ref(checkin): Measure check-in durations with Stopwatch (JAVA-576)

All four check-in paths kept a `long startTime = System.nanoTime()` and
subtracted it in a finally block: CheckInUtils and the SentryCheckInAdvice
in sentry-spring, sentry-spring-jakarta and sentry-spring-7.

The serialized duration is unchanged, to the bit. JavaUptimeClock.tickNanos()
is System.nanoTime(), and check-ins have no Android path where the two could
diverge, so this is the same arithmetic behind a name. That is the point of
naming the guarantee rather than the mechanism: it makes a conversion that
touches a customer-facing value provably inert, and therefore landable before
the major.

Each site carries a TODO [MAJOR] for the change that is not inert: on
elapsed-real-time, a cron job that spans device sleep would report the
duration a user would measure rather than the CPU time it had.

The clock is resolved as JavaUptimeClock.getInstance() rather than through
options, so an uninitialised SDK reaches a working clock without a scopes
lookup.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: runningcode

sentry-spring-7/src/main/java/io/sentry/spring7/checkin/SentryCheckInAdvice.java

@@ -9,6 +9,8 @@
 import io.sentry.ScopesAdapter;
 import io.sentry.SentryLevel;
 import io.sentry.protocol.SentryId;
+import io.sentry.time.JavaUptimeClock;
+import io.sentry.time.Stopwatch;
 import io.sentry.util.Objects;
 import io.sentry.util.TracingUtils;
 import java.lang.reflect.Method;
@@ -91,7 +93,9 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       TracingUtils.startNewTrace(scopes);
 
       @Nullable SentryId checkInId = null;
-      final long startTime = System.nanoTime();
+      // TODO [MAJOR]: switch to ElapsedRealtimeClock, so that a job spanning device sleep
+      // reports the duration a user would measure rather than the CPU time it had.
+      final @NotNull Stopwatch stopwatch = Stopwatch.started(JavaUptimeClock.getInstance());
       boolean didError = false;
 
       try {
@@ -105,7 +109,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       } finally {
         final @NotNull CheckInStatus status = didError ? CheckInStatus.ERROR : CheckInStatus.OK;
         CheckIn checkIn = new CheckIn(checkInId, monitorSlug, status);
-        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(stopwatch.elapsedNanos()));
         scopes.captureCheckIn(checkIn);
       }
     }

sentry-spring-jakarta/src/main/java/io/sentry/spring/jakarta/checkin/SentryCheckInAdvice.java

@@ -9,6 +9,8 @@
 import io.sentry.ScopesAdapter;
 import io.sentry.SentryLevel;
 import io.sentry.protocol.SentryId;
+import io.sentry.time.JavaUptimeClock;
+import io.sentry.time.Stopwatch;
 import io.sentry.util.Objects;
 import io.sentry.util.TracingUtils;
 import java.lang.reflect.Method;
@@ -91,7 +93,9 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       TracingUtils.startNewTrace(scopes);
 
       @Nullable SentryId checkInId = null;
-      final long startTime = System.nanoTime();
+      // TODO [MAJOR]: switch to ElapsedRealtimeClock, so that a job spanning device sleep
+      // reports the duration a user would measure rather than the CPU time it had.
+      final @NotNull Stopwatch stopwatch = Stopwatch.started(JavaUptimeClock.getInstance());
       boolean didError = false;
 
       try {
@@ -105,7 +109,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       } finally {
         final @NotNull CheckInStatus status = didError ? CheckInStatus.ERROR : CheckInStatus.OK;
         CheckIn checkIn = new CheckIn(checkInId, monitorSlug, status);
-        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(stopwatch.elapsedNanos()));
         scopes.captureCheckIn(checkIn);
       }
     }

sentry-spring/src/main/java/io/sentry/spring/checkin/SentryCheckInAdvice.java

@@ -9,6 +9,8 @@
 import io.sentry.ScopesAdapter;
 import io.sentry.SentryLevel;
 import io.sentry.protocol.SentryId;
+import io.sentry.time.JavaUptimeClock;
+import io.sentry.time.Stopwatch;
 import io.sentry.util.Objects;
 import io.sentry.util.TracingUtils;
 import java.lang.reflect.Method;
@@ -94,7 +96,9 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       TracingUtils.startNewTrace(scopes);
 
       @Nullable SentryId checkInId = null;
-      final long startTime = System.nanoTime();
+      // TODO [MAJOR]: switch to ElapsedRealtimeClock, so that a job spanning device sleep
+      // reports the duration a user would measure rather than the CPU time it had.
+      final @NotNull Stopwatch stopwatch = Stopwatch.started(JavaUptimeClock.getInstance());
       boolean didError = false;
 
       try {
@@ -108,7 +112,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       } finally {
         final @NotNull CheckInStatus status = didError ? CheckInStatus.ERROR : CheckInStatus.OK;
         CheckIn checkIn = new CheckIn(checkInId, monitorSlug, status);
-        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(stopwatch.elapsedNanos()));
         scopes.captureCheckIn(checkIn);
       }
     }

sentry/src/main/java/io/sentry/util/CheckInUtils.java

@@ -9,6 +9,8 @@
 import io.sentry.MonitorConfig;
 import io.sentry.Sentry;
 import io.sentry.protocol.SentryId;
+import io.sentry.time.JavaUptimeClock;
+import io.sentry.time.Stopwatch;
 import java.util.List;
 import java.util.concurrent.Callable;
 import org.jetbrains.annotations.ApiStatus;
@@ -37,7 +39,9 @@ public static <U> U withCheckIn(
     try (final @NotNull ISentryLifecycleToken ignored =
             Sentry.forkedScopes("CheckInUtils").makeCurrent()) {
       final @NotNull IScopes scopes = Sentry.getCurrentScopes();
-      final long startTime = System.nanoTime();
+      // TODO [MAJOR]: switch to ElapsedRealtimeClock, so that a job spanning device sleep
+      // reports the duration a user would measure rather than the CPU time it had.
+      final @NotNull Stopwatch stopwatch = Stopwatch.started(JavaUptimeClock.getInstance());
       boolean didError = false;
 
       TracingUtils.startNewTrace(scopes);
@@ -61,7 +65,7 @@ public static <U> U withCheckIn(
         if (environment != null) {
           checkIn.setEnvironment(environment);
         }
-        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(stopwatch.elapsedNanos()));
         scopes.captureCheckIn(checkIn);
       }
     }