Changeset 65406 in vbox for trunk/src/libs/xpcom18a4

Timestamp:

Jan 23, 2017 3:47:55 PM (8 years ago)

Author:

vboxsync

Message:

XPCOM/nsISupportsImpl.h: switch to an extremely paranoid AddRef/Release implementation for the threadsafe variant

File:

• trunk/src/libs/xpcom18a4/xpcom/glue/nsISupportsImpl.h (modified) (8 diffs)

trunk/src/libs/xpcom18a4/xpcom/glue/nsISupportsImpl.h

@@ -50 +50 @@
 
 #include "nsDebug.h"
-#include "nsTraceRefcnt.h" 
+#include "nsTraceRefcnt.h"
+#ifdef VBOX
+# include "iprt/asm.h"
+# include "iprt/assert.h"
+#endif
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -80 +84 @@
 
  public:
-    nsAutoRefCnt() : mValue(0) {}
+    nsAutoRefCnt() : mValue(0)
+#ifdef VBOX
+        , mState(0)
+#endif
+    {}
     nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
 
@@ -86 +94 @@
     nsrefcnt operator++() { return ++mValue; }
     nsrefcnt operator--() { return --mValue; }
-    
+
     nsrefcnt operator=(nsrefcnt aValue) { return (mValue = aValue); }
     operator nsrefcnt() const { return mValue; }
     nsrefcnt get() const { return mValue; }
+#ifdef VBOX
+    nsrefcnt *ref() { return &mValue; }
+    PRUint32 getState() const { return mState; }
+    PRUint32 *refState() { return &mState; }
+#endif
  private:
     // do not define these to enforce the faster prefix notation
@@ -95 +108 @@
     nsrefcnt operator--(int);
     nsrefcnt mValue;
+#ifdef VBOX
+    PRUint32 mState;
+#endif
 };
 
@@ -685 +701 @@
  */
 
+#ifdef VBOX
+#define NS_IMPL_THREADSAFE_ADDREF(_class)                                     \
+NS_IMETHODIMP_(nsrefcnt) _class::AddRef(void)                                 \
+{                                                                             \
+  nsrefcnt count = mRefCnt.get();                                             \
+  PRUint32 state = mRefCnt.getState();                                        \
+  AssertReleaseMsg(   state <= 1                                              \
+                   && (   (state == 0 && count == 0)                          \
+                       || (state == 1 && count < PR_UINT32_MAX/2)),           \
+                   ("AddRef: illegal refcnt=%u state=%d\n", count, state));   \
+  switch (state)                                                              \
+  {                                                                           \
+    case 0:                                                                   \
+      if (!ASMAtomicCmpXchgU32(mRefCnt.refState(), 1, 0))                     \
+        AssertReleaseMsgFailed(("AddRef: racing for first increment\n"));     \
+      count = ASMAtomicIncU32(mRefCnt.ref());                                 \
+      AssertReleaseMsg(count == 1,                                            \
+                       ("AddRef: unexpected refcnt=%u\n", count));            \
+      break;                                                                  \
+    case 1:                                                                   \
+      count = ASMAtomicIncU32(mRefCnt.ref());                                 \
+      AssertReleaseMsg(count <= PR_UINT32_MAX/2,                              \
+                       ("AddRef: unexpected refcnt=%u\n", count));            \
+      break;                                                                  \
+    case 2:                                                                   \
+      AssertReleaseMsgFailed(("AddRef: freed object\n"));                     \
+      break;                                                                  \
+    default:                                                                  \
+      AssertReleaseMsgFailed(("AddRef: garbage object\n"));                   \
+  }                                                                           \
+  NS_LOG_ADDREF(this, count, #_class, sizeof(*this));                         \
+  return count;                                                               \
+}
+#else
 #define NS_IMPL_THREADSAFE_ADDREF(_class)                                     \
 NS_IMETHODIMP_(nsrefcnt) _class::AddRef(void)                                 \
@@ -694 +744 @@
   return count;                                                               \
 }
+#endif
 
 /**
@@ -700 +751 @@
  */
 
+#ifdef VBOX
+#define NS_IMPL_THREADSAFE_RELEASE(_class)                                    \
+NS_IMETHODIMP_(nsrefcnt) _class::Release(void)                                \
+{                                                                             \
+  nsrefcnt count = mRefCnt.get();                                             \
+  PRUint32 state = mRefCnt.getState();                                        \
+  AssertReleaseMsg(state == 1 && count <= PR_UINT32_MAX/2,                    \
+                   ("Release: illegal refcnt=%u state=%d\n", count, state));  \
+  switch (state)                                                              \
+  {                                                                           \
+    case 0:                                                                   \
+      AssertReleaseMsgFailed(("Release: new object\n"));                      \
+      break;                                                                  \
+    case 1:                                                                   \
+      count = ASMAtomicDecU32(mRefCnt.ref());                                 \
+      AssertReleaseMsg(count < PR_UINT32_MAX/2,                               \
+                       ("Release: unexpected refcnt=%u\n", count));           \
+      if (count == 0)                                                         \
+      {                                                                       \
+        if (!ASMAtomicCmpXchgU32(mRefCnt.refState(), 2, 1))                   \
+          AssertReleaseMsgFailed(("Release: racing for state free\n"));       \
+        /* Use better stabilization: reserve everything with top bit set. */  \
+        if (!ASMAtomicCmpXchgU32(mRefCnt.ref(), PR_UINT32_MAX/4*3, 0))        \
+          AssertReleaseMsgFailed(("Release: racing for refcnt stabilize\n")); \
+        NS_DELETEXPCOM(this);                                                 \
+      }                                                                       \
+      break;                                                                  \
+    case 2:                                                                   \
+      AssertReleaseMsgFailed(("Release: freed object\n"));                    \
+      break;                                                                  \
+    default:                                                                  \
+      AssertReleaseMsgFailed(("Release: garbage object\n"));                  \
+  }                                                                           \
+  NS_LOG_RELEASE(this, count, #_class);                                       \
+  return count;                                                               \
+}
+#else
 #define NS_IMPL_THREADSAFE_RELEASE(_class)                                    \
 NS_IMETHODIMP_(nsrefcnt) _class::Release(void)                                \
@@ -716 +804 @@
   return count;                                                               \
 }
+#endif
 
 #define NS_IMPL_THREADSAFE_ISUPPORTS0(_class)                                 \