This library is an utility that exposes abstract classes and utilities to read and write data from random access sources. Currently, this library includes classes that allows to read and write data directly from memory blocks allocated inside and outside the JVM, and System V shared memory segments. This I/O operations have been optimized to have a good performance in reading and writing huge amount of data, using any byte order. It is expected in the future to add more data sources to work with, and complete the existing ones.
WARNING: This library has only been tested in x86 and x64 architectures with unaligned memory access. It might fail in other scenarios.
WARNING: This library is not compatible with Java 9+ (yet), as it uses reflection operations restricted by this version of Java.
Since this library performs direct memory access, it includes some code in C that must be compiled and loaded in order to make the library work. The repository includes some pre-compiled binaries for Linux/macOS with generic x86 and x64 processors. Nevertheless, it is recommended to compile the binaries by yourself in the machine that will run the library, since it may take advantage of the instructions sets of its processor to improve a little bit the performance of the library, especially in I/O operations that requires changing the byte order of the input data (this task might be faster in processors with vectorized instructions sets, for example). Binaries for macOS x86 are not included in the repository because the new macOS systems won't support x86 binaries.
The library has been tested in macOS and Linux, but should work in any other POSIX-compliant operating system. I don't give a cat about Windows.
The library will recognize three different filenames. Supposing that we're on a Linux system, the recognized filenames are:
- libaccessors.so: It is expected to contain the most native binary for the current platform.
- libaccessors32.so or libaccessors64.so: They are expected to contain the most generic binaries for x86 and x64 architectures, respectively.
The library will try to load the first available binary, using the
priority defined in the list above. First of all will try to find the
binaries in the folders specified in the java.library.path. If
they're not present there, it will try to load them from the java
classpath, copying them to a temporary location during the execution
of the JVM. This mean that you can install the libraries on your
system, or bundle it in your jar or classpath, without changing any
other environment variable or JVM configuration.
The repository includes different scripts to compile the natives by yourself:
build_generic_natives_*.shwill allow you to compile generic natives for x86 and x64 platforms (the ones included in the repository).build_natives_*.shwill allow you to compile a native library targeted to your current platform.
Both scripts requires a compiler that satisfies the GCC dependency (for example, clang in macOS). Also, both scripts will output the results to the src/main/resources folder.
This software is under the GNU GPL v3 license. This mean, in a nutshell, that you can freely use and distribute open source software that uses this library, but you cannot use it for privative projects that you are intending to distribute. For more details about this license, please refer to the file LICENSE present in this repository.