/** 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;
}
/** Returns true if this response can be stored to later serve another request. */
public boolean isCacheable(RequestHeaders request) {
/*
* Always go to network for uncacheable response codes (RFC 2616, 13.4),
* This implementation doesn't support caching partial content.
*/
int responseCode = headers.getResponseCode();
if (responseCode != HttpURLConnection.HTTP_OK
&& responseCode != HttpURLConnection.HTTP_NOT_AUTHORITATIVE
&& responseCode != HttpURLConnection.HTTP_MULT_CHOICE
&& responseCode != HttpURLConnection.HTTP_MOVED_PERM
&& responseCode != HttpURLConnection.HTTP_GONE) {
return false;
}
/*
* Responses to authorized requests aren't cacheable unless they include
* a 'public', 'must-revalidate' or 's-maxage' directive.
*/
if (request.hasAuthorization() && !isPublic && !mustRevalidate && sMaxAgeSeconds == -1) {
return false;
}
if (noStore) {
return false;
}
return true;
}
/** 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));
}
public void stripContentEncoding() {
contentEncoding = null;
headers.removeAll("Content-Encoding");
}
public ResponseHeaders(URI uri, RawHeaders headers) {
this.uri = uri;
this.headers = headers;
HeaderParser.CacheControlHandler handler =
new HeaderParser.CacheControlHandler() {
@Override
public void handle(String directive, String parameter) {
if (directive.equalsIgnoreCase("no-cache")) {
noCache = true;
} else if (directive.equalsIgnoreCase("no-store")) {
noStore = true;
} else if (directive.equalsIgnoreCase("max-age")) {
maxAgeSeconds = HeaderParser.parseSeconds(parameter);
} else if (directive.equalsIgnoreCase("s-maxage")) {
sMaxAgeSeconds = HeaderParser.parseSeconds(parameter);
} else if (directive.equalsIgnoreCase("public")) {
isPublic = true;
} else if (directive.equalsIgnoreCase("must-revalidate")) {
mustRevalidate = true;
}
}
};
for (int i = 0; i < headers.length(); i++) {
String fieldName = headers.getFieldName(i);
String value = headers.getValue(i);
if ("Cache-Control".equalsIgnoreCase(fieldName)) {
HeaderParser.parseCacheControl(value, handler);
} else if ("Date".equalsIgnoreCase(fieldName)) {
servedDate = HttpDate.parse(value);
} else if ("Expires".equalsIgnoreCase(fieldName)) {
expires = HttpDate.parse(value);
} else if ("Last-Modified".equalsIgnoreCase(fieldName)) {
lastModified = HttpDate.parse(value);
} else if ("ETag".equalsIgnoreCase(fieldName)) {
etag = value;
} else if ("Pragma".equalsIgnoreCase(fieldName)) {
if (value.equalsIgnoreCase("no-cache")) {
noCache = true;
}
} else if ("Age".equalsIgnoreCase(fieldName)) {
ageSeconds = HeaderParser.parseSeconds(value);
} else if ("Vary".equalsIgnoreCase(fieldName)) {
// Replace the immutable empty set with something we can mutate.
if (varyFields.isEmpty()) {
varyFields = new TreeSet<String>(String.CASE_INSENSITIVE_ORDER);
}
for (String varyField : value.split(",")) {
varyFields.add(varyField.trim());
}
} else if ("Content-Encoding".equalsIgnoreCase(fieldName)) {
contentEncoding = value;
} else if ("Transfer-Encoding".equalsIgnoreCase(fieldName)) {
transferEncoding = value;
} else if ("Content-Length".equalsIgnoreCase(fieldName)) {
try {
contentLength = Integer.parseInt(value);
} catch (NumberFormatException ignored) {
}
} else if ("Connection".equalsIgnoreCase(fieldName)) {
connection = value;
} else if ("Proxy-Authenticate".equalsIgnoreCase(fieldName)) {
proxyAuthenticate = value;
} else if ("WWW-Authenticate".equalsIgnoreCase(fieldName)) {
wwwAuthenticate = value;
} else if (SENT_MILLIS.equalsIgnoreCase(fieldName)) {
sentRequestMillis = Long.parseLong(value);
} else if (RECEIVED_MILLIS.equalsIgnoreCase(fieldName)) {
receivedResponseMillis = Long.parseLong(value);
}
}
}