store/src/main/java/org/apache/rocketmq/store/ConsumeQueue.java [1134:1164]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        for (MappedFile mappedFile : mappedFiles) {
            int start = 0;
            int len = mappedFile.getFileSize();

            // calculate start and len for first segment and last segment to reduce scanning
            // first file segment
            if (mappedFile.getFileFromOffset() <= physicalOffsetFrom) {
                start = (int) (physicalOffsetFrom - mappedFile.getFileFromOffset());
                if (mappedFile.getFileFromOffset() + mappedFile.getFileSize() >= physicalOffsetTo) {
                    // current mapped file covers search range completely.
                    len = (int) (physicalOffsetTo - physicalOffsetFrom);
                } else {
                    len = mappedFile.getFileSize() - start;
                }
            }

            // last file segment
            if (0 == start && mappedFile.getFileFromOffset() + mappedFile.getFileSize() > physicalOffsetTo) {
                len = (int) (physicalOffsetTo - mappedFile.getFileFromOffset());
            }

            // select partial data to scan
            SelectMappedBufferResult slice = mappedFile.selectMappedBuffer(start, len);
            if (null != slice) {
                try {
                    ByteBuffer buffer = slice.getByteBuffer();
                    int current = 0;
                    while (current < len) {
                        // skip physicalOffset and message length fields.
                        buffer.position(current + MSG_TAG_OFFSET_INDEX);
                        long tagCode = buffer.getLong();
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



store/src/main/java/org/apache/rocketmq/store/queue/BatchConsumeQueue.java [1106:1136]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        for (MappedFile mappedFile : mappedFiles) {
            int start = 0;
            int len = mappedFile.getFileSize();

            // calculate start and len for first segment and last segment to reduce scanning
            // first file segment
            if (mappedFile.getFileFromOffset() <= physicalOffsetFrom) {
                start = (int) (physicalOffsetFrom - mappedFile.getFileFromOffset());
                if (mappedFile.getFileFromOffset() + mappedFile.getFileSize() >= physicalOffsetTo) {
                    // current mapped file covers search range completely.
                    len = (int) (physicalOffsetTo - physicalOffsetFrom);
                } else {
                    len = mappedFile.getFileSize() - start;
                }
            }

            // last file segment
            if (0 == start && mappedFile.getFileFromOffset() + mappedFile.getFileSize() > physicalOffsetTo) {
                len = (int) (physicalOffsetTo - mappedFile.getFileFromOffset());
            }

            // select partial data to scan
            SelectMappedBufferResult slice = mappedFile.selectMappedBuffer(start, len);
            if (null != slice) {
                try {
                    ByteBuffer buffer = slice.getByteBuffer();
                    int current = 0;
                    while (current < len) {
                        // skip physicalOffset and message length fields.
                        buffer.position(current + MSG_TAG_OFFSET_INDEX);
                        long tagCode = buffer.getLong();
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -