123 lines
2.4 KiB
Go
123 lines
2.4 KiB
Go
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// Licensed to Elasticsearch B.V. under one or more contributor
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// license agreements. See the NOTICE file distributed with
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// this work for additional information regarding copyright
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// ownership. Elasticsearch B.V. licenses this file to you under
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// the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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package watcher
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import (
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"hash/fnv"
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"io/ioutil"
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"os"
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"time"
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"github.com/elastic/beats/libbeat/logp"
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)
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type Watch interface {
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Stop()
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}
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type filePoller struct {
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done chan struct{}
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}
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type fileChangeTester struct {
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path string
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sz int
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hash uint64
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stat os.FileInfo
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}
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func NewFilePoller(
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path string,
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poll time.Duration,
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do func([]byte),
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) (Watch, error) {
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fw := &filePoller{
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done: make(chan struct{}),
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}
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tester := &fileChangeTester{path: path, sz: -1}
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if content, changed := tester.check(); changed {
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do(content)
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}
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go func() {
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ticker := time.NewTicker(poll)
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defer ticker.Stop()
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for {
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if content, changed := tester.check(); changed {
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do(content)
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}
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select {
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case <-fw.done:
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return
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case <-ticker.C:
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}
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}
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}()
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return fw, nil
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}
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func (f *filePoller) Stop() {
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close(f.done)
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}
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func (w *fileChangeTester) check() ([]byte, bool) {
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f, err := os.Open(w.path)
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if err != nil {
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logp.Info("Failed to load file: %v", err)
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return nil, false
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}
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defer f.Close()
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stat, err := f.Stat()
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if err != nil {
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logp.Info("Reading file '%v' stat failed with: %v", w.path, err)
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return nil, false
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}
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if w.stat != nil {
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if stat.Size() == w.stat.Size() && !stat.ModTime().After(w.stat.ModTime()) {
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return nil, false
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}
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}
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content, err := ioutil.ReadAll(f)
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if err != nil {
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logp.Info("Reading file '%v' failed with: %v", w.path, err)
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return nil, false
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}
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var hash uint64
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if len(content) != 0 || w.sz == 0 {
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hasher := fnv.New64a()
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hasher.Write(content)
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hash = hasher.Sum64()
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if w.hash == hash {
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return nil, false
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}
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}
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w.hash = hash
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w.stat = stat
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w.sz = len(content)
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return content, true
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}
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