github.com/scaleoutsean/fusego@v0.0.0-20220224074057-4a6429e46bb8/internal/freelist/freelist.go (about)

     1  // Copyright 2015 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package freelist
    16  
    17  import "unsafe"
    18  
    19  // A freelist for arbitrary pointers. Not safe for concurrent access.
    20  type Freelist struct {
    21  	list []unsafe.Pointer
    22  }
    23  
    24  // Get an element from the freelist, returning nil if empty.
    25  func (fl *Freelist) Get() unsafe.Pointer {
    26  	l := len(fl.list)
    27  	if l == 0 {
    28  		return nil
    29  	}
    30  
    31  	p := fl.list[l-1]
    32  	fl.list = fl.list[:l-1]
    33  
    34  	return p
    35  }
    36  
    37  // Contribute an element back to the freelist.
    38  func (fl *Freelist) Put(p unsafe.Pointer) {
    39  	fl.list = append(fl.list, p)
    40  }