ok2c commented on code in PR #420:
URL:
https://github.com/apache/httpcomponents-client/pull/420#discussion_r1129879704
##########
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/ResponseCachingPolicy.java:
##########
@@ -320,4 +360,100 @@ private boolean from1_0Origin(final HttpResponse
response) {
return HttpVersion.HTTP_1_0.equals(version);
}
+ /**
+ * Calculates the freshness lifetime of a response, based on the headers
in the response.
+ * <p>
+ * This method follows the algorithm for calculating the freshness
lifetime.
+ * The freshness lifetime represents the time interval in seconds during
which the response can be served without
+ * being considered stale. The freshness lifetime calculation takes into
account the s-maxage, max-age, Expires, and
+ * Date headers as follows:
+ * <ul>
+ * <li>If the s-maxage directive is present in the Cache-Control header of
the response, its value is used as the
+ * freshness lifetime for shared caches, which typically serve multiple
users or clients.</li>
+ * <li>If the max-age directive is present in the Cache-Control header of
the response, its value is used as the
+ * freshness lifetime for private caches, which serve a single user or
client.</li>
+ * <li>If the Expires header is present in the response, its value is used
as the expiration time of the response.
+ * The freshness lifetime is calculated as the difference between the
expiration time and the time specified in the
+ * Date header of the response.</li>
+ * <li>If none of the above headers are present or if the calculated
freshness lifetime is invalid, a default value of
+ * 5 minutes is returned.</li>
+ * </ul>
+ *
+ * <p>
+ * Note that caching is a complex topic and cache control directives may
interact with each other in non-trivial ways.
+ * This method provides a basic implementation of the freshness lifetime
calculation algorithm and may not be suitable
+ * for all use cases. Developers should consult the HTTP caching
specifications for more information and consider
+ * implementing additional caching mechanisms as needed.
+ * </p>
+ *
+ * @param response the HTTP response for which to calculate the freshness
lifetime
+ * @return the freshness lifetime of the response, in seconds
+ */
+ private Duration calculateFreshnessLifetime(final HttpResponse response) {
+ // Check if s-maxage is present and use its value if it is
+ final Header cacheControl =
response.getFirstHeader(HttpHeaders.CACHE_CONTROL);
+ if (cacheControl == null) {
+ // If no cache-control header is present, assume no caching
directives and return a default value
+ return DEFAULT_FRESHNESS_DURATION; // 5 minutes
+ }
+
+ final String cacheControlValue = cacheControl.getValue();
+ final String[] headerValues = cacheControlValue.split(",");
+
+ long maxAge = -1;
+ long sharedMaxAge = -1;
+
+ for (final String headerValue : headerValues) {
+ final Tokenizer.Cursor cursor = new Tokenizer.Cursor(0,
headerValue.length());
+ while (!cursor.atEnd()) {
+ final String token = tokenParser.parseToken(headerValue,
cursor, DELIMITER);
+ if (token.trim().startsWith("max-age=")) {
+ try {
+ maxAge =
Long.parseLong(token.trim().substring("max-age=".length()));
+ } catch (final NumberFormatException e) {
+ // Handle malformed header value
+ maxAge = -1;
+ if (LOG.isWarnEnabled()) {
+ LOG.warn("Malformed 'max-age' header value '{}'",
token);
+ }
+ }
+ } else if (token.trim().startsWith("s-maxage=")) {
+ try {
+ sharedMaxAge =
Long.parseLong(token.trim().substring("s-maxage=".length()));
+ } catch (final NumberFormatException e) {
+ // Handle malformed header value
+ sharedMaxAge = -1;
+ if (LOG.isWarnEnabled()) {
+ LOG.warn("Malformed 's-maxage' header value '{}'",
token);
+ }
+ }
+ }
+ }
+ }
+
+ if (sharedMaxAge != -1) {
+ return Duration.ofSeconds(sharedMaxAge);
+ } else if (maxAge != -1) {
+ return Duration.ofSeconds(maxAge);
+ }
+
+ // Check if Expires is present and use its value minus the value of
the Date header
+ Instant expiresInstant = null;
+ Instant dateInstant = null;
+ if (response.containsHeader(HttpHeaders.EXPIRES)) {
Review Comment:
@arturobernalg Please do not do that. Please do not use two method calls
where a single method call and a null check should perfectly suffice.
