github.com/facebookincubator/go-belt@v0.0.0-20230703220935-39cd348f1a38/tool/logger/types/hook.go

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package types

import (
	"github.com/facebookincubator/go-belt"
	"github.com/facebookincubator/go-belt/pkg/field"
)

// Hook is a pre-processor for log entries.
// It may for example modify them or cancel them.
type Hook interface {
	// ProcessLogEntry is called right before sending the Entry to a Emitter.
	//
	// If the returned value is false, then the sending and processing by other hooks
	// are cancelled.
	//
	// It is allowed to modify the entry.
	ProcessLogEntry(*Entry) bool

	// Flush gracefully empties any buffers the hook may have.
	Flush()
}

// Hooks is a collection of Hook-s.
type Hooks []Hook

var _ Hook = (Hooks)(nil)

// ProcessLogEntry implements Hook.
func (s Hooks) ProcessLogEntry(e *Entry) bool {
	for _, hook := range s {
		if !hook.ProcessLogEntry(e) {
			return false
		}
	}
	return true
}

// Flush implements Hook.
func (s Hooks) Flush() {
	for _, hook := range s {
		hook.Flush()
	}
}

// PreHookResult is a result of computations returned by a PreHook.
type PreHookResult struct {
	// Skip forces a Logger to do not log this Entry.
	Skip bool

	// ExtraFields adds additional fields to the Entry.
	ExtraFields field.AbstractFields

	// ExtraEntryProperties adds additional Entry.Properties.
	ExtraEntryProperties EntryProperties
}

// PreHook is executed very early in a Logger, allowing to discard or change
// an Entry before any essential computations are done.
//
// For example it may be useful for samplers.
type PreHook interface {
	// ProcessInput is executed when functions Log, Trace, Debug, Info, Warn, Error, Panic and Fatal are called.
	//
	// TraceIDs are provided by Logger/CompactLogger and the rest arguments are just passed-through.
	ProcessInput(belt.TraceIDs, Level, ...any) PreHookResult

	// ProcessInputf is executed when functions Logf, Tracef, Debugf, Infof, Warnf, Errorf, Panicf and Fatalf are called.
	//
	// TraceIDs are provided by Logger/CompactLogger and the rest arguments are just passed-through.
	ProcessInputf(belt.TraceIDs, Level, string, ...any) PreHookResult

	// ProcessInputf is executed when functions LogFields, TraceFields, DebugFields, InfoFields, WarnFields, ErrorFields, PanicFields and FatalFields are called.
	//
	// TraceIDs are provided by Logger/CompactLogger and the rest arguments are just passed-through.
	ProcessInputFields(belt.TraceIDs, Level, string, field.AbstractFields) PreHookResult
}

// PreHooks is a collection of PreHook-s.
type PreHooks []PreHook

var _ PreHook = (PreHooks)(nil)

// ProcessInput implements PreHook.
func (s PreHooks) ProcessInput(traceIDs belt.TraceIDs, level Level, values ...any) PreHookResult {
	var result PreHookResult
	for _, hook := range s {
		oneResult := hook.ProcessInput(traceIDs, level, values...)
		result.Skip = oneResult.Skip
		if result.Skip {
			return result
		}
		result.ExtraEntryProperties = append(result.ExtraEntryProperties, oneResult.ExtraEntryProperties)
		result.ExtraFields = field.Add(result.ExtraFields, oneResult.ExtraFields)
	}

	return result
}

// ProcessInputf implements PreHook.
func (s PreHooks) ProcessInputf(traceIDs belt.TraceIDs, level Level, format string, args ...any) PreHookResult {
	var result PreHookResult
	for _, hook := range s {
		oneResult := hook.ProcessInputf(traceIDs, level, format, args...)
		result.Skip = oneResult.Skip
		if result.Skip {
			return result
		}
		result.ExtraEntryProperties = append(result.ExtraEntryProperties, oneResult.ExtraEntryProperties)
		result.ExtraFields = field.Add(result.ExtraFields, oneResult.ExtraFields)
	}

	return result
}

// ProcessInputFields implements PreHook.
func (s PreHooks) ProcessInputFields(traceIDs belt.TraceIDs, level Level, message string, addFields field.AbstractFields) PreHookResult {
	var result PreHookResult
	for _, hook := range s {
		oneResult := hook.ProcessInputFields(traceIDs, level, message, addFields)
		result.Skip = oneResult.Skip
		if result.Skip {
			return result
		}
		result.ExtraEntryProperties = append(result.ExtraEntryProperties, oneResult.ExtraEntryProperties)
		result.ExtraFields = field.Add(result.ExtraFields, oneResult.ExtraFields)
	}

	return result
}