Makes the timeout behavior more intuitive.

Previously, it would try once "up to" the timeout, but in practice it would
just fall through. This modifies the behavior to block until the timeout has
been reached.

api/lock.go

@@ -167,6 +167,7 @@ func (l *Lock) Lock(stopCh <-chan struct{}) (<-chan struct{}, error) {
 		WaitTime: l.opts.LockWaitTime,
 	}
 
+	start := time.Now()
 	attempts := 0
 WAIT:
 	// Check if we should quit
@@ -176,9 +177,14 @@ WAIT:
 	default:
 	}
 
-	// See if we completed a one-shot.
-	if attempts > 0 && l.opts.LockTryOnce {
-		return nil, nil
+	// Handle the one-shot mode.
+	if l.opts.LockTryOnce && attempts > 0 {
+		elapsed := time.Now().Sub(start)
+		if elapsed > qOpts.WaitTime {
+			return nil, nil
+		}
+
+		qOpts.WaitTime -= elapsed
 	}
 	attempts++
 

api/lock_test.go

@@ -541,8 +541,9 @@ func TestLock_OneShot(t *testing.T) {
 	if ch != nil {
 		t.Fatalf("should not be leader")
 	}
-	if diff := time.Now().Sub(start); diff > 2*contender.opts.LockWaitTime {
-		t.Fatalf("took too long: %9.6f", diff.Seconds())
+	diff := time.Now().Sub(start)
+	if diff < contender.opts.LockWaitTime || diff > 2*contender.opts.LockWaitTime {
+		t.Fatalf("time out of bounds: %9.6f", diff.Seconds())
 	}
 
 	// Unlock and then make sure the contender can get it.

api/semaphore.go

@@ -186,6 +186,7 @@ func (s *Semaphore) Acquire(stopCh <-chan struct{}) (<-chan struct{}, error) {
 		WaitTime: s.opts.SemaphoreWaitTime,
 	}
 
+	start := time.Now()
 	attempts := 0
 WAIT:
 	// Check if we should quit
@@ -195,9 +196,14 @@ WAIT:
 	default:
 	}
 
-	// See if we completed a one-shot.
-	if attempts > 0 && s.opts.SemaphoreTryOnce {
-		return nil, nil
+	// Handle the one-shot mode.
+	if s.opts.SemaphoreTryOnce && attempts > 0 {
+		elapsed := time.Now().Sub(start)
+		if elapsed > qOpts.WaitTime {
+			return nil, nil
+		}
+
+		qOpts.WaitTime -= elapsed
 	}
 	attempts++
 

api/semaphore_test.go

@@ -499,8 +499,9 @@ func TestSemaphore_OneShot(t *testing.T) {
 	if ch != nil {
 		t.Fatalf("should not have acquired the semaphore")
 	}
-	if diff := time.Now().Sub(start); diff > 2*contender.opts.SemaphoreWaitTime {
-		t.Fatalf("took too long: %9.6f", diff.Seconds())
+	diff := time.Now().Sub(start)
+	if diff < contender.opts.SemaphoreWaitTime || diff > 2*contender.opts.SemaphoreWaitTime {
+		t.Fatalf("time out of bounds: %9.6f", diff.Seconds())
 	}
 
 	// Give up a slot and make sure the third one can get it.

command/lock.go

@@ -75,8 +75,8 @@ Options:
   -name=""                   Optional name to associate with lock session.
   -token=""                  ACL token to use. Defaults to that of agent.
   -pass-stdin                Pass stdin to child process.
-  -try=duration              Make a single attempt to acquire the lock, waiting
-                             up to the given duration (eg. "15s").
+  -try=timeout               Attempt to acquire the lock up to the given
+                             timeout (eg. "15s").
   -monitor-retry=n           Retry up to n times if Consul returns a 500 error
                              while monitoring the lock. This allows riding out brief
                              periods of unavailability without causing leader
@@ -145,12 +145,12 @@ func (c *LockCommand) run(args []string, lu **LockUnlock) int {
 		var err error
 		wait, err = time.ParseDuration(try)
 		if err != nil {
-			c.Ui.Error(fmt.Sprintf("Error parsing duration for 'try' option: %s", err))
+			c.Ui.Error(fmt.Sprintf("Error parsing try timeout: %s", err))
 			return 1
 		}
 
-		if wait < 0 {
-			c.Ui.Error("Duration for 'try' option must be positive")
+		if wait <= 0 {
+			c.Ui.Error("Try timeout must be positive")
 			return 1
 		}
 

command/lock_test.go

@@ -29,8 +29,9 @@ func argFail(t *testing.T, args []string, expected string) {
 }
 
 func TestLockCommand_BadArgs(t *testing.T) {
-	argFail(t, []string{"-try=blah", "test/prefix", "date"}, "parsing duration")
-	argFail(t, []string{"-try=-10s", "test/prefix", "date"}, "must be positive")
+	argFail(t, []string{"-try=blah", "test/prefix", "date"}, "parsing try timeout")
+	argFail(t, []string{"-try=0s", "test/prefix", "date"}, "timeout must be positive")
+	argFail(t, []string{"-try=-10s", "test/prefix", "date"}, "timeout must be positive")
 	argFail(t, []string{"-monitor-retry=-5", "test/prefix", "date"}, "must be >= 0")
 }
 

website/source/docs/commands/lock.html.markdown

@@ -62,10 +62,9 @@ The list of available flags are:
 
 * `-pass-stdin` - Pass stdin to child process.
 
-* `-try` - Make a single attempt to acquire the lock, waiting up to the given
-  duration supplied as the argument. The duration is a decimal number, with
-  unit suffix, such as "500ms". Valid time units are "ns", "us" (or "µs"), "ms",
-  "s", "m", "h".
+* `-try` - Attempt to acquire the lock up to the given timeout. The timeout is a
+  positive decimal number, with unit suffix, such as "500ms". Valid time units
+  are "ns", "us" (or "µs"), "ms", "s", "m", "h".
 
 * `-monitor-retry` - Retry up to this number of times if Consul returns a 500 error
    while monitoring the lock. This allows riding out brief periods of unavailability