Use persistent memory for receiving metrics from sub-processes.

content/browser/browser_child_process_host_impl.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 "content/browser/browser_child_process_host_impl.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/dump_without_crashing.h"
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/persistent_histogram_allocator.h"
+#include "base/metrics/persistent_memory_allocator.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "components/tracing/common/tracing_switches.h"
 #include "content/browser/histogram_message_filter.h"
 #include "content/browser/loader/resource_message_filter.h"
 #include "content/browser/memory/memory_message_filter.h"
 #include "content/browser/profiler_message_filter.h"
@@ skipping 49 matching lines @@
   FOR_EACH_OBSERVER(BrowserChildProcessObserver, g_observers.Get(),
                     BrowserChildProcessKilled(data, exit_code));
 }
 
 }  // namespace
 
 BrowserChildProcessHost* BrowserChildProcessHost::Create(
     content::ProcessType process_type,
     BrowserChildProcessHostDelegate* delegate) {
   return new BrowserChildProcessHostImpl(
-      process_type, delegate, mojo::edk::GenerateRandomToken());
+      process_type, delegate, mojo::edk::GenerateRandomToken(), 0, nullptr);
 }
 
 BrowserChildProcessHost* BrowserChildProcessHost::Create(
     content::ProcessType process_type,
     BrowserChildProcessHostDelegate* delegate,
     const std::string& mojo_child_token) {
-  return new BrowserChildProcessHostImpl(
-      process_type, delegate, mojo_child_token);
+  return new BrowserChildProcessHostImpl(process_type, delegate,
+                                         mojo_child_token, 0, nullptr);
 }
 
 BrowserChildProcessHost* BrowserChildProcessHost::FromID(int child_process_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   BrowserChildProcessHostImpl::BrowserChildProcessList* process_list =
       g_child_process_list.Pointer();
   for (BrowserChildProcessHostImpl* host : *process_list) {
     if (host->GetData().id == child_process_id)
       return host;
   }
@@ skipping 22 matching lines @@
 // static
 void BrowserChildProcessHostImpl::RemoveObserver(
     BrowserChildProcessObserver* observer) {
   // TODO(phajdan.jr): Check thread after fixing http://crbug.com/167126.
   g_observers.Get().RemoveObserver(observer);
 }
 
 BrowserChildProcessHostImpl::BrowserChildProcessHostImpl(
     content::ProcessType process_type,
     BrowserChildProcessHostDelegate* delegate,
-    const std::string& mojo_child_token)
+    const std::string& mojo_child_token,
+    size_t shared_metrics_memory_size,
+    base::StringPiece shared_metrics_name)
     : data_(process_type),
       delegate_(delegate),
       mojo_child_token_(mojo_child_token),
       power_monitor_message_broadcaster_(this),
       is_channel_connected_(false),
       notify_child_disconnected_(false),
       weak_factory_(this) {
   data_.id = ChildProcessHostImpl::GenerateChildProcessUniqueId();
 
 #if USE_ATTACHMENT_BROKER
@@ skipping 12 matching lines @@
   child_process_host_.reset(ChildProcessHost::Create(this));
   AddFilter(new TraceMessageFilter(data_.id));
   AddFilter(new ProfilerMessageFilter(process_type));
   AddFilter(new HistogramMessageFilter);
   AddFilter(new MemoryMessageFilter(this, process_type));
 
   g_child_process_list.Get().push_back(this);
   GetContentClient()->browser()->BrowserChildProcessHostCreated(this);
 
   power_monitor_message_broadcaster_.Init();
+
+  // Create a persistent memory segment for subprocess histograms only if
+  // they're active in the browser.
+  if (shared_metrics_memory_size > 0 && base::GlobalHistogramAllocator::Get()) {
+    std::unique_ptr<base::SharedMemory> shm(new base::SharedMemory());
+    shm->CreateAndMapAnonymous(shared_metrics_memory_size);
+    metrics_allocator_.reset(new base::SharedPersistentMemoryAllocator(
+        std::move(shm), static_cast<uint64_t>(data_.id), shared_metrics_name,
+        /*readonly=*/false));
+  }
 }
 
