JarCastingUsage
Gradle
compile group: 'com.github.akurilov', name: 'java-commons', version: '2.3.6'
Library Content
Collections
Circular Buffer
Allows to reuse the buffer for the elements inserting and removing w/o memory copy.
import com.github.akurilov.commons.collection.CircularBuffer;
import com.github.akurilov.commons.collection.CircularArrayBuffer;
...
final var buff = (CircularBuffer<String>) new CircularArrayBuffer<>(capacity);
...
Trees
- Deep copy
import com.github.akurilov.commons.collection.TreeUtil;
...
final var srcTree = (Map<String, Object>) ...
final var dstTree = (Map<String, Object>) TreeUtil.copyTree(srcTree);
- Add branch
final var branch = (Map<String, Object>) ...
TreeUtil.addBranches(dstTree, branch);
- Deep merge
TODO
- Reduce a forest into a tree
final var forest = (Map<String, Object>) ...
final var tree = (Map<String, Object>) TreeUtil.reduceForest(forest);
Range
The range described with at least one bound (begin or end position) and optional size.
Concurrency
AsyncRunnable
The entity with the following defined states:
INITIALSTARTEDSHUTDOWNSTOPPEDCLOSED
The corresponding methods (start/shutdown/stop/close) are available guaranteeing the thread-safe transition. Each method provides the extension points for user action upon transitions. Also, there are also a pair of await methods intended to block until the instance leaves the STARTED state.
A user should extend the AsyncRunnableBase class.
Throttles
A throttles provide semaphore-like non-blocking functionality. All throttles also support batch permits acquiring.
Rate throttle example:
final var rateLimit = 0.1;
final var throttle = (Throttle) new RateThrottle(rateLimit);
...
n = throttle.tryAcquire(10);
Complex weighted throttle example:
final var weights = new int[] { 80, 20 }; // permits distribution 80% in the 1st direction vs 20% in the 2nd one
final var weightedThrottle = (IndexThrottle) new SequentialWeightsThrottle(weights);
...
if(weightedThrottle.tryAcquire(0)) {
// a permit in the 1st direction is acquired
...
}
...
n = weightedThrottle.tryAcquire(1, 10); // try to acquire up to 10 permits in the 2nd direction
Functional Programming
Partial Functions
TODO
Object I/O
Binary
TODO
Collections
TODO
Expressions
A values input evaluating an expression and returning the result. Utilizing the Java Unified Expression Language functionality.
Current time millis supplying example:
final var in = ExpressionInput.<Long>builder()
.expr("${time:millisSinceEpoch()}")
.func("time", "millisSinceEpoch", System.class.getMethod("currentTimeMillis"))
.build();
...
System.out.println(in.get());
Custom random dynamic string example:
final IntFunction<String> idSupplier = (radix) -> Long.toString(
abs(Long.reverse(currentTimeMillis()) ^ Long.reverseBytes(nanoTime())),
radix
);
final var in = ExpressionInput.<String>builder()
.value("idSupplier", idSupplier, IntFunction.class)
.value("radix", 36, int.class)
.expr("${idSupplier.apply(radix)}")
.build();
System.out.println(in.get());
The most interesting feature is the ability to evaluate the expression on the previous expression result:
final var in = ExpressionInput.builder()
.expression("${this.last() + 1}%{-1}")
.type(int.class)
.build();
in.get(); // will return 0
in.get(); // 1
in.get(); // 2
...
In other words, it's possible to calculate each next value using the previous one.
Text
TODO
Math
Includes the XorShift and greatest common divisor methods.
Networking
TODO
Lang
Contains the method void throwUnchecked(final Throwable t) allowing to throw checked exceptions as unchecked ones.
Reflection
Types Comparison
TODO
System
Direct Memory
Thread local direct memory byte buffers cache. Useful for the zero-copy I/O. Instead of allocating the buffer of exact size find the most suitable sized byte buffer in the thread local cache. The cache contains the sequence of buffers with a sizes 1, 2, 4, ..., 16MB. The total count of the buffers in the cache is 25 and their summary size is less than 32MB.
Examples:
MappedByteBuffer bbuff;
bbuff = DirectMemUtil.getThreadLocalReusableBuff(0); // will return the byte buffer with the size of 1 bytes (min)
bbuff = DirectMemUtil.getThreadLocalReusableBuff(1); // will return the byte buffer with the size of 1 bytes
bbuff = DirectMemUtil.getThreadLocalReusableBuff(12345); // will return the byte buffer with the size of 16 KB
bbuff = DirectMemUtil.getThreadLocalReusableBuff(1_000_000_000_000L); // will return the byte buffer with the size of 16 MB (max)
Size In Bytes
The class to represent some size data. A size may be formatted into the form like "1.234MB". Also the size may be not fixed but describe some size range with the given bias.