gecko.dom.ipc进程通信：PContent,PNuwa,Process三系分析

于 2018-10-10 16:40:42 发布
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本文链接：https://blog.youkuaiyun.com/hunter___/article/details/82999413
本文深入解析了Gecko浏览器中IPC模块的工作原理，详细介绍了PContent和PNuwa两个核心系列的类继承关系及其实现细节。通过分析自动生成的头文件和手动编写的实现文件之间的联系，揭示了Gecko如何利用IPC机制实现不同进程间的通信。

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gecko/dom/ipc/此模块承担的工作是什么：

 

dom/ipc如下，每个ipdl文件对应3个头文件，

ipdl的生成文件，

 

几个类的继承关系

两个系列：PContent  和PNuwa，Process系，三个系

 

一 PContent系

PContent.ipdl生成三个文件：

objdir-gecko/ipc/ipdl/_ipdlheaders/mozilla/dom/PContent.h

objdir-gecko/ipc/ipdl/_ipdlheaders/mozilla/dom/PContentParent.h

objdir-gecko/ipc/ipdl/_ipdlheaders/mozilla/dom/PContentChild.h

dom/ipc/PContent.ipdl包罗万象，总之被另外两个自动生成的头文件继承实现了，之后，那两个头文件分别被手动写的实现文件继承。

 

乱七八糟。。。

ContentParnet.h

ContentChild.h

ContentProces.h是PContent.ipdl生成文件的继承后的实现？错，对了一部分。它只用了PContentChild.h部分，所以在Nuwa一侧？

关系，

（1）

PContent.ipdl

|

./ipc/ipdl/_ipdlheaders/mozilla/dom/PContentChild.h


#include "mozilla/dom/PContent.h"
#ifdef DEBUG
#include "prenv.h"
#endif // DEBUG
#include "base/id_map.h"
#include "mozilla/ipc/MessageChannel.h"

 

class PContentChild :
    public mozilla::ipc::IProtocol,
    protected mozilla::ipc::IProtocolManager<mozilla::ipc::IProtocol>,
    public mozilla::ipc::IToplevelProtocol
{
    friend class mozilla::media::PMediaChild;

 

dom/ipc/ContentChild.h


#include "mozilla/Attributes.h"
#include "mozilla/dom/ContentBridgeParent.h"
#include "mozilla/dom/nsIContentChild.h"
#include "mozilla/dom/PBrowserOrId.h"
#include "mozilla/dom/PContentChild.h"
#include "nsHashKeys.h"
#include "nsIObserver.h"
#include "nsTHashtable.h"

#include "nsWeakPtr.h"
#include "nsIWindowProvider.h"

class ContentChild final : public PContentChild
                         , public nsIWindowProvider
                         , public nsIContentChild
{
    typedef mozilla::dom::ClonedMessageData ClonedMessageData;
    typedef mozilla::ipc::OptionalURIParams OptionalURIParams;
    typedef mozilla::ipc::PFileDescriptorSetChild PFileDescriptorSetChild;
    typedef mozilla::ipc::URIParams URIParams;

 

 并列

gecko/ipc/glue/ProcessChild.h 单独用


#include "base/message_loop.h"
#include "base/process.h"

#include "chrome/common/child_process.h"

// ProcessChild is the base class for all subprocesses of the main
// browser process.  Its code runs on the thread that started in
// main().

namespace mozilla {
namespace ipc {

class ProcessChild : public ChildProcess {
protected:
  typedef base::ProcessId ProcessId;

public:
  explicit ProcessChild(ProcessId aParentPid);
  virtual ~ProcessChild();

  virtual bool Init() = 0;
  virtual void CleanUp()
  { }

  static MessageLoop* message_loop() {
    return gProcessChild->mUILoop;
  }

protected:
  static ProcessChild* current() {
    return gProcessChild;
  }

  ProcessId ParentPid() {
    return mParentPid;
  }

private:
  static ProcessChild* gProcessChild;

  MessageLoop* mUILoop;
  ProcessId mParentPid;

  DISALLOW_EVIL_CONSTRUCTORS(ProcessChild);
};

} // namespace ipc
} // namespace mozilla

 

gecko/dom/ipc/ContentProces.h如下


#include "mozilla/ipc/ProcessChild.h"
#include "mozilla/ipc/ScopedXREEmbed.h"
#include "ContentChild.h"

namespace mozilla {
namespace dom {

/**
 * ContentProcess is a singleton on the content process which represents
 * the main thread where tab instances live.
 */
class ContentProcess : public mozilla::ipc::ProcessChild
{
    typedef mozilla::ipc::ProcessChild ProcessChild;

public:
    explicit ContentProcess(ProcessId aParentPid)
        : ProcessChild(aParentPid)
    { }

