[DOMStorage] Rate limiting writes to disk.

content/browser/dom_storage/dom_storage_area_unittest.cc

Index: content/browser/dom_storage/dom_storage_area_unittest.cc
diff --git a/content/browser/dom_storage/dom_storage_area_unittest.cc b/content/browser/dom_storage/dom_storage_area_unittest.cc
index c074cc0709bc0840638e131181d7cdb5160449d4..1115590996b515bab42baf391acafcefc4c60dea 100644
--- a/content/browser/dom_storage/dom_storage_area_unittest.cc
+++ b/content/browser/dom_storage/dom_storage_area_unittest.cc
@@ -472,4 +472,51 @@ TEST_F(DOMStorageAreaTest, DatabaseFileNames) {
           base::FilePath().AppendASCII(".extensiononly")));
 }
 
+TEST_F(DOMStorageAreaTest, RateLimiter) {
+  // Limit to 1000 samples per second
+  DOMStorageArea::RateLimiter rate_limiter(
+      1000, base::TimeDelta::FromSeconds(1));
+
+  // No samples have been added so no time/delay should be needed.
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeTimeNeeded());
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeDelayNeeded(base::TimeDelta()));
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeDelayNeeded(base::TimeDelta::FromDays(1)));
+
+  // Add a seconds worth of samples.
+  rate_limiter.add_samples(1000);
+  EXPECT_EQ(base::TimeDelta::FromSeconds(1),
+            rate_limiter.ComputeTimeNeeded());
+  EXPECT_EQ(base::TimeDelta::FromSeconds(1),
+            rate_limiter.ComputeDelayNeeded(base::TimeDelta()));
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeDelayNeeded(base::TimeDelta::FromSeconds(1)));
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(250),
+            rate_limiter.ComputeDelayNeeded(
+                base::TimeDelta::FromMilliseconds(750)));
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeDelayNeeded(
+                base::TimeDelta::FromDays(1)));
+
+  // And another half seconds worth.
+  rate_limiter.add_samples(500);
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(1500),
+            rate_limiter.ComputeTimeNeeded());
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(1500),
+            rate_limiter.ComputeDelayNeeded(base::TimeDelta()));
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(500),
+            rate_limiter.ComputeDelayNeeded(base::TimeDelta::FromSeconds(1)));
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(750),
+            rate_limiter.ComputeDelayNeeded(
+                base::TimeDelta::FromMilliseconds(750)));
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeDelayNeeded(
+                base::TimeDelta::FromMilliseconds(1500)));
+  EXPECT_EQ(base::TimeDelta(),
+            rate_limiter.ComputeDelayNeeded(
+                base::TimeDelta::FromDays(1)));
+}
+
 }  // namespace content