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/
snippet_paginator.go
95 lines (80 loc) · 2.03 KB
/
snippet_paginator.go
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// Copyright 2019 Google LLC
//
// 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 samplrapi
import (
"errors"
"fmt"
"github.com/GoogleCloudPlatform/devrel-services/samplr"
"sync"
"time"
)
type snippetPage struct {
snps []*samplr.Snippet
idx int
}
type snippetPaginator struct {
set map[time.Time]snippetPage
mu sync.Mutex
}
func (p *snippetPaginator) PurgeOldRecords() {
p.mu.Lock()
defer p.mu.Unlock()
now := time.Now()
for t := range p.set {
if now.Sub(t).Hours() > 2 {
delete(p.set, t)
}
}
}
func (p *snippetPaginator) CreatePage(s []*samplr.Snippet) (time.Time, error) {
p.mu.Lock()
defer p.mu.Unlock()
key := time.Now().UTC().Truncate(0)
if _, ok := p.set[key]; ok {
return time.Unix(0, 0), errors.New("Key already exists")
}
p.set[key] = snippetPage{
snps: s,
idx: 0,
}
return key, nil
}
func (p *snippetPaginator) GetPage(key time.Time, n int) ([]*samplr.Snippet, int, error) {
p.mu.Lock()
defer p.mu.Unlock()
key = key.UTC()
if _, ok := p.set[key]; !ok {
return nil, 0, fmt.Errorf("Page key: %v not found", key)
}
val := p.set[key]
nremain := len(val.snps) - val.idx
log.Debugf("There are %v records remaining, requested %v", nremain, n)
if n > nremain {
n = nremain
}
if n == 0 {
//return nil, 0, errors.New("Get 0 from page")
return []*samplr.Snippet{}, -1, nil
}
retset := val.snps[val.idx:(val.idx + n)]
val.idx = val.idx + n
retidx := val.idx
if val.idx == len(val.snps) {
delete(p.set, key)
retidx = -1
} else {
p.set[key] = val
}
return retset, retidx, nil
}