fleetctl: add tryWaitForUnitStates() and getBlockAttempts()

Djalal Harouni · Djalal Harouni · commit 75b60886e6f6 · 2016-02-17T12:16:17.000+01:00
* tryWaitForUnitStates() tries to wait for units to reach the desired state.
* getBlockAttempts() gets the correct value of how many attempts to try
		     before giving up on an operation.

These helpers will be used to make the code more consistent and clean.
We do not intended to change any behaviour here.

---
diff --git a/fleetctl/fleetctl.go b/fleetctl/fleetctl.go
@@ -745,6 +745,56 @@ func setTargetStateOfUnits(units []string, state job.JobState) ([]*schema.Unit,
 	return triggered, nil
 }
 
+// getBlockAttempts gets the correct value of how many attempts to try
+// before giving up on an operation.
+// It returns a negative value which means try forever, if zero is
+// returned then do not make any attempt, and if a positive value is
+// returned then try up to that value
+func getBlockAttempts() int {
+	// By default we wait forever
+	var attempts int = -1
+
+	// Up to BlockAttempts
+	if sharedFlags.BlockAttempts > 0 {
+		attempts = sharedFlags.BlockAttempts
+	}
+
+	// NoBlock we do not wait
+	if sharedFlags.NoBlock {
+		attempts = 0
+	}
+
+	return attempts
+}
+
+// tryWaitForUnitStates tries to wait for units to reach the desired state.
+// It takes 5 arguments, the units to wait for, the desired state, the
+// desired JobState, how many attempts before timing out and a writer
+// interface.
+// tryWaitForUnitStates polls each of the indicated units until they
+// reach the desired state. If maxAttempts is zero, then it will not
+// wait, it will assume that all units reached their desired state.
+// If maxAttempts is negative tryWaitForUnitStates will retry forever, and
+// if it is greater than zero, it will retry up to the indicated value.
+// It returns 0 on success or 1 on errors.
+func tryWaitForUnitStates(units []string, state string, js job.JobState, maxAttempts int, out io.Writer) (ret int) {
+	// We do not wait just assume we reached the desired state
+	if maxAttempts == 0 {
+		for _, name := range units {
+			stdout("Triggered unit %s %s", name, state)
+		}
+		return
+	}
+
+	errchan := waitForUnitStates(units, js, maxAttempts, out)
+	for err := range errchan {
+		stderr("Error waiting for units: %v", err)
+		ret = 1
+	}
+
+	return
+}
+
 // waitForUnitStates polls each of the indicated units until each of their
 // states is equal to that which the caller indicates, or until the
 // polling operation times out. waitForUnitStates will retry forever, or
