internal/debug: rename flags in log namespace, fix some pprof flags

[s1na]

This PR moves the flags --debug, --backtrace to the log namespace (i.e. --log.backtrace, etc.). It keeps the previous ones but marks them as deprecated. In case both the current and deprecated flags are passed, the deprecated has lower precedence.

I noticed that the --memprofilerate and --blockprofilerate are right now ineffective (they're always overridden even if --pprof.memprofilerate is not set). This is also fixed.

[karalabe]

There configs are incorrect. GlobalIsSet will only return true if the user explicitly set it to something, but they will remain false if the defaults are left as is. This means that all the flag initialization will be skipped by the code in this PR.

[karalabe]

Given that all these calls have side effects, it's a bit messy, you have 4 cases that you need to handle

• no flag is set
• both are set
• legacy is set
• new flag is set

You handled 2 ok-ish. The one where nothing is set is a noop now, and the one were both is set may work, but it might have weird side effects.

What you could do is:

debug := ctx.GlobalBool(debugFlag.Name)
if ctx.GlobalIsSet(legacyDebugFlag.Name) {
    log.Warn("The flag --debug is deprecated and will be removed in the future, please use --log.debug")
    debug = ctx.GlobalBool(legacyDebugFlag.Name)
}
if ctx.GlobalIsSet(debugFlag.Name) {
    debug := ctx.GlobalBool(debugFlag.Name)
}
log.PrintOrigins(debug)

[karalabe]

Same for all the flags below

[karalabe]

Or

debug := ctx.GlobalBool(debugFlag.Name)
if ctx.GlobalIsSet(legacyDebugFlag.Name) && !ctx.GlobalIsSet(debugFlag.Name) {
    log.Warn("The flag --debug is deprecated and will be removed in the future, please use --log.debug")
    debug = ctx.GlobalBool(legacyDebugFlag.Name)
}
log.PrintOrigins(debug)

Though this will not warn you if both are set, so the former might be more correct, even if a bit unwieldy.

[s1na]

I had applied the solution you suggested to memprofilerate and blockprofilerate further down. But something I might be missing is whether the initialization methods should be invoked even when the value is empty? i.e. debug is by default false, does log.PrintOrigins has to be called explicitly even in that case? Because the only flag that has a non-empty default is verbosity which is initialised in init().

[s1na]

Aha now I see that glogger.Vmodule and glogger.BacktraceAt set some other variables that might have side-effects if unset. Will fix.

[s1na]

Updated the PR to use Peter's suggested solution for all flags.

[fjl]

Why should we change it at all? We've had --vmodule and --verbosity since the beginning, and their names are meaningful without the log. prefix.

[s1na]

I think @holiman suggested this to make them consistent with the new log.json flag. Also seems some other flags were also grouped under --pprof..