/// <summary>
/// Periodically performs the following steps:
/// 0. keep alive the session
// 1. collect the freshest command bulk
// 2. try-send bulk
// 3. validate response
// 4. parse response and enqueue for retry if needed
// 5. wait for N seconds (N grows with the number of consecutive connection failures)
/// </summary>
/// <returns>The send loop enumerator.</returns>
private IEnumerator APISendLoop(string target, PersistentBulkCommandQueue commandQueue)
{
const int WAIT_FOR_DEFAULT = 3;
var httpTarget = target + Constants.BULK_URL;
int consecutiveFailedRequests = 0;
while (true)
{
// Decide if we process retry commands or new commands in this round
List<object> commands = commandQueue.BulkDequeue(true);
if (commands.Count > 0)
{
// 1B: Prepare the http components
var httpBody = Json.Serialize(new Dictionary<string,object> {{"commands", commands}});
byte[] httpBodyBytes = Encoding.UTF8.GetBytes(httpBody);
Dictionary<string,string> httpHeaders = new Dictionary<string,string>{ {"Content-type", "application/json"} };
// 2. Send the bulk API request
WWW req = new WWW(httpTarget, httpBodyBytes, httpHeaders); //TODO: we could add a timeout functionality
yield return req;
// 3A: Check response for errors
if (!string.IsNullOrEmpty(req.error))
{
consecutiveFailedRequests++;
}
else
{
// 3B. Parse the API response
var responseBody = req.text;
Dictionary<string, object> apiResponse = (Dictionary<string, object>) Json.Deserialize(responseBody);
bool success = (bool) apiResponse["success"];
if(success)
{
consecutiveFailedRequests = 0;
// 4A: extract retry-commands and queue them back (if any)
var retryCommands = ExtractRetryCommands(apiResponse,commands);
commandQueue.MultiDequeue(commands.Count); //remove every command from this request
commandQueue.MultiPush(retryCommands); //re-add failed commands with the highest priority
}
else
{
consecutiveFailedRequests++;
}
}
}
// 5. Detemine wait time and go idle.
float waitSeconds = (float)System.Math.Pow(WAIT_FOR_DEFAULT, System.Math.Sqrt(consecutiveFailedRequests+1));
if(consecutiveFailedRequests == 0 && commandQueue.ElementCount > 0)
{
waitSeconds = 0f;
}
waitSeconds = System.Math.Min (waitSeconds, Constants.BULK_MAX - 3f);
yield return new WaitForSeconds(waitSeconds);
}
}
public Sender(string target, PersistentBulkCommandQueue commandQueue)
{
this.StartCoroutine (APISendLoop(target, commandQueue));
}
