ac8b4718bd
Imported golang.org/x/telemetry@9c0d19e to avoid go version requirement change. For #3815 For golang/go#70056
46 lines
2.5 KiB
Plaintext
46 lines
2.5 KiB
Plaintext
The upload process converts count files into reports, and
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uploads reports. There will be only one report, named YYYY-MM-DD.json,
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for a given day.
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First phase. Look at the localdir (os.UserConfigdir()/go/telemetry/local)
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and find all .count and .json files. Find the count files that are no
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longer active by looking at their metadata.
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Second phase. Group the inactive count files by their expiry date, and
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for each date generate the local report and the upload report. (The upload
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report only contains the counters in the upload configuration.) The upload
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report is saved in the local directory with a name like YYYY-MM-DD.json, if
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there is no file already existing with that name.
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If the local report is different, it is saved in the local directory
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with a name like local.YYYY-MM-DD.json. The new upload report is
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added to the list of .json files from the first phase. At this point
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the count files are no longer needed and can be deleted.
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Third phase. Look at the .json files in the list from the first phase.
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If the name starts with local, skip it. If there is a file with the
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identical name in the upload directory, remove the one in the local directory.
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Otherwise try to upload the one in the local directory,
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If the upload succeeds, move the file to the uploaded directory.
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There are various error conditions.
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1. Several processes could look at localdir and see work to do.
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1A. They could see different sets of expired count files for some day.
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This could happen if another process is removing count files. In this
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case there is already a YYYY-MM-DD.json file either in localdir
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or updatedir, so the process seeing fewer count files will not generate
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a report.
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1B. They could see the same count files, and no report in either directory.
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They will both generate (in memory) reports and check to see if there
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is a YYYY-MM-DD.json file in either directory. They could both then
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write two files with the same name, but different X values, but
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otherwise the same contents. The X values are very close to the front
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of the file. Assuming reasonable file system semantics one version of
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the file will be written. To minimize this, just before writing reports
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the code checks again to see if they exist.
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1C. Once there is an existing well-formed file YYYY-MM-DD.json in localdir
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eventually the upload will succeed, and the file will be moved to updatedir.
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It is possible that other processes will not see the file in updatedir and
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upload it again and also move it to uploaddir. This is harmless as all
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the uploaded files are identical.
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