##########
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/ResponseCachingPolicy.java:
##########
@@ -320,4 +354,87 @@ private boolean from1_0Origin(final HttpResponse response)
{
return HttpVersion.HTTP_1_0.equals(version);
}
+ /**
+ * Calculates the freshness lifetime of a response, based on the headers
in the response.
+ * <p>
+ * This method follows the algorithm for calculating the freshness
lifetime described in RFC 7234, section 4.2.1.
+ * The freshness lifetime represents the time interval in seconds during
which the response can be served without
+ * being considered stale. The freshness lifetime calculation takes into
account the s-maxage, max-age, Expires, and
+ * Date headers as follows:
+ * <ul>
+ * <li>If the s-maxage directive is present in the Cache-Control header of
the response, its value is used as the
+ * freshness lifetime for shared caches, which typically serve multiple
users or clients.</li>
+ * <li>If the max-age directive is present in the Cache-Control header of
the response, its value is used as the
+ * freshness lifetime for private caches, which serve a single user or
client.</li>
+ * <li>If the Expires header is present in the response, its value is used
as the expiration time of the response.
+ * The freshness lifetime is calculated as the difference between the
expiration time and the time specified in the
+ * Date header of the response.</li>
+ * <li>If none of the above headers are present or if the calculated
freshness lifetime is invalid, a default value of
+ * 5 minutes is returned.</li>
+ * </ul>
+ *
+ * <p>
+ * Note that caching is a complex topic and cache control directives may
interact with each other in non-trivial ways.
+ * This method provides a basic implementation of the freshness lifetime
calculation algorithm and may not be suitable
+ * for all use cases. Developers should consult the HTTP caching
specifications for more information and consider
+ * implementing additional caching mechanisms as needed.
+ * </p>
+ *
+ * @param response the HTTP response for which to calculate the freshness
lifetime
+ * @return the freshness lifetime of the response, in seconds
+ * @see <a href="https://tools.ietf.org/html/rfc7234#section-4.2.1";>RFC
7234 Section 4.2.1</a> for the freshness
+ * lifetime calculation algorithm.
+ * @see <a href="https://tools.ietf.org/html/rfc7234#section-5.2";>RFC 7234
Section 5.2</a> for a discussion of shared
+ * and private caches.
+ * @see <a href="https://tools.ietf.org/html/rfc2616#section-14.9.3";>RFC
2616 Section 14.9.3</a> for the Expires header
+ * specification.
+ * @see <a href="https://tools.ietf.org/html/rfc822#section-5";>RFC 822
Section 5</a> for the Date header specification.
+ */
+ private long calculateFreshnessLifetime(final HttpResponse response) {
+ // Check if s-maxage is present and use its value if it is
+ final Header cacheControl =
response.getFirstHeader(HttpHeaders.CACHE_CONTROL);
+ if (cacheControl == null) {
+ // If no cache-control header is present, assume no caching
directives and return a default value
+ return DEFAULT_FRESHNESS_DURATION; // 5 minutes
+ }
+
+ final String cacheControlValue = cacheControl.getValue();
+ final String[] headerValues = cacheControlValue.split(",");
+
+ long maxAge = -1;
+ long sharedMaxAge = -1;
+
+ for (final String headerValue : headerValues) {
Review Comment:
@arturobernalg This is even worse then before. You should do all the parsing
with `Tokenizer` and there should be no `split`, `trim` or `substring` and
there should be almost no intermediate garbage. Please see how `Tokenizer`is
being used to parse other complex headers, like `Set-Cookie` for instance.
Please take a look at `RFC6265CookieSpec#parse`.
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