Implement ServiceManager

mojo/shell/service_manager.cc

+// Copyright 2013 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 "mojo/shell/service_manager.h"
+
+#include "base/bind.h"
+#include "base/callback_helpers.h"
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/scoped_native_library.h"
+#include "base/threading/simple_thread.h"
+#include "mojo/public/bindings/lib/remote_ptr.h"
+#include "mojo/shell/context.h"
+#include "mojo/shell/switches.h"
+#include "mojom/shell.h"
+
+typedef MojoResult (*MojoMainFunction)(MojoHandle pipe);
+
+namespace mojo {
+namespace shell {
+
+class ServiceManager::Service
+    : public ::shell::ShellStub,
+      public Loader::Delegate,
+      public base::DelegateSimpleThread::Delegate {
+ public:
+  Service(ServiceManager* manager, const GURL& url)
+      : manager_(manager),
+        url_(url),
+        weak_factory_(this) {
+    base::AutoLock lock(lock_);
+    ScopedMessagePipeHandle shell_handle;
+    CreateMessagePipe(&shell_handle, &service_handle_);
+    shell_client_.reset(shell_handle.Pass());
+    shell_client_.SetPeer(this);
+    request_ = manager_->context_->loader()->Load(url_, this);
+  }
+
+  virtual ~Service() {}
+
+  void ConnectToClient(ScopedMessagePipeHandle handle) {
+    if (handle.is_valid())
+      shell_client_->Connect(handle.Pass());
+  }
+
+  virtual void Connect(const mojo::String& url,
+                       ScopedMessagePipeHandle client_pipe) MOJO_OVERRIDE {
+    manager_->Connect(GURL(url.To<std::string>()), client_pipe.Pass());
+  }
+
+ private:
+  // From Loader::Delegate.
+  virtual void DidCompleteLoad(const GURL& app_url,
+                               const base::FilePath& app_path) OVERRIDE {
+    base::AutoLock lock(lock_);
+    app_path_ = app_path;
+    ack_closure_ =
+        base::Bind(&Service::AppCompleted, weak_factory_.GetWeakPtr());
+    thread_.reset(new base::DelegateSimpleThread(this, "app_thread"));
+    thread_->Start();
+  }
+
+  // From base::DelegateSimpleThread::Delegate.
+  virtual void Run() OVERRIDE {
+    base::AutoLock lock(lock_);

[abarth-chromium, 2013/12/10 01:06:03]

So, this lock is held as long as the app is running?

I don't understand the point of this lock.  It seems like all the functions that
take the lock happen in sequence.  DidCompleteLoad() can't be called until the
constructor completes and Run() can't be called until DidCompleteLoad calls
Start().

[DaveMoore, 2013/12/10 03:00:45]

You are right. It was left in accidentally
On 2013/12/10 01:06:03, abarth wrote:

+    base::ScopedClosureRunner app_deleter(
+        base::Bind(base::IgnoreResult(&base::DeleteFile), app_path_, false));
+    base::ScopedNativeLibrary app_library(
+        base::LoadNativeLibrary(app_path_, NULL));
+    if (!app_library.is_valid()) {
+      LOG(ERROR) << "Failed to load library: " << app_path_.value().c_str();
+      return;
+    }
+
+    MojoMainFunction main_function = reinterpret_cast<MojoMainFunction>(
+        app_library.GetFunctionPointer("MojoMain"));
+    if (!main_function) {
+      LOG(ERROR) << "Entrypoint MojoMain not found.";
+      return;
+    }
+
+    // |MojoMain()| takes ownership of the app handle.
+    MojoResult result = main_function(service_handle_.release().value());
+    if (result < MOJO_RESULT_OK) {
+      LOG(ERROR) << "MojoMain returned an error: " << result;
+      return;
+    }
+    manager_->context_->task_runners()->ui_runner()->PostTask(
+        FROM_HERE,
+        ack_closure_);
+  }
+
+  void AppCompleted() {
+    thread_->Join();
+    thread_.reset();
+  }
+
+  base::Lock lock_;
+  ServiceManager* manager_;
+  GURL url_;
+  mojo::RemotePtr<::shell::ShellClient> shell_client_;
+  base::FilePath app_path_;
+  base::Closure ack_closure_;
+  scoped_ptr<Loader::Job> request_;
+  scoped_ptr<base::DelegateSimpleThread> thread_;
+  ScopedMessagePipeHandle service_handle_;
+
+  base::WeakPtrFactory<Service> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Service);
+};
+
+ServiceManager::ServiceManager(Context* context) : context_(context) {
+}
+
+ServiceManager::~ServiceManager() {
+}
+
+void ServiceManager::Connect(const GURL& url,
+                             ScopedMessagePipeHandle client_handle) {
+  GURL app_url = url;
+  if (url.scheme() == "mojo") {
+    const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+    std::string origin = command_line.GetSwitchValueASCII(switches::kOrigin);
+    std::string lib("lib" + url.ExtractFileName() + ".so");

[abarth-chromium, 2013/12/10 01:06:03]

This won't work on Window or Mac.

[DaveMoore, 2013/12/10 03:00:45]

You're right...it won't. I'll take a look at that while you look at my other
comments.
On 2013/12/10 01:06:03, abarth wrote:

+    app_url = GURL(origin + std::string("/") + lib);
+  }
+  base::AutoLock lock(service_map_lock_);

[abarth-chromium, 2013/12/10 01:06:03]

I don't understand this lock either.  Isn't this function always called on the
same thread?

[DaveMoore, 2013/12/10 03:00:45]

At one point I was thinking that each Service might get its own thread, or maybe
groups somehow, to reduce the risk of contention. Also at one point the
interaction with the Service object itself was more complicated, and it wasn't
allocated until later (on the thread running the app). I can remove this
locking. 
On 2013/12/10 01:06:03, abarth wrote:

+  ServiceMap::const_iterator service_it = url_to_service_.find(app_url);
+  Service* service;
+  if (service_it != url_to_service_.end()) {
+    service = service_it->second;
+  } else {
+    service = new Service(this, app_url);
+    url_to_service_[app_url] = service;
+  }
+  service->ConnectToClient(client_handle.Pass());
+}
+
+}  // namespace shell
+}  // namespace mojo