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SessionId.java
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SessionId.java
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/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/
package io.opentelemetry.android;
import static java.util.Objects.requireNonNull;
import androidx.annotation.Nullable;
import io.opentelemetry.api.trace.TraceId;
import io.opentelemetry.sdk.common.Clock;
import java.util.Random;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
class SessionId {
private static final long SESSION_LIFETIME_NANOS = TimeUnit.HOURS.toNanos(4);
private final Clock clock;
private final AtomicReference<String> value = new AtomicReference<>();
private final SessionIdTimeoutHandler timeoutHandler;
private volatile long createTimeNanos;
@Nullable private volatile SessionIdChangeListener sessionIdChangeListener;
SessionId(SessionIdTimeoutHandler timeoutHandler) {
this(Clock.getDefault(), timeoutHandler);
}
// for testing
SessionId(Clock clock, SessionIdTimeoutHandler timeoutHandler) {
this.clock = clock;
this.timeoutHandler = timeoutHandler;
value.set(createNewId());
createTimeNanos = clock.now();
}
private static String createNewId() {
Random random = new Random();
// The OTel TraceId has exactly the same format as a RUM SessionId, so let's re-use it here,
// rather than re-inventing the wheel.
return TraceId.fromLongs(random.nextLong(), random.nextLong());
}
SessionIdTimeoutHandler getTimeoutHandler() {
return timeoutHandler;
}
String getSessionId() {
// value will never be null
String oldValue = requireNonNull(value.get());
String currentValue = oldValue;
boolean sessionIdChanged = false;
if (sessionExpired() || timeoutHandler.hasTimedOut()) {
String newId = createNewId();
// if this returns false, then another thread updated the value already.
sessionIdChanged = value.compareAndSet(oldValue, newId);
if (sessionIdChanged) {
createTimeNanos = clock.nanoTime();
}
// value will never be null
currentValue = requireNonNull(value.get());
}
timeoutHandler.bump();
// sessionId change listener needs to be called after bumping the timer because it may
// create a new span
SessionIdChangeListener sessionIdChangeListener = this.sessionIdChangeListener;
if (sessionIdChanged && sessionIdChangeListener != null) {
sessionIdChangeListener.onChange(oldValue, currentValue);
}
return currentValue;
}
private boolean sessionExpired() {
long elapsedTime = clock.nanoTime() - createTimeNanos;
return elapsedTime >= SESSION_LIFETIME_NANOS;
}
void setSessionIdChangeListener(SessionIdChangeListener sessionIdChangeListener) {
this.sessionIdChangeListener = sessionIdChangeListener;
}
@Override
public String toString() {
// value will never be null
return requireNonNull(value.get());
}
}