Allow multiple consumers of sample data to only trigger work once

hystrix-contrib/hystrix-metrics-event-stream/src/main/java/com/netflix/hystrix/contrib/sample/stream/HystrixConfigSseServlet.java

@@ -18,8 +18,8 @@
 import com.netflix.config.DynamicIntProperty;
 import com.netflix.config.DynamicPropertyFactory;
 import com.netflix.hystrix.config.HystrixConfiguration;
+import com.netflix.hystrix.config.HystrixConfigurationStream;
 import rx.Observable;
-import rx.functions.Func1;
 
 import java.io.IOException;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -49,25 +49,16 @@ public class HystrixConfigSseServlet extends HystrixSampleSseServlet<HystrixConf
 
     private static final long serialVersionUID = -3599771169762858235L;
 
-    private static final int DEFAULT_ONNEXT_DELAY_IN_MS = 10000;
-
-    private final HystrixConfigurationJsonStream jsonStream;
-
     /* used to track number of connections and throttle */
     private static AtomicInteger concurrentConnections = new AtomicInteger(0);
     private static DynamicIntProperty maxConcurrentConnections = DynamicPropertyFactory.getInstance().getIntProperty("hystrix.config.stream.maxConcurrentConnections", 5);
 
     public HystrixConfigSseServlet() {
-        this.jsonStream = new HystrixConfigurationJsonStream();
-    }
-
-    /* package-private */ HystrixConfigSseServlet(Func1<Integer, Observable<HystrixConfiguration>> createStream) {
-        this.jsonStream = new HystrixConfigurationJsonStream(createStream);
+        super(HystrixConfigurationStream.getInstance().observe());
     }
 
-    @Override
-    int getDefaultDelayInMilliseconds() {
-        return DEFAULT_ONNEXT_DELAY_IN_MS;
+    /* package-private */ HystrixConfigSseServlet(Observable<HystrixConfiguration> sampleStream, int pausePollerThreadDelayInMs) {
+        super(sampleStream, pausePollerThreadDelayInMs);
     }
 
     @Override
@@ -90,11 +81,6 @@ protected void decrementCurrentConcurrentConnections() {
         concurrentConnections.decrementAndGet();
     }
 
-    @Override
-    protected Observable<HystrixConfiguration> getStream(int delay) {
-        return jsonStream.observe(delay);
-    }
-
     @Override
     protected String convertToString(HystrixConfiguration config) throws IOException {
         return HystrixConfigurationJsonStream.convertToString(config);

hystrix-contrib/hystrix-metrics-event-stream/src/main/java/com/netflix/hystrix/contrib/sample/stream/HystrixConfigurationJsonStream.java

@@ -46,15 +46,17 @@ public class HystrixConfigurationJsonStream {
     private static final JsonFactory jsonFactory = new JsonFactory();
     private final Func1<Integer, Observable<HystrixConfiguration>> streamGenerator;
 
+    @Deprecated //since 1.5.4
     public HystrixConfigurationJsonStream() {
         this.streamGenerator = new Func1<Integer, Observable<HystrixConfiguration>>() {
             @Override
             public Observable<HystrixConfiguration> call(Integer delay) {
-                return new HystrixConfigurationStream(delay).observe();
+                return HystrixConfigurationStream.getInstance().observe();
             }
         };
     }
 
+    @Deprecated //since 1.5.4
     public HystrixConfigurationJsonStream(Func1<Integer, Observable<HystrixConfiguration>> streamGenerator) {
         this.streamGenerator = streamGenerator;
     }
@@ -171,10 +173,25 @@ public static String convertToString(HystrixConfiguration config) throws IOExcep
         return jsonString.getBuffer().toString();
     }
 
+    /**
+     * @deprecated Not for public use.  Using the delay param prevents streams from being efficiently shared.
+     * Please use {@link HystrixConfigurationStream#observe()}
+     * @param delay interval between data emissions
+     * @return sampled utilization as Java object, taken on a timer
+     */
+    @Deprecated //deprecated in 1.5.4
     public Observable<HystrixConfiguration> observe(int delay) {
         return streamGenerator.call(delay);
     }
 
+    /**
+     * @deprecated Not for public use.  Using the delay param prevents streams from being efficiently shared.
+     * Please use {@link HystrixConfigurationStream#observe()}
+     * and you can map to JSON string via {@link HystrixConfigurationJsonStream#convertToString(HystrixConfiguration)}
+     * @param delay interval between data emissions
+     * @return sampled utilization as JSON string, taken on a timer
+     */
+    @Deprecated //deprecated in 1.5.4
     public Observable<String> observeJson(int delay) {
         return streamGenerator.call(delay).map(convertToJson);
     }

hystrix-contrib/hystrix-metrics-event-stream/src/main/java/com/netflix/hystrix/contrib/sample/stream/HystrixSampleSseServlet.java

