1 files changed, 64 insertions, 0 deletions
diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/LockInfo.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/LockInfo.java
new file mode 100644
index 00000000000..870ee12ebda
--- /dev/null
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/LockInfo.java
@@ -0,0 +1,64 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.curator;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Optional;
+
+/**
+ * Information about a lock.
+ *
+ * <p>Should be mutated by a single thread.  Other threads may see an inconsistent state of this instance.</p>
+ */
+public class LockInfo {
+
+    private final int threadHoldCountOnAcquire;
+    private final Instant acquireInstant;
+    private final Duration timeout;
+
+    private volatile Optional<Instant> lockAcquiredInstant = Optional.empty();
+    private volatile Optional<Instant> terminalStateInstant = Optional.empty();
+
+    public static LockInfo invokingAcquire(int holdCount, Duration timeout) {
+        return new LockInfo(holdCount, timeout);
+    }
+
+    public enum LockState {
+        ACQUIRING(false), TIMED_OUT(true), ACQUIRED(false), FAILED_TO_REENTER(true), RELEASED(true);
+
+        private final boolean terminal;
+
+        LockState(boolean terminal) { this.terminal = terminal; }
+
+        public boolean isTerminal() { return terminal; }
+    }
+
+    private volatile LockState lockState = LockState.ACQUIRING;
+
+    private LockInfo(int threadHoldCountOnAcquire, Duration timeout) {
+        this.threadHoldCountOnAcquire = threadHoldCountOnAcquire;
+        this.acquireInstant = Instant.now();
+        this.timeout = timeout;
+    }
+
+    public int getThreadHoldCountOnAcquire() { return threadHoldCountOnAcquire; }
+    public Instant getTimeAcquiredWasInvoked() { return acquireInstant; }
+    public Duration getAcquireTimeout() { return timeout; }
+    public LockState getLockState() { return lockState; }
+    public Optional<Instant> getTimeLockWasAcquired() { return lockAcquiredInstant; }
+    public Optional<Instant> getTimeTerminalStateWasReached() { return terminalStateInstant; }
+
+    void timedOut() { setTerminalState(LockState.TIMED_OUT); }
+    void failedToAcquireReentrantLock() { setTerminalState(LockState.FAILED_TO_REENTER); }
+    void released() { setTerminalState(LockState.RELEASED); }
+
+    void lockAcquired() {
+        lockState = LockState.ACQUIRED;
+        lockAcquiredInstant = Optional.of(Instant.now());
+    }
+
+    void setTerminalState(LockState terminalState) {
+        lockState = terminalState;
+        terminalStateInstant = Optional.of(Instant.now());
+    }
+}