Show all system process in the task_manager.

chrome/browser/chromeos/arc/arc_process_service.cc

 // Copyright 2016 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.
 //
 // The main point of this class is to cache ARC proc nspid<->pid mapping
 // globally. Since the calculation is costly, a dedicated worker thread is
 // used. All read/write of its internal data structure (i.e., the mapping)
 // should be on this thread.
 
 #include "chrome/browser/chromeos/arc/arc_process_service.h"
 
+#include <algorithm>
 #include <queue>
-#include <set>
 #include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
 
+#include "base/callback.h"
+#include "base/logging.h"
 #include "base/process/process.h"
 #include "base/process/process_iterator.h"
 #include "base/task_runner_util.h"
 #include "base/trace_event/trace_event.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace arc {
 
-namespace {
-
-const char kSequenceToken[] = "arc_process_service";
-
-// Weak pointer.  This class is owned by ArcServiceManager.
-ArcProcessService* g_arc_process_service = nullptr;
-
-}  // namespace
-
 using base::kNullProcessId;
 using base::Process;
 using base::ProcessId;
 using base::SequencedWorkerPool;
-using std::map;
-using std::set;
 using std::vector;
 
+namespace {
+
+// Weak pointer.  This class is owned by ArcServiceManager.
+ArcProcessService* g_arc_process_service = nullptr;
+static constexpr char kInitName[] = "/init";
+static constexpr bool kNotFocused = false;
+static constexpr int64_t kNoActivityTimeInfo = 0L;
+
+// Matches the process name "/init" in the process tree and get the
+// corresponding process ID.
+base::ProcessId GetArcInitProcessId(
+    const base::ProcessIterator::ProcessEntries& entry_list) {
+  for (const base::ProcessEntry& entry : entry_list) {
+    if (entry.cmd_line_args().empty()) {
+      continue;
+    }
+    // TODO(nya): Add more constraints to avoid mismatches.
+    const std::string& process_name = entry.cmd_line_args()[0];
+    if (process_name == kInitName) {
+      return entry.pid();
+    }
+  }
+  return base::kNullProcessId;
+}
+
+std::vector<arc::ArcProcess> GetArcSystemProcessList() {
+  std::vector<arc::ArcProcess> ret_processes;
+  const base::ProcessIterator::ProcessEntries& entry_list =
+      base::ProcessIterator(nullptr).Snapshot();
+  const base::ProcessId arc_init_pid = GetArcInitProcessId(entry_list);
+
+  if (arc_init_pid == base::kNullProcessId) {
+    return ret_processes;
+  }
+
+  // Enumerate the child processes of ARC init for gathering ARC System
+  // Processes.
+  for (const base::ProcessEntry& entry : entry_list) {
+    if (entry.cmd_line_args().empty()) {
+      continue;
+    }
+    // TODO(hctsai): For now, we only gather direct child process of init, need
+    // to get the processes below. For example, installd might fork dex2oat and
+    // it can be executed for minutes.
+    if (entry.parent_pid() == arc_init_pid) {
+      const base::ProcessId child_pid = entry.pid();
+      const base::ProcessId child_nspid =
+          base::Process(child_pid).GetPidInNamespace();
+      if (child_nspid != base::kNullProcessId) {
+        const std::string& process_name = entry.cmd_line_args()[0];
+        // The is_focused and last_activity_time is not needed thus mocked
+        ret_processes.emplace_back(child_nspid, child_pid, process_name,
+                                   mojom::ProcessState::PERSISTENT, kNotFocused,
+                                   kNoActivityTimeInfo);
+      }
+    }
+  }
+  return ret_processes;
+}
+
+void UpdateNspidToPidMap(
+    scoped_refptr<ArcProcessService::NSPidToPidMap> pid_map) {
+  TRACE_EVENT0("browser", "ArcProcessService::UpdateNspidToPidMap");
+
+  // NB: Despite of its name, ProcessIterator::Snapshot() may return
+  // inconsistent information because it simply walks procfs. Especially
+  // we must not assume the parent-child relationships are consistent.
+  const base::ProcessIterator::ProcessEntries& entry_list =
+      base::ProcessIterator(nullptr).Snapshot();
+
+  // Construct the process tree.
+  // NB: This can contain a loop in case of race conditions.
+  std::unordered_map<ProcessId, std::vector<ProcessId>> process_tree;
+  for (const base::ProcessEntry& entry : entry_list)
+    process_tree[entry.parent_pid()].push_back(entry.pid());
+
+  ProcessId arc_init_pid = GetArcInitProcessId(entry_list);
+
+  // Enumerate all processes under ARC init and create nspid -> pid map.
+  if (arc_init_pid != kNullProcessId) {
+    std::queue<ProcessId> queue;
+    std::unordered_set<ProcessId> visited;
+    queue.push(arc_init_pid);