    ~ContentProcess()
    { }

    virtual bool Init() override;
    virtual void CleanUp() override;

 

ContentProces.h是对ProcessChild.h，ContentChild.h"等的统合使用。

ContentProcess最后把Child支系的全收了，在此处进行大综合（即使用）。

目的是什么？gecko/ipc/glue/ProcessChild.h的作用是messageloop，获取当前线程ioloop等

ipdl的本质工作即是让parent端与child端能通信。相互搞些事情。

 

(2）

PContent.ipdl

|

./ipc/ipdl/_ipdlheaders/mozilla/dom/PContentParent.h

 

#include "mozilla/dom/PContent.h"
#ifdef DEBUG
#include "prenv.h"
#endif // DEBUG
#include "base/id_map.h"
#include "mozilla/ipc/MessageChannel.h"

c

namespace mozilla {
namespace dom {


class PContentParent :
    public mozilla::ipc::IProtocol,
    protected mozilla::ipc::IProtocolManager<mozilla::ipc::IProtocol>,
    public mozilla::ipc::IToplevelProtocol
{
    friend class mozilla::media::PMediaParent;

    friend class mozilla::jsipc::PJavaScriptParent;

 

dom/ipc/ContentParent.h


#include "mozilla/dom/NuwaParent.h"
#include "mozilla/dom/PContentParent.h"
#include "mozilla/dom/nsIContentParent.h"
#include "mozilla/ipc/GeckoChildProcessHost.h"
#include "mozilla/Attributes.h"
#include "mozilla/FileUtils.h"
#include "mozilla/HalTypes.h"
#include "mozilla/LinkedList.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/UniquePtr.h"

#include "nsDataHashtable.h"
#include "nsFrameMessageManager.h"
#include "nsHashKeys.h"
#include "nsIObserver.h"
#include "nsIThreadInternal.h"
#include "nsIDOMGeoPositionCallback.h"
#include "nsIDOMGeoPositionErrorCallback.h"
#include "PermissionMessageUtils.h"
#include "DriverCrashGuard.h"


class ContentParent final : public PContentParent
                          , public nsIContentParent
                          , public nsIObserver
                          , public nsIDOMGeoPositionCallback
                          , public nsIDOMGeoPositionErrorCallback
                          , public mozilla::LinkedListElement<ContentParent>
{
    typedef mozilla::ipc::GeckoChildProcessHost GeckoChildProcessHost;
    typedef mozilla::ipc::OptionalURIParams OptionalURIParams;
    typedef mozilla::ipc::PFileDescriptorSetParent PFileDescriptorSetParent;
    typedef mozilla::ipc::TestShellParent TestShellParent;
    typedef mozilla::ipc::URIParams URIParams;
    typedef mozilla::ipc::PrincipalInfo PrincipalInfo;
    typedef mozilla::dom::ClonedMessageData ClonedMessageData;

public:
#ifdef MOZ_NUWA_PROCESS
    static int32_t NuwaPid() {
        return sNuwaPid;
    }

    static bool IsNuwaReady() {
        return sNuwaReady;
    }
#endif
    virtual bool IsContentParent() override { return true; }
    /**

 

ContentParnet.h是对PNuwa系，PContent系中的引用，换句话说就是使用。，

 

下面是简洁版：

./ipc/ipdl/_ipdlheaders/mozilla/dom/PContent.h

//-----------------------------------------------------------------------------
// Code common to PContentChild and PContentParent
//
namespace mozilla {
namespace dom {
namespace PContent {

enum State {
    __Dead,
    __Null,
    __Error,
    __Dying,
    __Start = __Null
};

enum MessageType {
    PContentStart = PContentMsgStart << 16,
    Msg_P.。。。

1.3w+行，，，，很多message 类型，很多类，，，声明等

（1）

PContent.ipdl

./ipc/ipdl/_ipdlheaders/mozilla/dom/PContentChild.h

class PContentChild :
    public mozilla::ipc::IProtocol,
    protected mozilla::ipc::IProtocolManager<mozilla::ipc::IProtocol>,
    public mozilla::ipc::IToplevelProtocol
{  

dom/ipc/ContentChild.h


class ContentChild final : public PContentChild
                         , public nsIWindowProvider
                         , public nsIContentChild
{

