Make much of the proxy thread-safe with 1 great big lock.

ppapi/thunk/enter.h

 // Copyright (c) 2011 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.
 
 #ifndef PPAPI_THUNK_ENTER_H_
 #define PPAPI_THUNK_ENTER_H_
 
 #include "base/basictypes.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/proxy/interface_id.h"
 #include "ppapi/shared_impl/function_group_base.h"
+#include "ppapi/shared_impl/proxy_lock.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/tracker_base.h"
 #include "ppapi/shared_impl/resource_tracker.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 #include "ppapi/thunk/ppb_instance_api.h"
 #include "ppapi/thunk/resource_creation_api.h"
 
 namespace ppapi {
 namespace thunk {
 
-// EnterHost* helper objects: These objects wrap a call from the C PPAPI into
+// Enter* helper objects: These objects wrap a call from the C PPAPI into
 // the internal implementation. They make sure the lock is acquired and will
 // automatically set up some stuff for you.
 //
 // You should always check whether the enter succeeded before using the object.
 // If this fails, then the instance or resource ID supplied was invalid.
 //
 // The |report_error| arguments to the constructor should indicate if errors
 // should be logged to the console. If the calling function expects that the
 // input values are correct (the normal case), this should be set to true. In
-// some case like |IsFoo(PP_Resource)| the caller is quersioning whether their
+// some case like |IsFoo(PP_Resource)| the caller is questioning whether their
 // handle is this type, and we don't want to report an error if it's not.
 //
-// Standalone functions: EnterHostFunction
+// Standalone functions: EnterFunction
 //   Automatically gets the implementation for the function API for the
 //   supplied PP_Instance.
 //
-// Resource member functions: EnterHostResource
+// Resource member functions: EnterResource
 //   Automatically interprets the given PP_Resource as a resource ID and sets
 //   up the resource object for you.
 
-template<typename FunctionsT>
-class EnterFunction {
+namespace subtle {
+
+// This helps us define our RAII Enter classes easily. To make an RAII class
+// which locks the proxy lock on construction and unlocks on destruction,
+// inherit from |LockOnEntry<true>|. For cases where you don't want to lock,
+// inherit from |LockOnEntry<false>|. This allows us to share more code between
+// Enter* and Enter*NoLock classes.
+template <bool lock_on_entry>
+struct LockOnEntry;
+
+template <>
+struct LockOnEntry<false> {
+// TODO(dmichael) assert the lock is held.
+};
+
+template <>
+struct LockOnEntry<true> {
+  LockOnEntry() {
+    ppapi::ProxyLock::Acquire();
+  }
+  ~LockOnEntry() {
+    ppapi::ProxyLock::Release();
+  }
+};
+
+}  // namespace subtle
+
+
+template<typename FunctionsT, bool lock_on_entry = true>
+class EnterFunction : subtle::LockOnEntry<lock_on_entry> {
  public:
   EnterFunction(PP_Instance instance, bool report_error)
       : functions_(NULL) {
     FunctionGroupBase* base = TrackerBase::Get()->GetFunctionAPI(
         instance, FunctionsT::interface_id);
     if (base)
       functions_ = base->GetAs<FunctionsT>();
     // TODO(brettw) check error and if report_error is set, do something.
   }
+
   ~EnterFunction() {}
 
   bool succeeded() const { return !!functions_; }
   bool failed() const { return !functions_; }
 
   FunctionsT* functions() { return functions_; }
 
  private:
   FunctionsT* functions_;
 
   DISALLOW_COPY_AND_ASSIGN(EnterFunction);
 };
 
 // Like EnterResource but assumes the lock is already held.
-// TODO(brettw) actually implement locks, this is just a placeholder for now.
 template<typename FunctionsT>
-class EnterFunctionNoLock : public EnterFunction<FunctionsT> {
+class EnterFunctionNoLock : public EnterFunction<FunctionsT, false> {
  public:
   EnterFunctionNoLock(PP_Instance instance, bool report_error)
-      : EnterFunction<FunctionsT>(instance, report_error) {
-    // TODO(brettw) assert the lock is held.
+      : EnterFunction<FunctionsT, false>(instance, report_error) {
   }
 };
 
 // Used when a caller has a resource, and wants to do EnterFunction for the
 // instance corresponding to that resource.
 template<typename FunctionsT>
 class EnterFunctionGivenResource : public EnterFunction<FunctionsT> {
  public:
   EnterFunctionGivenResource(PP_Resource resource, bool report_error)
       : EnterFunction<FunctionsT>(GetInstanceForResource(resource),
                                   report_error) {
   }
 
  private:
   static PP_Instance GetInstanceForResource(PP_Resource resource) {
     Resource* object =
         TrackerBase::Get()->GetResourceTracker()->GetResource(resource);
     return object ? object->pp_instance() : 0;
   }
 };
 
 // EnterResource ---------------------------------------------------------------
 
-template<typename ResourceT>
-class EnterResource {
+template<typename ResourceT, bool lock_on_entry = true>
+class EnterResource : subtle::LockOnEntry<lock_on_entry> {
  public:
   EnterResource(PP_Resource resource, bool report_error)
       : object_(NULL) {
     resource_ = TrackerBase::Get()->GetResourceTracker()->GetResource(resource);
     if (resource_)
       object_ = resource_->GetAs<ResourceT>();
     // TODO(brettw) check error and if report_error is set, do something.
   }
   ~EnterResource() {}
 
   bool succeeded() const { return !!object_; }
   bool failed() const { return !object_; }
 
   ResourceT* object() { return object_; }
   Resource* resource() { return resource_; }
 
  private:
   Resource* resource_;
   ResourceT* object_;
 
   DISALLOW_COPY_AND_ASSIGN(EnterResource);
 };
 
 // Like EnterResource but assumes the lock is already held.
-// TODO(brettw) actually implement locks, this is just a placeholder for now.
 template<typename ResourceT>
-class EnterResourceNoLock : public EnterResource<ResourceT> {
+class EnterResourceNoLock : public EnterResource<ResourceT, false> {
  public:
   EnterResourceNoLock(PP_Resource resource, bool report_error)
-      : EnterResource<ResourceT>(resource, report_error) {
-    // TODO(brettw) assert the lock is held.
+      : EnterResource<ResourceT, false>(resource, report_error) {
   }
 };
 
 // Simpler wrapper to enter the resource creation API. This is used for every
 // class so we have this helper function to save template instantiations and
 // typing.
 class PPAPI_THUNK_EXPORT EnterResourceCreation
     : public EnterFunctionNoLock<ResourceCreationAPI> {
  public:
   EnterResourceCreation(PP_Instance instance);
   ~EnterResourceCreation();
 };
 
 // Simpler wrapper to enter the instance API from proxy code. This is used for
 // many interfaces so we have this helper function to save template
 // instantiations and typing.
 class PPAPI_THUNK_EXPORT EnterInstance
     : public EnterFunctionNoLock<PPB_Instance_FunctionAPI> {
  public:
   EnterInstance(PP_Instance instance);
   ~EnterInstance();
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_ENTER_H_