localStorage: Aggressively flush to disk for Android WebView.

content/browser/dom_storage/dom_storage_area.cc

Index: content/browser/dom_storage/dom_storage_area.cc
diff --git a/content/browser/dom_storage/dom_storage_area.cc b/content/browser/dom_storage/dom_storage_area.cc
index 56a1fd008a65538bc45e707c59f530d66ab24837..61181217a26f9ca7b7a3696ddff647776b81fbd4 100644
--- a/content/browser/dom_storage/dom_storage_area.cc
+++ b/content/browser/dom_storage/dom_storage_area.cc
@@ -42,6 +42,8 @@ const int kMaxCommitsPerHour = 6;
 
 }  // namespace
 
+bool DOMStorageArea::s_aggressive_flushing_enabled_ = false;
+
 DOMStorageArea::RateLimiter::RateLimiter(size_t desired_rate,
                                          base::TimeDelta time_quantum)
     : rate_(desired_rate), samples_(0), time_quantum_(time_quantum) {
@@ -90,6 +92,14 @@ GURL DOMStorageArea::OriginFromDatabaseFileName(const base::FilePath& name) {
   return storage::GetOriginFromIdentifier(origin_id);
 }
 
+// Commence aggressive flushing. This should be called early in the startup -
+// before any localStorage writing. Currently scheduled writes will not be
+// rescheduled and will be flushed at the scheduled time after which aggressive
+// flushing will commence.

[michaeln, 2015/05/07 23:19:03]

maybe put the comment in the .h file

[cmumford, 2015/05/08 16:02:48]

Done.

+void DOMStorageArea::EnableAggressiveCommitDelay() {
+  s_aggressive_flushing_enabled_ = true;
+}
+
 DOMStorageArea::DOMStorageArea(const GURL& origin,
                                const base::FilePath& directory,
                                DOMStorageTaskRunner* task_runner)
@@ -388,12 +398,20 @@ void DOMStorageArea::StartCommitTimer() {
 }
 
 base::TimeDelta DOMStorageArea::ComputeCommitDelay() const {
-  base::TimeDelta elapsed_time = base::TimeTicks::Now() - start_time_;
-  base::TimeDelta delay = std::max(
-      base::TimeDelta::FromSeconds(kCommitDefaultDelaySecs),
-      std::max(commit_rate_limiter_.ComputeDelayNeeded(elapsed_time),
-               data_rate_limiter_.ComputeDelayNeeded(elapsed_time)));
-  UMA_HISTOGRAM_LONG_TIMES("LocalStorage.CommitDelay", delay);
+  base::TimeDelta delay;
+  if (s_aggressive_flushing_enabled_) {
+    // Calculate very short delay to flush unwritten data soon. Used for
+    // Chromium hosts that do not write data during shutdown (Android WebView).
+    // More info at http://crbug.com/479767

[michaeln, 2015/05/07 23:19:03]

nit: Given the nicely named methods and members, much of the comment isn't
really needed and we generally prefer early returns to else where possible. In
the spirit of less is more...

if (s_aggressive_flushing_enabled_)
  return base::TimeDelta::FromSeconds(1);

[cmumford, 2015/05/08 16:02:48]

Done.

+    delay = base::TimeDelta::FromSeconds(1);
+  } else {
+    base::TimeDelta elapsed_time = base::TimeTicks::Now() - start_time_;
+    delay =
+        std::max(base::TimeDelta::FromSeconds(kCommitDefaultDelaySecs),
+                 std::max(commit_rate_limiter_.ComputeDelayNeeded(elapsed_time),
+                          data_rate_limiter_.ComputeDelayNeeded(elapsed_time)));
+    UMA_HISTOGRAM_LONG_TIMES("LocalStorage.CommitDelay", delay);
+  }
   return delay;
 }