Netflix Spectator多维时间序列记录库
Spectator 是记录多维时间序列的简单插装代码库，要求 Java 7 及以上版本。
代码示例：
// The Spectator class provides a static lookup for the default registry
Server 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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