Added flush ability to TelemetryClient and TelemetryChannel

core/src/main/java/com/microsoft/applicationinsights/TelemetryClient.java

@@ -393,6 +393,13 @@ public void track(Telemetry telemetry) {
         getChannel().send(telemetry);
     }
 
+    /**
+     * Flushes possible pending Telemetries in the channel.
+     */
+    public void flush() {
+        getChannel().flush();
+    }
+
     /**
      * Gets the channel used by the client.
      */

core/src/main/java/com/microsoft/applicationinsights/channel/TelemetryChannel.java

@@ -54,4 +54,9 @@ public interface TelemetryChannel {
      * @param timeUnit The units of the 'timeout' parameter
      */
     void stop(long timeout, TimeUnit timeUnit);
+
+    /**
+     * Flushes the data that the channel might have internally.
+     */
+    void flush();
 }

core/src/main/java/com/microsoft/applicationinsights/channel/concrete/inprocess/InProcessTelemetryChannel.java

@@ -173,6 +173,14 @@ public synchronized void stop(long timeout, TimeUnit timeUnit) {
         }
     }
 
+    /**
+     * Flushes the data that the channel might have internally.
+     */
+    @Override
+    public void flush() {
+        telemetryBuffer.flush();
+    }
+
     private void writeTelemetryToDebugOutput(Telemetry telemetry) {
         InternalLogger.INSTANCE.trace("InProcessTelemetryChannel sending telemetry");
     }

core/src/main/java/com/microsoft/applicationinsights/internal/channel/common/TelemetryBuffer.java

@@ -29,6 +29,7 @@
 
 import com.google.common.base.Preconditions;
 import com.microsoft.applicationinsights.internal.channel.TelemetriesTransmitter;
+import com.microsoft.applicationinsights.internal.logger.InternalLogger;
 import com.microsoft.applicationinsights.telemetry.Telemetry;
 
 /**
@@ -169,20 +170,33 @@ public void add(String telemetry) {
                 if (!sender.sendNow(prepareTelemetriesForSend())) {
                     // 'prepareTelemetriesForSend' already created a new container
                     // so basically we have nothing to do, the old container is lost
-                    // TODO: internal log
+                    InternalLogger.INSTANCE.error("Failed to send buffer data to network");
                 }
             } else if (currentSize == 1) {
                 if (!sender.scheduleSend(new TelemetryBufferTelemetriesFetcher(generation), transmitBufferTimeoutInSeconds, TimeUnit.SECONDS)) {
                     // We cannot schedule send so we give up the Telemetry
                     // The reason for this is that in case the maximum buffer size is greater than 2
                     // than in case a new Telemetry arrives it won't trigger the schedule and might be lost too
-                    // TODO: internal log
+                    InternalLogger.INSTANCE.error("Failed to schedule send of the buffer to network");
                     telemetries.clear();
                 }
             }
         }
     }
 
+    /**
+     * The method will flush the telemetries currently in the buffer to the {@link com.microsoft.applicationinsights.internal.channel.TelemetriesTransmitter}
+     */
+    public void flush() {
+        synchronized (lock) {
+            if (telemetries.size() != 0) {
+                if (!sender.sendNow(prepareTelemetriesForSend())) {
+                    InternalLogger.INSTANCE.error("Failed to flush buffer data to network");
+                }
+            }
+        }
+    }
+
     /**
      * The method assumes that the lock is held before calling it.
      *

core/src/main/java/com/microsoft/applicationinsights/internal/channel/simplehttp/SimpleHttpChannel.java

@@ -120,5 +120,9 @@ public void send(Telemetry item)
     public void stop(long timeout, TimeUnit timeUnit) {
     }
 
+    @Override
+    public void flush() {
+    }
+
     private boolean developerMode = false;
 }

core/src/main/java/com/microsoft/applicationinsights/internal/channel/stdout/StdOutChannel.java

@@ -66,4 +66,8 @@ public void send(Telemetry item) {
     @Override
     public void stop(long timeout, TimeUnit timeUnit) {
     }
+
+    @Override
+    public void flush() {
+    }
 }

core/src/test/java/com/microsoft/applicationinsights/TelemetryClientTests.java

@@ -336,6 +336,13 @@ public void initialize(TelemetryContext context) {
         client.track(telemetry);
     }
 
+    @Test
+    public void testFlush() {
+        client.flush();
+
+        Mockito.verify(channel, Mockito.times(1)).flush();
+    }
+
     // endregion Track tests
 