PContentChild > ContentChild

（2）

PContent.ipdl

./ipc/ipdl/_ipdlheaders/mozilla/dom/PContentParent.h

class PContentParent :
    public mozilla::ipc::IProtocol,
    protected mozilla::ipc::IProtocolManager<mozilla::ipc::IProtocol>,
    public mozilla::ipc::IToplevelProtocol
{

dom/ipc/ContentParent.h


class ContentParent final : public PContentParent
                          , public nsIContentParent
                          , public nsIObserver
                          , public nsIDOMGeoPositionCallback
                          , public nsIDOMGeoPositionErrorCallback
                          , public mozilla::LinkedListElement<ContentParent>
{

PContentParent > ContentParent

 

 

 

二PNuwa系

 

PNuwa.ipdl系，生成三个头文件，其继承关系如下：

PNuwa.h       

PNuwaParent.h

PNuwaChild.h  

在NuwaParent.h NuwaChild.h里面来实现各接口的功能。

 

gecko/dom/ipc/PNuwa.ipdl

sync protocol PNuwa
{
  manager PBackground;

child:
  // Ask the Nuwa process to create a new child process.
  async Fork();

  // This message will be sent to non-Nuwa process, or to Nuwa process during
  // test.
  async __delete__();

parent:
  async NotifyReady();
  sync AddNewProcess(uint32_t pid, ProtocolFdMapping[] aFds);
};

 

 ./ipc/ipdl/_ipdlheaders/mozilla/dom/PNuwa.h 几个消息类型的类，其他ipdl文件也一样

  ▶ MessageType : enum
      ▶ State : enum
      ▶ Msg_AddNewProcess : class
      ▶ Msg_Fork : class
      ▶ Msg_NotifyReady : class
      ▶ Msg___delete__ : class
      ▶ Reply_AddNewProcess : class
      ▶ Reply___delete__ : class

（1）

./ipc/ipdl/_ipdlheaders/mozilla/dom/PNuwaChild.h


#include "mozilla/dom/PNuwa.h"
#ifdef DEBUG
#include "prenv.h"
#endif // DEBUG
#include "base/id_map.h"
#include "mozilla/ipc/MessageChannel.h"


class PNuwaChild :
    public mozilla::ipc::IProtocol,
    protected mozilla::ipc::IProtocolManager<mozilla::ipc::IProtocol>
{
    friend class mozilla::ipc::PBackgroundChild;

protected:
    typedef mozilla::ipc::ActorHandle ActorHandle;.

。。。

    virtual bool    RecvFork() = 0;
    virtual bool    Recv__delete__();

    virtual void    ActorDestroy(ActorDestroyReason aWhy);

public:

。。。。

public:
    MOZ_IMPLICIT PNuwaChild();

    virtual ~PNuwaChild();

    PBackgroundChild*
    Manager() const;

    PNuwa::State
    state();

    bool    SendNotifyReady();

    bool    SendAddNewProcess(
            const uint32_t& pid,
            const nsTArray<ProtocolFdMapping>& aFds);

    virtual int32_t
    Registe。。。

gecko/dom/ipc/NuwaChild.h


#include "mozilla/Assertions.h"
#include "mozilla/dom/PNuwaChild.h"
#include "nsThreadUtils.h"

namespace mozilla {
namespace dom {
class NuwaChild: public mozilla::dom::PNuwaChild
{
public:
  virtual bool RecvFork() override;

  virtual void ActorDestroy(ActorDestroyReason aWhy) override
  { }

  static NuwaChild* GetSingleton();

private:
  static NuwaChild* sSingleton;
};

} // namespace dom
} // namespace mozilla

 

（2）

./ipc/ipdl/_ipdlheaders/mozilla/dom/PNuwaParent.h


#include "mozilla/dom/PNuwa.h"
#ifdef DEBUG
#include "prenv.h"
#endif // DEBUG
#include "base/id_map.h"
#include "mozilla/ipc/MessageChannel.h"

 

class PNuwaParent :
    public mozilla::ipc::IProtocol,
    protected mozilla::ipc::IProtocolManager<mozilla::ipc::IProtocol>
{
    friend class mozilla::ipc::PBackgroundParent;

protected:
    typedef mozilla::ipc::ActorHandle ActorHandle;
    typedef mo

gecko/dom/ipc/NuwaParent .h对接口进行实现


#include "base/message_loop.h"
#include "mozilla/dom/PNuwaParent.h"
#include "...