+    while (!queue.empty()) {
+      ProcessId pid = queue.front();
+      queue.pop();
+      // Do not visit the same process twice. Otherwise we may enter an infinite
+      // loop if |process_tree| contains a loop.
+      if (!visited.insert(pid).second)
+        continue;
+
+      const ProcessId nspid = base::Process(pid).GetPidInNamespace();
+
+      // All ARC processes should be in namespace so nspid is usually non-null,
+      // but this can happen if the process has already gone.
+      // Only add processes we're interested in (those appear as keys in
+      // |pid_map|).
+      if (nspid != kNullProcessId && pid_map->find(nspid) != pid_map->end())
+        (*pid_map)[nspid] = pid;
+
+      for (ProcessId child_pid : process_tree[pid])
+        queue.push(child_pid);
+    }
+  }
+}
+
+std::vector<ArcProcess> FilterProcessList(
+    const ArcProcessService::NSPidToPidMap& pid_map,
+    mojo::Array<arc::mojom::RunningAppProcessInfoPtr> processes) {
+  std::vector<ArcProcess> ret_processes;
+  for (const auto& entry : processes) {
+    const auto it = pid_map.find(entry->pid);
+    // The nspid could be missing due to race condition. For example, the
+    // process is still running when we get the process snapshot and ends when
+    // we update the nspid to pid mapping.
+    if (it == pid_map.end() || it->second == base::kNullProcessId) {
+      continue;
+    }
+    // Constructs the ArcProcess instance if the mapping is found.
+    ArcProcess arc_process(entry->pid, pid_map.at(entry->pid),
+                           entry->process_name, entry->process_state,
+                           entry->is_focused, entry->last_activity_time);
+    // |entry->packages| is provided only when process.mojom's verion is >=4.
+    if (entry->packages) {
+      for (const auto& package : entry->packages) {
+        arc_process.packages().push_back(package.get());
+      }
+    }
+    ret_processes.push_back(std::move(arc_process));
+  }
+  return ret_processes;
+}
+
+std::vector<ArcProcess> UpdateAndReturnProcessList(
+    scoped_refptr<ArcProcessService::NSPidToPidMap> nspid_map,
+    mojo::Array<arc::mojom::RunningAppProcessInfoPtr> processes) {
+  ArcProcessService::NSPidToPidMap& pid_map = *nspid_map;
+  // Cleanup dead pids in the cache |pid_map|.
+  std::unordered_set<ProcessId> nspid_to_remove;
+  for (const auto& entry : pid_map) {
+    nspid_to_remove.insert(entry.first);
+  }
+  bool unmapped_nspid = false;
+  for (const auto& entry : processes) {
+    // erase() returns 0 if coudln't find the key. It means a new process.
+    if (nspid_to_remove.erase(entry->pid) == 0) {
+      pid_map[entry->pid] = base::kNullProcessId;
+      unmapped_nspid = true;
+    }
+  }
+  for (const auto& entry : nspid_to_remove) {
+    pid_map.erase(entry);
+  }
+
+  // The operation is costly so avoid calling it when possible.
+  if (unmapped_nspid) {
+    UpdateNspidToPidMap(nspid_map);
+  }
+
+  return FilterProcessList(pid_map, std::move(processes));
+}
+
+void Reset(scoped_refptr<ArcProcessService::NSPidToPidMap> pid_map) {
+  if (pid_map.get())
+    pid_map->clear();
+}
+
+}  // namespace
+
 ArcProcessService::ArcProcessService(ArcBridgeService* bridge_service)
     : ArcService(bridge_service),
-      worker_pool_(new SequencedWorkerPool(1,
-                                           "arc_process_manager",
-                                           base::TaskPriority::USER_VISIBLE)),
+      heavy_task_thread_("ArcProcessServiceThread"),
+      nspid_to_pid_(new NSPidToPidMap()),
       weak_ptr_factory_(this) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   arc_bridge_service()->process()->AddObserver(this);
   DCHECK(!g_arc_process_service);
   g_arc_process_service = this;
-  // Not intended to be used from the creating thread.
-  thread_checker_.DetachFromThread();
+  heavy_task_thread_.Start();
 }
 
 ArcProcessService::~ArcProcessService() {
   DCHECK(g_arc_process_service == this);
+  heavy_task_thread_.Stop();
   g_arc_process_service = nullptr;
   arc_bridge_service()->process()->RemoveObserver(this);
-  worker_pool_->Shutdown();
 }
 
 // static
 ArcProcessService* ArcProcessService::Get() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   return g_arc_process_service;
 }
 
 void ArcProcessService::OnInstanceReady() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  worker_pool_->PostNamedSequencedWorkerTask(
-      kSequenceToken,
-      FROM_HERE,
-      base::Bind(&ArcProcessService::Reset,
-                 weak_ptr_factory_.GetWeakPtr()));
+  GetTaskRunner()->PostTask(FROM_HERE, base::Bind(&Reset, nspid_to_pid_));
 }
 
