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lease_history.go
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lease_history.go
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// Copyright 2017 The Cockroach Authors.
//
// 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 storage
import (
"github.com/cockroachdb/cockroach/pkg/roachpb"
"github.com/cockroachdb/cockroach/pkg/util/envutil"
"github.com/cockroachdb/cockroach/pkg/util/syncutil"
)
// leaseHistoryMaxEntries controls if replica lease histories are enabled and
// how much memory they take up when enabled.
var leaseHistoryMaxEntries = envutil.EnvOrDefaultInt("COCKROACH_LEASE_HISTORY", 5)
type leaseHistory struct {
syncutil.Mutex
index int
history []roachpb.Lease // A circular buffer with index.
}
func newLeaseHistory() *leaseHistory {
lh := &leaseHistory{
history: make([]roachpb.Lease, 0, leaseHistoryMaxEntries),
}
return lh
}
func (lh *leaseHistory) add(lease roachpb.Lease) {
lh.Lock()
defer lh.Unlock()
// Not through the first pass through the buffer.
if lh.index == len(lh.history) {
lh.history = append(lh.history, lease)
} else {
lh.history[lh.index] = lease
}
lh.index++
if lh.index >= leaseHistoryMaxEntries {
lh.index = 0
}
}
func (lh *leaseHistory) get() []roachpb.Lease {
lh.Lock()
defer lh.Unlock()
if len(lh.history) == 0 {
return nil
}
if len(lh.history) < leaseHistoryMaxEntries || lh.index == 0 {
result := make([]roachpb.Lease, len(lh.history))
copy(result, lh.history)
return lh.history
}
first := lh.history[lh.index:]
second := lh.history[:lh.index]
result := make([]roachpb.Lease, len(first)+len(second))
copy(result, first)
copy(result[len(first):], second)
return result
}