head.daveops.net

Snippets for yer computer needs

Java

Java

Types —– | type | note | |———|————————————————-| | byte | 8-bit signed two’s complement integer | | short | 16-bit signed two’s complement integer | | int | 32-bit signed two’s complement integer | | long | 64-bit two’s complement integer | | float | single-precision 32-bit IEEE 754 floating point | | double | double-precision 64-bit IEEE 754 floating point | | boolean | the size isn’t precisely defined |

Numeric literals

You can use underscore characters in SE7+ example: long hexBytes = 0xFF_CC_DA_B5;

AES intrinsics

Requires Java 8 and Intel 2010+ Westmere

-XX:+UseAES -XX:+UseAESIntrinsics

Zero copy

Avoid copying the file data across user/kernel boundary, instead have the kernel put the file in a buffer and use DMA to pass the data directly.

https://www.ibm.com/developerworks/linux/library/j-zerocopy/