Cache failed DNS resolutions for 1 second....

net/base/host_cache_unittest.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/host_cache.h"
 
 #include "base/format_macros.h"
 #include "base/stl_util-inl.h"
 #include "base/string_util.h"
 #include "net/base/net_errors.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace net {
 
 namespace {
 const int kMaxCacheEntries = 10;
-const int kCacheDurationMs = 10000;  // 10 seconds.
+
+const base::TimeDelta kSuccessEntryTTL = base::TimeDelta::FromSeconds(10);
+const base::TimeDelta kFailureEntryTTL = base::TimeDelta::FromSeconds(0);
 
 // Builds a key for |hostname|, defaulting the address family to unspecified.
 HostCache::Key Key(const std::string& hostname) {
   return HostCache::Key(hostname, ADDRESS_FAMILY_UNSPECIFIED);
 }
 
 }  // namespace
 
 TEST(HostCacheTest, Basic) {
-  HostCache cache(kMaxCacheEntries, kCacheDurationMs);
+  HostCache cache(kMaxCacheEntries, kSuccessEntryTTL, kFailureEntryTTL);
 
   // Start at t=0.
   base::TimeTicks now;
 
   const HostCache::Entry* entry1 = NULL;  // Entry for foobar.com.
   const HostCache::Entry* entry2 = NULL;  // Entry for foobar2.com.
 
   EXPECT_EQ(0U, cache.size());
 
   // Add an entry for "foobar.com" at t=0.
@@ skipping 36 matching lines @@
   EXPECT_EQ(entry1, cache.Lookup(Key("foobar.com"), now));
   EXPECT_EQ(entry2, cache.Lookup(Key("foobar2.com"), now));
 
   // Advance to t=20; both entries are now expired.
   now += base::TimeDelta::FromSeconds(10);
 
   EXPECT_TRUE(cache.Lookup(Key("foobar.com"), now) == NULL);
   EXPECT_TRUE(cache.Lookup(Key("foobar2.com"), now) == NULL);
 }
 
-// Try caching entries for a failed resolve attempt.
-TEST(HostCacheTest, NegativeEntry) {
-  HostCache cache(kMaxCacheEntries, kCacheDurationMs);
+// Try caching entries for a failed resolve attempt -- since we set
+// the TTL of such entries to 0 it won't work.
+TEST(HostCacheTest, NoCacheNegative) {
+  HostCache cache(kMaxCacheEntries, kSuccessEntryTTL, kFailureEntryTTL);
 
   // Set t=0.
   base::TimeTicks now;
 
   EXPECT_TRUE(cache.Lookup(Key("foobar.com"), base::TimeTicks()) == NULL);
   cache.Set(Key("foobar.com"), ERR_NAME_NOT_RESOLVED, AddressList(), now);
   EXPECT_EQ(1U, cache.size());
 
   // We disallow use of negative entries.
   EXPECT_TRUE(cache.Lookup(Key("foobar.com"), now) == NULL);
 
   // Now overwrite with a valid entry, and then overwrite with negative entry
   // again -- the valid entry should be kicked out.
   cache.Set(Key("foobar.com"), OK, AddressList(), now);
   EXPECT_FALSE(cache.Lookup(Key("foobar.com"), now) == NULL);
   cache.Set(Key("foobar.com"), ERR_NAME_NOT_RESOLVED, AddressList(), now);
   EXPECT_TRUE(cache.Lookup(Key("foobar.com"), now) == NULL);
 }
 
