move implementation to internal/ directory (#828)

internal/zfs/zfscmd/zfscmd_logging.go

@@ -0,0 +1,42 @@
+package zfscmd
+
+import (
+	"time"
+)
+
+// Implementation Note:
+//
+// Pre-events logged with debug
+// Post-event without error logged with info
+// Post-events with error _also_ logged with info
+// (Not all errors we observe at this layer) are actual errors in higher-level layers)
+
+func startPreLogging(c *Cmd, now time.Time) {
+	c.log().Debug("starting command")
+}
+
+func startPostLogging(c *Cmd, err error, now time.Time) {
+	if err == nil {
+		c.log().Info("started command")
+	} else {
+		c.log().WithError(err).Error("cannot start command")
+	}
+}
+
+func waitPreLogging(c *Cmd, now time.Time) {
+	c.log().Debug("start waiting")
+}
+
+func waitPostLogging(c *Cmd, u usage, err error, now time.Time) {
+
+	log := c.log().
+		WithField("total_time_s", u.total_secs).
+		WithField("systemtime_s", u.system_secs).
+		WithField("usertime_s", u.user_secs)
+
+	if err == nil {
+		log.Info("command exited without error")
+	} else {
+		log.WithError(err).Info("command exited with error")
+	}
+}