Merge pull request #804 from sbookworm/get_pid_from_file
add the NewPidFileFn to helper
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commit
f97b033d71
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@ -15,7 +15,11 @@ package prometheus
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import (
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"errors"
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"fmt"
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"io/ioutil"
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"os"
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"strconv"
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"strings"
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)
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type processCollector struct {
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@ -149,3 +153,20 @@ func (c *processCollector) reportError(ch chan<- Metric, desc *Desc, err error)
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}
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ch <- NewInvalidMetric(desc, err)
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}
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// NewPidFileFn returns a function that retrieves a pid from the specified file.
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// It is meant to be used for the PidFn field in ProcessCollectorOpts.
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func NewPidFileFn(pidFilePath string) func() (int, error) {
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return func() (int, error) {
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content, err := ioutil.ReadFile(pidFilePath)
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if err != nil {
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return 0, fmt.Errorf("can't read pid file %q: %+v", pidFilePath, err)
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}
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pid, err := strconv.Atoi(strings.TrimSpace(string(content)))
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if err != nil {
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return 0, fmt.Errorf("can't parse pid file %q: %+v", pidFilePath, err)
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}
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return pid, nil
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}
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}
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@ -18,8 +18,11 @@ package prometheus
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import (
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"bytes"
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"errors"
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"fmt"
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"os"
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"path/filepath"
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"regexp"
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"strings"
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"testing"
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"github.com/prometheus/common/expfmt"
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@ -101,3 +104,64 @@ func TestProcessCollector(t *testing.T) {
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t.Errorf("%d metrics collected, want 1", n)
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}
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}
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func TestNewPidFileFn(t *testing.T) {
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folderPath, err := os.Getwd()
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if err != nil {
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t.Error("failed to get current path")
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}
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mockPidFilePath := filepath.Join(folderPath, "mockPidFile")
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defer os.Remove(mockPidFilePath)
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testCases := []struct {
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mockPidFile func()
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expectedErrPrefix string
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expectedPid int
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desc string
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}{
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{
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mockPidFile: func() {
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os.Remove(mockPidFilePath)
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},
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expectedErrPrefix: "can't read pid file",
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expectedPid: 0,
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desc: "no existed pid file",
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},
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{
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mockPidFile: func() {
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os.Remove(mockPidFilePath)
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f, _ := os.Create(mockPidFilePath)
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f.Write([]byte("abc"))
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f.Close()
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},
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expectedErrPrefix: "can't parse pid file",
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expectedPid: 0,
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desc: "existed pid file, error pid number",
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},
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{
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mockPidFile: func() {
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os.Remove(mockPidFilePath)
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f, _ := os.Create(mockPidFilePath)
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f.Write([]byte("123"))
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f.Close()
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},
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expectedErrPrefix: "",
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expectedPid: 123,
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desc: "existed pid file, correct pid number",
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},
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}
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for _, tc := range testCases {
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fn := NewPidFileFn(mockPidFilePath)
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if fn == nil {
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t.Error("Should not get nil PidFileFn")
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}
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tc.mockPidFile()
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if pid, err := fn(); pid != tc.expectedPid || (err != nil && !strings.HasPrefix(err.Error(), tc.expectedErrPrefix)) {
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fmt.Println(err.Error())
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t.Error(tc.desc)
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}
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}
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}
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