带退避重试工作流
patterns
API调用的指数退避重试模式，具有可配置的重试限制、延迟计算、可重试错误检测以及永久故障时的优雅降级。
完整 FlowZap 代码
Client { # Client
n1: circle label:"Start"
n2: rectangle label:"Prepare API request"
n3: rectangle label:"Process successful response"
n4: rectangle label:"Handle permanent failure"
n5: circle label:"End"
n1.handle(right) -> n2.handle(left)
n2.handle(bottom) -> RetryHandler.n6.handle(top) [label="Send request"]
n3.handle(right) -> n5.handle(left)
n4.handle(right) -> n5.handle(left)
}
RetryHandler { # Retry Handler
n6: rectangle label:"Initialize retry state"
n7: rectangle label:"Execute HTTP request"
n8: diamond label:"Response status?"
n9: rectangle label:"Return success"
n10: diamond label:"Retryable error?"
n11: diamond label:"Retries remaining?"
n12: rectangle label:"Calculate backoff delay"
n13: rectangle label:"Wait exponential delay"
n14: rectangle label:"Increment retry counter"
n15: rectangle label:"Return final error"
n6.handle(right) -> n7.handle(left)
n7.handle(right) -> n8.handle(left)
n8.handle(right) -> n9.handle(left) [label="2xx"]
n8.handle(bottom) -> n10.handle(top) [label="4xx/5xx"]
n9.handle(top) -> Client.n3.handle(bottom) [label="Success"]
n10.handle(right) -> n11.handle(left) [label="Yes"]
n10.handle(bottom) -> n15.handle(top) [label="No"]
n11.handle(right) -> n12.handle(left) [label="Yes"]
n11.handle(bottom) -> n15.handle(top) [label="No"]
n12.handle(right) -> n13.handle(left)
n13.handle(right) -> n14.handle(left)
n14.handle(top) -> n7.handle(bottom) [label="Retry"]
n15.handle(top) -> Client.n4.handle(bottom) [label="Failed"]
loop [retry up to 3 times] n7 n8 n10 n11 n12 n13 n14
}
APIServer { # API Server
n16: rectangle label:"Receive request"
n17: diamond label:"Server healthy?"
n18: rectangle label:"Process request"
n19: rectangle label:"Return 503 Service Unavailable"
n20: rectangle label:"Return 200 OK"
n16.handle(right) -> n17.handle(left)
n17.handle(right) -> n18.handle(left) [label="Yes"]
n17.handle(bottom) -> n19.handle(top) [label="No"]
n18.handle(right) -> n20.handle(left)
n19.handle(top) -> RetryHandler.n8.handle(bottom) [label="Error"]
n20.handle(top) -> RetryHandler.n8.handle(bottom) [label="Success"]
}