@@ -33,15 +33,27 @@
 /**
  */
 public abstract class HystrixSampleSseServlet<SampleData> extends HttpServlet {
+    protected final Observable<SampleData> sampleStream;
 
     private static final Logger logger = LoggerFactory.getLogger(HystrixSampleSseServlet.class);
 
+    //wake up occasionally and check that poller is still alive.  this value controls how often
+    private static final int DEFAULT_PAUSE_POLLER_THREAD_DELAY_IN_MS = 500;
+
+    private final int pausePollerThreadDelayInMs;
+
     /* Set to true upon shutdown, so it's OK to be shared among all SampleSseServlets */
     private static volatile boolean isDestroyed = false;
 
-    private static final String DELAY_REQ_PARAM_NAME = "delay";
+    protected HystrixSampleSseServlet(Observable<SampleData> sampleStream) {
+        this.sampleStream = sampleStream;
+        this.pausePollerThreadDelayInMs = DEFAULT_PAUSE_POLLER_THREAD_DELAY_IN_MS;
+    }
 
-    abstract int getDefaultDelayInMilliseconds();
+    protected HystrixSampleSseServlet(Observable<SampleData> sampleStream, int pausePollerThreadDelayInMs) {
+        this.sampleStream = sampleStream;
+        this.pausePollerThreadDelayInMs = pausePollerThreadDelayInMs;
+    }
 
     abstract int getMaxNumberConcurrentConnectionsAllowed();
 
@@ -51,7 +63,7 @@ public abstract class HystrixSampleSseServlet<SampleData> extends HttpServlet {
 
     protected abstract void decrementCurrentConcurrentConnections();
 
-    protected abstract Observable<SampleData> getStream(int delay);
+    //protected abstract Observable<SampleData> getStream();
 
     protected abstract String convertToString(SampleData sampleData) throws IOException;
 
@@ -67,19 +79,6 @@ protected void doGet(HttpServletRequest request, HttpServletResponse response) t
         }
     }
 
-    /* package-private */
-    int getDelayFromHttpRequest(HttpServletRequest req) {
-        try {
-            String delay = req.getParameter(DELAY_REQ_PARAM_NAME);
-            if (delay != null) {
-                return Math.max(Integer.parseInt(delay), 1);
-            }
-        } catch (Throwable ex) {
-            //silently fail
-        }
-        return getDefaultDelayInMilliseconds();
-    }
-
     /**
      * WebSphere won't shutdown a servlet until after a 60 second timeout if there is an instance of the servlet executing
      * a request.  Add this method to enable a hook to notify Hystrix to shutdown.  You must invoke this method at
@@ -125,20 +124,18 @@ private void handleRequest(HttpServletRequest request, final HttpServletResponse
             if (numberConnections > maxNumberConnectionsAllowed) {
                 response.sendError(503, "MaxConcurrentConnections reached: " + maxNumberConnectionsAllowed);
             } else {
-                int delay = getDelayFromHttpRequest(request);
-
                 /* initialize response */
                 response.setHeader("Content-Type", "text/event-stream;charset=UTF-8");
                 response.setHeader("Cache-Control", "no-cache, no-store, max-age=0, must-revalidate");
                 response.setHeader("Pragma", "no-cache");
 
                 final PrintWriter writer = response.getWriter();
 
-                Observable<SampleData> sampledStream = getStream(delay);
+                //Observable<SampleData> sampledStream = getStream();
 
                 //since the sample stream is based on Observable.interval, events will get published on an RxComputation thread
                 //since writing to the servlet response is blocking, use the Rx IO thread for the write that occurs in the onNext
-                sampleSubscription = sampledStream
+                sampleSubscription = sampleStream
                         .observeOn(Schedulers.io())
                         .subscribe(new Subscriber<SampleData>() {
                             @Override
@@ -180,7 +177,7 @@ public void onNext(SampleData sampleData) {
 
                 while (moreDataWillBeSent.get() && !isDestroyed) {
                     try {
-                        Thread.sleep(delay);
+                        Thread.sleep(pausePollerThreadDelayInMs);
                     } catch (InterruptedException e) {
                         moreDataWillBeSent.set(false);
                     }

hystrix-contrib/hystrix-metrics-event-stream/src/main/java/com/netflix/hystrix/contrib/sample/stream/HystrixUtilizationJsonStream.java

@@ -55,15 +55,17 @@ public String call(HystrixUtilization utilization) {
         }
     };
 
