commit 7ca6c2600e633f38468a571c1514a3cc7eecf17a
author Steven Moreland <smoreland@google.com> Thu Dec 22 19:43:58 2022 +0000
committer Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> Thu Dec 22 19:43:58 2022 +0000
tree a1089f447e64669999625cf17df48fa2d1a4f281
parent c9f9505277384a6de88baf62beac58553f3e1411
parent 6f69c67d9f9f1af75b30d16d4b01811d4c479158

Merge "libbinder: cache interface descriptor if empty" am: 6f69c67d9f

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/2365608

Change-Id: Ifcf5eb92114787c8ea0ad3410791ad6a6181ffab
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

libs/binder/BpBinder.cpp

diff --git a/libs/binder/BpBinder.cpp b/libs/binder/BpBinder.cpp
index 54d2445..1c470a1 100644
--- a/libs/binder/BpBinder.cpp
+++ b/libs/binder/BpBinder.cpp
@@ -47,6 +47,8 @@
 binder_proxy_limit_callback BpBinder::sLimitCallback;
 bool BpBinder::sBinderProxyThrottleCreate = false;
 
+static StaticString16 kDescriptorUninit(u"<uninit descriptor>");
+
 // Arbitrarily high value that probably distinguishes a bad behaving app
 uint32_t BpBinder::sBinderProxyCountHighWatermark = 2500;
 // Another arbitrary value a binder count needs to drop below before another callback will be called
@@ -211,6 +213,7 @@
         mAlive(true),
         mObitsSent(false),
         mObituaries(nullptr),
+        mDescriptorCache(kDescriptorUninit),
         mTrackedUid(-1) {
     extendObjectLifetime(OBJECT_LIFETIME_WEAK);
 }
@@ -258,12 +261,12 @@
 
 bool BpBinder::isDescriptorCached() const {
     Mutex::Autolock _l(mLock);
-    return mDescriptorCache.size() ? true : false;
+    return mDescriptorCache.string() != kDescriptorUninit.string();
 }
 
 const String16& BpBinder::getInterfaceDescriptor() const
 {
-    if (isDescriptorCached() == false) {
+    if (!isDescriptorCached()) {
         sp<BpBinder> thiz = sp<BpBinder>::fromExisting(const_cast<BpBinder*>(this));
 
         Parcel data;
@@ -276,8 +279,7 @@
             Mutex::Autolock _l(mLock);
             // mDescriptorCache could have been assigned while the lock was
             // released.
-            if (mDescriptorCache.size() == 0)
-                mDescriptorCache = res;
+            if (mDescriptorCache.string() == kDescriptorUninit.string()) mDescriptorCache = res;
         }
     }
 
@@ -369,10 +371,7 @@
         if (data.dataSize() > LOG_TRANSACTIONS_OVER_SIZE) {
             Mutex::Autolock _l(mLock);
             ALOGW("Large outgoing transaction of %zu bytes, interface descriptor %s, code %d",
-                  data.dataSize(),
-                  mDescriptorCache.size() ? String8(mDescriptorCache).c_str()
-                                          : "<uncached descriptor>",
-                  code);
+                  data.dataSize(), String8(mDescriptorCache).c_str(), code);
         }
 
         if (status == DEAD_OBJECT) mAlive = 0;
@@ -647,7 +646,7 @@
     if(obits != nullptr) {
         if (!obits->isEmpty()) {
             ALOGI("onLastStrongRef automatically unlinking death recipients: %s",
-                  mDescriptorCache.size() ? String8(mDescriptorCache).c_str() : "<uncached descriptor>");
+                  String8(mDescriptorCache).c_str());
         }
 
         if (ipc) ipc->clearDeathNotification(binderHandle(), this);

libs/binder/tests/binderAllocationLimits.cpp

diff --git a/libs/binder/tests/binderAllocationLimits.cpp b/libs/binder/tests/binderAllocationLimits.cpp
index 55a3916..6a6e008 100644
--- a/libs/binder/tests/binderAllocationLimits.cpp
+++ b/libs/binder/tests/binderAllocationLimits.cpp
@@ -172,6 +172,24 @@
     a_binder->pingBinder();
 }
 
+TEST(BinderAllocation, InterfaceDescriptorTransaction) {
+    sp<IBinder> a_binder = GetRemoteBinder();
+
+    size_t mallocs = 0;
+    const auto on_malloc = OnMalloc([&](size_t bytes) {
+        mallocs++;
+        // Happens to be SM package length. We could switch to forking
+        // and registering our own service if it became an issue.
+        EXPECT_EQ(bytes, 78);
+    });
+
+    a_binder->getInterfaceDescriptor();
+    a_binder->getInterfaceDescriptor();
+    a_binder->getInterfaceDescriptor();
+
+    EXPECT_EQ(mallocs, 1);
+}
+
 TEST(BinderAllocation, SmallTransaction) {
     String16 empty_descriptor = String16("");
     sp<IServiceManager> manager = defaultServiceManager();