Replace scan and simple set methods with a Set

lib/sidekiq_alive.rb

@@ -8,6 +8,8 @@
 require "sidekiq_alive/helpers"
 require "sidekiq_alive/redis"
 
+SIDEKIQ_ALIVE_INDEX_NAME = "sidekiq-alive-index"
+
 module SidekiqAlive
   class << self
     def start
@@ -28,6 +30,7 @@ def start
           logger.info(startup_info)
 
           register_current_instance
+
           store_alive_key
           # Passing the hostname argument it's only for debugging enqueued jobs
           SidekiqAlive::Worker.perform_async(hostname)
@@ -63,11 +66,13 @@ def unregister_current_instance
       # Delete any pending jobs for this instance
       logger.info(shutdown_info)
       purge_pending_jobs
-      redis.delete(current_instance_register_key)
+      redis.zrem(SIDEKIQ_ALIVE_INDEX_NAME, current_instance_register_key)
     end
 
     def registered_instances
-      redis.match("#{config.registered_instance_key}::*")
+      # before we return we make sure we expire old keys
+      expire_old_keys
+      redis.zrange(SIDEKIQ_ALIVE_INDEX_NAME, 0, -1)
     end
 
     def purge_pending_jobs
@@ -136,6 +141,7 @@ def startup_info
         port: config.port,
         ttl: config.time_to_live,
         queue: current_queue,
+        register_set: SIDEKIQ_ALIVE_INDEX_NAME,
         liveness_key: current_lifeness_key,
         register_key: current_instance_register_key,
       }
@@ -144,11 +150,21 @@ def startup_info
     end
 
     def successful_startup_text
-      "Successfully started sidekiq-alive, registered with key: #{current_instance_register_key}"
+      "Successfully started sidekiq-alive, registered with key: "\
+        "#{current_instance_register_key} on set #{SIDEKIQ_ALIVE_INDEX_NAME}"
+    end
+
+    def expire_old_keys
+      # we get every key that should be expired by now
+      keys_to_expire = redis.zrangebyscore(SIDEKIQ_ALIVE_INDEX_NAME, 0, Time.now.to_i)
+      # then we remove it
+      keys_to_expire.each { |key| redis.zrem(SIDEKIQ_ALIVE_INDEX_NAME, key) }
     end
 
     def register_instance(instance_name)
-      redis.set(instance_name, time: Time.now.to_i, ex: config.registration_ttl.to_i)
+      expiration = Time.now.to_i + config.registration_ttl.to_i
+      redis.zadd(SIDEKIQ_ALIVE_INDEX_NAME, expiration, instance_name)
+      expire_old_keys
     end
   end
 end

lib/sidekiq_alive/redis/base.rb

@@ -7,7 +7,19 @@ def set(...)
         raise(NotImplementedError)
       end
 
-      def match(key)
+      def zadd(set_key, ex, key)
+        raise(NotImplementedError)
+      end
+
+      def zrange(set_key, start, stop)
+        raise(NotImplementedError)
+      end
+
+      def zrangebyscore(set_key, min, max)
+        raise(NotImplementedError)
+      end
+
+      def zrem(set_key, key)
         raise(NotImplementedError)
       end
 

lib/sidekiq_alive/redis/redis_client_gem.rb

@@ -15,8 +15,20 @@ def get(key)
         Sidekiq.redis { |redis| redis.call("GET", key) }
       end
 
-      def match(key)
-        Sidekiq.redis { |redis| redis.scan("MATCH", key).map { |key| key } }
+      def zadd(set_key, ex, key)
+        Sidekiq.redis { |redis| redis.call("ZADD", set_key, ex, key) }
+      end
+
+      def zrange(set_key, start, stop)
+        Sidekiq.redis { |redis| redis.call("ZRANGE", set_key, start, stop) }
+      end
+
+      def zrangebyscore(set_key, min, max)
+        Sidekiq.redis { |redis| redis.call("ZRANGEBYSCORE", set_key, min, max) }
+      end
+
+      def zrem(set_key, key)
+        Sidekiq.redis { |redis| redis.call("ZREM", set_key, key) }
       end
 
       def delete(key)

lib/sidekiq_alive/redis/redis_gem.rb

@@ -15,16 +15,20 @@ def get(key)
         redis.get(key)
       end
 
-      def match(key)
-        keys = []
-        cursor = 0
-
-        loop do
-          cursor, found_keys = redis.scan(cursor, match: key, count: 1000)
-          keys += found_keys if found_keys
-          break if cursor.to_i == 0
-        end
-        keys
+      def zadd(set_key, ex, key)
+        redis.zadd(set_key, ex, key)
+      end
+
+      def zrange(set_key, start, stop)
+        redis.zrange(set_key, start, stop)
+      end
+
+      def zrangebyscore(set_key, min, max)
+        redis.zrangebyscore(set_key, min, max)
+      end
+
+      def zrem(set_key, key)
+        redis.zrem(set_key, key)
       end
 
       def delete(key)

spec/redis_spec.rb

@@ -8,8 +8,10 @@
     redis.set("hello", time: time, ex: 60)
     expect(redis.ttl("hello") > 1).to(be(true))
     expect(redis.get("hello")).to(eq(time))
-    expect(redis.match("hello")).to(eq(["hello"]))
-    expect(redis.delete("hello")).to(eq(1))
-    expect(redis.get("hello")).to(be(nil))
+    redis.zadd("test_set", Time.now.to_i, "test-key-1")
+    redis.zadd("test_set", Time.now.to_i, "test-key-2")
+    expect(redis.zrange("test_set", 0, -1)).to(eq(["test-key-1", "test-key-2"]))
+    expect(redis.zrem("test_set", "test-key-1"))
+    expect(redis.zrange("test_set", 0, -1)).to(eq(["test-key-2"]))
   end
 end

spec/sidekiq_alive_spec.rb

@@ -133,7 +133,6 @@
 
       it "::registered_instances" do
         SidekiqAlive.start
-
         expect(SidekiqAlive.registered_instances.count).to(eq(1))
         expect(SidekiqAlive.registered_instances.first).to(include("test-hostname"))
       end