
                 }
+                collector.perfCacheProfilers[cpu] = &cacheProf
         }
 
         collector.desc = map[string]*prometheus.Desc{
@@ -425,7 +415,7 @@ func (c *perfCollector) Update(ch chan<- prometheus.Metric) error {
 func (c *perfCollector) updateHardwareStats(ch chan<- prometheus.Metric) error {
         for _, profiler := range c.perfHwProfilers {
                 cpuid := c.hwProfilerCPUMap[profiler]
-                cpuStr := fmt.Sprintf("%d", cpuid)
+                cpuStr := strconv.Itoa(cpuid)
                 hwProfile, err := (*profiler).Profile()
                 if err != nil {
                         return err