logtree: implement
This implements logtree, as per go/logtree .
Some API changes are present, the design doc will be updated to reflect
these and the rationale behind the changes.
This implementation is missing 'raw' log functionality, this will be
added in a diff on top (as the implementation is trivial, but we want
to keep this diff as simple as possible).
Test Plan: covered by tests
X-Origin-Diff: phab/D624
GitOrigin-RevId: 6d1e0fb16f47e4b0dc9a18765cecb9314bbcb441
diff --git a/core/pkg/logtree/logtree_publisher.go b/core/pkg/logtree/logtree_publisher.go
new file mode 100644
index 0000000..02243ac
--- /dev/null
+++ b/core/pkg/logtree/logtree_publisher.go
@@ -0,0 +1,151 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logtree
+
+import (
+ "fmt"
+ "runtime"
+ "strings"
+ "time"
+)
+
+// LeveledFor returns a LeveledLogger publishing interface for a given DN. An error may be returned if the DN is
+// malformed.
+func (l *LogTree) LeveledFor(dn DN) (LeveledLogger, error) {
+ return l.nodeByDN(dn)
+}
+
+// MustLeveledFor returns a LeveledLogger publishing interface for a given DN, or panics if the given DN is invalid.
+func (l *LogTree) MustLeveledFor(dn DN) LeveledLogger {
+ leveled, err := l.LeveledFor(dn)
+ if err != nil {
+ panic(fmt.Errorf("LeveledFor returned: %w", err))
+ }
+ return leveled
+}
+
+// SetVerbosity sets the verbosity for a given DN (non-recursively, ie. for that DN only, not its children).
+func (l *LogTree) SetVerbosity(dn DN, level VerbosityLevel) error {
+ node, err := l.nodeByDN(dn)
+ if err != nil {
+ return err
+ }
+ node.verbosity = level
+ return nil
+}
+
+// log builds a Payload and entry for a given message, including all related metadata, and appends it to the journal,
+// notifying all pertinent subscribers.
+func (n *node) log(depth int, severity Severity, msg string) {
+ _, file, line, ok := runtime.Caller(2 + depth)
+ if !ok {
+ file = "???"
+ line = 1
+ } else {
+ slash := strings.LastIndex(file, "/")
+ if slash >= 0 {
+ file = file[slash+1:]
+ }
+ }
+ p := &Payload{
+ timestamp: time.Now(),
+ severity: severity,
+ message: msg,
+ file: file,
+ line: line,
+ }
+ e := &entry{
+ origin: n.dn,
+ payload: p,
+ }
+ n.tree.journal.append(e)
+ n.tree.journal.notify(e)
+}
+
+// Info implements the LeveledLogger interface.
+func (n *node) Info(args ...interface{}) {
+ n.log(0, INFO, fmt.Sprint(args...))
+}
+
+// Infof implements the LeveledLogger interface.
+func (n *node) Infof(format string, args ...interface{}) {
+ n.log(0, INFO, fmt.Sprintf(format, args...))
+}
+
+// Warning implements the LeveledLogger interface.
+func (n *node) Warning(args ...interface{}) {
+ n.log(0, WARNING, fmt.Sprint(args...))
+}
+
+// Warningf implements the LeveledLogger interface.
+func (n *node) Warningf(format string, args ...interface{}) {
+ n.log(0, WARNING, fmt.Sprintf(format, args...))
+}
+
+// Error implements the LeveledLogger interface.
+func (n *node) Error(args ...interface{}) {
+ n.log(0, ERROR, fmt.Sprint(args...))
+}
+
+// Errorf implements the LeveledLogger interface.
+func (n *node) Errorf(format string, args ...interface{}) {
+ n.log(0, ERROR, fmt.Sprintf(format, args...))
+}
+
+// Fatal implements the LeveledLogger interface.
+func (n *node) Fatal(args ...interface{}) {
+ n.log(0, FATAL, fmt.Sprint(args...))
+}
+
+// Fatalf implements the LeveledLogger interface.
+func (n *node) Fatalf(format string, args ...interface{}) {
+ n.log(0, FATAL, fmt.Sprintf(format, args...))
+}
+
+// V implements the LeveledLogger interface.
+func (n *node) V(v VerbosityLevel) VerboseLeveledLogger {
+ return &verbose{
+ node: n,
+ enabled: n.verbosity >= v,
+ }
+}
+
+// verbose implements the VerboseLeveledLogger interface. It is a thin wrapper around node, with an 'enabled' bool. This
+// means that V(n)-returned VerboseLeveledLoggers must be short lived, as a changed in verbosity will not affect all
+// already existing VerboseLeveledLoggers.
+type verbose struct {
+ node *node
+ enabled bool
+}
+
+func (v *verbose) Enabled() bool {
+ return v.enabled
+}
+
+func (v *verbose) Info(args ...interface{}) {
+ if !v.enabled {
+ return
+ }
+ v.node.log(0, INFO, fmt.Sprint(args...))
+}
+
+func (v *verbose) Infof(format string, args ...interface{}) {
+ if !v.enabled {
+ return
+ }
+ v.node.log(0, INFO, fmt.Sprintf(format, args...))
+}