Rename logging to mirror
This commit is contained in:
Arthur Barr
@@ -1,185 +0,0 @@
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/*
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© Copyright IBM Corporation 2018
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Licensed under the Apache License, Version 2.0 (the "License");
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you may 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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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"bufio"
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"fmt"
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"os"
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"time"
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log "github.com/sirupsen/logrus"
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)
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// waitForFile waits until the specified file exists
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func waitForFile(path string) (os.FileInfo, error) {
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var fi os.FileInfo
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var err error
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// Wait for file to exist
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for {
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fi, err = os.Stat(path)
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if err != nil {
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if os.IsNotExist(err) {
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time.Sleep(500 * time.Millisecond)
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continue
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} else {
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return nil, err
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}
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}
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break
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}
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log.Debugf("File exists: %v, %v", path, fi.Size())
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return fi, nil
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}
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type mirrorFunc func(msg string)
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// mirrorAvailableMessages prints lines from the file, until no more are available
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func mirrorAvailableMessages(f *os.File, mf mirrorFunc) {
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scanner := bufio.NewScanner(f)
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count := 0
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for scanner.Scan() {
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t := scanner.Text()
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mf(t)
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// if strings.HasPrefix(t, "{") {
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// // Assume JSON, so just print it
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// fmt.Fprintln(w, t)
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// } else if strings.HasPrefix(t, "AMQ") {
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// // Only print MQ messages with AMQnnnn codes
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// log.Println(t)
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// //fmt.Fprintln(w, t)
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// }
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count++
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}
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log.Debugf("Mirrored %v log entries", count)
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err := scanner.Err()
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if err != nil {
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log.Errorf("Error reading file: %v", err)
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return
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}
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}
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// mirrorLog tails the specified file, and logs each line to stdout.
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// This is useful for usability, as the container console log can show
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// messages from the MQ error logs.
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func mirrorLog(path string, fromStart bool, mf mirrorFunc) (chan bool, error) {
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lifecycle := make(chan bool)
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var offset int64 = -1
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var f *os.File
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var err error
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var fi os.FileInfo
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// Need to check if the file exists before returning, otherwise we have a
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// race to see if the new file get created before we can test for it
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fi, err = os.Stat(path)
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if err != nil {
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if os.IsNotExist(err) {
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// File doesn't exist, so ensure we start at the beginning
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offset = 0
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} else {
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return nil, err
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}
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} else {
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// If the file exists, open it now, before we return. This makes sure
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// the file is open before the queue manager is created or started.
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// Otherwise, there would be the potential for a nearly-full file to
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// rotate before the goroutine had a chance to open it.
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f, err = os.OpenFile(path, os.O_RDONLY, 0)
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if err != nil {
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return nil, err
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}
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// File already exists, so start reading at the end
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offset = fi.Size()
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}
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go func() {
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if f == nil {
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// File didn't exist, so need to wait for it
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fi, err = waitForFile(path)
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if err != nil {
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log.Errorln(err)
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lifecycle <- true
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return
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}
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f, err = os.OpenFile(path, os.O_RDONLY, 0)
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if err != nil {
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log.Errorln(err)
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lifecycle <- true
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return
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}
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}
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fi, err = f.Stat()
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if err != nil {
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log.Errorln(err)
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lifecycle <- true
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return
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}
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// The file now exists. If it didn't exist before we started, offset=0
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// Always start at the beginning if we've been told to go from the start
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if offset != 0 && !fromStart {
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log.Debugf("Seeking %v", offset)
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f.Seek(offset, 0)
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}
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closing := false
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for {
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log.Debugln("Start of loop")
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// If there's already data there, mirror it now.
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mirrorAvailableMessages(f, mf)
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log.Debugf("Stat %v", path)
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newFI, err := os.Stat(path)
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if err != nil {
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log.Error(err)
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lifecycle <- true
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return
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}
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if !os.SameFile(fi, newFI) {
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log.Debugln("Not the same file!")
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// WARNING: There is a possible race condition here. If *another*
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// log rotation happens before we can open the new file, then we
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// could skip all those messages. This could happen with a very small
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// MQ error log size.
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mirrorAvailableMessages(f, mf)
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f.Close()
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// Re-open file
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log.Debugln("Re-opening error log file")
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// Used to work with this: f, err = waitForFile2(path)
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f, err = os.OpenFile(path, os.O_RDONLY, 0)
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if err != nil {
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fmt.Printf("ERROR: %v", err)
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return
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}
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fi = newFI
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// Don't seek this time, because we know it's a new file
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mirrorAvailableMessages(f, mf)
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}
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log.Debugln("Check for lifecycle event")
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select {
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// Have we been asked to shut down?
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case <-lifecycle:
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// Set a flag, to allow one more time through the loop
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closing = true
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default:
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if closing {
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log.Debugln("Shutting down mirror")
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lifecycle <- true
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return
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}
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time.Sleep(500 * time.Millisecond)
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}
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}
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}()
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return lifecycle, nil
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}
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