New API: RequestBody.isOneShot()

Closes: #4134

okhttp-tests/src/test/java/okhttp3/CallTest.java

@@ -1902,6 +1902,71 @@ private void postBodyRetransmittedAfterAuthorizationFail(String body) throws Exc
     assertEquals("Body", response.body().string());
   }
 
+  @Test public void canRetryNormalRequestBody() throws Exception {
+    server.enqueue(new MockResponse()
+        .setResponseCode(503)
+        .setHeader("Retry-After", "0")
+        .setBody("please retry"));
+    server.enqueue(new MockResponse()
+        .setBody("thank you for retrying"));
+
+    Request request = new Request.Builder()
+        .url(server.url("/"))
+        .post(new RequestBody() {
+          int attempt = 0;
+
+          @Override public @Nullable MediaType contentType() {
+            return null;
+          }
+
+          @Override public void writeTo(BufferedSink sink) throws IOException {
+            sink.writeUtf8("attempt " + (attempt++));
+          }
+        })
+        .build();
+    Response response = client.newCall(request).execute();
+    assertEquals(200, response.code());
+    assertEquals("thank you for retrying", response.body().string());
+
+    assertEquals("attempt 0", server.takeRequest().getBody().readUtf8());
+    assertEquals("attempt 1", server.takeRequest().getBody().readUtf8());
+    assertEquals(2, server.getRequestCount());
+  }
+
+  @Test public void cannotRetryOneShotRequestBody() throws Exception {
+    server.enqueue(new MockResponse()
+        .setResponseCode(503)
+        .setHeader("Retry-After", "0")
+        .setBody("please retry"));
+    server.enqueue(new MockResponse()
+        .setBody("thank you for retrying"));
+
+    Request request = new Request.Builder()
+        .url(server.url("/"))
+        .post(new RequestBody() {
+          int attempt = 0;
+
+          @Override public @Nullable MediaType contentType() {
+            return null;
+          }
+
+          @Override public void writeTo(BufferedSink sink) throws IOException {
+            sink.writeUtf8("attempt " + (attempt++));
+          }
+
+          @Override public boolean isOneShot() {
+            return true;
+          }
+        })
+        .build();
+    Response response = client.newCall(request).execute();
+    assertEquals(503, response.code());
+    assertEquals("please retry", response.body().string());
+
+    assertEquals("attempt 0", server.takeRequest().getBody().readUtf8());
+    assertEquals(1, server.getRequestCount());
+  }
+
   @Test public void propfindRedirectsToPropfindAndMaintainsRequestBody() throws Exception {
     // given
     server.enqueue(new MockResponse()

okhttp/src/main/java/okhttp3/RequestBody.java

@@ -44,8 +44,9 @@ public long contentLength() throws IOException {
 
   /**
    * A duplex request body is special in how it is <strong>transmitted</strong> on the network and
-   * in the <strong>API contract</strong> between OkHttp and the application. This method returns
-   * false unless it overridden by a subclass.
+   * in the <strong>API contract</strong> between OkHttp and the application.
+   *
+   * <p>This method returns false unless it is overridden by a subclass.
    *
    * <h3>Duplex Transmission</h3>
    *
@@ -76,6 +77,22 @@ public boolean isDuplex() {
     return false;
   }
 
+  /**
+   * Returns true if this body expects at most one call to {@link #writeTo} and can be transmitted
+   * at most once. This is typically used when writing the request body is destructive and it is not
+   * possible to recreate the request body after it has been sent.
+   *
+   * <p>This method returns false unless it is overridden by a subclass.
+   *
+   * <p>By default OkHttp will attempt to retransmit request bodies when the original request fails
+   * due to a stale connection, a client timeout (HTTP 408), a satisfied authorization challenge
+   * (HTTP 401 and 407), or a retryable server failure (HTTP 503 with a {@code Retry-After: 0}
+   * header).
+   */
+  public boolean isOneShot() {
+    return false;
+  }
+
   /**
    * Returns a new request body that transmits {@code content}. If {@code contentType} is non-null
    * and lacks a charset, this will use UTF-8.

okhttp/src/main/java/okhttp3/internal/http/RetryAndFollowUpInterceptor.java

@@ -18,7 +18,6 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InterruptedIOException;
-import java.net.HttpRetryException;
 import java.net.ProtocolException;
 import java.net.Proxy;
 import java.net.SocketTimeoutException;
@@ -126,6 +125,11 @@ public RetryAndFollowUpInterceptor(OkHttpClient client) {
         return response;
       }
 
+      RequestBody followUpBody = followUp.body();
+      if (followUpBody != null && followUpBody.isOneShot()) {
+        return response;
+      }
+
       closeQuietly(response.body());
       if (transmitter.hasExchange()) {
         exchange.detachWithViolence();
@@ -135,10 +139,6 @@ public RetryAndFollowUpInterceptor(OkHttpClient client) {
         throw new ProtocolException("Too many follow-up requests: " + followUpCount);
       }
 
-      if (followUp.body() instanceof UnrepeatableRequestBody) {
-        throw new HttpRetryException("Cannot retry streamed HTTP body", response.code());
-      }
-
       request = followUp;
       priorResponse = response;
     }
@@ -156,7 +156,7 @@ private boolean recover(IOException e, Transmitter transmitter,
     if (!client.retryOnConnectionFailure()) return false;
 
     // We can't send the request body again.
-    if (requestSendStarted && requestIsUnrepeatable(e, userRequest)) return false;
+    if (requestSendStarted && requestIsOneShot(e, userRequest)) return false;
 
     // This exception is fatal.
     if (!isRecoverable(e, requestSendStarted)) return false;
@@ -168,8 +168,9 @@ private boolean recover(IOException e, Transmitter transmitter,
     return true;
   }
 
-  private boolean requestIsUnrepeatable(IOException e, Request userRequest) {
-    return userRequest.body() instanceof UnrepeatableRequestBody
+  private boolean requestIsOneShot(IOException e, Request userRequest) {
+    RequestBody requestBody = userRequest.body();
+    return (requestBody != null && requestBody.isOneShot())
         || e instanceof FileNotFoundException;
   }
 
@@ -289,7 +290,8 @@ private Request followUpRequest(Response userResponse, @Nullable Route route) th
           return null;
         }
 
-        if (userResponse.request().body() instanceof UnrepeatableRequestBody) {
+        RequestBody requestBody = userResponse.request().body();
+        if (requestBody != null && requestBody.isOneShot()) {
           return null;
         }