Merging logs written to the syslog for text-format

[raj-prince]

Description

When gcsfuse writes the logs to syslog in text-format. We were getting multiple lines for a single logs, due to multiple calls of writer inside text-writer method.

But this issue was not happening in case of writing logs to a log-file. Here is the reason, why it was not happening in case of file-writer:-

// Output writes the output for a logging event. The string s contains
// the text to print after the prefix specified by the flags of the
// Logger. A newline is appended if the last character of s is not
// already a newline. Calldepth is the count of the number of
// frames to skip when computing the file name and line number
// if Llongfile or Lshortfile is set; a value of 1 will print the details
// for the caller of Output.
func Output(calldepth int, s string) error {
	return std.Output(calldepth+1, s) // +1 for this frame.
}

file-name - google-golang/src/log/log.go

To write any types of logs, we use this output method, which implicitly add '\n` character in the last.

Logs before this change:

2023-03-20T15:41:15.245221+05:30 33princer.hyd.corp.google.com gcsfuse[2489872]: I
2023-03-20T15:41:15.245390+05:30 33princer.hyd.corp.google.com gcsfuse[2489872]: 0320 15:41:15.245131
2023-03-20T15:41:15.245564+05:30 33princer.hyd.corp.google.com gcsfuse[2489872]:  
2023-03-20T15:41:15.245737+05:30 33princer.hyd.corp.google.com gcsfuse[2489872]: Error while mounting gcsfuse: mountWithConn: Mount: mount: running /usr/bin/fusermount3: exit status 1

Logs after this change:

2023-03-21T09:56:51.475043+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: I0321 09:56:51.474998 Creating a mount at "/usr/local/google/home/princer/Downloads/mnt"
2023-03-21T09:56:51.476144+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: I0321 09:56:51.476085 Creating a new server...
2023-03-21T09:56:51.476235+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: I0321 09:56:51.476131 Set up root directory for bucket princer-working-dirs
2023-03-21T09:56:51.476285+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: D0321 09:56:51.476173 gcs: Req              0x0: <- ListObjects("")
2023-03-21T09:56:52.330972+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: D0321 09:56:52.330789 gcs: Req              0x0: -> ListObjects("") (854.59719ms): OK
2023-03-21T09:56:52.331347+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: I0321 09:56:52.330902 Mounting file system "princer-working-dirs"...
2023-03-21T09:56:52.335218+05:30 33princer.hyd.corp.google.com gcsfuse[2854760]: I0321 09:56:52.335035 Error while mounting gcsfuse: mountWithConn: Mount: mount: running /usr/bin/fusermount3: exit status 1

Testing

1. Manual
   Checked the logs in file with this change:

321 09:48:11.461464 Opening GCS connection...
I0321 09:48:11.462350 Creating a mount at "/usr/local/google/home/princer/Downloads/mnt"
I0321 09:48:11.463601 Creating a new server...
I0321 09:48:11.463641 Set up root directory for bucket princer-working-dirs
D0321 09:48:11.463670 gcs: Req              0x0: <- ListObjects("")
D0321 09:48:12.753526 gcs: Req              0x0: -> ListObjects("") (1.289840961s): OK
I0321 09:48:12.753641 Mounting file system "princer-working-dirs"...
I0321 09:48:12.757755 Error while mounting gcsfuse: mountWithConn: Mount: mount: running /usr/bin/fusermount3: exit status 1

[sethiay]

Can we write in PR description that this change is specifically to fix logging in case of syslog and also that it didn't break logging in case of log file ?

[raj-prince]

Can we write in PR description that this change is specifically to fix logging in case of syslog and also that it didn't break logging in case of log file ?

Done.