Spectator是记录多维时间序列的简单插装代码库，要求Java7及以上版本。
代码示例：
// The Spectator class provides a static lookup for the default registryServer s = new Server(Spectator.registry());public class Server { private final ExtendedRegistry registry; private final Id requestCountId; private final Timer requestLatency; private final DistributionSummary responseSizes; // We can pass in the registry to make unit testing easier. Outside of tests it should typically // be bound to Spectator.registry() to make sure data goes to the right place. public Server(ExtendedRegistry registry) { this.registry = registry; // Create a base id for the request count. The id will get refined with additional dimensions // when we receive a request. requestCountId = registry.createId("server.requestCount"); // Create a timer for tracking the latency. The reference can be held onto to avoid // additional lookup cost in critical paths. requestLatency = registry.timer("server.requestLatency"); // Create a distribution summary meter for tracking the response sizes. responseSizes = registry.distributionSummary("server.responseSizes"); // Gauge type that can be sampled. In this case it will invoke the specified method via // reflection to get the value. The registry will keep a weak reference to the object passed // in so that registration will not prevent garbage collection of the server object. registry.methodValue("server.numConnections", this, "getNumConnections"); } public Response handle(Request req) { final long s = System.nanoTime(); try { Response res = doSomething(req); // Update the counter id with dimensions based on the request. The counter will then // be looked up in the registry which should be fairly cheap, such as lookup of id object // in a ConcurrentHashMap. However, it is more expensive than having a local variable set // to the counter. final Id cntId = requestCountId .withTag("country", req.country()) .withTag("status", res.status()); registry.counter(cntId).increment(); responseSizes.record(res.body().size()); return res; } catch (Exception e) { final Id cntId = requestCountId .withTag("country", req.country()) .withTag("status", "exception") .withTag("error", e.getClass().getSimpleName()); registry.counter(cntId).increment(); throw e; } finally { // Update the latency timer. This should typically be done in a finally block. requestLatency.record(System.nanoTime() - s, TimeUnit.NANOSECONDS); } } public int getNumConnections() { // however we determine the current number of connections on the server }}
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