int S3fsMultiCurl::MultiRead()

in src/curl_multi.cpp [181:293]
88 lines of code
23 McCabe index (conditional complexity)

int S3fsMultiCurl::MultiRead()
{
    int result = 0;

    for(s3fscurllist_t::iterator iter = clist_req.begin(); iter != clist_req.end(); ){
        S3fsCurl* s3fscurl = *iter;

        bool isRetry = false;
        bool isPostpone = false;
        bool isNeedResetOffset = true;
        long responseCode = S3fsCurl::S3FSCURL_RESPONSECODE_NOTSET;
        CURLcode curlCode = s3fscurl->GetCurlCode();

        if(s3fscurl->GetResponseCode(responseCode, false) && curlCode == CURLE_OK){
            if(S3fsCurl::S3FSCURL_RESPONSECODE_NOTSET == responseCode){
                // This is a case where the processing result has not yet been updated (should be very rare).
                isPostpone = true;
            }else if(400 > responseCode){
                // add into stat cache
                if(SuccessCallback && !SuccessCallback(s3fscurl)){
                    S3FS_PRN_WARN("error from callback function(%s).", s3fscurl->url.c_str());
                }
            }else if(400 == responseCode){
                // as possibly in multipart
                S3FS_PRN_WARN("failed a request(%ld: %s)", responseCode, s3fscurl->url.c_str());
                isRetry = true;
            }else if(404 == responseCode){
                // not found
                // HEAD requests on readdir_multi_head can return 404
                if(s3fscurl->GetOp() != "HEAD"){
                    S3FS_PRN_WARN("failed a request(%ld: %s)", responseCode, s3fscurl->url.c_str());
                }
            }else if(500 == responseCode){
                // case of all other result, do retry.(11/13/2013)
                // because it was found that ossfs got 500 error from OSS, but could success
                // to retry it.
                S3FS_PRN_WARN("failed a request(%ld: %s)", responseCode, s3fscurl->url.c_str());
                isRetry = true;
            }else{
                // Retry in other case.
                S3FS_PRN_WARN("failed a request(%ld: %s)", responseCode, s3fscurl->url.c_str());
                isRetry = true;
            }
        }else{
            S3FS_PRN_ERR("failed a request(Unknown response code: %s)", s3fscurl->url.c_str());
            // Reuse partical file
            switch(curlCode){
                case CURLE_OPERATION_TIMEDOUT:
                    isRetry = true;
                    isNeedResetOffset = false;
                    break; 

                case CURLE_PARTIAL_FILE:
                    isRetry = true;
                    isNeedResetOffset = false;
                    break; 

                default:
                    S3FS_PRN_ERR("###curlCode: %d  msg: %s", curlCode, curl_easy_strerror(curlCode));
                    isRetry = true;
                    break;
            }
        }

        if(isPostpone){
            clist_req.erase(iter);
            clist_req.push_back(s3fscurl);    // Re-evaluate at the end
            iter = clist_req.begin();
        }else{
            if(!isRetry || 0 != result){
                // If an EIO error has already occurred, it will be terminated
                // immediately even if retry processing is required. 
                s3fscurl->DestroyCurlHandle();
                delete s3fscurl;
            }else{
                S3fsCurl* retrycurl = NULL;

                // Reset offset
                if(isNeedResetOffset){
                    S3fsCurl::ResetOffset(s3fscurl);
                }

                // For retry
                if(RetryCallback){
                    retrycurl = RetryCallback(s3fscurl);
                    if(NULL != retrycurl){
                        clist_all.push_back(retrycurl);
                    }else{
                        // set EIO and wait for other parts.
                        result = -EIO;
                    }
                }
                if(s3fscurl != retrycurl){
                    s3fscurl->DestroyCurlHandle();
                    delete s3fscurl;
                }
            }
            iter = clist_req.erase(iter);
        }
    }
    clist_req.clear();

    if(0 != result){
        // If an EIO error has already occurred, clear all retry objects.
        for(s3fscurllist_t::iterator iter = clist_all.begin(); iter != clist_all.end(); ++iter){
            S3fsCurl* s3fscurl = *iter;
            s3fscurl->DestroyCurlHandle();
            delete s3fscurl;
        }
        clist_all.clear();
    }
    return result;
}