+    @Deprecated //since 1.5.4
     public HystrixUtilizationJsonStream() {
         this.streamGenerator = new Func1<Integer, Observable<HystrixUtilization>>() {
             @Override
             public Observable<HystrixUtilization> call(Integer delay) {
-                return new HystrixUtilizationStream(delay).observe();
+                return HystrixUtilizationStream.getInstance().observe();
             }
         };
     }
 
+    @Deprecated //since 1.5.4
     public HystrixUtilizationJsonStream(Func1<Integer, Observable<HystrixUtilization>> streamGenerator) {
         this.streamGenerator = streamGenerator;
     }
@@ -111,10 +113,24 @@ protected static String convertToJson(HystrixUtilization utilization) throws IOE
         return jsonString.getBuffer().toString();
     }
 
+    /**
+     * @deprecated Not for public use.  Using the delay param prevents streams from being efficiently shared.
+     * Please use {@link HystrixUtilizationStream#observe()}
+     * @param delay interval between data emissions
+     * @return sampled utilization as Java object, taken on a timer
+     */
+    @Deprecated //deprecated as of 1.5.4
     public Observable<HystrixUtilization> observe(int delay) {
         return streamGenerator.call(delay);
     }
 
+    /**
+     * @deprecated Not for public use.  Using the delay param prevents streams from being efficiently shared.
+     * Please use {@link HystrixUtilizationStream#observe()}
+     * and the {@link #convertToJson(HystrixUtilization)} method
+     * @param delay interval between data emissions
+     * @return sampled utilization as JSON string, taken on a timer
+     */
     public Observable<String> observeJson(int delay) {
         return streamGenerator.call(delay).map(convertToJsonFunc);
     }

hystrix-contrib/hystrix-metrics-event-stream/src/main/java/com/netflix/hystrix/contrib/sample/stream/HystrixUtilizationSseServlet.java

@@ -18,8 +18,8 @@
 import com.netflix.config.DynamicIntProperty;
 import com.netflix.config.DynamicPropertyFactory;
 import com.netflix.hystrix.metric.sample.HystrixUtilization;
+import com.netflix.hystrix.metric.sample.HystrixUtilizationStream;
 import rx.Observable;
-import rx.functions.Func1;
 
 import java.io.IOException;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -49,27 +49,17 @@ public class HystrixUtilizationSseServlet extends HystrixSampleSseServlet<Hystri
 
     private static final long serialVersionUID = -7812908330777694972L;
 
-    private static final int DEFAULT_ONNEXT_DELAY_IN_MS = 100;
-
-    private final HystrixUtilizationJsonStream jsonStream;
-
     /* used to track number of connections and throttle */
     private static AtomicInteger concurrentConnections = new AtomicInteger(0);
     private static DynamicIntProperty maxConcurrentConnections =
             DynamicPropertyFactory.getInstance().getIntProperty("hystrix.config.stream.maxConcurrentConnections", 5);
 
     public HystrixUtilizationSseServlet() {
-        this.jsonStream = new HystrixUtilizationJsonStream();
-
+        super(HystrixUtilizationStream.getInstance().observe());
     }
 
-    /* package-private */ HystrixUtilizationSseServlet(Func1<Integer, Observable<HystrixUtilization>> createStream) {
-        this.jsonStream = new HystrixUtilizationJsonStream(createStream);
-    }
-
-    @Override
-    int getDefaultDelayInMilliseconds() {
-        return DEFAULT_ONNEXT_DELAY_IN_MS;
+    /* package-private */ HystrixUtilizationSseServlet(Observable<HystrixUtilization> sampleStream, int pausePollerThreadDelayInMs) {
+        super(sampleStream, pausePollerThreadDelayInMs);
     }
 
     @Override
@@ -92,11 +82,6 @@ protected void decrementCurrentConcurrentConnections() {
         concurrentConnections.decrementAndGet();
     }
 
-    @Override
-    protected Observable<HystrixUtilization> getStream(int delay) {
-        return jsonStream.observe(delay);
-    }
-
     @Override
     protected String convertToString(HystrixUtilization utilization) throws IOException {
         return HystrixUtilizationJsonStream.convertToJson(utilization);

hystrix-contrib/hystrix-metrics-event-stream/src/test/java/com/netflix/hystrix/contrib/sample/stream/HystrixConfigSseServletTest.java

@@ -16,7 +16,6 @@
 package com.netflix.hystrix.contrib.sample.stream;
 
 import com.netflix.hystrix.config.HystrixConfiguration;
-import com.netflix.hystrix.config.HystrixConfigurationStream;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -58,15 +57,6 @@ public HystrixConfiguration call(Long timestamp) {
         }
     });
 
