impl Display for SyncStatus

[posvyatokum]

Implement Display for SyncStatus that is only different from Debug in StateSync variant, i.e. it does not write potentially huge HashMap.
Use it in tracing of client.sync_status to remove noise from logs.

[nikurt]

Would it be possible to format StateSync with the use of this function (to be made public)?

nearcore/chain/client/src/client.rs

Line 2287 in a5ede1d

fn format_shard_sync_phase_per_shard(

[nikurt]

Maybe the better way if to define ShardSyncDownload::debug using format_shard_sync_phase()

[nagisa]

it does not write potentially huge HashMap

A better way to achieve this is to use the alternate formatting flag (#) and make the decision within the Debug implementation still. Display is meant to be used for end-user facing output (I’d imagine in this case that would be e.g. a nicely formatted table)

[posvyatokum]

I suspect I made things worse, here is a summary:

1. Moved state sync status formatting functions closer to structure definitions to avoid circular dependencies. Now I can use it.
2. Changed accessing element 0 in the formatting function to safe getter, because the localnet test was failing otherwise.
3. I generally listened to @nagisa's comment, but I don't know how to redefine Debug for just one variant and I didn't want to 'print' all variants by hand, so I added extra structure just to define pretty debugging. This prompted little refactoring around client.
4. I didn't find a way to pass # flag in tracing the way we pass ? or %, so changed the debug line that started it all a little.

[nagisa]

I didn't find a way to pass # flag in tracing the way we pass ? or %, so changed the debug line that started it all a little.

Ah, you’re right – tracing only provides means to use plain Debug or plain Display formatting. That’s unfortunate. A work-around that @mina86 was fond of is to add a newtype struct that would modify how printing is done for tracing specifically (so e.g. you’d have a PrintWithHashMap<'a>(&'a InnerT) for one kind of output and PrintWithoutHashMap<'a>(&'a InnerT) for the other), but I think using format! is reasonable enough as well if the performance of tracing that particular line isn’t a huge concern.