From 2a019ecf4f4326b45e14d62f9fe2ca994e21742f Mon Sep 17 00:00:00 2001
From: Hans Boehm <hboehm@google.com>
Date: Tue, 7 Aug 2018 23:45:25 +0000
Subject: Revert^2 "Prepare to fail in RefBase destructor if count is
 untouched"

This reverts commit b9d0753d2ba88cc60947823e68bb3bed60268361.

Reason for revert: Re-land with MacOS workaround.

Test: Build (on Linux) and boot AOSP, with weak symbols enabled and disabled.

Change-Id: I5150cd90367178f3b039761dca3bccc9c2987df1
---
 libutils/RefBase.cpp | 57 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 34 insertions(+), 23 deletions(-)

(limited to 'libutils/RefBase.cpp')

diff --git a/libutils/RefBase.cpp b/libutils/RefBase.cpp
index 90748501d..3f1e79a04 100644
--- a/libutils/RefBase.cpp
+++ b/libutils/RefBase.cpp
@@ -17,30 +17,41 @@
 #define LOG_TAG "RefBase"
 // #define LOG_NDEBUG 0
 
+#include <memory>
+
 #include <utils/RefBase.h>
 
 #include <utils/CallStack.h>
 
+#include <utils/Mutex.h>
+
 #ifndef __unused
 #define __unused __attribute__((__unused__))
 #endif
 
-// compile with refcounting debugging enabled
-#define DEBUG_REFS                      0
+// Compile with refcounting debugging enabled.
+#define DEBUG_REFS 0
+
+// The following three are ignored unless DEBUG_REFS is set.
 
 // whether ref-tracking is enabled by default, if not, trackMe(true, false)
 // needs to be called explicitly
-#define DEBUG_REFS_ENABLED_BY_DEFAULT   0
+#define DEBUG_REFS_ENABLED_BY_DEFAULT 0
 
 // whether callstack are collected (significantly slows things down)
-#define DEBUG_REFS_CALLSTACK_ENABLED    1
+#define DEBUG_REFS_CALLSTACK_ENABLED 1
 
 // folder where stack traces are saved when DEBUG_REFS is enabled
 // this folder needs to exist and be writable
-#define DEBUG_REFS_CALLSTACK_PATH       "/data/debug"
+#define DEBUG_REFS_CALLSTACK_PATH "/data/debug"
 
 // log all reference counting operations
-#define PRINT_REFS                      0
+#define PRINT_REFS 0
+
+// Continue after logging a stack trace if ~RefBase discovers that reference
+// count has never been incremented. Normally we conspicuously crash in that
+// case.
+#define DEBUG_REFBASE_DESTRUCTION 1
 
 // ---------------------------------------------------------------------------
 
@@ -184,7 +195,7 @@ public:
                 char inc = refs->ref >= 0 ? '+' : '-';
                 ALOGD("\t%c ID %p (ref %d):", inc, refs->id, refs->ref);
 #if DEBUG_REFS_CALLSTACK_ENABLED
-                refs->stack.log(LOG_TAG);
+                CallStack::logStack(LOG_TAG, refs->stack.get());
 #endif
                 refs = refs->next;
             }
@@ -198,14 +209,14 @@ public:
                 char inc = refs->ref >= 0 ? '+' : '-';
                 ALOGD("\t%c ID %p (ref %d):", inc, refs->id, refs->ref);
 #if DEBUG_REFS_CALLSTACK_ENABLED
-                refs->stack.log(LOG_TAG);
+                CallStack::logStack(LOG_TAG, refs->stack.get());
 #endif
                 refs = refs->next;
             }
         }
         if (dumpStack) {
             ALOGE("above errors at:");
-            CallStack stack(LOG_TAG);
+            CallStack::logStack(LOG_TAG);
         }
     }
 
@@ -279,7 +290,7 @@ public:
                      this);
             int rc = open(name, O_RDWR | O_CREAT | O_APPEND, 644);
             if (rc >= 0) {
-                write(rc, text.string(), text.length());
+                (void)write(rc, text.string(), text.length());
                 close(rc);
                 ALOGD("STACK TRACE for %p saved in %s", this, name);
             }
@@ -294,7 +305,7 @@ private:
         ref_entry* next;
         const void* id;
 #if DEBUG_REFS_CALLSTACK_ENABLED
-        CallStack stack;
+        CallStack::CallStackUPtr stack;
 #endif
         int32_t ref;
     };
@@ -311,7 +322,7 @@ private:
             ref->ref = mRef;
             ref->id = id;
 #if DEBUG_REFS_CALLSTACK_ENABLED
-            ref->stack.update(2);
+            ref->stack = CallStack::getCurrent(2);
 #endif
             ref->next = *refs;
             *refs = ref;
@@ -346,7 +357,7 @@ private:
                 ref = ref->next;
             }
 
-            CallStack stack(LOG_TAG);
+            CallStack::logStack(LOG_TAG);
         }
     }
 
@@ -373,7 +384,7 @@ private:
                      inc, refs->id, refs->ref);
             out->append(buf);
 #if DEBUG_REFS_CALLSTACK_ENABLED
-            out->append(refs->stack.toString("\t\t"));
+            out->append(CallStack::stackToString("\t\t", refs->stack.get()));
 #else
             out->append("\t\t(call stacks disabled)");
 #endif
@@ -700,16 +711,16 @@ RefBase::~RefBase()
         if (mRefs->mWeak.load(std::memory_order_relaxed) == 0) {
             delete mRefs;
         }
-    } else if (mRefs->mStrong.load(std::memory_order_relaxed)
-            == INITIAL_STRONG_VALUE) {
+    } else if (mRefs->mStrong.load(std::memory_order_relaxed) == INITIAL_STRONG_VALUE) {
         // We never acquired a strong reference on this object.
-        LOG_ALWAYS_FATAL_IF(mRefs->mWeak.load() != 0,
-                "RefBase: Explicit destruction with non-zero weak "
-                "reference count");
-        // TODO: Always report if we get here. Currently MediaMetadataRetriever
-        // C++ objects are inconsistently managed and sometimes get here.
-        // There may be other cases, but we believe they should all be fixed.
-        delete mRefs;
+#if DEBUG_REFBASE_DESTRUCTION
+        // Treating this as fatal is prone to causing boot loops. For debugging, it's
+        // better to treat as non-fatal.
+        ALOGD("RefBase: Explicit destruction, weak count = %d (in %p)", mRefs->mWeak.load(), this);
+        CallStack::logStack(LOG_TAG);
+#else
+        LOG_ALWAYS_FATAL("RefBase: Explicit destruction, weak count = %d", mRefs->mWeak.load());
+#endif
     }
     // For debugging purposes, clear mRefs.  Ineffective against outstanding wp's.
     const_cast<weakref_impl*&>(mRefs) = nullptr;
-- 
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