Disable ChromeNetLog when there are no observers.

Performance gains are probably neglible, though it does
prevent locking.
Review URL: https://codereview.chromium.org/12209100

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@191485 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 89 insertions, 2 deletions

diff --git a/net/base/net_log.cc b/net/base/net_log.cc
index 12cfd81..4d9e55a 100644
--- a/net/base/net_log.cc
+++ b/net/base/net_log.cc
@@ -322,8 +322,11 @@ void NetLog::AddEntry(EventType type,
                       const Source& source,
                       EventPhase phase,
                       const NetLog::ParametersCallback* parameters_callback) {
+  LogLevel log_level = GetLogLevel();
+  if (log_level == LOG_NONE)
+    return;
   Entry entry(type, source, phase, base::TimeTicks::Now(),
-              parameters_callback, GetLogLevel());
+              parameters_callback, log_level);
   OnAddEntry(entry);
 }
 
diff --git a/net/base/net_log.h b/net/base/net_log.h
index 0dd97ee..8ae33e9 100644
--- a/net/base/net_log.h
+++ b/net/base/net_log.h
@@ -60,6 +60,10 @@ class NET_EXPORT NetLog {
   };
 
   // Specifies the granularity of events that should be emitted to the log.
+  //
+  // Since the LogLevel may be read and set on any thread without locking, it
+  // may be possible for an Observer to receive an event or parameters that
+  // normally wouldn't be logged at the currently active log level.
   enum LogLevel {
     // Log everything possible, even if it is slow and memory expensive.
     // Includes logging of transferred bytes.
@@ -69,8 +73,12 @@ class NET_EXPORT NetLog {
     // parameters for bytes sent/received events.
     LOG_ALL_BUT_BYTES,
 
-    // Only log events which are cheap, and don't consume much memory.
+    // Only log events which are cheap, and don't consume much memory.  This is
+    // the default value for observers.
     LOG_BASIC,
+
+    // Don't log any events.
+    LOG_NONE,
   };
 
   // A callback function that return a Value representation of the parameters
diff --git a/net/base/net_log_unittest.cc b/net/base/net_log_unittest.cc
new file mode 100644
index 0000000..d52f3b7
--- /dev/null
+++ b/net/base/net_log_unittest.cc
@@ -0,0 +1,75 @@
+// Copyright (c) 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 "net/base/net_log_unittest.h"
+
+#include "base/bind.h"
+#include "base/values.h"
+#include "net/base/net_errors.h"
+
+namespace net {
+
+namespace {
+
+base::Value* NetLogLevelCallback(NetLog::LogLevel log_level) {
+  base::DictionaryValue* dict = new base::DictionaryValue();
+  dict->SetInteger("log_level", log_level);
+  return dict;
+}
+
+TEST(NetLogTest, Basic) {
+  CapturingNetLog net_log;
+  net::CapturingNetLog::CapturedEntryList entries;
+  net_log.GetEntries(&entries);
+  EXPECT_EQ(0u, entries.size());
+
+  net_log.AddGlobalEntry(NetLog::TYPE_CANCELLED);
+
+  net_log.GetEntries(&entries);
+  ASSERT_EQ(1u, entries.size());
+  EXPECT_EQ(NetLog::TYPE_CANCELLED, entries[0].type);
+  EXPECT_EQ(NetLog::SOURCE_NONE, entries[0].source.type);
+  EXPECT_NE(NetLog::Source::kInvalidId, entries[0].source.id);
+  EXPECT_EQ(NetLog::PHASE_NONE, entries[0].phase);
+  EXPECT_GE(base::TimeTicks::Now(), entries[0].time);
+  EXPECT_FALSE(entries[0].params);
+}
+
+// Check that the correct LogLevel is sent to NetLog Value callbacks, and that
+// LOG_NONE logs no events.
+TEST(NetLogTest, LogLevels) {
+  CapturingNetLog net_log;
+  for (int log_level = NetLog::LOG_ALL; log_level <= NetLog::LOG_NONE;
+       ++log_level) {
+    net_log.SetLogLevel(static_cast<NetLog::LogLevel>(log_level));
+    EXPECT_EQ(log_level, net_log.GetLogLevel());
+
+    net_log.AddGlobalEntry(NetLog::TYPE_SOCKET_ALIVE,
+                           base::Bind(NetLogLevelCallback));
+
+    net::CapturingNetLog::CapturedEntryList entries;
+    net_log.GetEntries(&entries);
+
+    if (log_level == NetLog::LOG_NONE) {
+      EXPECT_EQ(0u, entries.size());
+    } else {
+      ASSERT_EQ(1u, entries.size());
+      EXPECT_EQ(NetLog::TYPE_SOCKET_ALIVE, entries[0].type);
+      EXPECT_EQ(NetLog::SOURCE_NONE, entries[0].source.type);
+      EXPECT_NE(NetLog::Source::kInvalidId, entries[0].source.id);
+      EXPECT_EQ(NetLog::PHASE_NONE, entries[0].phase);
+      EXPECT_GE(base::TimeTicks::Now(), entries[0].time);
+
+      int logged_log_level;
+      ASSERT_TRUE(entries[0].GetIntegerValue("log_level", &logged_log_level));
+      EXPECT_EQ(log_level, logged_log_level);
+    }
+
+    net_log.Clear();
+  }
+}
+
+}  // namespace
+
+}  // namespace net
diff --git a/net/net.gyp b/net/net.gyp
index 94c9e3c..715d7ef 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -1399,6 +1399,7 @@
         'base/mime_util_unittest.cc',
         'base/mock_filter_context.cc',
         'base/mock_filter_context.h',
+        'base/net_log_unittest.cc',
         'base/net_log_unittest.h',
         'base/net_util_unittest.cc',
         'base/network_change_notifier_win_unittest.cc',