/** 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;
}
/** Combines this cached header with a network header as defined by RFC 2616, 13.5.3. */
public ResponseHeaders combine(ResponseHeaders network) {
RawHeaders result = new RawHeaders();
for (int i = 0; i < headers.length(); i++) {
String fieldName = headers.getFieldName(i);
String value = headers.getValue(i);
if (fieldName.equals("Warning") && value.startsWith("1")) {
continue; // drop 100-level freshness warnings
}
if (!isEndToEnd(fieldName) || network.headers.get(fieldName) == null) {
result.add(fieldName, value);
}
}
for (int i = 0; i < network.headers.length(); i++) {
String fieldName = network.headers.getFieldName(i);
if (isEndToEnd(fieldName)) {
result.add(fieldName, network.headers.getValue(i));
}
}
return new ResponseHeaders(uri, result);
}
public void setLocalTimestamps(long sentRequestMillis, long receivedResponseMillis) {
this.sentRequestMillis = sentRequestMillis;
headers.add(SENT_MILLIS, Long.toString(sentRequestMillis));
this.receivedResponseMillis = receivedResponseMillis;
headers.add(RECEIVED_MILLIS, Long.toString(receivedResponseMillis));
}