This is small usability improvement in order to increase signal-to-noise in the bitcoind standard output:
Don't print debug output "Pre-allocating to position ..." and "Leaving block file ..." when running with -nodebug (default). Print them when running with -debug.
Expected standard output from bitcoind (when in steady state) before this patch:
$ src/bitcoind
…
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z Pre-allocating up to position 0x0000000 in rev00000.dat
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z Leaving block file 000: CBlockFileInfo(blocks=000, size=000000000, heights=000000...000000, time=0000-00-00...0000-00-00)
0000-00-00T00:00:00Z Pre-allocating up to position 0x0000000 in blk00000.dat
0000-00-00T00:00:00Z Pre-allocating up to position 0x000000 in rev00000.dat
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z Pre-allocating up to position 0x0000000 in rev00000.dat
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
Expected standard output from bitcoind (when in steady state) after this patch:
$ src/bitcoind
…
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
0000-00-00T00:00:00Z UpdateTip: new best=0000000000000000000000000000000000000000000000000000000000000000 height=000000 version=0x00000000 log0_work=00.000000 tx=000000000 date='0000-00-00T00:00:00Z' progress=0.000000 cache=000.0MiB(0000000txo)
I find the latter alternative much easier to visually scan for anomalies.