Finish codes of grpc segment client about channel control.

apm-network/src/test/java/org/skywalking/apm/network/trace/proto/GRPCNoServerTest.java

+package org.skywalking.apm.network.trace.proto;
+
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.Status;
+import io.grpc.StatusRuntimeException;
+import io.grpc.internal.DnsNameResolverProvider;
+import io.grpc.netty.NettyChannelBuilder;
+import io.grpc.stub.StreamObserver;
+import org.junit.Assert;
+import org.skywalking.apm.network.collecor.proto.Downstream;
+
+/**
+ * @author wusheng
+ */
+public class GRPCNoServerTest {
+    public static void main(String[] args) throws InterruptedException {
+        ManagedChannelBuilder<?> channelBuilder =
+            NettyChannelBuilder.forAddress("127.0.0.1", 8080)
+                .nameResolverFactory(new DnsNameResolverProvider())
+                .maxInboundMessageSize(1024 * 1024 * 50)
+                .usePlaintext(true);
+        ManagedChannel channel = channelBuilder.build();
+        TraceSegmentServiceGrpc.TraceSegmentServiceStub serviceStub = TraceSegmentServiceGrpc.newStub(channel);
+        final Status[] status = {null};
+        StreamObserver<UpstreamSegment> streamObserver = serviceStub.collect(new StreamObserver<Downstream>() {
+            @Override public void onNext(Downstream value) {
+
+            }
+
+            @Override public void onError(Throwable t) {
+                status[0] = ((StatusRuntimeException)t).getStatus();
+            }
+
+            @Override public void onCompleted() {
+
+            }
+        });
+
+        streamObserver.onNext(null);
+        streamObserver.onCompleted();
+
+        Thread.sleep(2 * 1000);
+
+        Assert.assertEquals(status[0].getCode(), Status.UNAVAILABLE.getCode());
+    }
+}

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/GRPCChannelManager.java

@@ -2,6 +2,8 @@ package org.skywalking.apm.agent.core.remote;
 
 import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
+import io.grpc.Status;
+import io.grpc.StatusRuntimeException;
 import io.grpc.internal.DnsNameResolverProvider;
 import io.grpc.netty.NettyChannelBuilder;
 import java.util.Collections;
@@ -32,7 +34,7 @@ public class GRPCChannelManager implements BootService, Runnable {
 
     @Override
     public void boot() throws Throwable {
-        this.startupInBackground(false);
+        this.connectInBackground(false);
     }
 
     @Override
@@ -40,7 +42,7 @@ public class GRPCChannelManager implements BootService, Runnable {
 
     }
 
-    private void startupInBackground(boolean forceStart) {
+    private void connectInBackground(boolean forceStart) {
         if (channelManagerThread == null || !channelManagerThread.isAlive()) {
             synchronized (this) {
                 if (forceStart) {
@@ -106,8 +108,37 @@ public class GRPCChannelManager implements BootService, Runnable {
         return managedChannel;
     }
 
-    public void reportError() {
-        this.startupInBackground(true);
+    /**
+     * If the given expcetion is triggered by network problem, connect in background.
+     * @param throwable
+     */
+    public void reportError(Throwable throwable) {
+        if (isNetworkError(throwable)) {
+            this.connectInBackground(true);
+        }
+    }
+
+    private boolean isNetworkError(Throwable throwable) {
+        if (throwable instanceof StatusRuntimeException) {
+            StatusRuntimeException statusRuntimeException = (StatusRuntimeException)throwable;
+            return statusEquals(statusRuntimeException.getStatus(),
+                Status.UNAVAILABLE,
+                Status.PERMISSION_DENIED,
+                Status.UNAUTHENTICATED,
+                Status.RESOURCE_EXHAUSTED,
+                Status.UNKNOWN
+            );
+        }
+        return false;
+    }
+
+    private boolean statusEquals(Status sourceStatus, Status... potentialStatus) {
+        for (Status status : potentialStatus) {
+            if (sourceStatus.getCode() == status.getCode()) {
+                return true;
+            }
+        }
+        return false;
     }
 
     private void resetNextStartTime() {

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/TraceSegmentServiceClient.java

@@ -66,7 +66,10 @@ public class TraceSegmentServiceClient implements BootService, IConsumer<TraceSe
                 @Override
                 public void onError(Throwable throwable) {
                     status.finished();
-                    ServiceManager.INSTANCE.findService(GRPCChannelManager.class).reportError();
+                    if (logger.isErrorEnable()) {
+                        logger.error(throwable, "Send UpstreamSegment to collector fail with a grpc internal exception.");
+                    }
+                    ServiceManager.INSTANCE.findService(GRPCChannelManager.class).reportError(throwable);
                 }
 
                 @Override