49 lines
1.5 KiB
Go
49 lines
1.5 KiB
Go
package mlog
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import (
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"github.com/mediocregopher/mediocre-go-lib/mcmp"
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"github.com/mediocregopher/mediocre-go-lib/mctx"
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)
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type cmpKey int
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// SetLogger sets the given logger onto the Component. The logger can later be
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// retrieved from the Component, or any of its children, using From.
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func SetLogger(cmp *mcmp.Component, l *Logger) {
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cmp.SetValue(cmpKey(0), l)
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}
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// DefaultLogger is an instance of Logger which is returned by From when a
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// Logger hasn't been previously set with SetLogger on the passed in Component.
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var DefaultLogger = NewLogger()
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// From returns the Logger which was set on the Component, or one of its
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// ancestors, using SetLogger. If no Logger was ever set then DefaultLogger is
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// returned.
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//
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// The returned Logger will be modified such that it will implicitly merge the
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// Contexts of any Message into the given Component's Context.
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func From(cmp *mcmp.Component) *Logger {
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var l *Logger
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if l, _ = cmp.Value(cmpKey(1)).(*Logger); l != nil {
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return l
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} else if lInt, ok := cmp.InheritedValue(cmpKey(0)); ok {
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l = lInt.(*Logger)
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} else {
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l = DefaultLogger
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}
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// if we're here it means a modified Logger wasn't set on this particular
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// Component, and therefore the current one must be modified.
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l = l.Clone()
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oldHandler := l.Handler()
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l.SetHandler(func(msg Message) error {
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ctx := mctx.MergeAnnotationsInto(cmp.Context(), msg.Contexts...)
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msg.Contexts = append(msg.Contexts[:0], ctx)
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return oldHandler(msg)
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})
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cmp.SetValue(cmpKey(1), l)
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return l
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}
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