From 38ee83e45b4de7edf89bf9f0ef629eb4c6ad0fa8 Mon Sep 17 00:00:00 2001
From: Christopher Speller <crspeller@gmail.com>
Date: Thu, 12 May 2016 23:56:07 -0400
Subject: Moving to glide

---
 .../golang/groupcache/singleflight/singleflight.go | 64 ++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 vendor/github.com/golang/groupcache/singleflight/singleflight.go

(limited to 'vendor/github.com/golang/groupcache/singleflight/singleflight.go')

diff --git a/vendor/github.com/golang/groupcache/singleflight/singleflight.go b/vendor/github.com/golang/groupcache/singleflight/singleflight.go
new file mode 100644
index 000000000..ff2c2ee4f
--- /dev/null
+++ b/vendor/github.com/golang/groupcache/singleflight/singleflight.go
@@ -0,0 +1,64 @@
+/*
+Copyright 2012 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package singleflight provides a duplicate function call suppression
+// mechanism.
+package singleflight
+
+import "sync"
+
+// call is an in-flight or completed Do call
+type call struct {
+	wg  sync.WaitGroup
+	val interface{}
+	err error
+}
+
+// Group represents a class of work and forms a namespace in which
+// units of work can be executed with duplicate suppression.
+type Group struct {
+	mu sync.Mutex       // protects m
+	m  map[string]*call // lazily initialized
+}
+
+// Do executes and returns the results of the given function, making
+// sure that only one execution is in-flight for a given key at a
+// time. If a duplicate comes in, the duplicate caller waits for the
+// original to complete and receives the same results.
+func (g *Group) Do(key string, fn func() (interface{}, error)) (interface{}, error) {
+	g.mu.Lock()
+	if g.m == nil {
+		g.m = make(map[string]*call)
+	}
+	if c, ok := g.m[key]; ok {
+		g.mu.Unlock()
+		c.wg.Wait()
+		return c.val, c.err
+	}
+	c := new(call)
+	c.wg.Add(1)
+	g.m[key] = c
+	g.mu.Unlock()
+
+	c.val, c.err = fn()
+	c.wg.Done()
+
+	g.mu.Lock()
+	delete(g.m, key)
+	g.mu.Unlock()
+
+	return c.val, c.err
+}
-- 
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