Update to logger

logger/wrap_handlers.go

@@ -0,0 +1,98 @@
+package logger
+
+// FuncHandler returns a Handler that logs records with the given
+// function.
+import (
+	"fmt"
+	"reflect"
+	"sync"
+	"time"
+)
+
+// Function handler wraps the declared function and returns the handler for it
+func FuncHandler(fn func(r *Record) error) LogHandler {
+	return funcHandler(fn)
+}
+
+// The type decleration for the function
+type funcHandler func(r *Record) error
+
+// The implementation of the Log
+func (h funcHandler) Log(r *Record) error {
+	return h(r)
+}
+
+// This function allows you to do a full declaration for the log,
+// it is recommended you use FuncHandler instead
+func HandlerFunc(log func(message string, time time.Time, level LogLevel, call CallStack, context ContextMap) error) LogHandler {
+	return remoteHandler(log)
+}
+
+// The type used for the HandlerFunc
+type remoteHandler func(message string, time time.Time, level LogLevel, call CallStack, context ContextMap) error
+
+// The Log implementation
+func (c remoteHandler) Log(record *Record) error {
+	return c(record.Message, record.Time, record.Level, record.Call, record.Context)
+}
+
+// SyncHandler can be wrapped around a handler to guarantee that
+// only a single Log operation can proceed at a time. It's necessary
+// for thread-safe concurrent writes.
+func SyncHandler(h LogHandler) LogHandler {
+	var mu sync.Mutex
+	return FuncHandler(func(r *Record) error {
+		defer mu.Unlock()
+		mu.Lock()
+		return h.Log(r)
+	})
+}
+
+// LazyHandler writes all values to the wrapped handler after evaluating
+// any lazy functions in the record's context. It is already wrapped
+// around StreamHandler and SyslogHandler in this library, you'll only need
+// it if you write your own Handler.
+func LazyHandler(h LogHandler) LogHandler {
+	return FuncHandler(func(r *Record) error {
+		for k, v := range r.Context {
+			if lz, ok := v.(Lazy); ok {
+				value, err := evaluateLazy(lz)
+				if err != nil {
+					r.Context[errorKey] = "bad lazy " + k
+				} else {
+					v = value
+				}
+			}
+		}
+
+		return h.Log(r)
+	})
+}
+
+func evaluateLazy(lz Lazy) (interface{}, error) {
+	t := reflect.TypeOf(lz.Fn)
+
+	if t.Kind() != reflect.Func {
+		return nil, fmt.Errorf("INVALID_LAZY, not func: %+v", lz.Fn)
+	}
+
+	if t.NumIn() > 0 {
+		return nil, fmt.Errorf("INVALID_LAZY, func takes args: %+v", lz.Fn)
+	}
+
+	if t.NumOut() == 0 {
+		return nil, fmt.Errorf("INVALID_LAZY, no func return val: %+v", lz.Fn)
+	}
+
+	value := reflect.ValueOf(lz.Fn)
+	results := value.Call([]reflect.Value{})
+	if len(results) == 1 {
+		return results[0].Interface(), nil
+	} else {
+		values := make([]interface{}, len(results))
+		for i, v := range results {
+			values[i] = v.Interface()
+		}
+		return values, nil
+	}
+}