Giant blob of minor changes

[dotfiles/.git] / .config / coc / extensions / coc-go-data / tools / pkg / mod / golang.org / x / sync@v0.0.0-20200625203802-6e8e738ad208 / singleflight / singleflight.go

diff --git a/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/sync@v0.0.0-20200625203802-6e8e738ad208/singleflight/singleflight.go b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/sync@v0.0.0-20200625203802-6e8e738ad208/singleflight/singleflight.go
new file mode 100644 (file)
index 0000000..97a1aa4
--- /dev/null
+++ b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/sync@v0.0.0-20200625203802-6e8e738ad208/singleflight/singleflight.go
@@ -0,0 +1,120 @@
+// Copyright 2013 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.
+
+// Package singleflight provides a duplicate function call suppression
+// mechanism.
+package singleflight // import "golang.org/x/sync/singleflight"
+
+import "sync"
+
+// call is an in-flight or completed singleflight.Do call
+type call struct {
+       wg sync.WaitGroup
+
+       // These fields are written once before the WaitGroup is done
+       // and are only read after the WaitGroup is done.
+       val interface{}
+       err error
+
+       // forgotten indicates whether Forget was called with this call's key
+       // while the call was still in flight.
+       forgotten bool
+
+       // These fields are read and written with the singleflight
+       // mutex held before the WaitGroup is done, and are read but
+       // not written after the WaitGroup is done.
+       dups  int
+       chans []chan<- Result
+}
+
+// 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
+}
+
+// Result holds the results of Do, so they can be passed
+// on a channel.
+type Result struct {
+       Val    interface{}
+       Err    error
+       Shared bool
+}
+
+// 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.
+// The return value shared indicates whether v was given to multiple callers.
+func (g *Group) Do(key string, fn func() (interface{}, error)) (v interface{}, err error, shared bool) {
+       g.mu.Lock()
+       if g.m == nil {
+               g.m = make(map[string]*call)
+       }
+       if c, ok := g.m[key]; ok {
+               c.dups++
+               g.mu.Unlock()
+               c.wg.Wait()
+               return c.val, c.err, true
+       }
+       c := new(call)
+       c.wg.Add(1)
+       g.m[key] = c
+       g.mu.Unlock()
+
+       g.doCall(c, key, fn)
+       return c.val, c.err, c.dups > 0
+}
+
+// DoChan is like Do but returns a channel that will receive the
+// results when they are ready.
+func (g *Group) DoChan(key string, fn func() (interface{}, error)) <-chan Result {
+       ch := make(chan Result, 1)
+       g.mu.Lock()
+       if g.m == nil {
+               g.m = make(map[string]*call)
+       }
+       if c, ok := g.m[key]; ok {
+               c.dups++
+               c.chans = append(c.chans, ch)
+               g.mu.Unlock()
+               return ch
+       }
+       c := &call{chans: []chan<- Result{ch}}
+       c.wg.Add(1)
+       g.m[key] = c
+       g.mu.Unlock()
+
+       go g.doCall(c, key, fn)
+
+       return ch
+}
+
+// doCall handles the single call for a key.
+func (g *Group) doCall(c *call, key string, fn func() (interface{}, error)) {
+       c.val, c.err = fn()
+       c.wg.Done()
+
+       g.mu.Lock()
+       if !c.forgotten {
+               delete(g.m, key)
+       }
+       for _, ch := range c.chans {
+               ch <- Result{c.val, c.err, c.dups > 0}
+       }
+       g.mu.Unlock()
+}
+
+// Forget tells the singleflight to forget about a key.  Future calls
+// to Do for this key will call the function rather than waiting for
+// an earlier call to complete.
+func (g *Group) Forget(key string) {
+       g.mu.Lock()
+       if c, ok := g.m[key]; ok {
+               c.forgotten = true
+       }
+       delete(g.m, key)
+       g.mu.Unlock()
+}