[DOMStorage] Rate limiting writes to disk.

content/browser/dom_storage/dom_storage_area_unittest.cc

 // Copyright 2013 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 "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/message_loop/message_loop.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 454 matching lines @@
       DOMStorageDatabase::GetJournalFilePath(parent.AppendASCII("file")));
   EXPECT_EQ(
       base::FilePath().AppendASCII("-journal"),
       DOMStorageDatabase::GetJournalFilePath(base::FilePath()));
   EXPECT_EQ(
       base::FilePath().AppendASCII(".extensiononly-journal"),
       DOMStorageDatabase::GetJournalFilePath(
           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