namespace mozilla {
namespace dom {

class ContentParent;

class NuwaParent : public mozilla::dom::PNuwaParent
{
public:
  explicit NuwaParent();

  // Called on the main thread.
  bool ForkNewProcess(uint32_t& aPid,
                      UniquePtr<nsTArray<ProtocolFdMapping>>&& aFds,
                      bool aBlocking);

  // Called on the background thread.
  bool ActorConstructed();

  // Both the worker thread and the main thread hold a ref to this.
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(NuwaParent)

  // Functions to be invoked by the manager of this actor to alloc/dealloc the
  // actor.
  static NuwaParent* Alloc();

...

protected:
  virtual ~NuwaParent();

  virtual bool RecvNotifyReady() override;
  virtual bool RecvAddNewProcess(const uint32_t& aPid,
                                 nsTArray<ProtocolFdMapping>&& aFds) override;
  virtual mozilla::ipc::IProtocol*
  CloneProtocol(Channel* aChannel,
                ProtocolCloneContext* aCtx) override;

  virtual void ActorDestroy(ActorDestroyReason aWhy) override;

private:

...
};

} // namespace dom
} // namespace mozilla

 

三Process 系

Process 系是对前面两个系的使用？没有ProcessParent，但承担此角色的可能是ProcessUtils_linux.h等？可能不是

gecko/ipc/chromium/src/chrome/common/child_process.h


// Base class for child processes of the browser process (i.e. renderer and
// plugin host). This is a singleton object for each child process.
class ChildProcess {
 public:
  // Child processes should have an object that derives from this class.  The
  // constructor will return once ChildThread has started.
  explicit ChildProcess(ChildThread* child_thread);
  virtual ~ChildProcess();

  // Getter for this process' main thread.
  ChildThread* child_thread() { return child_thread_.get(); }

  // A global event object that is signalled when the main thread's message
  // loop exits

gecko/ipc/glue/ProcessChild.h


#include "base/message_loop.h"
#include "base/process.h"

#include "chrome/common/child_process.h"

 

// ProcessChild is the base class for all subprocesses of the main
// browser process.  Its code runs on the thread that started in
// main().

namespace mozilla {
namespace ipc {

class ProcessChild : public ChildProcess {

protected:
  typedef base::ProcessId ProcessId;

public:
  explicit ProcessChild(ProcessId aParentPid);
  virtual ~ProcessChild();
。。。

gecko/dom/ipc/ContentProcess.h

/**
 * ContentProcess is a singleton on the content process which represents
 * the main thread where tab instances live.
 */
class ContentProcess : public mozilla::ipc::ProcessChild
{
    typedef mozilla::ipc::ProcessChild ProcessChild;

public:
    explicit ContentProcess(ProcessId aParentPid)
        : ProcessChild(aParentPid)
    { }

    ~ContentProcess()
    { }

    virtual bool Init() override;
    virtual void CleanUp() override;

    void SetAppDir(const nsACString& aPath);

private:
    ContentChild mContent;
    mozilla::ipc::ScopedXREEmbed mXREEmbed;

    DISALLOW_EVIL_CONSTRUCTORS(ContentProcess);
};

 

gecko/ipc/glue/ProcessChild.cpp

创建实例时将同时创建io子线程，开启uimessageloop获取当前的消息循环队列,传入父id,
ProcessChild::ProcessChild(ProcessId aParentPid)
  : ChildProcess(new IOThreadChild())
  , mUILoop(MessageLoop::current())
  , mParentPid(aParentPid)
{
  MOZ_ASSERT(mUILoop, "UILoop should be created by now");
  MOZ_ASSERT(!gProcessChild, "should only be one ProcessChild");
  gProcessChild = this;
}

 

继承关系：ChildProcess > ProcessChild >  ContentProcess

 

主要要看gecko/dom/ipc/ContentProcess.cpp。源码表明，其作用主要是初始化contentprocess进程,初始化xpcom,初始化显示设备数据。设置app目录。

void
ContentProcess::SetAppDir(const nsACString& aPath)
{
  mXREEmbed.SetAppDir(aPath);
}

bool
ContentProcess::Init()
{
  mContent.Init(IOThreadChild::message_loop(),
                ParentPid(),
                IOThreadChild::channel());
  mXREEmbed.Start();
  mContent.InitXPCOM();
  mContent.InitGraphicsDeviceData();

#if defined(XP_WIN) && defined(MOZ_CONTENT_SANDBOX)
  SetUpSandboxEnvironment();
#endif

  return true;
}

 

三系的关系：没有关系？

 

 

 

 

 

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