Pull request 1751: imp-querylog

Merge in DNS/adguard-home from imp-querylog to master

Squashed commit of the following:

commit 40b88f9dac46576399cd4d1fad52ecffd8f5945d
Merge: fcfe40b3 bb80a7c2
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Feb 27 17:14:34 2023 +0300

    Merge branch 'master' into imp-querylog

commit fcfe40b33143f82fe4ef03fd883c3159dfb06026
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Feb 27 17:13:45 2023 +0300

    querylog: imp docs, names

commit 21722c6d853465c97e6f18693095a0bc86308ea3
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Feb 22 20:28:49 2023 +0300

    querylog: fix race; refactor

internal/querylog/qlog.go

@@ -31,7 +31,8 @@ type queryLog struct {
 
 	// bufferLock protects buffer.
 	bufferLock sync.RWMutex
-	// buffer contains recent log entries.
+	// buffer contains recent log entries.  The entries in this buffer must not
+	// be modified.
 	buffer []*logEntry
 
 	fileFlushLock sync.Mutex // synchronize a file-flushing goroutine and main thread
@@ -100,6 +101,13 @@ type logEntry struct {
 	AuthenticatedData bool `json:"AD,omitempty"`
 }
 
+// shallowClone returns a shallow clone of e.
+func (e *logEntry) shallowClone() (clone *logEntry) {
+	cloneVal := *e
+
+	return &cloneVal
+}
+
 func (l *queryLog) Start() {
 	if l.conf.HTTPRegister != nil {
 		l.initWeb()