Reduce Logger interface to Log method

logger.go

@@ -7,8 +7,7 @@ import (
 )
 
 // The values for log levels are chosen such that the zero value means that no
-// log level was specified and we can default to LogLevelDebug to preserve
-// the behavior that existed prior to log level introduction.
+// log level was specified.
 const (
 	LogLevelTrace = 6
 	LogLevelDebug = 5
@@ -19,15 +18,9 @@ const (
 )
 
 // Logger is the interface used to get logging from pgx internals.
-// https://github.com/inconshreveable/log15 is the recommended logging package.
-// This logging interface was extracted from there. However, it should be simple
-// to adapt any logger to this interface.
 type Logger interface {
 	// Log a message at the given level with context key/value pairs
-	Debug(msg string, ctx ...interface{})
-	Info(msg string, ctx ...interface{})
-	Warn(msg string, ctx ...interface{})
-	Error(msg string, ctx ...interface{})
+	Log(level int, msg string, ctx ...interface{})
 }
 
 // LogLevelFromString converts log level string to constant