public long readLong()

in fluss-common/src/main/java/com/alibaba/fluss/row/compacted/CompactedRowReader.java [110:185]
64 lines of code
13 McCabe index (conditional complexity)

    public long readLong() {
        // Influenced by Protobuf CodedInputStream.
        // Implementation notes:
        //
        // Optimized for one-byte values, expected to be common.
        // The particular code below was selected from various candidates
        // empirically.
        //
        // Sign extension of (signed) Java bytes is usually a nuisance, but
        // we exploit it here to more easily obtain the sign of bytes read.
        // Instead of cleaning up the sign extension bits by masking eagerly,
        // we delay until we find the final (positive) byte, when we clear all
        // accumulated bits with one xor.  We depend on javac to constant fold.
        fastPath:
        {
            int tempPos = position;
            if (limit == tempPos) {
                break fastPath; // illegal, throws exception
            }
            final MemorySegment segment = this.segment;
            long x;
            int y;
            if ((y = segment.get(tempPos++)) >= 0) {
                position = tempPos;
                return y;
            } else if (limit - tempPos < 9) {
                break fastPath;
            } else if ((y ^= (segment.get(tempPos++) << 7)) < 0) {
                x = y ^ (~0 << 7);
            } else if ((y ^= (segment.get(tempPos++) << 14)) >= 0) {
                x = y ^ ((~0 << 7) ^ (~0 << 14));
            } else if ((y ^= (segment.get(tempPos++) << 21)) < 0) {
                x = y ^ ((~0 << 7) ^ (~0 << 14) ^ (~0 << 21));
            } else if ((x = y ^ ((long) segment.get(tempPos++) << 28)) >= 0L) {
                x ^= (~0L << 7) ^ (~0L << 14) ^ (~0L << 21) ^ (~0L << 28);
            } else if ((x ^= ((long) segment.get(tempPos++) << 35)) < 0L) {
                x ^= (~0L << 7) ^ (~0L << 14) ^ (~0L << 21) ^ (~0L << 28) ^ (~0L << 35);
            } else if ((x ^= ((long) segment.get(tempPos++) << 42)) >= 0L) {
                x ^=
                        (~0L << 7)
                                ^ (~0L << 14)
                                ^ (~0L << 21)
                                ^ (~0L << 28)
                                ^ (~0L << 35)
                                ^ (~0L << 42);
            } else if ((x ^= ((long) segment.get(tempPos++) << 49)) < 0L) {
                x ^=
                        (~0L << 7)
                                ^ (~0L << 14)
                                ^ (~0L << 21)
                                ^ (~0L << 28)
                                ^ (~0L << 35)
                                ^ (~0L << 42)
                                ^ (~0L << 49);
            } else {
                x ^= ((long) segment.get(tempPos++) << 56);
                x ^=
                        (~0L << 7)
                                ^ (~0L << 14)
                                ^ (~0L << 21)
                                ^ (~0L << 28)
                                ^ (~0L << 35)
                                ^ (~0L << 42)
                                ^ (~0L << 49)
                                ^ (~0L << 56);
                if (x < 0L) {
                    if (segment.get(tempPos++) < 0L) {
                        break fastPath; // illegal, throws exception
                    }
                }
            }
            position = tempPos;
            return x;
        }
        return readLongSlowPath();
    }