patterncsharpCritical
Cleanest way to write retry logic?
Viewed 0 times
cleanestwritewaylogicretry
Problem
Occasionally I have a need to retry an operation several times before giving up. My code is like:
I would like to rewrite this in a general retry function like:
Is it possible in C#? What would be the code for the
int retries = 3;
while(true) {
try {
DoSomething();
break; // success!
} catch {
if(--retries == 0) throw;
else Thread.Sleep(1000);
}
}I would like to rewrite this in a general retry function like:
TryThreeTimes(DoSomething);Is it possible in C#? What would be the code for the
TryThreeTimes() method?Solution
Blanket catch statements that simply retry the same call can be dangerous if used as a general exception handling mechanism. Having said that, here's a lambda-based retry wrapper that you can use with any method. I chose to factor the number of retries and the retry timeout out as parameters for a bit more flexibility:
You can now use this utility method to perform retry logic:
or:
or:
Or you could even make an
public static class Retry
{
public static void Do(
Action action,
TimeSpan retryInterval,
int maxAttemptCount = 3)
{
Do(() =>
{
action();
return null;
}, retryInterval, maxAttemptCount);
}
public static T Do(
Func action,
TimeSpan retryInterval,
int maxAttemptCount = 3)
{
var exceptions = new List();
for (int attempted = 0; attempted 0)
{
Thread.Sleep(retryInterval);
}
return action();
}
catch (Exception ex)
{
exceptions.Add(ex);
}
}
throw new AggregateException(exceptions);
}
}You can now use this utility method to perform retry logic:
Retry.Do(() => SomeFunctionThatCanFail(), TimeSpan.FromSeconds(1));or:
Retry.Do(SomeFunctionThatCanFail, TimeSpan.FromSeconds(1));or:
int result = Retry.Do(SomeFunctionWhichReturnsInt, TimeSpan.FromSeconds(1), 4);Or you could even make an
async overload.Code Snippets
public static class Retry
{
public static void Do(
Action action,
TimeSpan retryInterval,
int maxAttemptCount = 3)
{
Do<object>(() =>
{
action();
return null;
}, retryInterval, maxAttemptCount);
}
public static T Do<T>(
Func<T> action,
TimeSpan retryInterval,
int maxAttemptCount = 3)
{
var exceptions = new List<Exception>();
for (int attempted = 0; attempted < maxAttemptCount; attempted++)
{
try
{
if (attempted > 0)
{
Thread.Sleep(retryInterval);
}
return action();
}
catch (Exception ex)
{
exceptions.Add(ex);
}
}
throw new AggregateException(exceptions);
}
}Retry.Do(() => SomeFunctionThatCanFail(), TimeSpan.FromSeconds(1));Retry.Do(SomeFunctionThatCanFail, TimeSpan.FromSeconds(1));int result = Retry.Do(SomeFunctionWhichReturnsInt, TimeSpan.FromSeconds(1), 4);Context
Stack Overflow Q#1563191, score: 650
Revisions (0)
No revisions yet.