asset: create btcwallet+neutrino log dir and file without initialization

[ukane-philemon]

This fixes an issue where wallet recovery deletes the existing neutrino log file but logging initialization is a one-time operation. Closes #1944.

[JoeGruffins]

Looks fixed to me.

[buck54321]

Looks like the spvWallet.dir is

dir: filepath.Join(cfg.WalletCFG.DataDir, cfg.ChainParams.Name, "spv"),

and the log file is created in that directory.

If we instead created the log files in, say,

filepath.Join(cfg.WalletCFG.DataDir, cfg.ChainParams.Name, "spvlogs")

this wouldn't be an issue.

[ukane-philemon]

If we instead created the log files in, say,
filepath.Join(cfg.WalletCFG.DataDir, cfg.ChainParams.Name, "spvlogs")
this wouldn't be an issue.

I think the issue is that only the log dir is created while the neutrino.log file is not, causing an error when trying to retrieve the log file. This PR allows rotator.New(...) to create the neutrino.log file when the wallet is created so that calls to download wallet logs will find the neutrino.log file.

[buck54321]

My read might be wrong, but it seems to me that the problem is that (*spvWallet).moveWalletData is moving log files in the first place.

[ukane-philemon]

My read might be wrong, but it seems to me that the problem is that (*spvWallet).moveWalletData is moving log files in the first place.

What is the expected behaviour for new wallets(the create wallet method does not know it's a recovery)? And does it mean the wallet log should be untouched in any scenario?

[buck54321]

I don't see a reason to start new log files when we perform recovery. We'll want the record to be continuous, no?

[ukane-philemon]

I don't see a reason to start new log files when we perform recovery. We'll want the record to be continuous, no?

Hmm, maybe not, because we ought to keep all details regarding the old wallet including the logs on the assetdb-backup directory. So the new wallet will have to start clean?

[chappjc]

I think Buck is saying we should just not delete the logs. We can still copy them.

Also with the current PR, dcrwallet loggers keep using the old log rotator. I don't see how it's working.

[ukane-philemon]

I think Buck is saying we should just not delete the logs. We can still copy them.

Okay, I had assumed the expected behaviour for recovery is to remove everything related to the previous wallet(including logs) from the main wallet dir. However, @buck54321 suggestion(#1946 (comment)) will help keep changes minimal, I think.

[ukane-philemon]

@buck54321, RE: #1946 (comment), I had to move some things around in 1e56f6d

[chappjc]

Works so that the wallet file is accessible (and continuous) after recover.

Just need to rework the file copy code so it is buffered, not loading a whole file into memory.