 BrowserChildProcessHostImpl::~BrowserChildProcessHostImpl() {
   g_child_process_list.Get().remove(this);
 
   if (notify_child_disconnected_) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                             base::Bind(&NotifyProcessHostDisconnected, data_));
   }
 }
@@ skipping 80 matching lines @@
 
 const base::Process& BrowserChildProcessHostImpl::GetProcess() const {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(child_process_.get())
       << "Requesting a child process handle before launching.";
   DCHECK(child_process_->GetProcess().IsValid())
       << "Requesting a child process handle before launch has completed OK.";
   return child_process_->GetProcess();
 }
 
+std::unique_ptr<base::SharedPersistentMemoryAllocator>
+BrowserChildProcessHostImpl::TakeMetricsAllocator() {
+  return std::move(metrics_allocator_);
+}
+
 void BrowserChildProcessHostImpl::SetName(const base::string16& name) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   data_.name = name;
 }
 
 void BrowserChildProcessHostImpl::SetHandle(base::ProcessHandle handle) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   data_.handle = handle;
 }
 
@@ skipping 47 matching lines @@
   // error on the IPC channel.
   early_exit_watcher_.StopWatching();
 #endif
 
   BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                           base::Bind(&NotifyProcessHostConnected, data_));
 
   delegate_->OnChannelConnected(peer_pid);
 
   if (IsProcessLaunched()) {
+    ShareMetricsAllocatorToProcess();
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                             base::Bind(&NotifyProcessLaunchedAndConnected,
                                        data_));
   }
 }
 
 void BrowserChildProcessHostImpl::OnChannelError() {
   delegate_->OnChannelError();
 }
 
@@ skipping 81 matching lines @@
     }
 #endif
   }
   delete delegate_;  // Will delete us
 }
 
 bool BrowserChildProcessHostImpl::Send(IPC::Message* message) {
   return child_process_host_->Send(message);
 }
 
+void BrowserChildProcessHostImpl::ShareMetricsAllocatorToProcess() {
+  if (metrics_allocator_) {
+    base::SharedMemoryHandle shm_handle;
+    metrics_allocator_->shared_memory()->ShareToProcess(data_.handle,
+                                                        &shm_handle);
+    Send(new ChildProcessMsg_SetHistogramMemory(
+        shm_handle, metrics_allocator_->shared_memory()->mapped_size()));
+  }
+}
+
 void BrowserChildProcessHostImpl::OnProcessLaunchFailed(int error_code) {
   delegate_->OnProcessLaunchFailed(error_code);
   notify_child_disconnected_ = false;
   delete delegate_;  // Will delete us
 }
 
 void BrowserChildProcessHostImpl::OnProcessLaunched() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   const base::Process& process = child_process_->GetProcess();
   DCHECK(process.IsValid());
 
 #if defined(OS_WIN)
   // Start a WaitableEventWatcher that will invoke OnProcessExitedEarly if the
   // child process exits. This watcher is stopped once the IPC channel is
   // connected and the exit of the child process is detecter by an error on the
   // IPC channel thereafter.
   DCHECK(!early_exit_watcher_.GetWatchedObject());
   early_exit_watcher_.StartWatchingOnce(process.Handle(), this);
 #endif
 
   // TODO(rvargas) crbug.com/417532: Don't store a handle.
   data_.handle = process.Handle();
   delegate_->OnProcessLaunched();
 
   if (is_channel_connected_) {
+    ShareMetricsAllocatorToProcess();
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
                             base::Bind(&NotifyProcessLaunchedAndConnected,
                                        data_));
   }
 }
 
 bool BrowserChildProcessHostImpl::IsProcessLaunched() const {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   return child_process_.get() && child_process_->GetProcess().IsValid();
@@ skipping 28 matching lines @@
 
 #if defined(OS_WIN)
 
 void BrowserChildProcessHostImpl::OnObjectSignaled(HANDLE object) {
   OnChildDisconnected();
 }
 
 #endif
 
 }  // namespace content