Add daily quota for precache

components/precache/core/precache_fetcher.cc

Index: components/precache/core/precache_fetcher.cc
diff --git a/components/precache/core/precache_fetcher.cc b/components/precache/core/precache_fetcher.cc
index 90d05bb776b6eb6b841c69369f29a3acc5846c87..e8129d47c39ff15c8c48e3eb84f93ac7ff379f31 100644
--- a/components/precache/core/precache_fetcher.cc
+++ b/components/precache/core/precache_fetcher.cc
@@ -27,6 +27,7 @@
 #include "components/precache/core/precache_database.h"
 #include "components/precache/core/precache_switches.h"
 #include "components/precache/core/proto/precache.pb.h"
+#include "components/precache/core/proto/quota.pb.h"
 #include "components/precache/core/proto/unfinished_work.pb.h"
 #include "net/base/completion_callback.h"
 #include "net/base/escape.h"
@@ -204,6 +205,15 @@ std::deque<ManifestHostInfo> RetrieveManifestInfo(
   return hosts_info;
 }
 
+PrecacheQuota RetrieveQuotaInfo(
+    const base::WeakPtr<PrecacheDatabase>& precache_database) {
+  PrecacheQuota quota;
+  if (precache_database) {
+    quota = precache_database->GetQuota();
+  }
+  return quota;
+}
+
 }  // namespace
 
 PrecacheFetcher::Fetcher::Fetcher(
@@ -466,10 +476,11 @@ void PrecacheFetcher::StartNextResourceFetch() {
   DCHECK(unfinished_work_->has_config_settings());
   while (!resources_to_fetch_.empty() && pool_.IsAvailable()) {
     const auto& resource = resources_to_fetch_.front();
-    const size_t max_bytes =
+    const size_t max_bytes = std::min(
+        quota_.remaining(),
         std::min(unfinished_work_->config_settings().max_bytes_per_resource(),
                  unfinished_work_->config_settings().max_bytes_total() -
-                     unfinished_work_->total_bytes());
+                     unfinished_work_->total_bytes()));
     VLOG(3) << "Fetching " << resource.first << " " << resource.second;
     pool_.Add(base::MakeUnique<Fetcher>(
         request_context_.get(), resource.first, resource.second,
@@ -506,9 +517,13 @@ void PrecacheFetcher::NotifyDone(
 
 void PrecacheFetcher::StartNextFetch() {
   DCHECK(unfinished_work_->has_config_settings());
-  // If over the precache total size cap, then stop prefetching.
-  if (unfinished_work_->total_bytes() >
-      unfinished_work_->config_settings().max_bytes_total()) {
+  DCHECK(base::Time::FromInternalValue(quota_.expiry_time()) >

[sclittle, 2016/09/21 20:07:24]

This DCHECK will not hold if the user changes their clock to be back in time.

[Raj, 2016/09/22 18:34:33]

Done.

+         base::Time::Now());
+
+  // If over the precache total size cap or daily quota, then stop prefetching.
+  if ((unfinished_work_->total_bytes() >
+       unfinished_work_->config_settings().max_bytes_total()) ||
+      quota_.remaining() == 0) {
     size_t pending_manifests_in_pool = 0;
     size_t pending_resources_in_pool = 0;
     for (const auto& element_pair : pool_.elements()) {
@@ -622,6 +637,27 @@ void PrecacheFetcher::OnManifestInfoRetrieved(
     }
   }
   unfinished_work_->set_num_manifest_urls(top_hosts_to_fetch_.size());
+
+  PostTaskAndReplyWithResult(
+      db_task_runner_.get(), FROM_HERE,
+      base::Bind(&RetrieveQuotaInfo, precache_database_),
+      base::Bind(&PrecacheFetcher::OnQuotaInfoRetrieved, AsWeakPtr()));
+}
+
+void PrecacheFetcher::OnQuotaInfoRetrieved(const PrecacheQuota& quota) {
+  quota_ = quota;
+  base::Time time_now = base::Time::Now();
+  if (base::Time::FromInternalValue(quota_.expiry_time()) <= time_now) {

[sclittle, 2016/09/21 20:07:24]

What happens if the user changes their clock? If a user sets their clock back in
time, then the quota here wouldn't update.

Perhaps you could store a timestamp in Quota that signifies when the quota was
last reset, instead of an expiry time? Then, you could check to see if the last
time the quota was reset is on a different day than the current day according to
Time::Now(), and then only reset the quota if it was a different day.

[Raj, 2016/09/22 18:34:33]

Done. I have added start_time and expiry_hours.

+    // This is a new day. Update daily quota, that expires by end of today.
+    quota_.set_expiry_time(
+        (time_now.LocalMidnight() + base::TimeDelta::FromDays(1))
+            .ToInternalValue());
+    quota_.set_remaining(
+        unfinished_work_->config_settings().daily_quota_total());
+    db_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&PrecacheDatabase::SaveQuota, precache_database_, quota_));
+  }
   StartNextFetch();
 }
 
@@ -696,6 +732,17 @@ void PrecacheFetcher::UpdateStats(int64_t response_bytes,
       unfinished_work_->total_bytes() + response_bytes);
   unfinished_work_->set_network_bytes(
       unfinished_work_->network_bytes() + network_response_bytes);
+
+  if (base::Time::FromInternalValue(quota_.expiry_time()) > base::Time::Now()) {
+    int64_t remaining =
+        static_cast<int64_t>(quota_.remaining()) - network_response_bytes;
+    if (remaining < 0)
+      remaining = 0;
+    quota_.set_remaining(static_cast<uint64_t>(remaining));
+    db_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&PrecacheDatabase::SaveQuota, precache_database_, quota_));
+  }
 }
 
 }  // namespace precache