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The official client SDK for Bandwidth's Voice, Messaging, MFA, and WebRTC APIs
/*
* BandwidthLib
*
* This file was automatically generated by APIMATIC v3.0 ( https://www.apimatic.io ).
*/
package com.bandwidth.http.client;
import com.bandwidth.http.request.HttpMethod;
import java.io.IOException;
import java.net.SocketException;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import okhttp3.Interceptor;
import okhttp3.Request;
import okhttp3.Response;
/**
* RetryInterceptor intercepts and retry requests if failed based on configuration.
*/
public class RetryInterceptor implements Interceptor {
private static final DateTimeFormatter RFC1123_DATE_TIME_FORMATTER =
DateTimeFormatter.ofPattern("EEE, dd MMM yyyy HH:mm:ss z")
.withZone(ZoneId.of("GMT"));
/**
* To keep track of requests being sent and its current state.
*/
private final ConcurrentMap requestEntries;
/**
* User specified retry configurations.
*/
private final ReadonlyHttpClientConfiguration httpClientConfiguration;
/**
* Default Constructor, Initializes the httpClientConfiguration attribute.
*
* @param httpClientConfig the user specified configurations.
*/
public RetryInterceptor(ReadonlyHttpClientConfiguration httpClientConfig) {
this.httpClientConfiguration = httpClientConfig;
requestEntries = new ConcurrentHashMap<>();
}
/**
* Intercepts and retry requests if failed based on configuration.
* @see okhttp3.Interceptor#intercept(okhttp3.Interceptor.Chain)
*/
@SuppressWarnings("resource")
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
RequestState requestState = getRequestState(request);
Response response = null;
try {
response = chain.proceed(request);
} catch (IOException ioException) {
if (httpClientConfiguration.shouldRetryOnTimeout()
&& httpClientConfiguration.getNumberOfRetries() > 0) {
response = retryOnTimeout(chain, request, requestState, ioException);
}
}
while (requestState != null && needToRetry(request, response)) {
requestState.retryCount++;
// Performing wait time calculation.
calculateWaitTime(requestState, response);
// Checking total wait time against allowed max back-off time
if (hasWaitTimeLimitExceeded(requestState)) {
break;
}
// Waiting before making next request
holdExecution(requestState);
// proceeding with execution of next request
try {
response.close();
response = chain.proceed(request);
} catch (SocketException socketException) {
response = chain.proceed(request);
} catch (IOException ioException) {
if (httpClientConfiguration.shouldRetryOnTimeout()
&& httpClientConfiguration.getNumberOfRetries() > 0) {
response = retryOnTimeout(chain, request, requestState, ioException);
}
}
}
this.requestEntries.remove(request);
return response;
}
/**
* Adds entry into Request entry map.
* @param okHttpRequest the OK HTTP Request.
*/
public void addRequestEntry(Request okHttpRequest) {
this.requestEntries.put(okHttpRequest, new RequestState());
}
/**
* Checks if the overall wait time has reached to its limit.
* @param requestState the current state of request entry.
* @return true if total wait time exceeds maximum back-off time.
*/
private boolean hasWaitTimeLimitExceeded(RequestState requestState) {
return this.httpClientConfiguration.getMaximumRetryWaitTime() > 0
&& toMilliseconds(this.httpClientConfiguration
.getMaximumRetryWaitTime()) < requestState.totalWaitTimeInMilliSeconds;
}
/**
* Checks if the retry request is to be made against provided response.
* @param request the HTTP request.
* @param response the HTTP response.
* @return true if request is needed to be retried.
*/
private boolean needToRetry(Request request, Response response) {
return (getRequestState(request).retryCount < this.httpClientConfiguration
.getNumberOfRetries()
&& this.httpClientConfiguration.getHttpMethodsToRetry()
.contains(HttpMethod.valueOf(request.method()))
&& response != null && (this.httpClientConfiguration.getHttpStatusCodesToRetry()
.contains(response.code()) || hasRetryAfterHeader(response)));
}
/**
* Calculates the wait time for next request.
* @param requestState the current state of request entry.
* @param response the HTTP response.
