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Fix Ultrasonic sensor runner thread (#1598)

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When there is more than one ultrasonic sensor, only the last sensor
instantiated would work due to incorrect array index management. This
replaces the previous approach with range-based for loops like the C++
implementation.

Supersedes #1589.
This commit is contained in:
Tyler Veness
2019-02-14 20:25:56 -08:00
committed by Peter Johnson
parent 74f7ba04b0
commit 182758c05b
1 changed files with 10 additions and 22 deletions
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32
wpilibj/src/main/java/edu/wpi/first/wpilibj/Ultrasonic.java
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@@ -46,7 +46,7 @@ public class Ultrasonic extends SendableBase implements PIDSource {
// ultrasonic sensor list
private static final List<Ultrasonic> m_sensors = new ArrayList<>();
// automatic round robin mode
private static boolean m_automaticEnabled;
private static volatile boolean m_automaticEnabled;
private DigitalInput m_echoChannel;
private DigitalOutput m_pingChannel;
private boolean m_allocatedChannels;
@@ -70,30 +70,18 @@ public class Ultrasonic extends SendableBase implements PIDSource {
private static class UltrasonicChecker extends Thread {
@Override
public synchronized void run() {
int sensorIndex = 0;
Ultrasonic ultrasonic;
while (m_automaticEnabled) {
//lock list to ensure deletion doesn't occur between empty check and retrieving sensor
synchronized (m_sensors) {
if (m_sensors.isEmpty()) {
return;
for (Ultrasonic sensor: m_sensors) {
if (!m_automaticEnabled) {
break;
}
if (sensorIndex >= m_sensors.size()) {
sensorIndex = m_sensors.size() - 1;
}
ultrasonic = m_sensors.get(sensorIndex);
}
if (ultrasonic.isEnabled()) {
// Do the ping
ultrasonic.m_pingChannel.pulse(kPingTime);
}
if (sensorIndex < m_sensors.size()) {
sensorIndex++;
} else {
sensorIndex = 0;
}
Timer.delay(.1); // wait for ping to return
if (sensor.isEnabled()) {
sensor.m_pingChannel.pulse(kPingTime); // do the ping
}
Timer.delay(0.1); // wait for ping to return
}
}
}
}