Cassandra Datastax驅動程序重試策略

Question

我們可以像這樣創建一個集羣實例。

cluster = Cluster 
.builder() 
.addContactPoint("192.168.0.30") 
.withRetryPolicy(DefaultRetryPolicy.INSTANCE) 
.build(); 

我們將提供詢問時請求重試的次數信息。

任何意見表示讚賞。

感謝

Answer 1

爲了指定這些值，你必須創建自己的實施RetryPolicy interface的。

以下僅僅是一個例子 - 使自己實現以下的規則：

public class CustomRetryPolicy implements RetryPolicy { 

    private final int readAttempts; 
    private final int writeAttempts; 
    private final int unavailableAttempts; 

    public CustomRetryPolicy(int readAttempts, int writeAttempts, int unavailableAttempts) { 
     this.readAttempts = readAttempts; 
     this.writeAttempts = writeAttempts; 
     this.unavailableAttempts = unavailableAttempts; 
    } 

    @Override 
    public RetryDecision onReadTimeout(Statement stmnt, ConsistencyLevel cl, int requiredResponses, int receivedResponses, boolean dataReceived, int rTime) { 
     if (dataReceived) { 
      return RetryDecision.ignore(); 
     } else if (rTime < readAttempts) { 
      return RetryDecision.retry(cl); 
     } else { 
      return RetryDecision.rethrow(); 
     } 

    } 

    @Override 
    public RetryDecision onWriteTimeout(Statement stmnt, ConsistencyLevel cl, WriteType wt, int requiredResponses, int receivedResponses, int wTime) { 
     if (wTime < writeAttempts) { 
      return RetryDecision.retry(cl); 
     } 
     return RetryDecision.rethrow(); 
    } 

    @Override 
    public RetryDecision onUnavailable(Statement stmnt, ConsistencyLevel cl, int requiredResponses, int receivedResponses, int uTime) { 
       if (uTime < unavailableAttempts) { 
      return RetryDecision.retry(ConsistencyLevel.ONE); 
     } 
     return RetryDecision.rethrow(); 
    } 

} 

這是很容易做到......然後，你將在你的Cluster ...

RetryPolicy rc = new CustomRetryPolicy(3, 3, 2); 
Cluster cluster = Cluster.builder().addContactPoint("192.168.0.30").withRetryPolicy(rc).build(); 

HTH， 卡羅