     // region Private methods

core/src/test/java/com/microsoft/applicationinsights/internal/channel/common/TelemetryBufferTest.java

@@ -31,7 +31,6 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 import com.microsoft.applicationinsights.internal.channel.TelemetriesTransmitter;
-import com.microsoft.applicationinsights.telemetry.Telemetry;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -208,7 +207,6 @@ public void testSendWhenBufferIsFullInNonDeveloperMode() throws Exception {
         TelemetryBuffer testedBuffer = new TelemetryBuffer(mockSender, 2, 1200);
 
         for (int i = 0; i < 2; ++i) {
-            Telemetry mockTelemetry = Mockito.mock(Telemetry.class);
             testedBuffer.add("mockTelemetry");
         }
 
@@ -252,7 +250,6 @@ public Collection<String> getSendNowCollection() {
         List<String> all = new ArrayList<String>();
         List<String> expected = new ArrayList<String>();
         for (int i = 0; i < 4; ++i) {
-            Telemetry mockTelemetry = Mockito.mock(Telemetry.class);
             String mockSerializedTelemetry = "mockTelemtry" + String.valueOf(i);
             all.add(mockSerializedTelemetry);
 
@@ -285,7 +282,6 @@ public void testSendWhenBufferIsFullInDeveloperMode() throws Exception {
         TelemetryBuffer testedBuffer = new TelemetryBuffer(mockSender, 1, 1200);
 
         for (int i = 0; i < 2; ++i) {
-            Telemetry mockTelemetry = Mockito.mock(Telemetry.class);
             testedBuffer.add("mockTelemetry");
         }
 
@@ -324,10 +320,49 @@ public void testSendBufferAfterTimeoutExpiresButBufferWasAlreadySent() throws Ex
         TelemetryBuffer testedBuffer = new TelemetryBuffer(mockSender, 10, 3);
 
         for (int i = 0; i < 10; ++i) {
-            Telemetry mockTelemetry = Mockito.mock(Telemetry.class);
             testedBuffer.add("mockTelemetry");
         }
 
         mockSender.waitForFinish(6L);
     }
+
+    @Test
+    public void testFlushWithZero() throws Exception {
+        TelemetriesTransmitter mockSender = Mockito.mock(TelemetriesTransmitter.class);
+
+        // Create a buffer with max buffer size of 10 and timeout of 10 seconds
+        TelemetryBuffer testedBuffer = new TelemetryBuffer(mockSender, 10, 3);
+        testedBuffer.flush();
+
+        Mockito.verify(mockSender, Mockito.never()).sendNow(anyCollectionOf(String.class));
+    }
+
+    @Test
+    public void testFlushWithOneInTheBuffer() throws Exception {
+        testFlushWithData(1);
+    }
+
+    @Test
+    public void testFlushWithSevenInTheBuffer() throws Exception {
+        testFlushWithData(7);
+    }
+
+    private void testFlushWithData(int expectedTelemetriesNumberInSendNow) {
+        MockSender mockSender = new MockSender()
+                .setExpectedNumberOfScheduleSendCalls(1)
+                .setExpectedNumberOfSendNowCalls(1)
+                .setExpectedTelemetriesNumberInScheduleSend(0)
+                .setExpectedTelemetriesNumberInSendNow(expectedTelemetriesNumberInSendNow);
+
+        // Create a buffer with max buffer size of 10 and timeout of 10 seconds
+        TelemetryBuffer testedBuffer = new TelemetryBuffer(mockSender, 10, 3);
+
+        for (int i = 0; i < expectedTelemetriesNumberInSendNow; ++i) {
+            testedBuffer.add("mockTelemetry");
+        }
+
+        testedBuffer.flush();
+
+        mockSender.waitForFinish(6L);
+    }
 }

logging/common/src/test/java/com/microsoft/applicationinsights/internal/shared/LogChannelMock.java

@@ -21,6 +21,7 @@
 
 package com.microsoft.applicationinsights.internal.shared;
 
+import java.lang.Override;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
@@ -52,4 +53,8 @@ public void send(Telemetry item) {
     @Override
     public void stop(long timeout, TimeUnit timeUnit) {
     }
+
+    @Override
+    public void flush() {
+    }
 }

web/src/test/java/com/microsoft/applicationinsights/web/utils/MockTelemetryChannel.java

@@ -68,6 +68,10 @@ public void stop(long timeout, TimeUnit timeUnit) {
 
     }
 
+    @Override
+    public void flush() {
+    }
+
     public void reset() {
         telemetryItems.clear();
     }