1 files changed, 66 insertions, 0 deletions

diff --git a/vendor/github.com/hashicorp/terraform/helper/shadow/ordered_value.go b/vendor/github.com/hashicorp/terraform/helper/shadow/ordered_value.go
new file mode 100644
index 0000000..0a43d4d
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/helper/shadow/ordered_value.go
@@ -0,0 +1,66 @@
+package shadow
+
+import (
+        "container/list"
+        "sync"
+)
+
+// OrderedValue is a struct that keeps track of a value in the order
+// it is set. Each time Value() is called, it will return the most recent
+// calls value then discard it.
+//
+// This is unlike Value that returns the same value once it is set.
+type OrderedValue struct {
+        lock    sync.Mutex
+        values  *list.List
+        waiters *list.List
+}
+
+// Value returns the last value that was set, or blocks until one
+// is received.
+func (w *OrderedValue) Value() interface{} {
+        w.lock.Lock()
+
+        // If we have a pending value already, use it
+        if w.values != nil && w.values.Len() > 0 {
+                front := w.values.Front()
+                w.values.Remove(front)
+                w.lock.Unlock()
+                return front.Value
+        }
+
+        // No pending value, create a waiter
+        if w.waiters == nil {
+                w.waiters = list.New()
+        }
+
+        var val Value
+        w.waiters.PushBack(&val)
+        w.lock.Unlock()
+
+        // Return the value once we have it
+        return val.Value()
+}
+
+// SetValue sets the latest value.
+func (w *OrderedValue) SetValue(v interface{}) {
+        w.lock.Lock()
+        defer w.lock.Unlock()
+
+        // If we have a waiter, notify it
+        if w.waiters != nil && w.waiters.Len() > 0 {
+                front := w.waiters.Front()
+                w.waiters.Remove(front)
+
+                val := front.Value.(*Value)
+                val.SetValue(v)
+                return
+        }
+
+        // Add it to the list of values
+        if w.values == nil {
+                w.values = list.New()
+        }
+
+        w.values.PushBack(v)
+}