1 files changed, 128 insertions, 0 deletions
diff --git a/vendor/github.com/hashicorp/terraform/helper/shadow/compared_value.go b/vendor/github.com/hashicorp/terraform/helper/shadow/compared_value.go
new file mode 100644
index 00000000..4223e925
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/helper/shadow/compared_value.go
@@ -0,0 +1,128 @@
+package shadow
+
+import (
+	"sync"
+)
+
+// ComparedValue is a struct that finds a value by comparing some key
+// to the list of stored values. This is useful when there is no easy
+// uniquely identifying key that works in a map (for that, use KeyedValue).
+//
+// ComparedValue is very expensive, relative to other Value types. Try to
+// limit the number of values stored in a ComparedValue by potentially
+// nesting it within a KeyedValue (a keyed value points to a compared value,
+// for example).
+type ComparedValue struct {
+	// Func is a function that is given the lookup key and a single
+	// stored value. If it matches, it returns true.
+	Func func(k, v interface{}) bool
+
+	lock    sync.Mutex
+	once    sync.Once
+	closed  bool
+	values  []interface{}
+	waiters map[interface{}]*Value
+}
+
+// Close closes the value. This can never fail. For a definition of
+// "close" see the ErrClosed docs.
+func (w *ComparedValue) Close() error {
+	w.lock.Lock()
+	defer w.lock.Unlock()
+
+	// Set closed to true always
+	w.closed = true
+
+	// For all waiters, complete with ErrClosed
+	for k, val := range w.waiters {
+		val.SetValue(ErrClosed)
+		delete(w.waiters, k)
+	}
+
+	return nil
+}
+
+// Value returns the value that was set for the given key, or blocks
+// until one is available.
+func (w *ComparedValue) Value(k interface{}) interface{} {
+	v, val := w.valueWaiter(k)
+	if val == nil {
+		return v
+	}
+
+	return val.Value()
+}
+
+// ValueOk gets the value for the given key, returning immediately if the
+// value doesn't exist. The second return argument is true if the value exists.
+func (w *ComparedValue) ValueOk(k interface{}) (interface{}, bool) {
+	v, val := w.valueWaiter(k)
+	return v, val == nil
+}
+
+func (w *ComparedValue) SetValue(v interface{}) {
+	w.lock.Lock()
+	defer w.lock.Unlock()
+	w.once.Do(w.init)
+
+	// Check if we already have this exact value (by simply comparing
+	// with == directly). If we do, then we don't insert it again.
+	found := false
+	for _, v2 := range w.values {
+		if v == v2 {
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		// Set the value, always
+		w.values = append(w.values, v)
+	}
+
+	// Go through the waiters
+	for k, val := range w.waiters {
+		if w.Func(k, v) {
+			val.SetValue(v)
+			delete(w.waiters, k)
+		}
+	}
+}
+
+func (w *ComparedValue) valueWaiter(k interface{}) (interface{}, *Value) {
+	w.lock.Lock()
+	w.once.Do(w.init)
+
+	// Look for a pre-existing value
+	for _, v := range w.values {
+		if w.Func(k, v) {
+			w.lock.Unlock()
+			return v, nil
+		}
+	}
+
+	// If we're closed, return that
+	if w.closed {
+		w.lock.Unlock()
+		return ErrClosed, nil
+	}
+
+	// Pre-existing value doesn't exist, create a waiter
+	val := w.waiters[k]
+	if val == nil {
+		val = new(Value)
+		w.waiters[k] = val
+	}
+	w.lock.Unlock()
+
+	// Return the waiter
+	return nil, val
+}
+
+// Must be called with w.lock held.
+func (w *ComparedValue) init() {
+	w.waiters = make(map[interface{}]*Value)
+	if w.Func == nil {
+		w.Func = func(k, v interface{}) bool { return k == v }
+	}
+}