Add StoredInteger

1 files changed, 52 insertions, 0 deletions

diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/StoredInteger.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/StoredInteger.java
new file mode 100644
index 00000000000..61c0624e6a9
--- /dev/null
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/StoredInteger.java
@@ -0,0 +1,52 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.hosted.node.admin.task.util.file;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.util.OptionalInt;
+import java.util.function.Supplier;
+
+/**
+ * Class wrapping an integer stored on disk
+ *
+ * @author freva
+ */
+public class StoredInteger implements Supplier<OptionalInt> {
+
+    private final Path path;
+    private OptionalInt value;
+    private boolean hasBeenRead = false;
+
+    public StoredInteger(Path path) {
+        this.path = path;
+    }
+
+    @Override
+    public OptionalInt get() {
+        if (!hasBeenRead) {
+            try {
+                String value = new String(Files.readAllBytes(path));
+                this.value = OptionalInt.of(Integer.valueOf(value));
+            } catch (NoSuchFileException e) {
+                this.value = OptionalInt.empty();
+            } catch (IOException e) {
+                throw new UncheckedIOException("Failed to read integer in " + path, e);
+            }
+            hasBeenRead = true;
+        }
+        return value;
+    }
+
+    public void write(int value) {
+        try {
+            Files.write(path, Integer.toString(value).getBytes());
+            this.value = OptionalInt.of(value);
+            this.hasBeenRead = true;
+        } catch (IOException e) {
+            throw new UncheckedIOException("Failed to store integer in " + path, e);
+        }
+    }
+}