Avoid accessing VarTracker from multiple threads.

ppapi/shared_impl/var_tracker.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/shared_impl/var_tracker.h"
 
 #include <string.h>
 
 #include <limits>
 
@@ skipping 15 matching lines @@
       track_with_no_reference_count(0) {
 }
 
 VarTracker::VarTracker() : last_var_id_(0) {
 }
 
 VarTracker::~VarTracker() {
 }
 
 int32 VarTracker::AddVar(Var* var) {
+  DCHECK(CalledOnValidThread());
+
   return AddVarInternal(var, ADD_VAR_TAKE_ONE_REFERENCE);
 }
 
 Var* VarTracker::GetVar(int32 var_id) const {
+  DCHECK(CalledOnValidThread());
+
   VarMap::const_iterator result = live_vars_.find(var_id);
   if (result == live_vars_.end())
     return NULL;
   return result->second.var.get();
 }
 
 Var* VarTracker::GetVar(const PP_Var& var) const {
+  DCHECK(CalledOnValidThread());
+
   if (!IsVarTypeRefcounted(var.type))
     return NULL;
   return GetVar(static_cast<int32>(var.value.as_id));
 }
 
 bool VarTracker::AddRefVar(int32 var_id) {
+  DCHECK(CalledOnValidThread());
+
   DLOG_IF(ERROR, !CheckIdType(var_id, PP_ID_TYPE_VAR))
       << var_id << " is not a PP_Var ID.";
   VarMap::iterator found = live_vars_.find(var_id);
   if (found == live_vars_.end()) {
     NOTREACHED();  // Invalid var.
     return false;
   }
 
   VarInfo& info = found->second;
   if (info.ref_count == 0) {
     // All live vars with no refcount should be tracked objects.
     DCHECK(info.track_with_no_reference_count > 0);
     DCHECK(info.var->GetType() == PP_VARTYPE_OBJECT);
 
     TrackedObjectGettingOneRef(found);
   }
 
   // Basic refcount increment.
   info.ref_count++;
   return true;
 }
 
 bool VarTracker::AddRefVar(const PP_Var& var) {
+  DCHECK(CalledOnValidThread());
+
   if (!IsVarTypeRefcounted(var.type))
     return false;
   return AddRefVar(static_cast<int32>(var.value.as_id));
 }
 
 bool VarTracker::ReleaseVar(int32 var_id) {
+  DCHECK(CalledOnValidThread());
+
   DLOG_IF(ERROR, !CheckIdType(var_id, PP_ID_TYPE_VAR))
       << var_id << " is not a PP_Var ID.";
   VarMap::iterator found = live_vars_.find(var_id);
   if (found == live_vars_.end()) {
     NOTREACHED() << "Unref-ing an invalid var";
     return false;
   }
 
   VarInfo& info = found->second;
   if (info.ref_count == 0) {
@@ skipping 11 matching lines @@
       // All other var types can just be released.
       DCHECK(info.track_with_no_reference_count == 0);
       info.var->ResetVarID();
       live_vars_.erase(found);
     }
   }
   return true;
 }
 
 bool VarTracker::ReleaseVar(const PP_Var& var) {
+  DCHECK(CalledOnValidThread());
+
   if (!IsVarTypeRefcounted(var.type))
     return false;
   return ReleaseVar(static_cast<int32>(var.value.as_id));
 }
 
 int32 VarTracker::AddVarInternal(Var* var, AddVarRefMode mode) {
   // If the plugin manages to create millions of strings.
   if (last_var_id_ == std::numeric_limits<int32>::max() >> kPPIdTypeBits)
     return 0;
 
   int32 new_id = MakeTypedId(++last_var_id_, PP_ID_TYPE_VAR);
   live_vars_.insert(std::make_pair(new_id,
       VarInfo(var, mode == ADD_VAR_TAKE_ONE_REFERENCE ? 1 : 0)));
 
   return new_id;
 }
 
 VarTracker::VarMap::iterator VarTracker::GetLiveVar(int32 id) {
   return live_vars_.find(id);
 }
 
 int VarTracker::GetRefCountForObject(const PP_Var& plugin_object) {
+  DCHECK(CalledOnValidThread());
+
   VarMap::iterator found = GetLiveVar(plugin_object);
   if (found == live_vars_.end())
     return -1;
   return found->second.ref_count;
 }
 
 int VarTracker::GetTrackedWithNoReferenceCountForObject(
     const PP_Var& plugin_object) {
+  DCHECK(CalledOnValidThread());
+
   VarMap::iterator found = GetLiveVar(plugin_object);
   if (found == live_vars_.end())
     return -1;
   return found->second.track_with_no_reference_count;
 }
 
 VarTracker::VarMap::iterator VarTracker::GetLiveVar(const PP_Var& var) {
   return live_vars_.find(static_cast<int32>(var.value.as_id));
 }
 
 VarTracker::VarMap::const_iterator VarTracker::GetLiveVar(
     const PP_Var& var) const {
   return live_vars_.find(static_cast<int32>(var.value.as_id));
 }
 
 bool VarTracker::IsVarTypeRefcounted(PP_VarType type) const {
   return type >= PP_VARTYPE_STRING;
 }
 
 PP_Var VarTracker::MakeArrayBufferPPVar(uint32 size_in_bytes) {
+  DCHECK(CalledOnValidThread());
+
   scoped_refptr<ArrayBufferVar> array_buffer(CreateArrayBuffer(size_in_bytes));
   if (!array_buffer)
     return PP_MakeNull();
   return array_buffer->GetPPVar();
 }
 
 PP_Var VarTracker::MakeArrayBufferPPVar(uint32 size_in_bytes,
                                         const void* data) {
+  DCHECK(CalledOnValidThread());
+
   scoped_refptr<ArrayBufferVar> array_buffer(CreateArrayBuffer(size_in_bytes));
   if (!array_buffer)
     return PP_MakeNull();
   memcpy(array_buffer->Map(), data, size_in_bytes);
   return array_buffer->GetPPVar();
 }
 
 std::vector<PP_Var> VarTracker::GetLiveVars() {
+  DCHECK(CalledOnValidThread());
+
   std::vector<PP_Var> var_vector;
   var_vector.reserve(live_vars_.size());
   for (VarMap::const_iterator iter = live_vars_.begin();
        iter != live_vars_.end();
        ++iter) {
     var_vector.push_back(iter->second.var->GetPPVar());
   }
   return var_vector;
 }
 
 void VarTracker::TrackedObjectGettingOneRef(VarMap::const_iterator obj) {
   // Anybody using tracked objects should override this.
   NOTREACHED();
 }
 
 void VarTracker::ObjectGettingZeroRef(VarMap::iterator iter) {
   DeleteObjectInfoIfNecessary(iter);
 }
 
 bool VarTracker::DeleteObjectInfoIfNecessary(VarMap::iterator iter) {
   if (iter->second.ref_count != 0 ||
       iter->second.track_with_no_reference_count != 0)
     return false;  // Object still alive.
   iter->second.var->ResetVarID();
   live_vars_.erase(iter);
   return true;
 }
 
 }  // namespace ppapi