New API to disable retry for an OkHttpClient.

[swankjesse]

Most applications won't want to disable retry globally. Instead, use
clone() to get an OkHttpClient for a specific, non-idempotent request,
then configure that client with the setting.

Closes #1043

[codefromthecrypt]

Excellent idea and docs.

[ValleZ]

yay! Thanks!

[floating-cat]

Can I ask a stupid question?

  /**
   * Configure this client to retry or not when a connectivity problem is encountered. By default,
   * this client silently recovers from the following problems:
   *
   * <ul>
   *   <li><strong>Unreachable IP addresses.</strong> If the URL's host has multiple IP addresses,
   *       failure to reach any individual IP address doesn't fail the overall request. This can
   *       increase availability of multi-homed services.
   *   <li><strong>Stale pooled connections.</strong> The {@link ConnectionPool} reuses sockets
   *       to decrease request latency, but these connections will occasionally time out.
   *   <li><strong>Unreachable proxy servers.</strong> A {@link ProxySelector} can be used to
   *       attempt multiple proxy servers in sequence, eventually falling back to a direct
   *       connection.
   * </ul>
   *
   * Set this to false to avoid retrying requests when doing so is destructive. In this case the
   * calling application should do its own recovery of connectivity failures.
   */
  public final void setRetryOnConnectionFailure(boolean retryOnConnectionFailure) {
    this.retryOnConnectionFailure = retryOnConnectionFailure;
  }

If I send a non-idempotent request to server (like comment in GitHub), and one of those problems above happens. Won't this request handled by server twice (like comment in GitHub twice)?
I guess Unreachable proxy servers won't, but I am not sure others.

[JakeWharton]

If this is set to true (which is the default) then yes that will happen if all of the request body successfully made it to the server. This was the existing behavior of OkHttp. The added API in this pull request only adds the ability to disable this functionality for those poorly written APIs.

[floating-cat]

Thank you!

[narayank]

The "stale pooled connections" case worries me a little bit. See https://code.google.com/p/android/issues/detail?id=61706 for why this will be quite common on linux based OSes. Depending on request patterns, some users might hit this 100% of the time.

[swankjesse]

@narayank agreed. Which is why you have to explicitly opt-out of retry. We're also conservative about pooled connections for non-GET requests.

[1zaman]

Why not provide an option for disabling retries based on the potential non-idempotency of the HTTP method itself? I am sure that the overwhelming majority of use-cases for disabling retries are for this. Absent this option, I ended up writing my own delegator class to implement this.

Note that while HttpUrlConnection has always been broken, it is required by the IETF standard for HTTP clients to not retry requests with non-idempotent methods. #1043 was closed against this feature, although it requested compliant behavior.

[afinas-em]

OkHttpClient okHttpClient= null;
        okHttpClient = new OkHttpClient.Builder()
                .sslSocketFactory(new TLSSocketFactory(),trustManager)
                .connectTimeout(2, TimeUnit.MINUTES)
                .readTimeout(2, TimeUnit.MINUTES)
                .writeTimeout(2, TimeUnit.MINUTES)
                //.sslSocketFactory(sslSocketFactory, trustManager)
                .followRedirects(false)
                .followSslRedirects(false)
                .retryOnConnectionFailure(false)
                .cache(null)//new Cache(sContext.getCacheDir(),10*1024*1024)
                .build();