debug logger: remove logger callbacks#209
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| // values. | ||
| var regionNames map[ProductRegion]string | ||
| // debugMutex protects access to product debug region/enabled information. | ||
| var debugMutex sync.RWMutex |
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Renamed the globals to clearly indicate that they are only for debug log handling.
| "sync" | ||
| ) | ||
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| // ProductRegion is a numerical value assigned to an area of the product. |
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Added docs throughout the file.
| // startup. | ||
| func RegisterRegions(regions map[ProductRegion]string) { | ||
| regionNames = regions | ||
| debugMutex.Lock() |
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Used the mutex for ALL debugRegions and debugEnabled accesses. We no longer assume that some functions are only called at program startup. Consistent use of the mutex is easier to explain that implicit conventions.
| regionsEnabled[region] = true | ||
| regionName := RegionName(region) | ||
| debugEnabled[region] = true | ||
| regionName := debugRegions[region] |
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InitDebugLogs() directly accesses debugRegions because RegionName() now uses debugMutex; we need InitDebugLogs() to hold the mutex until its work is complete.
All debug logger instances were previously attached to a global set of callbacks. This was done so loggers could be informed if they were ever enabled dynamically. Unfortunately, loggers were never removed from this set of callbacks, which meant that those loggers could never be reclaimed by the garbage collector. Debug loggers are often constructed as the program runs, adding fields and values to assist with tracing. This meant that programs often did not have a static set of loggers, but were always creating new debug loggers, which were always seen as live objects. Now, debug loggers always ask their enabled status from the map tracking enabled state. This incurs the cost of a mutex-read lock and map lookup at runtime.
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| // | ||
| // Equivalent to `debugLogger.WithField("sub_region", subregion)` | ||
| func (l *debugLogger) WithSubRegion(subregion string) DebugLogger { | ||
| newLgr := l.Logger.WithField("sub_region", subregion) |
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This isn't really relevant for this PR but I don't understand why WithSubRegion exists. Why not just call WithFields() like we do in the tests down below?
gr.WithFields(Fields{
"region": "alfa",
"sub_region": "drinks",
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I do not want to alter the public API.
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The API exists because folks wanted a well-known field name.
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All debug logger instances were previously attached to a global set of callbacks. This was done so loggers could be informed if they were ever enabled dynamically. Unfortunately, loggers were never removed from this set of callbacks, which meant that those loggers could never be reclaimed by the garbage collector. Debug loggers are often constructed as the program runs, adding fields and values to assist with tracing. This meant that programs often did not have a static set of loggers, but were always creating new debug loggers, which were always seen as live objects.
Now, debug loggers always ask their enabled status from the map tracking enabled state. This incurs the cost of a mutex-read lock and map lookup at runtime.
This change is associated with Connect issue 29616