RpcSession attaches/detaches thread on JVM (second attempt)
If AndroidRuntimeGetJavaVM exists, attach current
thread before the while loop in join, and detach after
the while loop.
This ensures the Java thread is attached / detached
appropriately for binder threads that handles RPC calls.
Test: run aservice on Java services
Bug: 190450693
Change-Id: Ie37aea20047294d4c24c79aa95965d6dde5965b3
diff --git a/libs/binder/RpcSession.cpp b/libs/binder/RpcSession.cpp
index ee5e8bb..151b421 100644
--- a/libs/binder/RpcSession.cpp
+++ b/libs/binder/RpcSession.cpp
@@ -18,16 +18,20 @@
#include <binder/RpcSession.h>
+#include <dlfcn.h>
#include <inttypes.h>
#include <poll.h>
+#include <pthread.h>
#include <unistd.h>
#include <string_view>
#include <android-base/macros.h>
+#include <android_runtime/vm.h>
#include <binder/Parcel.h>
#include <binder/RpcServer.h>
#include <binder/Stability.h>
+#include <jni.h>
#include <utils/String8.h>
#include "RpcSocketAddress.h"
@@ -274,10 +278,66 @@
};
}
+namespace {
+// RAII object for attaching / detaching current thread to JVM if Android Runtime exists. If
+// Android Runtime doesn't exist, no-op.
+class JavaThreadAttacher {
+public:
+ JavaThreadAttacher() {
+ // Use dlsym to find androidJavaAttachThread because libandroid_runtime is loaded after
+ // libbinder.
+ auto vm = getJavaVM();
+ if (vm == nullptr) return;
+
+ char threadName[16];
+ if (0 != pthread_getname_np(pthread_self(), threadName, sizeof(threadName))) {
+ constexpr const char* defaultThreadName = "UnknownRpcSessionThread";
+ memcpy(threadName, defaultThreadName,
+ std::min<size_t>(sizeof(threadName), strlen(defaultThreadName) + 1));
+ }
+ LOG_RPC_DETAIL("Attaching current thread %s to JVM", threadName);
+ JavaVMAttachArgs args;
+ args.version = JNI_VERSION_1_2;
+ args.name = threadName;
+ args.group = nullptr;
+ JNIEnv* env;
+
+ LOG_ALWAYS_FATAL_IF(vm->AttachCurrentThread(&env, &args) != JNI_OK,
+ "Cannot attach thread %s to JVM", threadName);
+ mAttached = true;
+ }
+ ~JavaThreadAttacher() {
+ if (!mAttached) return;
+ auto vm = getJavaVM();
+ LOG_ALWAYS_FATAL_IF(vm == nullptr,
+ "Unable to detach thread. No JavaVM, but it was present before!");
+
+ LOG_RPC_DETAIL("Detaching current thread from JVM");
+ if (vm->DetachCurrentThread() != JNI_OK) {
+ mAttached = false;
+ } else {
+ ALOGW("Unable to detach current thread from JVM");
+ }
+ }
+
+private:
+ DISALLOW_COPY_AND_ASSIGN(JavaThreadAttacher);
+ bool mAttached = false;
+
+ static JavaVM* getJavaVM() {
+ static auto fn = reinterpret_cast<decltype(&AndroidRuntimeGetJavaVM)>(
+ dlsym(RTLD_DEFAULT, "AndroidRuntimeGetJavaVM"));
+ if (fn == nullptr) return nullptr;
+ return fn();
+ }
+};
+} // namespace
+
void RpcSession::join(sp<RpcSession>&& session, PreJoinSetupResult&& setupResult) {
sp<RpcConnection>& connection = setupResult.connection;
if (setupResult.status == OK) {
+ JavaThreadAttacher javaThreadAttacher;
while (true) {
status_t status = session->state()->getAndExecuteCommand(connection, session,
RpcState::CommandType::ANY);