/** Returns the source to satisfy {@code request} given this cached response. */
public ResponseSource chooseResponseSource(long nowMillis, RequestHeaders request) {
/*
* If this response shouldn't have been stored, it should never be used
* as a response source. This check should be redundant as long as the
* persistence store is well-behaved and the rules are constant.
*/
if (!isCacheable(request)) {
return ResponseSource.NETWORK;
}
if (request.isNoCache() || request.hasConditions()) {
return ResponseSource.NETWORK;
}
long ageMillis = computeAge(nowMillis);
long freshMillis = computeFreshnessLifetime();
if (request.getMaxAgeSeconds() != -1) {
freshMillis = Math.min(freshMillis, TimeUnit.SECONDS.toMillis(request.getMaxAgeSeconds()));
}
long minFreshMillis = 0;
if (request.getMinFreshSeconds() != -1) {
minFreshMillis = TimeUnit.SECONDS.toMillis(request.getMinFreshSeconds());
}
long maxStaleMillis = 0;
if (!mustRevalidate && request.getMaxStaleSeconds() != -1) {
maxStaleMillis = TimeUnit.SECONDS.toMillis(request.getMaxStaleSeconds());
}
if (!noCache && ageMillis + minFreshMillis < freshMillis + maxStaleMillis) {
if (ageMillis + minFreshMillis >= freshMillis) {
headers.add("Warning", "110 HttpURLConnection \"Response is stale\"");
}
/*
* not available in API 8
if (ageMillis > TimeUnit.HOURS.toMillis(24) && isFreshnessLifetimeHeuristic()) {
*/
if (ageMillis > 24L * 60L * 60L * 1000L && isFreshnessLifetimeHeuristic()) {
headers.add("Warning", "113 HttpURLConnection \"Heuristic expiration\"");
}
return ResponseSource.CACHE;
}
if (etag != null) {
request.setIfNoneMatch(etag);
} else if (lastModified != null) {
request.setIfModifiedSince(lastModified);
} else if (servedDate != null) {
request.setIfModifiedSince(servedDate);
}
return request.hasConditions() ? ResponseSource.CONDITIONAL_CACHE : ResponseSource.NETWORK;
}
