phi-accrual-failure-detector

A port of Akka's Phi Accrual Failure Detector.

Implementation of 'The Phi Accrual Failure Detector' by Hayashibara et al. as defined in their paper

The suspicion level of failure is given by a value called φ (phi). The basic idea of the φ failure detector is to express the value of φ on a scale that is dynamically adjusted to reflect current network conditions. A configurable threshold is used to decide if φ is considered to be a failure.

The value of φ is calculated as:

φ = -log10(1 - F(timeSinceLastHeartbeat)

where F is the cumulative distribution function of a normal distribution with mean and standard deviation estimated from historical heartbeat inter-arrival times.

Install

Gradle

dependencies {
    compile 'org.komamitsu:phi-accrual-failure-detector:1.0.0'
}

Maven

<dependency>
    <groupId>org.komamitsu</groupId>
    <artifactId>phi-accrual-failure-detector</artifactId>
    <version>1.0.0</version>
</dependency>

Usage

PhiAccrualFailureDetector failureDetector = new PhiAccrualFailureDetector.Builder().build();
System.out.println("The node is alive.");
for (int i = 0; i < 5; i++) {
    failureDetector.heartbeat();
    System.out.println(failureDetector.phi());
    TimeUnit.SECONDS.sleep(1);
}
System.out.println("The node got crashed.");
for (int i = 0; i < 5; i++) {
    System.out.println(failureDetector.phi());
    TimeUnit.SECONDS.sleep(1);
}
System.out.println("The node is up.");
for (int i = 0; i < 5; i++) {
    failureDetector.heartbeat();
    System.out.println(failureDetector.phi());
    TimeUnit.SECONDS.sleep(1);
}

>>>
The node is alive.
0.07503303214093988
0.04123372001754947
0.02973367253880404
0.024211164763365475
0.0210350451959075
The node got crashed.
0.434230547557814
2.026327722139659
5.53345508216027
12.239567237632542
23.67083400864969
The node is up.
0.09372488186862751
0.09191309083825062
0.08979724362880628
0.0875398030863105
0.08525179892208078