* querylog: fix end of log handling

internal/agherr/agherr.go

@@ -7,6 +7,14 @@ import (
 	"strings"
 )
 
+// Error is the constant error type.
+type Error string
+
+// Error implements the error interface for Error.
+func (err Error) Error() (msg string) {
+	return string(err)
+}
+
 // manyError is an error containing several wrapped errors.  It is created to be
 // a simpler version of the API provided by github.com/joomcode/errorx.
 type manyError struct {

internal/querylog/qlog_file.go

@@ -7,13 +7,17 @@ import (
 	"sync"
 	"time"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/agherr"
 	"github.com/AdguardTeam/golibs/log"
 )
 
 // ErrSeekNotFound is returned from the Seek method
 // if we failed to find the desired record
 var ErrSeekNotFound = errors.New("Seek not found the record")
 
+// ErrEndOfLog is returned when the end of the current log is reached.
+var ErrEndOfLog agherr.Error = "end of log"
+
 // TODO: Find a way to grow buffer instead of relying on this value when reading strings
 const maxEntrySize = 16 * 1024
 
@@ -106,6 +110,8 @@ func (q *QLogFile) Seek(timestamp int64) (int64, int, error) {
 			// the scope is too narrow and we won't find anything anymore
 			log.Error("querylog: didn't find timestamp:%v", timestamp)
 			return 0, depth, ErrSeekNotFound
+		} else if lineIdx == end && lineEndIdx == end {
+			return 0, depth, ErrEndOfLog
 		}
 
 		// Save the last found idx

internal/querylog/qlog_reader.go

@@ -1,6 +1,7 @@
 package querylog
 
 import (
+	"errors"
 	"io"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/agherr"
@@ -52,11 +53,14 @@ func (r *QLogReader) Seek(timestamp int64) error {
 	for i := len(r.qFiles) - 1; i >= 0; i-- {
 		q := r.qFiles[i]
 		_, _, err := q.Seek(timestamp)
-		if err == nil {
-			// Our search is finished, we found the element we were looking for
-			// Update currentFile only, position is already set properly in the QLogFile
+		if err == nil || errors.Is(err, ErrEndOfLog) {
+			// Our search is finished, and we either found the
+			// element we were looking for or reached the end of the
+			// log.  Update currentFile only, position is already
+			// set properly in QLogFile.
 			r.currentFile = i
-			return nil
+
+			return err
 		}
 	}
 

internal/querylog/querylog_search.go

@@ -1,6 +1,7 @@
 package querylog
 
 import (
+	"errors"
 	"io"
 	"time"
 
@@ -45,6 +46,7 @@ func (l *queryLog) search(params *searchParams) ([]*logEntry, time.Time) {
 		// remove extra records
 		entries = entries[:totalLimit]
 	}
+
 	if params.offset > 0 {
 		if len(entries) > params.offset {
 			entries = entries[params.offset:]
@@ -53,11 +55,9 @@ func (l *queryLog) search(params *searchParams) ([]*logEntry, time.Time) {
 			oldest = time.Time{}
 		}
 	}
-	if len(entries) == totalLimit {
-		// change the "oldest" value here.
-		// we cannot use the "oldest" we got from "searchFiles" anymore
-		// because after adding in-memory records and removing extra records
-		// the situation has changed
+
+	if len(entries) > 0 && len(entries) <= totalLimit {
+		// Update oldest after merging in the memory buffer.
 		oldest = entries[len(entries)-1].Time
 	}
 
@@ -95,6 +95,9 @@ func (l *queryLog) searchFiles(params *searchParams) ([]*logEntry, time.Time, in
 			// The one that was specified in the "oldest" param is not needed,
 			// we need only the one next to it
 			_, err = r.ReadNext()
+		} else if errors.Is(err, ErrEndOfLog) {
+			// We've reached the end of the log.
+			return entries, time.Time{}, 0
 		}
 	}