Merge pull request #37 from nstdio/stale-if-error

feat(cache): Add support for stale-if-error Cache-Control extension.
nstdio · Mar 18, 2022 · 3835742 · 3835742
2 parents cf63a81 + a42139f
commit 3835742
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Showing 3 changed files with 62 additions and 5 deletions.
diff --git a/src/main/java/io/github/nstdio/http/ext/CacheEntryMetadata.java b/src/main/java/io/github/nstdio/http/ext/CacheEntryMetadata.java
@@ -208,6 +208,10 @@ long maxAge() {
         return maxAge;
     }
 
+    long staleFor() {
+        return age(MILLISECONDS) - maxAge;
+    }
+
     long requestTime() {
         return requestTimeMs;
     }

diff --git a/src/main/java/io/github/nstdio/http/ext/CachingInterceptor.java b/src/main/java/io/github/nstdio/http/ext/CachingInterceptor.java
@@ -20,6 +20,7 @@
 import static io.github.nstdio.http.ext.Headers.HEADER_IF_MODIFIED_SINCE;
 import static io.github.nstdio.http.ext.Headers.HEADER_IF_NONE_MATCH;
 import static io.github.nstdio.http.ext.Responses.gatewayTimeoutResponse;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.stream.Collectors.toList;
 import static lombok.Lombok.sneakyThrow;
 
@@ -210,9 +211,28 @@ private boolean isFresh(RequestContext ctx, Cache.CacheEntry entry) {
 
     private <T> HttpResponse<T> possiblyCached(RequestContext ctx, Cache.CacheEntry entry, HttpResponse<T> r) {
         CacheEntryMetadata metadata = entry != null ? entry.metadata() : null;
-        if (metadata != null && r.statusCode() == 304) {
-            metadata.update(r.headers(), ctx.requestTimeLong(), ctx.responseTimeLong());
-            return createCachedResponse(ctx, entry);
+        if (metadata != null) {
+            switch (r.statusCode()) {
+                case 304: {
+                    metadata.update(r.headers(), ctx.requestTimeLong(), ctx.responseTimeLong());
+                    return createCachedResponse(ctx, entry);
+                }
+                case 500:
+                case 502:
+                case 503:
+                case 504: {
+                    long staleIfError = Math.max(
+                            ctx.cacheControl().staleIfError(MILLISECONDS),
+                            metadata.responseCacheControl().staleIfError(MILLISECONDS)
+                    );
+
+                    if (staleIfError > metadata.staleFor()) {
+                        return createCachedResponse(ctx, entry);
+                    }
+
+                    break;
+                }
+            }
         }
 
         return r;

diff --git a/src/test/java/io/github/nstdio/http/ext/ExtendedHttpClientContract.java b/src/test/java/io/github/nstdio/http/ext/ExtendedHttpClientContract.java
@@ -16,11 +16,13 @@
 
 package io.github.nstdio.http.ext;
 
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
 import static com.github.tomakehurst.wiremock.client.WireMock.created;
 import static com.github.tomakehurst.wiremock.client.WireMock.delete;
 import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;
 import static com.github.tomakehurst.wiremock.client.WireMock.get;
 import static com.github.tomakehurst.wiremock.client.WireMock.getRequestedFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.matching;
 import static com.github.tomakehurst.wiremock.client.WireMock.noContent;
 import static com.github.tomakehurst.wiremock.client.WireMock.post;
 import static com.github.tomakehurst.wiremock.client.WireMock.put;
@@ -35,6 +37,7 @@
 import static io.github.nstdio.http.ext.Headers.HEADER_CACHE_CONTROL;
 import static io.github.nstdio.http.ext.Headers.HEADER_DATE;
 import static io.github.nstdio.http.ext.Headers.HEADER_ETAG;
+import static io.github.nstdio.http.ext.Headers.HEADER_IF_MODIFIED_SINCE;
 import static io.github.nstdio.http.ext.Headers.HEADER_IF_NONE_MATCH;
 import static io.github.nstdio.http.ext.Headers.HEADER_LAST_MODIFIED;
 import static io.github.nstdio.http.ext.Headers.toRFC1123;
@@ -587,9 +590,39 @@ default void shouldWorkWithPathSubscriber(@TempDir Path tempDir) throws Exceptio
         Assertions.assertThat(r2Path).exists().hasContent(body);
     }
 
+    /**
+     * https://datatracker.ietf.org/doc/html/rfc5861#section-4
+     */
     @Test
-    @Disabled("https://datatracker.ietf.org/doc/html/rfc5861#section-4")
-    default void shouldRespectStaleIfError() {
+    default void shouldRespectStaleIfError() throws Exception {
+        //given
+        var clock = FixedRateTickClock.of(clock(), Duration.ofSeconds(1));
+        var client = client(clock);
+        var bodyHandler = ofString();
+        var urlPattern = urlEqualTo(path());
+
+        stubFor(get(urlPattern)
+                .willReturn(ok()
+                        .withHeader(HEADER_CACHE_CONTROL, "max-age=1,stale-if-error=10")
+                        .withBody("abc")
+                )
+        );
+        stubFor(get(urlPattern)
+                .withHeader(HEADER_IF_MODIFIED_SINCE, matching(".+"))
+                .willReturn(aResponse().withStatus(500))
+        );
+
+        //when
+        var r1 = client.send(requestBuilder().build(), bodyHandler);
+        var r2 = await().until(() -> client.send(requestBuilder().header("Cache-Control", "stale-if-error=4").build(), bodyHandler), isCached());
+        var r3 = await().until(() -> client.send(requestBuilder().header("Cache-Control", "stale-if-error=100").build(), bodyHandler), isCached());
+        var r4 = client.send(requestBuilder().header("Cache-Control", "stale-if-error=1").build(), bodyHandler);
+
+        //then
+        assertThat(r1).isNotCached().hasBody("abc");
+        assertThat(r2).isCached().hasBody("abc");
+        assertThat(r3).isCached().hasBody("abc");
+        assertThat(r4).isNotCached().hasStatusCode(500);
     }
 
     @Test