cmd/geth: add dbstats command

[holiman]

Small wip/poc PR that makes it possible to dump out the leveldb statistics. Might be useful for analyzing errors, e.g #21809 and syndtr/goleveldb#346

Usage examples:

[user@work go-ethereum]$ ./build/bin/geth --goerli dbstats
INFO [11-22|10:26:23.066] Maximum peer count                       ETH=50 LES=0 total=50
INFO [11-22|10:26:23.066] Smartcard socket not found, disabling    err="stat /run/pcscd/pcscd.comm: no such file or directory"
ERROR[11-22|10:26:23.077] Failed to enumerate USB devices          hub=ledger vendor=11415 failcount=1 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[11-22|10:26:23.077] Failed to enumerate USB devices          hub=trezor vendor=21324 failcount=1 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[11-22|10:26:23.077] Failed to enumerate USB devices          hub=trezor vendor=4617  failcount=1 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[11-22|10:26:23.077] Failed to enumerate USB devices          hub=ledger vendor=11415 failcount=2 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[11-22|10:26:23.077] Failed to enumerate USB devices          hub=trezor vendor=21324 failcount=2 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[11-22|10:26:23.077] Failed to enumerate USB devices          hub=trezor vendor=4617  failcount=2 err="failed to initialize libusb: libusb: unknown error [code -99]"
INFO [11-22|10:26:23.078] Set global gas cap                       cap=25000000
INFO [11-22|10:26:23.078] Allocated cache and file handles         database=/home/user/.ethereum/goerli/geth/chaindata cache=1024.00MiB handles=1000
INFO [11-22|10:26:23.120] Checking stats 
Compactions
 Level |   Tables   |    Size(MB)   |    Time(sec)  |    Read(MB)   |   Write(MB)
-------+------------+---------------+---------------+---------------+---------------
   1   |         22 |      42.68468 |       0.00000 |       0.00000 |       0.00000
-------+------------+---------------+---------------+---------------+---------------
 Total |         22 |      42.68468 |       0.00000 |       0.00000 |       0.00000

[user@work go-ethereum]$ ./build/bin/geth --nousb dbstats
INFO [11-22|10:28:21.239] Maximum peer count                       ETH=50 LES=0 total=50
INFO [11-22|10:28:21.239] Smartcard socket not found, disabling    err="stat /run/pcscd/pcscd.comm: no such file or directory"
INFO [11-22|10:28:21.240] Set global gas cap                       cap=25000000
INFO [11-22|10:28:21.240] Allocated cache and file handles         database=/home/user/.ethereum/geth/chaindata cache=1024.00MiB handles=1000
INFO [11-22|10:28:21.278] Checking stats 
Compactions
 Level |   Tables   |    Size(MB)   |    Time(sec)  |    Read(MB)   |   Write(MB)
-------+------------+---------------+---------------+---------------+---------------
   0   |          2 |       0.00097 |       0.00000 |       0.00000 |       0.00000
   3   |        322 |     644.93655 |       0.00000 |       0.00000 |       0.00000
-------+------------+---------------+---------------+---------------+---------------
 Total |        324 |     644.93752 |       0.00000 |       0.00000 |       0.00000

[user@work go-ethereum]$ 

[holiman]

Updated this PR, the syntax is now geth leveldb.stats for checking basic stats, and geth leveldb.compact to trigger a compaction.

[rjl493456442]

nitpicks, would be nice to have a new file dbcmd.go and put all db related commands there(also make the new category DATABASE COMMANDS.

[holiman]

Closed in favour of #22014