Pepper WebSocket API: Fix memory leak issue

ppapi/cpp/var.cc

Index: ppapi/cpp/var.cc
diff --git a/ppapi/cpp/var.cc b/ppapi/cpp/var.cc
index 3e76593bd2763ff5fec11c110bef977ea0a8dc1a..9560f747bb27d299be8627177588f3c7d06b8c60 100644
--- a/ppapi/cpp/var.cc
+++ b/ppapi/cpp/var.cc
@@ -59,34 +59,34 @@ PP_Var VarFromUtf8Helper(const char* utf8_str, uint32_t len) {
 Var::Var() {
   memset(&var_, 0, sizeof(var_));
   var_.type = PP_VARTYPE_UNDEFINED;
-  needs_release_ = false;
+  needs_release_ = true;

[Takashi Toyoshima, 2012/09/07 17:18:27]

NeedsRefcounting() tell us if the PP_Var requires refcounting.
So needs_release_ should means that the PP_Var resource should be managed by
this class instance.
It means that constructor Var(DontManage, PP_Var) is the only case which set
needs_release_ as false.

[dmichael (off chromium), 2012/09/07 18:36:58]

Currently, it only tells you if the Var's *type* requires reference counting. So
you're changing its meaning...

I think this is a reasonable way to go, but for me, it reinforces that we need
to get rid of DontManage. Then, we wouldn't need to store any data beyond the
PP_Var, and we would always just use NeedsRefcounting() to decide whether to
release.

[Takashi Toyoshima, 2012/09/10 13:21:27]

I meant that we can change the meaning of |needs_release_|. I can keep the
original meaning of NeedsRefcounting() here.

Current implementation, |needs_release_| means that the instance should manage
the internal PP_Var resource, AND the PP_Var is refcounted object. But the
latter condition looks redundant because we can always know it via
NeedsRefcounting().

So my suggestion is to change the meaning of |needs_release_| to only the former
meaning that the PP_Var is passed via DontManage or not. Maybe it's good to
change its name from needs_release_ to needs_manage_.

So 'needs_manage_ && NeedsRefcounting(var_)' is a right condition to release the
internal PP_Var as shown in the revised destructor.

 }
 
 Var::Var(Null) {
   memset(&var_, 0, sizeof(var_));
   var_.type = PP_VARTYPE_NULL;
-  needs_release_ = false;
+  needs_release_ = true;
 }
 
 Var::Var(bool b) {
   var_.type = PP_VARTYPE_BOOL;
   var_.padding = 0;
   var_.value.as_bool = PP_FromBool(b);
-  needs_release_ = false;
+  needs_release_ = true;
 }
 
 Var::Var(int32_t i) {
   var_.type = PP_VARTYPE_INT32;
   var_.padding = 0;
   var_.value.as_int = i;
-  needs_release_ = false;
+  needs_release_ = true;
 }
 
 Var::Var(double d) {
   var_.type = PP_VARTYPE_DOUBLE;
   var_.padding = 0;
   var_.value.as_double = d;
-  needs_release_ = false;
+  needs_release_ = true;
 }
 
 Var::Var(const char* utf8_str) {
@@ -103,21 +103,17 @@ Var::Var(const std::string& utf8_str) {
 
 Var::Var(const Var& other) {
   var_ = other.var_;
+  needs_release_ = true;
   if (NeedsRefcounting(var_)) {
-    if (has_interface<PPB_Var_1_0>()) {
-      needs_release_ = true;
+    if (has_interface<PPB_Var_1_0>())
       get_interface<PPB_Var_1_0>()->AddRef(var_);
-    } else {
+    else
       var_.type = PP_VARTYPE_NULL;
-      needs_release_ = false;
-    }
-  } else {
-    needs_release_ = false;
   }
 }
 
 Var::~Var() {
-  if (needs_release_ && has_interface<PPB_Var_1_0>())
+  if (needs_release_ && NeedsRefcounting(var_) && has_interface<PPB_Var_1_0>())

[Takashi Toyoshima, 2012/09/07 17:18:27]

PP_Var leaked when PP_Var was updated after construction.
WebSocket ReceiveMessage completion callback did so.

     get_interface<PPB_Var_1_0>()->Release(var_);
 }
 
@@ -131,15 +127,13 @@ Var& Var::operator=(const Var& other) {
   // Be careful to keep the ref alive for cases where we're assigning an
   // object to itself by addrefing the new one before releasing the old one.
   bool old_needs_release = needs_release_;
+  needs_release_ = true;
   if (NeedsRefcounting(other.var_)) {
     // Assume we already has_interface<PPB_Var_1_0> for refcounted vars or else
     // we couldn't have created them in the first place.
-    needs_release_ = true;
     get_interface<PPB_Var_1_0>()->AddRef(other.var_);
-  } else {
-    needs_release_ = false;
   }
-  if (old_needs_release)
+  if (old_needs_release && NeedsRefcounting(var_))
     get_interface<PPB_Var_1_0>()->Release(var_);
 
   var_ = other.var_;