err_msg: clarify some ambiguous error message (#1076)

[ti-chi-bot]

This is an automated cherry-pick of #1076

What problem does this PR solve?

Keeping improve BR errors and logs #1055

Some error message in BR is ambiguous and misleading.
i.e.

• If tikv has no permission to read from & write to backup storage, error message cannot clarify whether error occur on br side or tikv side. Users may think why I got "permission denied"? I'm running BR as root!
• If user want to restore tables or databases that have not been backup, error should occur.

Clarify the summary info including:

• data-size => total kv size
• size => backup data size(after compressed)

What is changed and how it works?

1. Adjust the backup and restore summary:

• the data-size field has been changed to total-kv-size
• the size field in backup summary has been changed to backup data size(after compressed)
• the size field in restore summary has been changed to restore data size(after decompressed)

2. Some error messages are changed, and will clarify what is going on when error occur.

• Original error message is as following

[2021/05/18 16:37:28.517 +08:00] [ERROR] [push.go:147] ["backup occur unknown error"] [error="Io(Os { code: 13, kind: PermissionDenied...})"] [stack="github.com/pingcap/br/pkg/backup.(*pushDown).pushBackup\n\t/home/zwj/log_improve/br/pkg/backup/push.go:147\ngithub.jparrowsec.cn/pingcap/br/pkg/backup.(*Client).BackupRange\n\t/home/zwj/log_improve/br/pkg/backup/client.go:540\ngithub.jparrowsec.cn/pingcap/br/pkg/backup.(*Client).BackupRanges.func2.1\n\t/home/zwj/log_improve/br/pkg/backup/client.go:476\ngithub.jparrowsec.cn/pingcap/br/pkg/utils.(*WorkerPool).ApplyOnErrorGroup.func1\n\t/home/zwj/log_improve/br/pkg/utils/worker.go:63\ngolang.org/x/sync/errgroup.(*Group).Go.func1\n\t/root/go/pkg/mod/golang.org/x/[email protected]/errgroup/errgroup.go:57"]

• For now, the error message output is as following:

[2021/05/19 15:43:43.305 +08:00] [ERROR] [push.go:175] [error="[BR:KV:ErrKVStorage]tikv storage occur I/O error: I/O permission denied error occurs on TiKV Node(store id: 1; Address: 127.0.0.1:20162)"] ["work around"="please ensure tikv has permission to read from & write to the storage."] [stack="github.com/pingcap/br/pkg/backup.(*pushDown).pushBackup\n\t/home/zwj/log_improve/br/pkg/backup/push.go:175\ngithub.jparrowsec.cn/pingcap/br/pkg/backup.(*Client).BackupRange\n\t/home/zwj/log_improve/br/pkg/backup/client.go:540\ngithub.jparrowsec.cn/pingcap/br/pkg/backup.(*Client).BackupRanges.func2.1\n\t/home/zwj/log_improve/br/pkg/backup/client.go:476\ngithub.jparrowsec.cn/pingcap/br/pkg/utils.(*WorkerPool).ApplyOnErrorGroup.func1\n\t/home/zwj/log_improve/br/pkg/utils/worker.go:63\ngolang.org/x/sync/errgroup.(*Group).Go.func1\n\t/root/go/pkg/mod/golang.org/x/[email protected]/errgroup/errgroup.go:57"]

3. When user want to restore tables or databases that have not been backup, error should occur.

Check List

Tests

• Manual test (add detailed scripts or steps below)

1. If user want to restore a table or database that has not been backup, an error should occur to notice the user
   
   
2. If user restore a empty table, the summary should notice the user there is nothing to restore.
   
3. Summary message have improve, data-size => total-kv-size and size => backup data size(after compressed)
   

• Integration test

Code changes

• Has exported variable/fields change

Release Note

• No realease note

[YuJuncen]

Here is a conflict.

[ZipFast]

/run-all-tests

[YuJuncen]

/lgtm

[3pointer]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• 3pointer
• YuJuncen

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[ZipFast]

/merge

[ti-chi-bot]

@Zwj-coder: /merge is only allowed for the committers, you can assign this pull request to the committer in list by filling /assign @committer in the comment to help merge this pull request.

In response to this:

/merge

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