Move TimeBudget to vespajlib and use Clock

3 files changed, 119 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/time/TimeBudget.java b/vespajlib/src/main/java/com/yahoo/time/TimeBudget.java
new file mode 100644
index 00000000000..6f28d5d80e8
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/time/TimeBudget.java
@@ -0,0 +1,63 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.time;
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+
+/**
+ * A TimeBudget can be used to track the time of an ongoing operation with a timeout.
+ *
+ * @author hakon
+ */
+public class TimeBudget {
+    private final Clock clock;
+    private final Instant start;
+    private final Duration timeout;
+
+    /** Returns a TimeBudget with a start time of now, and with the given timeout. */
+    public static TimeBudget fromNow(Clock clock, Duration timeout) {
+        return new TimeBudget(clock, clock.instant(), timeout);
+    }
+
+    private TimeBudget(Clock clock, Instant start, Duration timeout) {
+        this.clock = clock;
+        this.start = start;
+        this.timeout = makeNonNegative(timeout);
+    }
+
+    /** Returns time since start. */
+    public Duration timePassed() {
+        return nonNegativeBetween(start, clock.instant());
+    }
+
+    /** Returns the original timeout. */
+    public Duration originalTimeout() {
+        return timeout;
+    }
+
+    /**
+     * Returns the time until deadline.
+     *
+     * @return time until deadline. It's toMillis() is guaranteed to be positive.
+     * @throws UncheckedTimeoutException if the deadline has been reached or passed.
+     */
+    public Duration timeLeftOrThrow() {
+        Instant now = clock.instant();
+        Duration left = Duration.between(now, start.plus(timeout));
+        if (left.toMillis() <= 0) {
+            throw new UncheckedTimeoutException("Time since start " + nonNegativeBetween(start, now) +
+                    " exceeds timeout " + timeout);
+        }
+
+        return left;
+    }
+
+    private static Duration nonNegativeBetween(Instant start, Instant end) {
+        return makeNonNegative(Duration.between(start, end));
+    }
+
+    private static Duration makeNonNegative(Duration duration) {
+        return duration.isNegative() ? Duration.ZERO : duration;
+    }
+}
diff --git a/vespajlib/src/main/java/com/yahoo/time/UncheckedTimeoutException.java b/vespajlib/src/main/java/com/yahoo/time/UncheckedTimeoutException.java
new file mode 100644
index 00000000000..3b53ffbdcf6
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/time/UncheckedTimeoutException.java
@@ -0,0 +1,18 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.time;
+
+/**
+ * Exception thrown when a blocking operation times out.
+ *
+ * <p>Mirrors {@link java.util.concurrent.TimeoutException}
+ *
+ * @author hakon
+ */
+@SuppressWarnings("serial")
+public class UncheckedTimeoutException extends RuntimeException {
+    public UncheckedTimeoutException() { }
+
+    public UncheckedTimeoutException(String message) {
+        super(message);
+    }
+}
diff --git a/vespajlib/src/test/java/com/yahoo/time/TimeBudgetTestCase.java b/vespajlib/src/test/java/com/yahoo/time/TimeBudgetTestCase.java
new file mode 100644
index 00000000000..ef664f95d33
--- /dev/null
+++ b/vespajlib/src/test/java/com/yahoo/time/TimeBudgetTestCase.java
@@ -0,0 +1,38 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.time;
+
+import org.junit.Test;
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class TimeBudgetTestCase {
+    private final Clock clock = mock(Clock.class);
+
+    @Test
+    public void testBasics() {
+        when(clock.instant()).thenReturn(Instant.ofEpochSecond(0));
+        TimeBudget timeBudget = TimeBudget.fromNow(clock, Duration.ofSeconds(10));
+
+        when(clock.instant()).thenReturn(Instant.ofEpochSecond(7));
+        assertEquals(Duration.ofSeconds(3), timeBudget.timeLeftOrThrow());
+
+        // Verify that toMillis() of >=1 is fine, but 0 is not.
+
+        when(clock.instant()).thenReturn(Instant.ofEpochSecond(9, 999000000));
+        assertEquals(1, timeBudget.timeLeftOrThrow().toMillis());
+        when(clock.instant()).thenReturn(Instant.ofEpochSecond(9, 999000001));
+        try {
+            timeBudget.timeLeftOrThrow();
+            fail();
+        } catch (UncheckedTimeoutException e) {
+            // OK
+        }
+    }
+}
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