Volley RetryPolicy querying twice before timeout time is reached

Question

I have set a retry policy for volley. The query is being sent twice despite the the timeout period not being reached.

 StringRequest stringRequest = new StringRequest(method, currentURL,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    S.L("response: " + currentURL);
                    listener.onRequestExecuted("response", response, downloadId);
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d("CCC", "Error " + error.toString());                                             
                }
            })

This was the retry policy earlier

stringRequest.setRetryPolicy(new RetryPolicy() {
        @Override
        public int getCurrentTimeout() {
            return 8000;
        }

        @Override
        public int getCurrentRetryCount() {
            return 1;
        }

        @Override
        public void retry(VolleyError error) throws VolleyError {
            S.L("Retry error: " + error);
        }
    });

On SO there was another question pertaining to this. It appears to do so when volley detects a slow connection despite timeout period is not reached. Here the solution was to use a different retry policy:

stringRequest.setRetryPolicy(new DefaultRetryPolicy(8000,
            DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
            DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

This worked and is sending only a single query in the timeout period

Why is there a difference in behaviour between the retry policies?

earthw0rmjim · Accepted Answer · 2016-10-21T06:42:53.150

Why is there a difference in behaviour between the retry policies?

Because of the different retry() implementations.

From the source code of DefaultRetryPolicy:

@Override
public void retry(VolleyError error) throws VolleyError {
    mCurrentRetryCount++;
    mCurrentTimeoutMs += (mCurrentTimeoutMs * mBackoffMultiplier);
    if (!hasAttemptRemaining()) {
        throw error;
    }
}

protected boolean hasAttemptRemaining() {
    return mCurrentRetryCount <= mMaxNumRetries;
}

By passing DefaultRetryPolicy.DEFAULT_MAX_RETRIES to the constructor, you're effectively setting mMaxNumRetries to 1.

On the second retry hasAttemptRemaining() will return false and the VolleyError will be thrown.

Volley RetryPolicy querying twice before timeout time is reached

1 Answers1