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..1f0d160f478081db344aaac955f8fe16c3243772 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()) >
+         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_ = std::move(quota);

[sclittle, 2016/09/14 17:59:15]

nit: There's no point in std::move-ing this, since it's a const ref, so this is
basically just a copy anyways.

[Raj, 2016/09/14 20:01:50]

Done.

+  if (base::Time::FromInternalValue(quota_.expiry_time()) <=
+      base::Time::Now()) {
+    // This is a new day. Update daily quota, that expires by end of today.
+    quota_.set_expiry_time(
+        (base::Time::Now().LocalMidnight() + base::TimeDelta::FromDays(1))

[sclittle, 2016/09/14 17:59:15]

nit: Instead of calling base::Time::Now() twice, could you just call it once,
store that in a variable, and re-use it? base::Time::Now() isn't free to call,
plus it could get weird if e.g. the chrome process was suspended or something,
so it's technically possible for this later call to Now() to happen much later
than the earlier call.

[Raj, 2016/09/14 20:01:50]

Done.

+            .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<size_t>(remaining));

[sclittle, 2016/09/14 17:59:15]

Cast this to a uint64_t, not a size_t. size_t might only be 32 bits, e.g. on a
32 bit system.

[Raj, 2016/09/14 20:01:50]

Done.

+    db_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&PrecacheDatabase::SaveQuota, precache_database_, quota_));
+  }
 }
 
 }  // namespace precache