SocketExecutor: Add getTotalPendingWriteBytes and getTotalPendingReadBytes

This metric helps you know across all clients how backed up you are either consuming data into the application (likely cpu or otherwise bound by the application), or write bound (network or remote side being the bottleneck).

Author: jentfoo

src/main/java/org/threadly/litesockets/SocketExecuter.java

@@ -29,6 +29,23 @@ public interface SocketExecuter extends Service {
    */
   public void setPerConnectionStatsEnabled(boolean enabled);
 
+  
+  /**
+   * Check the total number of bytes pending to be sent by clients.  This is data which has been 
+   * provided to the client to write, but is waiting on the network and kernel to accept the write.
+   * 
+   * @return The total number of bytes pending to write by clients
+   */
+  public long getTotalPendingWriteBytes();
+  
+  /**
+   * Check the total amount of pending reads across all associated clients.  Bytes here indicate 
+   * that the client has been notified a read is available but has not consumed it.
+   * 
+   * @return The total number of bytes pending to read by clients
+   */
+  public long getTotalPendingReadBytes();
+  
   /**
    * This will create a UDPServer on the specified {@link SocketExecuter}.
    * 

src/main/java/org/threadly/litesockets/SocketExecuterCommonBase.java

@@ -47,6 +47,25 @@ abstract class SocketExecuterCommonBase extends AbstractService implements Socke
     this.acceptScheduler = acceptScheduler;
   }
 
+  @Override
+  public long getTotalPendingWriteBytes() {
+    long result = 0;
+    for (Client c : clients.values()) {
+      result += c.getWriteBufferSize();
+    }
+    return result;
+  }
+  
+  @Override
+  public long getTotalPendingReadBytes() {
+    long result = 0;
+    for (Client c : clients.values()) {
+      result += c.getReadBufferSize();
+    }
+    return result;
+  }
+
+  @Override
   public void setPerConnectionStatsEnabled(boolean enabled) {
     perConnectionStatsEnabled = enabled;
   }