1 files changed, 46 insertions, 0 deletions
diff --git a/config-provisioning/src/main/java/com/yahoo/config/provision/zone/NodeSlice.java b/config-provisioning/src/main/java/com/yahoo/config/provision/zone/NodeSlice.java
new file mode 100644
index 00000000000..acb93139b27
--- /dev/null
+++ b/config-provisioning/src/main/java/com/yahoo/config/provision/zone/NodeSlice.java
@@ -0,0 +1,46 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config.provision.zone;
+
+import java.util.Objects;
+import java.util.OptionalDouble;
+import java.util.OptionalLong;
+
+/**
+ * A slice of nodes, satisfied by either a minimum count or a fraction.
+ *
+ * @author mpolden
+ */
+public record NodeSlice(OptionalDouble fraction, OptionalLong minCount) {
+
+    public static final NodeSlice ALL = minCount(Long.MAX_VALUE);
+
+    public NodeSlice {
+        Objects.requireNonNull(fraction);
+        Objects.requireNonNull(minCount);
+        if (fraction.isEmpty() == minCount.isEmpty()) {
+            throw new IllegalArgumentException("Exactly one of 'fraction' or 'minCount' must be set");
+        }
+        if (fraction.isPresent() && fraction.getAsDouble() > 1.0D) {
+            throw new IllegalArgumentException("Fraction must be <= 1.0, got " + fraction.getAsDouble());
+        }
+    }
+
+    /** Returns whether this slice is satisfied by given node count, out of totalCount */
+    public boolean satisfiedBy(long count, long totalCount) {
+        if (fraction.isPresent()) {
+            return count + 1e-9 >= totalCount * fraction.getAsDouble();
+        }
+        return count >= Math.min(minCount.orElse(0), totalCount);
+    }
+
+    /** Returns a slice matching the given fraction of nodes */
+    public static NodeSlice fraction(double fraction) {
+        return new NodeSlice(OptionalDouble.of(fraction), OptionalLong.empty());
+    }
+
+    /** Returns a slice matching the given minimum number of nodes */
+    public static NodeSlice minCount(long count) {
+        return new NodeSlice(OptionalDouble.empty(), OptionalLong.of(count));
+    }
+
+}