Add the Enabled method to the Logger (#5071)

* Add the Enabled method to the Logger

* Add a changelog entry

* Rename enabled.go to min_sev.go

* Remove MinSeverityProcessor

* Document lack of interaction between OnEmit and Enabled

* Update sdk/log/processor.go

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>

log/logger.go

@@ -29,6 +29,28 @@ type Logger interface {
 	// Implementations of this method need to be safe for a user to call
 	// concurrently.
 	Emit(ctx context.Context, record Record)
+
+	// Enabled returns whether the Logger emits for the given context and
+	// record.
+	//
+	// The passed record is likely to be a partial record with only the
+	// bridge-relevant information being provided (e.g a record with only the
+	// Severity set). If a Logger needs more information than is provided, it
+	// is said to be in an indeterminate state (see below).
+	//
+	// The returned value will be true when the Logger will emit for the
+	// provided context and record, and will be false if the Logger will not
+	// emit. The returned value may be true or false in an indeterminate state.
+	// An implementation should default to returning true for an indeterminate
+	// state, but may return false if valid reasons in particular circumstances
+	// exist (e.g. performance, correctness).
+	//
+	// The record should not be held by the implementation. A copy should be
+	// made if the record needs to be held after the call returns.
+	//
+	// Implementations of this method need to be safe for a user to call
+	// concurrently.
+	Enabled(ctx context.Context, record Record) bool
 }
 
 // LoggerOption applies configuration options to a [Logger].

log/noop/noop.go

@@ -45,3 +45,6 @@ type Logger struct{ embedded.Logger }
 
 // Emit does nothing.
 func (Logger) Emit(context.Context, log.Record) {}
+
+// Enabled returns false. No log records are ever emitted.
+func (Logger) Enabled(context.Context, log.Record) bool { return false }