+// Try caching entries for a failed resolves for 10 seconds.
+TEST(HostCacheTest, CacheNegativeEntry) {
+  HostCache cache(kMaxCacheEntries,
+                  base::TimeDelta::FromSeconds(0), // success entry TTL.
+                  base::TimeDelta::FromSeconds(10)); // failure entry TTL.
+
+  // Start at t=0.
+  base::TimeTicks now;
+
+  const HostCache::Entry* entry1 = NULL;  // Entry for foobar.com.
+  const HostCache::Entry* entry2 = NULL;  // Entry for foobar2.com.
+
+  EXPECT_EQ(0U, cache.size());
+
+  // Add an entry for "foobar.com" at t=0.
+  EXPECT_TRUE(cache.Lookup(Key("foobar.com"), base::TimeTicks()) == NULL);
+  cache.Set(Key("foobar.com"), ERR_NAME_NOT_RESOLVED, AddressList(), now);
+  entry1 = cache.Lookup(Key("foobar.com"), base::TimeTicks());
+  EXPECT_FALSE(entry1 == NULL);
+  EXPECT_EQ(1U, cache.size());
+
+  // Advance to t=5.
+  now += base::TimeDelta::FromSeconds(5);
+
+  // Add an entry for "foobar2.com" at t=5.
+  EXPECT_TRUE(cache.Lookup(Key("foobar2.com"), base::TimeTicks()) == NULL);
+  cache.Set(Key("foobar2.com"), ERR_NAME_NOT_RESOLVED, AddressList(), now);
+  entry2 = cache.Lookup(Key("foobar2.com"), base::TimeTicks());
+  EXPECT_FALSE(NULL == entry1);
+  EXPECT_EQ(2U, cache.size());
+
+  // Advance to t=9
+  now += base::TimeDelta::FromSeconds(4);
+
+  // Verify that the entries we added are still retrievable, and usable.
+  EXPECT_EQ(entry1, cache.Lookup(Key("foobar.com"), now));
+  EXPECT_EQ(entry2, cache.Lookup(Key("foobar2.com"), now));
+
+  // Advance to t=10; entry1 is now expired.
+  now += base::TimeDelta::FromSeconds(1);
+
+  EXPECT_TRUE(cache.Lookup(Key("foobar.com"), now) == NULL);
+  EXPECT_EQ(entry2, cache.Lookup(Key("foobar2.com"), now));
+
+  // Update entry1, so it is no longer expired.
+  cache.Set(Key("foobar.com"), ERR_NAME_NOT_RESOLVED, AddressList(), now);
+  // Re-uses existing entry storage.
+  EXPECT_EQ(entry1, cache.Lookup(Key("foobar.com"), now));
+  EXPECT_EQ(2U, cache.size());
+
+  // Both entries should still be retrievable and usable.
+  EXPECT_EQ(entry1, cache.Lookup(Key("foobar.com"), now));
+  EXPECT_EQ(entry2, cache.Lookup(Key("foobar2.com"), now));
+
+  // Advance to t=20; both entries are now expired.
+  now += base::TimeDelta::FromSeconds(10);
+
+  EXPECT_TRUE(cache.Lookup(Key("foobar.com"), now) == NULL);
+  EXPECT_TRUE(cache.Lookup(Key("foobar2.com"), now) == NULL);
+}
+
 TEST(HostCacheTest, Compact) {
   // Initial entries limit is big enough to accomadate everything we add.
-  HostCache cache(kMaxCacheEntries, kCacheDurationMs);
+  HostCache cache(kMaxCacheEntries, kSuccessEntryTTL, kFailureEntryTTL);
 
   EXPECT_EQ(0U, cache.size());
 
   // t=10
   base::TimeTicks now = base::TimeTicks() + base::TimeDelta::FromSeconds(10);
 
   // Add five valid entries at t=10.
   for (int i = 0; i < 5; ++i) {
     std::string hostname = StringPrintf("valid%d", i);
     cache.Set(Key(hostname), OK, AddressList(), now);
@@ skipping 45 matching lines @@
 
   // Shrink further -- this time the compact will start dropping valid entries
   // to make space.
   cache.max_entries_ = 3;
   cache.Compact(now, NULL);
   EXPECT_EQ(3U, cache.size());
 }
 
 // Add entries while the cache is at capacity, causing evictions.
 TEST(HostCacheTest, SetWithCompact) {
-  HostCache cache(3, kCacheDurationMs);
+  HostCache cache(3, kSuccessEntryTTL, kFailureEntryTTL);
 
