forked from google/cadvisor
/
stats_buffer.go
70 lines (61 loc) · 1.92 KB
/
stats_buffer.go
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// Copyright 2014 Google Inc. All Rights Reserved.
//
// 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 memory
import (
"github.com/google/cadvisor/info"
)
// A circular buffer for ContainerStats.
type StatsBuffer struct {
buffer []info.ContainerStats
size int
index int
}
// Returns a new thread-compatible StatsBuffer.
func NewStatsBuffer(size int) *StatsBuffer {
return &StatsBuffer{
buffer: make([]info.ContainerStats, size),
size: 0,
index: size - 1,
}
}
// Adds an element to the start of the buffer (removing one from the end if necessary).
func (self *StatsBuffer) Add(item *info.ContainerStats) {
if self.size < len(self.buffer) {
self.size++
}
self.index = (self.index + 1) % len(self.buffer)
self.buffer[self.index] = *item
}
// Returns the first N elements in the buffer. If N > size of buffer, size of buffer elements are returned.
func (self *StatsBuffer) FirstN(n int) []*info.ContainerStats {
// Cap n at the number of elements we have.
if n > self.size {
n = self.size
}
// index points to the latest element, get n before that one (keeping in mind we may have gone through 0).
start := self.index - (n - 1)
if start < 0 {
start += len(self.buffer)
}
// Copy the elements.
res := make([]*info.ContainerStats, n)
for i := 0; i < n; i++ {
index := (start + i) % len(self.buffer)
res[i] = &self.buffer[index]
}
return res
}
func (self *StatsBuffer) Size() int {
return self.size
}