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-rw-r--r--spec/util_hashring_spec.lua85
1 files changed, 85 insertions, 0 deletions
diff --git a/spec/util_hashring_spec.lua b/spec/util_hashring_spec.lua
new file mode 100644
index 00000000..d8801774
--- /dev/null
+++ b/spec/util_hashring_spec.lua
@@ -0,0 +1,85 @@
+local hashring = require "util.hashring";
+
+describe("util.hashring", function ()
+
+ local sha256 = require "util.hashes".sha256;
+
+ local ring = hashring.new(128, sha256);
+
+ it("should fail to get a node that does not exist", function ()
+ assert.is_nil(ring:get_node("foo"))
+ end);
+
+ it("should support adding nodes", function ()
+ ring:add_node("node1");
+ end);
+
+ it("should return a single node for all keys if only one node exists", function ()
+ for i = 1, 100 do
+ assert.is_equal("node1", ring:get_node(tostring(i)))
+ end
+ end);
+
+ it("should support adding a second node", function ()
+ ring:add_node("node2");
+ end);
+
+ it("should fail to remove a non-existent node", function ()
+ assert.is_falsy(ring:remove_node("node3"));
+ end);
+
+ it("should succeed to remove a node", function ()
+ assert.is_truthy(ring:remove_node("node1"));
+ end);
+
+ it("should return the only node for all keys", function ()
+ for i = 1, 100 do
+ assert.is_equal("node2", ring:get_node(tostring(i)))
+ end
+ end);
+
+ it("should support adding multiple nodes", function ()
+ ring:add_nodes({ "node1", "node3", "node4", "node5" });
+ end);
+
+ it("should disrupt a minimal number of keys on node removal", function ()
+ local orig_ring = ring:clone();
+ local node_tallies = {};
+
+ local n = 1000;
+
+ for i = 1, n do
+ local key = tostring(i);
+ local node = ring:get_node(key);
+ node_tallies[node] = (node_tallies[node] or 0) + 1;
+ end
+
+ --[[
+ for node, key_count in pairs(node_tallies) do
+ print(node, key_count, ("%.2f%%"):format((key_count/n)*100));
+ end
+ ]]
+
+ ring:remove_node("node5");
+
+ local disrupted_keys = 0;
+ for i = 1, n do
+ local key = tostring(i);
+ if orig_ring:get_node(key) ~= ring:get_node(key) then
+ disrupted_keys = disrupted_keys + 1;
+ end
+ end
+ assert.is_equal(node_tallies["node5"], disrupted_keys);
+ end);
+
+ it("should support removing multiple nodes", function ()
+ ring:remove_nodes({"node2", "node3", "node4", "node5"});
+ end);
+
+ it("should return a single node for all keys if only one node remains", function ()
+ for i = 1, 100 do
+ assert.is_equal("node1", ring:get_node(tostring(i)))
+ end
+ end);
+
+end);