Make trace files lexicographically ordered #1828
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I checked wavefront tailer, and they just slurp all XML files, which is probably what others do as well. |
ajbeamon
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There exists here a function cleanupTraceFiles which is sorting the trace files, and this can get much simpler if the filenames are lexicographic. I think we should also update that.
Let's also add a release note indicating the change to the trace file name format.
This resolves apple#1825 The basic idea is that we prefix every sequence number with its with, separated by a dot. That way the filename length isn't increased drastically (unlike using a fixed whidth number with 0-padding) and the file names will be lexicographically ordered.
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flow/FileTraceLogWriter.cpp
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| // this should be enough - if not we could make the base larger... | ||
| ASSERT(index > 0 && index < 10); | ||
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| int indexWidth = int(::floor(log10f(float(index)) + 1.0)); |
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index is currently an int, so the maximum it could be is ~2B. I suppose if we wanted to support all of that range, we could do that by removing the + 1.0 from indexWidth to start at 0, and then stick with the characters 0-9. Or, if we want to support an extended range, we should also increase the size of index. It seems unlikely to me that it will be necessary, but I'm fine either way. If we do support the extended range, we should update the comment above that suggests making the base larger.
flow/FileTraceLogWriter.cpp
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| lastError(errno); | ||
| if (errno == EEXIST) | ||
| finalname = format("%s.%d.%s", basename.c_str(), ++index, extension.c_str()); | ||
| finalname = format("%s.%c.%d.%s", basename.c_str(), indexWidthC, ++index, extension.c_str()); |
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Because we are incrementing index here, indexWidthC may need to change as well.
Co-Authored-By: A.J. Beamon <[email protected]>
Co-Authored-By: A.J. Beamon <[email protected]>
…mpilman/foundationdb into features/lexicographical-ordered-traces
there can be at most 2^32 files with a distinct index. Therefore `log10(index) < 10` - this means base 10 is good enough.
Co-Authored-By: A.J. Beamon <[email protected]>
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@fdb-build test this please |
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This resolves #1825
The basic idea is that we prefix every sequence number with its with,
separated by a dot. That way the filename length isn't increased
drastically (unlike using a fixed whidth number with 0-padding)
and the file names will be lexicographically ordered.
The main motivation for this case is to make it easier to investigate issues
in traces through the command-line. Without this change a command like this:
won't necessary work as one would expect as the last trace-file in the list might not be the newest one.