Codereview request: 7109837 Provide a mechanism for computing an Adler32 checksum for the contents of a ByteBuffer

[Xueming Shen]

Hi,

java.util.zip.Adler32/CRC32 do not have update method that accepts 
ByteBuffer.
As of JDK7, you have to copy the content of the ByteBuffer into a 
byte[], then
invoke Adler32/CRC32.update() method, which might have significant 
performance
impact for some applications. Here I'm proposing to add two update 
methods in
j.u.z.Adler32 and CRC32 classes respectively to address this issue.

Here is the webrev

http://cr.openjdk.java.net/~sherman/7109837/webrev

Attached is the result of TimeChecksum.java, which also serves as a 
simple Benchmark.

Thanks!
Sherman

-------------------------------------------------------------------------------------------------------------------------

sherman at sherman-linux:~/Workspace/jdk8_bugfix/test/java/util/zip$ java 
TimeChecksum
---------- Adler32 ----------
Warmup...      59,535      59,495      59,948

Length    byte[](ns/len)  ByteBuffer(direct)   ByteBuffer
1      13,409,610       2,990,525 (  77%)  13,196,357 (   1%)     
checksum=bd00bd
2       5,808,804       1,664,460 (  71%)   7,069,931 ( -21%)     
checksum=19000d3
4       3,009,793         858,267 (  71%)   3,516,799 ( -16%)     
checksum=55f01fe
8       1,560,870         508,546 (  67%)   1,754,650 ( -12%)     
checksum=11cc03d4
16         792,323         298,697 (  62%)     931,902 ( -17%)     
checksum=40fb071b
32         430,367         185,262 (  56%)     487,747 ( -13%)     
checksum=ed2b0e1d
64         242,277         123,685 (  48%)     277,898 ( -14%)     
checksum=d0601df1
128         147,870          96,570 (  34%)     164,493 ( -11%)     
checksum=29d13ac0
256         107,230          80,315 (  25%)     114,297 (  -6%)     
checksum=20807ab7
512          85,729          73,765 (  13%)      90,236 (  -5%)     
checksum=feb1face
1024          74,593          67,872 (   9%)      77,241 (  -3%)     
checksum=7721ffb7
2048          71,558          68,599 (   4%)      72,673 (  -1%)     
checksum=717c0800
4096          70,053          64,908 (   7%)      67,246 (   4%)     
checksum=53b5fbe1
8192          62,689          60,908 (   2%)      62,205 (   0%)     
checksum=7ae5e6b3
16384          60,721          59,802 (   1%)      60,920 (   0%)     
checksum=89e1b861

---------- CRC32 ----------
Warmup...     100,600     101,373     100,795

Length    byte[](ns/len)  ByteBuffer(direct)   ByteBuffer
1      10,929,099       3,562,762 (  67%)  13,328,815 ( -21%)     
checksum=10d5102a
2       5,811,664       1,846,604 (  68%)   6,924,621 ( -19%)     
checksum=fd7d461a
4       3,048,740         968,395 (  68%)   3,522,863 ( -15%)     
checksum=a1ab61ba
8       1,605,356         539,462 (  66%)   1,778,894 ( -10%)     
checksum=cdc2506e
16         859,704         318,999 (  62%)     926,758 (  -7%)     
checksum=1c3db3a3
32         474,646         216,487 (  54%)     489,307 (  -3%)     
checksum=19bbc99e
64         282,917         157,252 (  44%)     280,958 (   0%)     
checksum=df43e0e0
128         195,853         127,730 (  34%)     164,068 (  16%)     
checksum=5fa8c160
256         147,025         116,742 (  20%)     113,715 (  22%)     
checksum=854200ac
512         121,620         108,233 (  11%)      90,232 (  25%)     
checksum=1b6cc88e
1024         110,529         106,890 (   3%)      77,241 (  30%)     
checksum=1456003f
2048         105,115         103,971 (   1%)      72,716 (  30%)     
checksum=187766b0
4096         102,661         103,858 (  -1%)      67,646 (  34%)     
checksum=91c34ea3
8192         101,280         103,494 (  -2%)      62,359 (  38%)     
checksum=2b8921aa
16384         104,444         105,407 (   0%)      61,126 (  41%)     
checksum=6f921ec0