avoid repeated reading disk (#7369)

* avoid repeated reading disk

* checks both flush time AND read position advancement

* wait on cond

* fix reading

Gap detection and skipping to earliest memory time
Time-based reads that include events at boundary times for first reads (offset ≤ 0)
Aggregated subscriber wake-up via ListenersWaits signaling

* address comments

weed/util/log_buffer/log_read.go

@@ -270,7 +270,7 @@ func (logBuffer *LogBuffer) LoopProcessLogDataWithOffset(readerName string, star
 				return
 			}
 
-			// CRITICAL FIX: If we're reading offset-based and there's no data in LogBuffer,
+			// If we're reading offset-based and there's no data in LogBuffer,
 			// return ResumeFromDiskError to let Subscribe try reading from disk again.
 			// This prevents infinite blocking when all data is on disk (e.g., after restart).
 			if startPosition.IsOffsetBased {
@@ -355,7 +355,6 @@ func (logBuffer *LogBuffer) LoopProcessLogDataWithOffset(readerName string, star
 				continue
 			}
 
-
 			glog.V(4).Infof("Unmarshaled log entry %d: TsNs=%d, Offset=%d, Key=%s", batchSize+1, logEntry.TsNs, logEntry.Offset, string(logEntry.Key))
 
 			// Handle offset-based filtering for offset-based start positions
@@ -377,7 +376,7 @@ func (logBuffer *LogBuffer) LoopProcessLogDataWithOffset(readerName string, star
 				// println("stopTsNs", stopTsNs, "logEntry.TsNs", logEntry.TsNs)
 				return
 			}
-			// CRITICAL FIX: Use logEntry.Offset + 1 to move PAST the current entry
+			// Use logEntry.Offset + 1 to move PAST the current entry
 			// This prevents infinite loops where we keep requesting the same offset
 			lastReadPosition = NewMessagePosition(logEntry.TsNs, logEntry.Offset+1)