libgsid: Document quirks of GetGsiService()

GetGsiService() blocks for at least one full second if the caller
(binder client) didn't start a threadpool.
Document this quirk in the header so future users don't fall into this
performance pitfall.

Make libgsid actually include libgsid.h. This fixes codesearch cross
reference, I hope.

Bug: 241739850
Test: Presubmit
Change-Id: Ic846b2d9d8aeb09afe06deec65b0ad6ea2f57186

7 files changed, 12 insertions, 7 deletions

diff --git a/daemon.cpp b/daemon.cpp
index 2123599..33e7705 100644
--- a/daemon.cpp
+++ b/daemon.cpp
@@ -65,7 +65,7 @@ int main(int argc, char** argv) {
         }
     }
 
-    android::gsi::GsiService::Register();
+    android::gsi::GsiService::Register(android::gsi::kGsiServiceName);
     {
         sp<ProcessState> ps(ProcessState::self());
         ps->startThreadPool();
diff --git a/gsi_service.cpp b/gsi_service.cpp
index 10bbb51..75f9286 100644
--- a/gsi_service.cpp
+++ b/gsi_service.cpp
@@ -87,10 +87,10 @@ GsiService::GsiService() {
     progress_ = {};
 }
 
-void GsiService::Register() {
+void GsiService::Register(const std::string& name) {
     auto lazyRegistrar = LazyServiceRegistrar::getInstance();
     android::sp<GsiService> service = new GsiService();
-    auto ret = lazyRegistrar.registerService(service, kGsiServiceName);
+    auto ret = lazyRegistrar.registerService(service, name);
 
     if (ret != android::OK) {
         LOG(FATAL) << "Could not register gsi service: " << ret;
diff --git a/gsi_service.h b/gsi_service.h
index c50c101..3c4c278 100644
--- a/gsi_service.h
+++ b/gsi_service.h
@@ -36,7 +36,7 @@ namespace gsi {
 
 class GsiService : public BinderService<GsiService>, public BnGsiService {
   public:
-    static void Register();
+    static void Register(const std::string& name);
 
     binder::Status openInstall(const std::string& install_dir, int* _aidl_return) override;
     binder::Status closeInstall(int32_t* _aidl_return) override;
diff --git a/gsi_tool.cpp b/gsi_tool.cpp
index a6a79a5..181452b 100644
--- a/gsi_tool.cpp
+++ b/gsi_tool.cpp
@@ -35,6 +35,7 @@
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
 #include <android/gsi/IGsiService.h>
+#include <binder/ProcessState.h>
 #include <cutils/android_reboot.h>
 #include <libgsi/libgsi.h>
 #include <libgsi/libgsid.h>
@@ -714,6 +715,8 @@ static int usage(int /* argc */, char* argv[]) {
 int main(int argc, char** argv) {
     android::base::InitLogging(argv, android::base::StderrLogger, android::base::DefaultAborter);
 
+    // Start a threadpool to service waitForService() callbacks.
+    android::ProcessState::self()->startThreadPool();
     android::sp<IGsiService> service = GetGsiService();
     if (!service) {
         return EX_SOFTWARE;
diff --git a/include/libgsi/libgsi.h b/include/libgsi/libgsi.h
index 41898df..5318341 100644
--- a/include/libgsi/libgsi.h
+++ b/include/libgsi/libgsi.h
@@ -24,8 +24,6 @@
 namespace android {
 namespace gsi {
 
-static constexpr char kGsiServiceName[] = "gsiservice";
-
 #define DSU_METADATA_PREFIX "/metadata/gsi/dsu/"
 
 // These files need to be globally readable so that fs_mgr_fstab, which is
diff --git a/include/libgsi/libgsid.h b/include/libgsi/libgsid.h
index 46f8ef5..1229ce7 100644
--- a/include/libgsi/libgsid.h
+++ b/include/libgsi/libgsid.h
@@ -21,6 +21,10 @@
 namespace android {
 namespace gsi {
 
+static constexpr char kGsiServiceName[] = "gsiservice";
+
+// Caller should start a threadpool before calling this method, otherwise waitForService() could
+// block for at least 1 second.
 android::sp<IGsiService> GetGsiService();
 
 }  // namespace gsi
diff --git a/libgsid.cpp b/libgsid.cpp
index 23eeae4..4689dcd 100644
--- a/libgsid.cpp
+++ b/libgsid.cpp
@@ -17,7 +17,7 @@
 #include <android-base/logging.h>
 #include <android/gsi/IGsiService.h>
 #include <binder/IServiceManager.h>
-#include <libgsi/libgsi.h>
+#include <libgsi/libgsid.h>
 
 namespace android {
 namespace gsi {