New documentation for resource.h, core.h, and common.h

ppapi/cpp/core.h

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// 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_CPP_CORE_H_
 #define PPAPI_CPP_CORE_H_
 
 #include "ppapi/c/ppb_core.h"
 
+/// @file
+/// This file defines APIs related to memory management, time, and threads.
+
 namespace pp {
 
 class CompletionCallback;
 class Module;
 
-// Simple wrapper around the PPB_Core interface. Some of these wrappers add
-// nothing over the C interface, but some allow the use of C++ arguments.
+/// APIs related to memory management, time, and threads.
 class Core {
  public:
   // Note that we explicitly don't expose Resource& versions of this function
   // since Resource will normally manage the refcount properly. These should
   // be called only when doing manual management on raw PP_Resource handles,
   // which should be fairly rare.
+
+  /// A function that increments the reference count for the provided resource.
+  ///
+  /// @param[in] resource A PP_Resource containing the resource.
   void AddRefResource(PP_Resource resource) {
     interface_->AddRefResource(resource);
   }
+
+  /// A function that decrements the reference count for the provided resource.
+  /// The resource will be deallocated if the reference count reaches zero.
+  ///
+  /// @param[in] resource A PP_Resource containing the resource.
   void ReleaseResource(PP_Resource resource) {
     interface_->ReleaseResource(resource);
   }
 
+  /// A function that allocates memory.
+  ///
+  /// @param[in] @param[in] num_bytes A number of bytes to allocate.
+  /// @return A pointer to the memory if successful, NULL If the
+  /// allocation fails.
   void* MemAlloc(uint32_t num_bytes) {
     return interface_->MemAlloc(num_bytes);
   }
+
+  /// A function that deallocates memory.
+  ///
+  /// @param[in] ptr A pointer to the memory to deallocate. It is safe to
+  /// pass NULL to this function.
   void MemFree(void* ptr) {
     interface_->MemFree(ptr);
   }
 
+  /// A function that that returns the "wall clock time" according to the
+  /// browser.
+  ///
+  /// @return A PP_Time containing the "wall clock time" according to the
+  /// browser.
   PP_Time GetTime() {
     return interface_->GetTime();
   }
 
+  /// A function that that returns the "tick time" according to the browser.
+  /// This clock is used by the browser when passing some event times to the
+  /// plugin (e.g., via the PP_InputEvent::time_stamp_seconds field). It is
+  /// not correlated to any actual wall clock time (like GetTime()). Because
+  /// of this, it will not change if the user changes their computer clock.
+  ///
+  /// @return A PP_TimeTicks containing the "tick time" according to the
+  /// browser.
   PP_TimeTicks GetTimeTicks() {
     return interface_->GetTimeTicks();
   }
 
+  /// A function that schedules work to be executed on the main pepper thread
+  /// after the specified delay. The delay may be 0 to specify a call back as
+  /// soon as possible.
+  ///
+  /// The |result| parameter will just be passed as the second argument to the
+  /// callback. Many applications won't need this, but it allows a plugin to
+  /// emulate calls of some callbacks which do use this value.
+  ///
+  /// NOTE: CallOnMainThread, even when used from the main thread with a delay
+  /// of 0 milliseconds, will never directly invoke the callback.  Even in this
+  /// case, the callback will be scheduled asynchronously.
+  ///
+  /// NOTE: If the browser is shutting down or if the plugin has no instances,
+  /// then the callback function may not be called.
+  ///
+  /// @param[in] delay_in_milliseconds An int32_t delay in milliseconds.
+  /// @param[in] callback A CompletionCallback callback function that the
+  /// browser will call after the specified delay.
+  /// @param[in] result An int32_t that the browser will pass to the given
+  /// CompletionCallback.
   void CallOnMainThread(int32_t delay_in_milliseconds,
                         const CompletionCallback& callback,
                         int32_t result = 0);
 
+
+  /// A function that returns true if the current thread is the main pepper
+  /// thread.
+  ///
+  /// This function is useful for implementing sanity checks, and deciding if
+  /// dispatching using CallOnMainThread() is required.
+  ///
+  /// @return A PP_BOOL containing PP_TRUE if the current thread is the main
+  /// pepper thread, otherwise PP_FALSE.
   bool IsMainThread();
 
  private:
   // Allow Module to construct.
   friend class Module;
 
   // Only module should make this class so this constructor is private.
   Core(const PPB_Core* inter) : interface_(inter) {}
 
   // Copy and assignment are disallowed.
   Core(const Core& other);
   Core& operator=(const Core& other);
 
   const PPB_Core* interface_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_CORE_H_