commit 2a42935f0b273904cb684d9f6f563d79576ff151
author Ken Chen <cken@google.com> Sat Dec 22 21:46:55 2018 +0800
committer Ken Chen <cken@google.com> Thu Feb 14 11:48:21 2019 +0800
tree 2afe522d290cee405d7b07ae7ecf403d5eacdc60
parent 4fe1b9c0640d079288fe8642869e89290cc368d4

Improve resolver cache lock and thread synchronization

This change comprises:
1. replace pthread_mutex with std::mutex to realize RAII.
2. have a single condition variable to prevent race condition between
   threads.
3. add 'predicate' to avoid spurious awakenings.
4. add a parameter in GetResolverInfo API which enabling test cases to
   know if timeout happened among concurrent DNS queries. Also, dump it in
   bugreport.
5. verify if test case GetAddrInfoV6_concurrent,
   GetAddrInfoStressTest_Binder_100 and
   GetAddrInfoStressTest_Binder_100000 pass because of timeout on
   concurrent DNS queries.

Bug: 120794954
Test: runtests.sh pass
Test: run ResolverTest.GetAddrInfoV6_concurrent 100 times
Test: run ResolverTest.GetAddrInfoStressTest_Binder_100 100 times
Test: run ResolverTest.GetAddrInfoStressTest_Binder_100000 100 times
The test script:
----------------------------
for i in $(seq 1 100)
do
  adb shell resolv_integration_test --gtest_filter=ResolverTest.GetAddrInfoV6_concurrent
  adb shell resolv_integration_test --gtest_filter=ResolverTest.GetAddrInfoStressTest_Binder_100
  adb shell resolv_integration_test --gtest_filter=ResolverTest.GetAddrInfoStressTest_Binder_100000
done
exit 0

Change-Id: I4bdc394ba7ded7a6b7239f2d35b559a4262cb7b9

server/NetdNativeService.cpp

diff --git a/server/NetdNativeService.cpp b/server/NetdNativeService.cpp
index 2098ad5..5b213b4 100644
--- a/server/NetdNativeService.cpp
+++ b/server/NetdNativeService.cpp
@@ -538,16 +538,15 @@
     return binder::Status::ok();
 }
 
-binder::Status NetdNativeService::getResolverInfo(int32_t netId, std::vector<std::string>* servers,
-                                                  std::vector<std::string>* domains,
-                                                  std::vector<std::string>* tlsServers,
-                                                  std::vector<int32_t>* params,
-                                                  std::vector<int32_t>* stats) {
+binder::Status NetdNativeService::getResolverInfo(
+        int32_t netId, std::vector<std::string>* servers, std::vector<std::string>* domains,
+        std::vector<std::string>* tlsServers, std::vector<int32_t>* params,
+        std::vector<int32_t>* stats, std::vector<int32_t>* wait_for_pending_req_timeout_count) {
     // This function intentionally does not lock within Netd, as Bionic is thread-safe.
     ENFORCE_PERMISSION(NETWORK_STACK);
 
-    int err =
-            gCtls->resolverCtrl.getResolverInfo(netId, servers, domains, tlsServers, params, stats);
+    int err = gCtls->resolverCtrl.getResolverInfo(netId, servers, domains, tlsServers, params,
+                                                  stats, wait_for_pending_req_timeout_count);
     if (err != 0) {
         return binder::Status::fromServiceSpecificError(-err,
                 String8::format("ResolverController error: %s", strerror(-err)));