-    private Func1<Integer, Observable<HystrixConfiguration>> generateStream(final Observable<HystrixConfiguration> o) {
-        return new Func1<Integer, Observable<HystrixConfiguration>>() {
-            @Override
-            public Observable<HystrixConfiguration> call(Integer integer) {
-                return o;
-            }
-        };
-    }
-
     private final Observable<HystrixConfiguration> streamOfOnNextThenOnError = Observable.create(new Observable.OnSubscribe<HystrixConfiguration>() {
         @Override
         public void call(Subscriber<? super HystrixConfiguration> subscriber) {
@@ -109,7 +99,7 @@ public void tearDown() {
 
     @Test
     public void shutdownServletShouldRejectRequests() throws ServletException, IOException {
-        servlet = new HystrixConfigSseServlet(generateStream(streamOfOnNexts));
+        servlet = new HystrixConfigSseServlet(streamOfOnNexts, 10);
         try {
             servlet.init();
         } catch (ServletException ex) {
@@ -126,7 +116,7 @@ public void shutdownServletShouldRejectRequests() throws ServletException, IOExc
 
     @Test
     public void testConfigDataWithInfiniteOnNextStream() throws IOException, InterruptedException {
-        servlet = new HystrixConfigSseServlet(generateStream(streamOfOnNexts));
+        servlet = new HystrixConfigSseServlet(streamOfOnNexts, 10);
         try {
             servlet.init();
         } catch (ServletException ex) {
@@ -182,13 +172,13 @@ public void run() {
         Thread.sleep(100);
 
         System.out.println("WRITES : " + writes.get());
-        assertEquals(9, writes.get());
+        assertTrue(writes.get() >= 9);
         assertEquals(0, servlet.getNumberCurrentConnections());
     }
 
     @Test
     public void testConfigDataWithStreamOnError() throws IOException, InterruptedException {
-        servlet = new HystrixConfigSseServlet(generateStream(streamOfOnNextThenOnError));
+        servlet = new HystrixConfigSseServlet(streamOfOnNextThenOnError, 10);
         try {
             servlet.init();
         } catch (ServletException ex) {
@@ -241,7 +231,7 @@ public void run() {
 
     @Test
     public void testConfigDataWithStreamOnCompleted() throws IOException, InterruptedException {
-        servlet = new HystrixConfigSseServlet(generateStream(streamOfOnNextThenOnCompleted));
+        servlet = new HystrixConfigSseServlet(streamOfOnNextThenOnCompleted, 10);
         try {
             servlet.init();
         } catch (ServletException ex) {
@@ -294,7 +284,7 @@ public void run() {
 
     @Test
     public void testConfigDataWithIoExceptionOnWrite() throws IOException, InterruptedException {
-        servlet = new HystrixConfigSseServlet(generateStream(streamOfOnNexts));
+        servlet = new HystrixConfigSseServlet(streamOfOnNexts, 10);
         try {
             servlet.init();
         } catch (ServletException ex) {
@@ -303,7 +293,6 @@ public void testConfigDataWithIoExceptionOnWrite() throws IOException, Interrupt
 
         final AtomicInteger writes = new AtomicInteger(0);
 
-        when(mockReq.getParameter("delay")).thenReturn("100");
         when(mockResp.getWriter()).thenReturn(mockPrintWriter);
         Mockito.doAnswer(new Answer<Void>() {
             @Override

hystrix-contrib/hystrix-reactivesocket-event-stream/src/main/java/com/netflix/hystrix/contrib/reactivesocket/EventStream.java

@@ -32,10 +32,6 @@
 import java.util.function.Supplier;
 
 class EventStream implements Supplier<Observable<Payload>> {
-
-    private final static int CONFIGURATION_DATA_INTERVAL_IN_MS = 500;
-    private final static int UTILIZATION_DATA_INTERVAL_IN_MS = 500;
-
     private final Observable<Payload> source;
     private final AtomicBoolean isSourceCurrentlySubscribed = new AtomicBoolean(false);
 
@@ -57,7 +53,7 @@ public static EventStream getInstance(EventStreamEnum eventStreamEnum) {
 
         switch (eventStreamEnum) {
             case CONFIG_STREAM:
-                source = new HystrixConfigurationStream(CONFIGURATION_DATA_INTERVAL_IN_MS)
+                source = HystrixConfigurationStream.getInstance()
                         .observe()
                         .map(SerialHystrixConfiguration::toBytes)
                         .map(SerialHystrixMetric::toPayload);
@@ -69,7 +65,7 @@ public static EventStream getInstance(EventStreamEnum eventStreamEnum) {
                         .map(SerialHystrixMetric::toPayload);
                 break;
             case UTILIZATION_STREAM:
-                source = new HystrixUtilizationStream(UTILIZATION_DATA_INTERVAL_IN_MS)
+                source = HystrixUtilizationStream.getInstance()
                         .observe()
                         .map(SerialHystrixUtilization::toBytes)
                         .map(SerialHystrixMetric::toPayload);