   // t=10
-  base::TimeTicks now =
-      base::TimeTicks() + base::TimeDelta::FromMilliseconds(kCacheDurationMs);
+  base::TimeTicks now = base::TimeTicks() + kSuccessEntryTTL;
 
   cache.Set(Key("host1"), OK, AddressList(), now);
   cache.Set(Key("host2"), OK, AddressList(), now);
-  cache.Set(Key("expired"), OK, AddressList(),
-      now - base::TimeDelta::FromMilliseconds(kCacheDurationMs));
+  cache.Set(Key("expired"), OK, AddressList(), now - kSuccessEntryTTL);
 
   EXPECT_EQ(3U, cache.size());
 
   // Should all be retrievable except "expired".
   EXPECT_FALSE(NULL == cache.Lookup(Key("host1"), now));
   EXPECT_FALSE(NULL == cache.Lookup(Key("host2"), now));
   EXPECT_TRUE(NULL == cache.Lookup(Key("expired"), now));
 
   // Adding the fourth entry will cause "expired" to be evicted.
   cache.Set(Key("host3"), OK, AddressList(), now);
   EXPECT_EQ(3U, cache.size());
   EXPECT_TRUE(cache.Lookup(Key("expired"), now) == NULL);
   EXPECT_FALSE(cache.Lookup(Key("host1"), now) == NULL);
   EXPECT_FALSE(cache.Lookup(Key("host2"), now) == NULL);
   EXPECT_FALSE(cache.Lookup(Key("host3"), now) == NULL);
 
   // Add two more entries. Something should be evicted, however "host5"
   // should definitely be in there (since it was last inserted).
   cache.Set(Key("host4"), OK, AddressList(), now);
   EXPECT_EQ(3U, cache.size());
   cache.Set(Key("host5"), OK, AddressList(), now);
   EXPECT_EQ(3U, cache.size());
   EXPECT_FALSE(cache.Lookup(Key("host5"), now) == NULL);
 }
 
 // Tests that the same hostname can be duplicated in the cache, so long as
 // the address family differs.
 TEST(HostCacheTest, AddressFamilyIsPartOfKey) {
-  HostCache cache(kMaxCacheEntries, kCacheDurationMs);
+  HostCache cache(kMaxCacheEntries, kSuccessEntryTTL, kFailureEntryTTL);
 
   // t=0.
   base::TimeTicks now;
 
   HostCache::Key key1("foobar.com", ADDRESS_FAMILY_UNSPECIFIED);
   HostCache::Key key2("foobar.com", ADDRESS_FAMILY_IPV4);
 
   const HostCache::Entry* entry1 = NULL;  // Entry for key1
   const HostCache::Entry* entry2 = NULL;  // Entry for key2
 
@@ skipping 13 matching lines @@
   EXPECT_FALSE(entry2 == NULL);
   EXPECT_EQ(2U, cache.size());
 
   // Even though the hostnames were the same, we should have two unique
   // entries (because the address families differ).
   EXPECT_NE(entry1, entry2);
 }
 
 TEST(HostCacheTest, NoCache) {
   // Disable caching.
-  HostCache cache(0, kCacheDurationMs);
+  HostCache cache(0, kSuccessEntryTTL, kFailureEntryTTL);
   EXPECT_TRUE(cache.caching_is_disabled());
 
   // Set t=0.
   base::TimeTicks now;
 
   // Lookup and Set should have no effect.
   EXPECT_TRUE(cache.Lookup(Key("foobar.com"), base::TimeTicks()) == NULL);
   cache.Set(Key("foobar.com"), OK, AddressList(), now);
   EXPECT_TRUE(cache.Lookup(Key("foobar.com"), base::TimeTicks()) == NULL);
 
@@ skipping 67 matching lines @@
         EXPECT_TRUE(key2 < key1);
         EXPECT_FALSE(key2 == key1);
         break;
       default:
         FAIL() << "Invalid expectation. Can be only -1, 0, 1";
     }
   }
 }
 
 }  // namespace net