Support starting and stopping perfetto tracing sessions

This is important for testing, specifically, to enable starting
in-process tracing sessions.

Test: atest PerfettoTraceTest
Test: atest libtracing_perfetto_tests
Bug: 303199244
Flag: android.os.perfetto_sdk_tracing_v2
Change-Id: Iacfb795f8f60e8fc9dd56666e0022ab7bc7ed121

Author: zezeozue

libs/tracing_perfetto/include/tracing_sdk.h

@@ -27,6 +27,10 @@
 #include "perfetto/public/te_macros.h"
 #include "perfetto/public/track_event.h"
 
+#include "perfetto/public/abi/pb_decoder_abi.h"
+#include "perfetto/public/pb_utils.h"
+#include "perfetto/public/tracing_session.h"
+
 /**
  * The objects declared here are intended to be managed by Java.
  * This means the Java Garbage Collector is responsible for freeing the
@@ -452,6 +456,22 @@ class Proto {
   std::vector<PerfettoTeHlProtoField*> fields_;
 };
 
+class Session {
+ public:
+  Session(bool is_backend_in_process, void* buf, size_t len);
+  ~Session();
+  Session(const Session&) = delete;
+  Session& operator=(const Session&) = delete;
+
+  bool FlushBlocking(uint32_t timeout_ms);
+  void StopBlocking();
+  std::vector<uint8_t> ReadBlocking();
+
+  static void delete_session(Session* session);
+
+  struct PerfettoTracingSessionImpl* session_ = nullptr;
+};
+
 /**
  * @brief Activates a trigger.
  * @param name The name of the trigger.

libs/tracing_perfetto/tests/Android.bp

@@ -21,44 +21,12 @@ package {
     default_applicable_licenses: ["frameworks_native_license"],
 }
 
-cc_library_static {
-    name: "libtracing_perfetto_test_utils",
-    export_include_dirs: [
-        "include",
-    ],
-    static_libs: [
-        "libflagtest",
-        "libgmock",
-        "perfetto_trace_protos",
-    ],
-    cflags: [
-        "-Wall",
-        "-Werror",
-        "-Wno-enum-compare",
-        "-Wno-unused-function",
-    ],
-
-    srcs: [
-        "utils.cpp",
-    ],
-
-    shared_libs: [
-        "libperfetto_c",
-        "liblog",
-        "libprotobuf-cpp-lite",
-    ],
-    export_shared_lib_headers: [
-        "libperfetto_c",
-    ],
-}
-
 cc_test {
     name: "libtracing_perfetto_tests",
     static_libs: [
         "libflagtest",
         "libgmock",
         "perfetto_trace_protos",
-        "libtracing_perfetto_test_utils",
     ],
     cflags: [
         "-Wall",
@@ -68,12 +36,15 @@ cc_test {
         "android.os.flags-aconfig-cc-host",
         "libbase",
         "libperfetto_c",
-        "liblog",
         "libprotobuf-cpp-lite",
         "libtracing_perfetto",
     ],
     srcs: [
         "tracing_perfetto_test.cpp",
+        "utils.cpp",
+    ],
+    local_include_dirs: [
+        "include",
     ],
     test_suites: ["device-tests"],
 }

libs/tracing_perfetto/tracing_sdk.cpp

@@ -254,6 +254,47 @@ const PerfettoTeHlProtoFieldNested* ProtoFieldNested::get() const {
   return &field_;
 }
 
+Session::Session(bool is_backend_in_process, void* buf, size_t len) {
+  session_ = PerfettoTracingSessionCreate(is_backend_in_process
+                                              ? PERFETTO_BACKEND_IN_PROCESS
+                                              : PERFETTO_BACKEND_SYSTEM);
+
+  PerfettoTracingSessionSetup(session_, buf, len);
+
+  PerfettoTracingSessionStartBlocking(session_);
+}
+
+Session::~Session() {
+  PerfettoTracingSessionStopBlocking(session_);
+  PerfettoTracingSessionDestroy(session_);
+}
+
+bool Session::FlushBlocking(uint32_t timeout_ms) {
+  return PerfettoTracingSessionFlushBlocking(session_, timeout_ms);
+}
+
+void Session::StopBlocking() {
+  PerfettoTracingSessionStopBlocking(session_);
+}
+
+std::vector<uint8_t> Session::ReadBlocking() {
+  std::vector<uint8_t> data;
+  PerfettoTracingSessionReadTraceBlocking(
+      session_,
+      [](struct PerfettoTracingSessionImpl*, const void* trace_data,
+         size_t size, bool, void* user_arg) {
+        auto& dst = *static_cast<std::vector<uint8_t>*>(user_arg);
+        auto* src = static_cast<const uint8_t*>(trace_data);
+        dst.insert(dst.end(), src, src + size);
+      },
+      &data);
+  return data;
+}
+
+void Session::delete_session(Session* ptr) {
+  delete ptr;
+}
+
 void activate_trigger(const char* name, uint32_t ttl_ms) {
   const char* names[] = {name, nullptr};
   PerfettoProducerActivateTriggers(names, ttl_ms);