Support "shared" histograms between processes.
Histograms have tradionally been held on the local heap and
passed between processes using RPCs or simply lost when that
process stops. Shared histograms are read directly by another
process.
https://docs.google.com/document/d/1YvBXzi745UDjiFVLjP8IWUMFgYL9gDb2J4xuwcv-c7o/edit?usp=sharing
BUG=546019
TBR=mmenke,nasko,thakis
for base/*.{gn,gypi}, components/cronet/*, and content/child/*
Review URL: https://codereview.chromium.org/1425533011
Cr-Commit-Position: refs/heads/master@{#372760}
diff --git a/base/metrics/statistics_recorder.cc b/base/metrics/statistics_recorder.cc
index b18efad2..1bfa3480 100644
--- a/base/metrics/statistics_recorder.cc
+++ b/base/metrics/statistics_recorder.cc
@@ -31,6 +31,36 @@
namespace base {
+StatisticsRecorder::HistogramIterator::HistogramIterator(
+ const HistogramMap::iterator& iter, bool include_persistent)
+ : iter_(iter),
+ include_persistent_(include_persistent) {
+}
+
+StatisticsRecorder::HistogramIterator::HistogramIterator(
+ const HistogramIterator& rhs)
+ : iter_(rhs.iter_),
+ include_persistent_(rhs.include_persistent_) {
+}
+
+StatisticsRecorder::HistogramIterator::~HistogramIterator() {}
+
+StatisticsRecorder::HistogramIterator&
+StatisticsRecorder::HistogramIterator::operator++() {
+ const HistogramMap::iterator histograms_end = histograms_->end();
+ while (iter_ != histograms_end) {
+ ++iter_;
+ if (iter_ == histograms_end)
+ break;
+ if (!include_persistent_ && (iter_->second->flags() &
+ HistogramBase::kIsPersistent)) {
+ continue;
+ }
+ break;
+ }
+ return *this;
+}
+
// static
void StatisticsRecorder::Initialize() {
// Ensure that an instance of the StatisticsRecorder object is created.
@@ -66,7 +96,8 @@
histogram_to_return = histogram;
} else {
const std::string& name = histogram->histogram_name();
- uint64_t name_hash = histogram->name_hash();
+ const uint64_t name_hash = histogram->name_hash();
+ DCHECK_NE(0U, name_hash);
HistogramMap::iterator it = histograms_->find(name_hash);
if (histograms_->end() == it) {
(*histograms_)[name_hash] = histogram;
@@ -264,7 +295,7 @@
return false;
callbacks_->insert(std::make_pair(name, cb));
- HistogramMap::iterator it = histograms_->find(HashMetricName(name));
+ auto it = histograms_->find(HashMetricName(name));
if (it != histograms_->end()) {
DCHECK_EQ(name, it->second->histogram_name()) << "hash collision";
it->second->SetFlags(HistogramBase::kCallbackExists);
@@ -284,7 +315,7 @@
callbacks_->erase(name);
// We also clear the flag from the histogram (if it exists).
- HistogramMap::iterator it = histograms_->find(HashMetricName(name));
+ auto it = histograms_->find(HashMetricName(name));
if (it != histograms_->end()) {
DCHECK_EQ(name, it->second->histogram_name()) << "hash collision";
it->second->ClearFlags(HistogramBase::kCallbackExists);
@@ -305,7 +336,18 @@
: OnSampleCallback();
}
-// private static
+// static
+StatisticsRecorder::HistogramIterator StatisticsRecorder::begin(
+ bool include_persistent) {
+ return HistogramIterator(histograms_->begin(), include_persistent);
+}
+
+// static
+StatisticsRecorder::HistogramIterator StatisticsRecorder::end() {
+ return HistogramIterator(histograms_->end(), true);
+}
+
+// static
void StatisticsRecorder::GetSnapshot(const std::string& query,
Histograms* snapshot) {
if (lock_ == NULL)
