/// <summary>
/// It's recommended to use this method (or another TryAwaitOrTimeout or AwaitOrTimeout method)
/// instead of just Task.WhenAny(taskToAwait, Task.Delay(timeout))
/// because this method cancels the timer for timeout while <c>Task.Delay(timeout)</c>.
/// If the number of “zombie” timer jobs starts becoming significant, performance could suffer.
/// For more detailed explanation see https://devblogs.microsoft.com/pfxteam/crafting-a-task-timeoutafter-method/
/// </summary>
/// <returns><c>true</c> if <c>taskToAwait</c> completed before the timeout, <c>false</c> otherwise</returns>
internal static async Task <bool> TryAwaitOrTimeout(this IAgentTimer agentTimer, Task taskToAwait
, AgentTimeInstant until, CancellationToken cancellationToken = default
)
{
var timeoutDelayCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
var timeoutDelayTask = agentTimer.Delay(until, timeoutDelayCts.Token);
try
{
var completedTask = await Task.WhenAny(taskToAwait, timeoutDelayTask);
if (completedTask == taskToAwait)
{
// await taskToAwait to make it throw if taskToAwait is faulted or cancelled so it will throw as it should
await taskToAwait;
return(true);
}
Assertion.IfEnabled?.That(completedTask == timeoutDelayTask
, $"{nameof(completedTask)}: {completedTask}, {nameof(timeoutDelayTask)}: timeOutTask, {nameof(taskToAwait)}: taskToAwait");
// await timeout task in case it is cancelled and did not timed out so it will throw as it should
await timeoutDelayTask;
return(false);
}
finally
{
if (!timeoutDelayTask.IsCompleted)
{
timeoutDelayCts.Cancel();
}
timeoutDelayCts.Dispose();
}
}
protected override async Task WorkLoopIteration()
{
++_dbgIterationsCount;
var waitingLogSeverity = LogLevel.Trace;
WaitInfoS waitInfo;
HttpRequestMessage httpRequest = null;
HttpResponseMessage httpResponse = null;
string httpResponseBody = null;
try
{
httpRequest = BuildHttpRequest(_eTag);
(httpResponse, httpResponseBody) = await FetchConfigHttpResponseAsync(httpRequest);
ConfigDelta configDelta;
(configDelta, waitInfo) = ProcessHttpResponse(httpResponse, httpResponseBody);
if (configDelta != null)
{
UpdateConfigStore(configDelta);
_eTag = httpResponse.Headers.ETag;
}
}
catch (OperationCanceledException)
{
throw;
}
catch (Exception ex)
{
var severity = LogLevel.Error;
waitInfo = new WaitInfoS(WaitTimeIfAnyError, "Default wait time is used because exception was thrown"
+ " while fetching configuration from APM Server and parsing it.");
if (ex is FailedToFetchConfigException fEx)
{
severity = fEx.Severity;
fEx.WaitInfo?.Let(it => { waitInfo = it; });
}
if (severity == LogLevel.Error)
{
waitingLogSeverity = LogLevel.Information;
}
_logger.IfLevel(severity)
?.LogException(ex, "Exception was thrown while fetching configuration from APM Server and parsing it."
+ " ETag: `{ETag}'. URL: `{Url}'. Apm Server base URL: `{ApmServerUrl}'. WaitInterval: {WaitInterval}."
+ " dbgIterationsCount: {dbgIterationsCount}."
+ Environment.NewLine + "+-> Request:{HttpRequest}"
+ Environment.NewLine + "+-> Response:{HttpResponse}"
+ Environment.NewLine + "+-> Response body [length: {HttpResponseBodyLength}]:{HttpResponseBody}"
, _eTag.AsNullableToString(), _getConfigAbsoluteUrl, HttpClientInstance.BaseAddress, waitInfo.Interval.ToHms(),
_dbgIterationsCount
, httpRequest == null ? " N/A" : Environment.NewLine + TextUtils.Indent(httpRequest.ToString())
, httpResponse == null ? " N/A" : Environment.NewLine + TextUtils.Indent(httpResponse.ToString())
, httpResponseBody == null ? "N/A" : httpResponseBody.Length.ToString()
, httpResponseBody == null ? " N/A" : Environment.NewLine + TextUtils.Indent(httpResponseBody));
}
finally
{
httpRequest?.Dispose();
httpResponse?.Dispose();
}
_logger.IfLevel(waitingLogSeverity)
?.Log("Waiting {WaitInterval}... {WaitReason}. dbgIterationsCount: {dbgIterationsCount}."
, waitInfo.Interval.ToHms(), waitInfo.Reason, _dbgIterationsCount);
await _agentTimer.Delay(_agentTimer.Now + waitInfo.Interval, CtsInstance.Token);
}