*/
private void calculateWaitTime(RequestState requestState, Response response) {
long retryAfterHeaderValue = 0;
if (hasRetryAfterHeader(response)) {
retryAfterHeaderValue = getCalculatedHeaderValue(response.header("Retry-After"));
}
long calculatedBackOffInMilliSeconds = getCalculatedBackOffValue(requestState);
requestState.currentWaitInMilliSeconds =
calculatedBackOffInMilliSeconds > retryAfterHeaderValue
? calculatedBackOffInMilliSeconds
: retryAfterHeaderValue;
requestState.totalWaitTimeInMilliSeconds += requestState.currentWaitInMilliSeconds;
}
/**
* Checks if the response contains Retry-After header.
* @param response the HTTP response.
* @return true if response contains Retry-After header.
*/
private boolean hasRetryAfterHeader(Response response) {
String retryAfter = response.header("Retry-After");
if (retryAfter != null && !retryAfter.isEmpty()) {
return true;
}
return false;
}
/**
* Analyzes the header value and checks the header if it contains date in proper format or
* seconds. If header value is date then it calculates the delta time in milliseconds.
* @param headerValue the retry-after header value.
* @return long value of calculated wait time in milliseconds.
*/
private long getCalculatedHeaderValue(String headerValue) {
try {
return toMilliseconds(Long.parseLong(headerValue));
} catch (NumberFormatException nfe) {
long requestAtValueInSeconds = LocalDateTime
.parse(headerValue, RFC1123_DATE_TIME_FORMATTER).toEpochSecond(ZoneOffset.UTC);
long currentDateTimeInSeconds = LocalDateTime
.now(ZoneOffset.UTC).toEpochSecond(ZoneOffset.UTC);
return toMilliseconds(requestAtValueInSeconds - currentDateTimeInSeconds);
}
}
/**
* Calculates the back-off value based on a formula which uses back-off factor and retry Count.
* @param requestState the current state of request entry.
* @return long value of back-off time based on formula in milliseconds.
*/
private long getCalculatedBackOffValue(RequestState requestState) {
return (long) (1000 * this.httpClientConfiguration.getRetryInterval()
* Math.pow(this.httpClientConfiguration.getBackOffFactor(),
requestState.retryCount - 1) + Math.random() * 100);
}
/**
* Holds the execution for stored wait time in milliseconds of this thread.
* @param requestState the current state of request entry.
*/
private void holdExecution(RequestState requestState) {
try {
TimeUnit.MILLISECONDS.sleep(requestState.currentWaitInMilliSeconds);
} catch (InterruptedException e) {
// No handler needed
}
}
/**
* Converts the seconds to milliseconds.
* @param seconds The seconds to convert.
* @return long value of milliseconds.
*/
private long toMilliseconds(long seconds) {
return seconds * 1000;
}
/**
* getter for current request state entry from map.
* @param okHttpRequest the OK HTTP Request.
* @return RequestEntry the current request entry.
*/
private RequestState getRequestState(Request okHttpRequest) {
return this.requestEntries.get(okHttpRequest);
}
/**
* Retries on the request which caused the request timeout to occur based on HTTP Client
* Configurations.
* @param chain The interceptor chain.
* @param request The OkHttp request.
* @param exception The thrown exception.
* @return The OKHttp response.
* @throws IOException the same exception which was thrown while retrying.
*/
private okhttp3.Response retryOnTimeout(Chain chain, Request request, RequestState requestState,
IOException exception) throws IOException {
while (requestState.retryCount++ < httpClientConfiguration.getNumberOfRetries()
&& !this.hasWaitTimeLimitExceeded(requestState)) {
try {
return chain.proceed(request);
} catch (IOException ioException) {
exception = ioException;
} finally {
requestState.totalWaitTimeInMilliSeconds +=
toMilliseconds(httpClientConfiguration.getTimeout());
}
}
throw exception;
}
/**
* Class to hold the request info until request completes.
*/
private class RequestState {
/**
* To keep track of requests count.
*/
private int retryCount = 0;
/**
* To store the wait time for next request.
*/
private long currentWaitInMilliSeconds = 0;
/**
* To keep track of overall wait time.
*/
private long totalWaitTimeInMilliSeconds = 0;
}
}