Remove Client provider indirection.

Those who desire lazy initialization can do so through a custom Client implementation which creates the delegate on first invocation. Also we can ensure OkHttp does initialization requiring i/o (e.g., disk cache) lazily.

retrofit/src/main/java/retrofit/Platform.java

@@ -60,7 +60,7 @@ abstract class Platform {
   }
 
   abstract Converter defaultConverter();
-  abstract Client.Provider defaultClient();
+  abstract Client defaultClient();
   abstract Executor defaultHttpExecutor();
   abstract Executor defaultCallbackExecutor();
   abstract RestAdapter.Log defaultLog();
@@ -71,18 +71,11 @@ abstract class Platform {
       return new GsonConverter(new Gson());
     }
 
-    @Override Client.Provider defaultClient() {
-      final Client client;
+    @Override Client defaultClient() {
       if (hasOkHttpOnClasspath()) {
-        client = OkClientInstantiator.instantiate();
-      } else {
-        client = new UrlConnectionClient();
+        return OkClientInstantiator.instantiate();
       }
-      return new Client.Provider() {
-        @Override public Client get() {
-          return client;
-        }
-      };
+      return new UrlConnectionClient();
     }
 
     @Override Executor defaultHttpExecutor() {
@@ -117,20 +110,14 @@ abstract class Platform {
       return new GsonConverter(new Gson());
     }
 
-    @Override Client.Provider defaultClient() {
-      final Client client;
+    @Override Client defaultClient() {
       if (hasOkHttpOnClasspath()) {
-        client = OkClientInstantiator.instantiate();
-      } else if (Build.VERSION.SDK_INT < Build.VERSION_CODES.GINGERBREAD) {
-        client = new AndroidApacheClient();
-      } else {
-        client = new UrlConnectionClient();
+        return OkClientInstantiator.instantiate();
       }
-      return new Client.Provider() {
-        @Override public Client get() {
-          return client;
-        }
-      };
+      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.GINGERBREAD) {
+        return new AndroidApacheClient();
+      }
+      return new UrlConnectionClient();
     }
 
     @Override Executor defaultHttpExecutor() {
@@ -156,13 +143,8 @@ abstract class Platform {
   }
 
   private static class AppEngine extends Base {
-    @Override Client.Provider defaultClient() {
-      final UrlFetchClient client = new UrlFetchClient();
-      return new Client.Provider() {
-        @Override public Client get() {
-          return client;
-        }
-      };
+    @Override Client defaultClient() {
+      return new UrlFetchClient();
     }
   }
 

retrofit/src/main/java/retrofit/RestAdapter.java

@@ -153,17 +153,17 @@ public class RestAdapter {
   final Log log;
   final ErrorHandler errorHandler;
 
-  private final Client.Provider clientProvider;
+  private final Client client;
   private final Profiler profiler;
   private RxSupport rxSupport;
 
   volatile LogLevel logLevel;
 
-  private RestAdapter(Endpoint server, Client.Provider clientProvider, Executor httpExecutor,
+  private RestAdapter(Endpoint server, Client client, Executor httpExecutor,
       Executor callbackExecutor, RequestInterceptor requestInterceptor, Converter converter,
       Profiler profiler, ErrorHandler errorHandler, Log log, LogLevel logLevel) {
     this.server = server;
-    this.clientProvider = clientProvider;
+    this.client = client;
     this.httpExecutor = httpExecutor;
     this.callbackExecutor = callbackExecutor;
     this.requestInterceptor = requestInterceptor;
@@ -318,7 +318,7 @@ public class RestAdapter {
         }
 
         long start = System.nanoTime();
-        Response response = clientProvider.get().execute(request);
+        Response response = client.execute(request);
         long elapsedTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start);
 
         int statusCode = response.getStatus();
@@ -527,22 +527,12 @@ public class RestAdapter {
   /**
    * Build a new {@link RestAdapter}.
    * <p>
-   * Calling the following methods is required before calling {@link #build()}:
-   * <ul>
-   * <li>{@link #setEndpoint(Endpoint)}</li>
-   * <li>{@link #setClient(Client.Provider)}</li>
-   * <li>{@link #setConverter(Converter)}</li>
-   * </ul>
-   * <p>
-   * If you are using asynchronous execution (i.e., with {@link Callback Callbacks}) the following
-   * is also required:
-   * <ul>
-   * <li>{@link #setExecutors(java.util.concurrent.Executor, java.util.concurrent.Executor)}</li>
-   * </ul>
+   * Calling {@link #setEndpoint} is required before calling {@link #build()}. All other methods
+   * are optional.
    */
   public static class Builder {
     private Endpoint endpoint;
-    private Client.Provider clientProvider;
+    private Client client;
     private Executor httpExecutor;
     private Executor callbackExecutor;
     private RequestInterceptor requestInterceptor;
@@ -571,23 +561,11 @@ public class RestAdapter {
     }
 
     /** The HTTP client used for requests. */
-    public Builder setClient(final Client client) {
+    public Builder setClient(Client client) {
       if (client == null) {
         throw new NullPointerException("Client may not be null.");
       }
-      return setClient(new Client.Provider() {
-        @Override public Client get() {
-          return client;
-        }
-      });
-    }
-
-    /** The HTTP client used for requests. */
-    public Builder setClient(Client.Provider clientProvider) {
-      if (clientProvider == null) {
-        throw new NullPointerException("Client provider may not be null.");
-      }
-      this.clientProvider = clientProvider;
+      this.client = client;
       return this;
     }
 
@@ -674,7 +652,7 @@ public class RestAdapter {
         throw new IllegalArgumentException("Endpoint may not be null.");
       }
       ensureSaneDefaults();
-      return new RestAdapter(endpoint, clientProvider, httpExecutor, callbackExecutor,
+      return new RestAdapter(endpoint, client, httpExecutor, callbackExecutor,
           requestInterceptor, converter, profiler, errorHandler, log, logLevel);
     }
 
@@ -682,8 +660,8 @@ public class RestAdapter {
       if (converter == null) {
         converter = Platform.get().defaultConverter();
       }
-      if (clientProvider == null) {
-        clientProvider = Platform.get().defaultClient();
+      if (client == null) {
+        client = Platform.get().defaultClient();
       }
       if (httpExecutor == null) {
         httpExecutor = Platform.get().defaultHttpExecutor();

retrofit/src/main/java/retrofit/client/Client.java

@@ -31,13 +31,4 @@ public interface Client {
    * these values as they might have been set as a result of an application-level configuration.
    */
   Response execute(Request request) throws IOException;
-
-  /**
-   * Deferred means of obtaining a {@link Client}. For asynchronous requests this will always be
-   * called on a background thread.
-   */
-  interface Provider {
-    /** Obtain an HTTP client. Called once for each request. */
-    Client get();
-  }
 }