fix: json: cannot unmarshal number (#28)

* fixes hipages/php-fpm_exporter#26
* better comments & fix tests

phpfpm/phpfpm.go

@@ -84,6 +84,8 @@ type Pool struct {
 	Processes           []PoolProcess `json:"processes"`
 }
 
+type requestDuration int64
+
 // PoolProcess describes a single PHP-FPM process. A pool can have multiple processes.
 type PoolProcess struct {
 	PID               int64           `json:"pid"`
@@ -91,7 +93,7 @@ type PoolProcess struct {
 	StartTime         int64           `json:"start time"`
 	StartSince        int64           `json:"start since"`
 	Requests          int64           `json:"requests"`
-	RequestDuration   int64   `json:"request duration"`
+	RequestDuration   requestDuration `json:"request duration"`
 	RequestMethod     string          `json:"request method"`
 	RequestURI        string          `json:"request uri"`
 	ContentLength     int64           `json:"content length"`
@@ -257,6 +259,25 @@ func (t *timestamp) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+// This is because of bug in php-fpm that can return 'request duration' which can't
+// fit to int64. For details check links:
+// https://bugs.php.net/bug.php?id=62382
+// https://serverfault.com/questions/624977/huge-request-duration-value-for-a-particular-php-script
+func (rd *requestDuration) MarshalJSON() ([]byte, error) {
+	stamp := fmt.Sprint(rd)
+	return []byte(stamp), nil
+}
+
+func (rd *requestDuration) UnmarshalJSON(b []byte) error {
+	rdc, err := strconv.Atoi(string(b))
+	if err != nil {
+		*rd = 0
+	} else {
+		*rd = requestDuration(rdc)
+	}
+	return nil
+}
+
 // SetLogger configures the used logger
 func SetLogger(logger logger) {
 	log = logger

phpfpm/phpfpm_test.go

@@ -91,7 +91,9 @@ func TestCannotUnmarshalNumberIssue10(t *testing.T) {
 
 	err := json.Unmarshal(content, &pool)
 
-	assert.NotNil(t, err, err.Error())
+	assert.Nil(t, err, "successfully unmarshal on invalid 'request duration'")
+	assert.Equal(t, int(pool.Processes[0].RequestDuration), 295, "request duration set to 0 because it couldn't be deserialized")
+	assert.Equal(t, int(pool.Processes[1].RequestDuration), 0, "request duration set to 0 because it couldn't be deserialized")
 }
 
 func TestParseURL(t *testing.T) {