.gitignore added

[dotfiles/.git] / .config / coc / extensions / coc-go-data / tools / pkg / mod / golang.org / x / mod@v0.4.1 / sumdb / cache.go

diff --git a/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/mod@v0.4.1/sumdb/cache.go b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/mod@v0.4.1/sumdb/cache.go
new file mode 100644 (file)
index 0000000..629e591
--- /dev/null
+++ b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/mod@v0.4.1/sumdb/cache.go
@@ -0,0 +1,59 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parallel cache.
+// This file is copied from cmd/go/internal/par.
+
+package sumdb
+
+import (
+       "sync"
+       "sync/atomic"
+)
+
+// parCache runs an action once per key and caches the result.
+type parCache struct {
+       m sync.Map
+}
+
+type cacheEntry struct {
+       done   uint32
+       mu     sync.Mutex
+       result interface{}
+}
+
+// Do calls the function f if and only if Do is being called for the first time with this key.
+// No call to Do with a given key returns until the one call to f returns.
+// Do returns the value returned by the one call to f.
+func (c *parCache) Do(key interface{}, f func() interface{}) interface{} {
+       entryIface, ok := c.m.Load(key)
+       if !ok {
+               entryIface, _ = c.m.LoadOrStore(key, new(cacheEntry))
+       }
+       e := entryIface.(*cacheEntry)
+       if atomic.LoadUint32(&e.done) == 0 {
+               e.mu.Lock()
+               if atomic.LoadUint32(&e.done) == 0 {
+                       e.result = f()
+                       atomic.StoreUint32(&e.done, 1)
+               }
+               e.mu.Unlock()
+       }
+       return e.result
+}
+
+// Get returns the cached result associated with key.
+// It returns nil if there is no such result.
+// If the result for key is being computed, Get does not wait for the computation to finish.
+func (c *parCache) Get(key interface{}) interface{} {
+       entryIface, ok := c.m.Load(key)
+       if !ok {
+               return nil
+       }
+       e := entryIface.(*cacheEntry)
+       if atomic.LoadUint32(&e.done) == 0 {
+               return nil
+       }
+       return e.result
+}