Tardigrade Backend: Dependencies

vendor/github.com/spacemonkeygo/monkit/v3/funcset.go

@@ -0,0 +1,78 @@
+// Copyright (C) 2015 Space Monkey, 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 monkit
+
+import (
+	"sync"
+)
+
+// funcSet is a set data structure (keeps track of unique functions). funcSet
+// has a fast path for dealing with cases where the set only has one element.
+//
+// to reduce memory usage for functions, funcSet exposes its mutex for use in
+// other contexts
+type funcSet struct {
+	// sync/atomic things
+	first *Func
+
+	// protected by mtx
+	sync.Mutex
+	rest map[*Func]struct{}
+}
+
+var (
+	// used to signify that we've specifically added a nil function, since nil is
+	// used internally to specify an empty set.
+	nilFunc = &Func{}
+)
+
+func (s *funcSet) Add(f *Func) {
+	if f == nil {
+		f = nilFunc
+	}
+	if loadFunc(&s.first) == f {
+		return
+	}
+	if compareAndSwapFunc(&s.first, nil, f) {
+		return
+	}
+	s.Mutex.Lock()
+	if s.rest == nil {
+		s.rest = map[*Func]struct{}{}
+	}
+	s.rest[f] = struct{}{}
+	s.Mutex.Unlock()
+}
+
+// Iterate loops over all unique elements of the set.
+func (s *funcSet) Iterate(cb func(f *Func)) {
+	s.Mutex.Lock()
+	uniq := make(map[*Func]struct{}, len(s.rest)+1)
+	for f := range s.rest {
+		uniq[f] = struct{}{}
+	}
+	s.Mutex.Unlock()
+	f := loadFunc(&s.first)
+	if f != nil {
+		uniq[f] = struct{}{}
+	}
+	for f := range uniq {
+		if f == nilFunc {
+			cb(nil)
+		} else {
+			cb(f)
+		}
+	}
+}