commit b86e9cacbd47e7bf8d50de9fc2f2551019dd50be
author Primiano Tucci <primiano@google.com> Mon Dec 03 20:20:11 2018 +0100
committer Primiano Tucci <primiano@google.com> Tue Dec 04 07:10:32 2018 +0000
tree 0ceffa033daffe5823acd2d64a031f4ba0deef9a
parent 676f0cca7d933f3aef00d3f1920b7934c97d25a4

Add data source to poll IHealth (battery counters) service

This CL adds a new "power" data source to poll battery
counters (AKA Coulomb counters) from the perfetto
traced_probes service. Doing so requires making HWBinder
transactions on the Android IHealth service. This has two
drawbacks: (1) the IHealth svc and hwbinder are internal
only and not part of the NDK; (2) using hwbinder requires
pulling 6 .so(s), which adds 150 KB of private dirty memory
due to linker relocations.

Both aspects are solved as follows:
1) libperfetto_android_internal.so is loaded/unloaded
   dynamically to access the the hwbinder, loading
   recursively libhwbinder.so etc.
3) In standalone builds, libperfetto_android_internal.so
   will not be found and the power data source will
   gracefully fail.

This CL depends on SELinux CL aosp/838610.

Bug: 113076327
Change-Id: Ice56c79bb1c8eec051f6c5d0afec01570a76a0a4

src/traced/probes/probes_producer.cc

diff --git a/src/traced/probes/probes_producer.cc b/src/traced/probes/probes_producer.cc
index b7d666c..07c86d3 100644
--- a/src/traced/probes/probes_producer.cc
+++ b/src/traced/probes/probes_producer.cc
@@ -35,6 +35,7 @@
 #include "perfetto/tracing/ipc/producer_ipc_client.h"
 #include "src/traced/probes/filesystem/inode_file_data_source.h"
 #include "src/traced/probes/ftrace/ftrace_data_source.h"
+#include "src/traced/probes/power/android_power_data_source.h"
 #include "src/traced/probes/probes_data_source.h"
 
 #include "perfetto/trace/filesystem/inode_file_map.pbzero.h"
@@ -55,6 +56,7 @@
 constexpr char kProcessStatsSourceName[] = "linux.process_stats";
 constexpr char kInodeMapSourceName[] = "linux.inode_file_map";
 constexpr char kSysStatsSourceName[] = "linux.sys_stats";
+constexpr char kAndroidPowerSourceName[] = "android.power";
 
 }  // namespace.
 
@@ -102,6 +104,12 @@
     desc.set_name(kSysStatsSourceName);
     endpoint_->RegisterDataSource(desc);
   }
+
+  {
+    DataSourceDescriptor desc;
+    desc.set_name(kAndroidPowerSourceName);
+    endpoint_->RegisterDataSource(desc);
+  }
 }
 
 void ProbesProducer::OnDisconnect() {
@@ -150,6 +158,8 @@
     data_source = CreateProcessStatsDataSource(session_id, instance_id, config);
   } else if (config.name() == kSysStatsSourceName) {
     data_source = CreateSysStatsDataSource(session_id, instance_id, config);
+  } else if (config.name() == kAndroidPowerSourceName) {
+    data_source = CreateAndroidPowerDataSource(session_id, instance_id, config);
   }
 
   if (!data_source) {
@@ -247,6 +257,17 @@
       config));
 }
 
+std::unique_ptr<AndroidPowerDataSource>
+ProbesProducer::CreateAndroidPowerDataSource(TracingSessionID session_id,
+                                             DataSourceInstanceID id,
+                                             const DataSourceConfig& config) {
+  base::ignore_result(id);
+  auto buffer_id = static_cast<BufferID>(config.target_buffer());
+  return std::unique_ptr<AndroidPowerDataSource>(
+      new AndroidPowerDataSource(config, task_runner_, session_id,
+                                 endpoint_->CreateTraceWriter(buffer_id)));
+}
+
 std::unique_ptr<SysStatsDataSource> ProbesProducer::CreateSysStatsDataSource(
     TracingSessionID session_id,
     DataSourceInstanceID id,