-void ArcProcessService::Reset() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  nspid_to_pid_.clear();
-}
-
-bool ArcProcessService::RequestProcessList(
+void ArcProcessService::RequestSystemProcessList(
     RequestProcessListCallback callback) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
+  base::PostTaskAndReplyWithResult(GetTaskRunner().get(), FROM_HERE,
+                                   base::Bind(&GetArcSystemProcessList),
+                                   callback);
+}
+
+bool ArcProcessService::RequestAppProcessList(
+    RequestProcessListCallback callback) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
   arc::mojom::ProcessInstance* process_instance =
       arc_bridge_service()->process()->instance();
   if (!process_instance) {
     return false;
   }
   process_instance->RequestProcessList(
       base::Bind(&ArcProcessService::OnReceiveProcessList,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
   return true;
 }
 
 void ArcProcessService::OnReceiveProcessList(
     const RequestProcessListCallback& callback,
-    mojo::Array<arc::mojom::RunningAppProcessInfoPtr> mojo_processes) {
+    mojo::Array<arc::mojom::RunningAppProcessInfoPtr> instance_processes) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
-  auto* raw_processes = new vector<mojom::RunningAppProcessInfoPtr>();
-  mojo_processes.Swap(raw_processes);
-
-  auto* ret_processes = new vector<ArcProcess>();
-  // Post to its dedicated worker thread to avoid race condition.
-  // Since no two tasks with the same token should be run at the same.
-  // Note: GetSequencedTaskRunner's shutdown behavior defaults to
-  // SKIP_ON_SHUTDOWN (ongoing task blocks shutdown).
-  // So in theory using Unretained(this) should be fine since the life cycle
-  // of |this| is the same as the main browser.
-  // To be safe I still use weak pointers, but weak_ptrs can only bind to
-  // methods without return values. That's why I can't use
-  // PostTaskAndReplyWithResult but handle the return object by myself.
-  auto runner = worker_pool_->GetSequencedTaskRunner(
-      worker_pool_->GetNamedSequenceToken(kSequenceToken));
-  runner->PostTaskAndReply(
-      FROM_HERE,
-      base::Bind(&ArcProcessService::UpdateAndReturnProcessList,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 base::Owned(raw_processes),
-                 base::Unretained(ret_processes)),
-      base::Bind(&ArcProcessService::CallbackRelay,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback,
-                 base::Owned(ret_processes)));
+  base::PostTaskAndReplyWithResult(
+      GetTaskRunner().get(), FROM_HERE,
+      base::Bind(&UpdateAndReturnProcessList, nspid_to_pid_,
+                 base::Passed(&instance_processes)),
+      callback);
 }
 
-void ArcProcessService::CallbackRelay(
-    const RequestProcessListCallback& callback,
-    const vector<ArcProcess>* ret_processes) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  callback.Run(*ret_processes);
+scoped_refptr<base::SingleThreadTaskRunner> ArcProcessService::GetTaskRunner() {
+  return heavy_task_thread_.task_runner();
 }
 
-void ArcProcessService::UpdateAndReturnProcessList(
-    const vector<arc::mojom::RunningAppProcessInfoPtr>* raw_processes,
-    vector<ArcProcess>* ret_processes) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+inline ArcProcessService::NSPidToPidMap::NSPidToPidMap() {}
 
-  // Cleanup dead pids in the cache |nspid_to_pid_|.
-  set<ProcessId> nspid_to_remove;
-  for (const auto& entry : nspid_to_pid_) {
-    nspid_to_remove.insert(entry.first);
-  }
-  bool unmapped_nspid = false;
-  for (const auto& entry : *raw_processes) {
-    // erase() returns 0 if coudln't find the key. It means a new process.
-    if (nspid_to_remove.erase(entry->pid) == 0) {
-      nspid_to_pid_[entry->pid] = kNullProcessId;
-      unmapped_nspid = true;
-    }
-  }
-  for (const auto& entry : nspid_to_remove) {
-    nspid_to_pid_.erase(entry);
-  }
-
-  // The operation is costly so avoid calling it when possible.
-  if (unmapped_nspid) {
-    UpdateNspidToPidMap();
-  }
-
-  PopulateProcessList(raw_processes, ret_processes);
-}
-
-void ArcProcessService::PopulateProcessList(
-    const vector<arc::mojom::RunningAppProcessInfoPtr>* raw_processes,
-    vector<ArcProcess>* ret_processes) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  for (const auto& entry : *raw_processes) {
-    const auto it = nspid_to_pid_.find(entry->pid);
-    // In case the process already dies so couldn't find corresponding pid.
-    if (it != nspid_to_pid_.end() && it->second != kNullProcessId) {
-      ArcProcess arc_process(entry->pid, it->second, entry->process_name,
-                             entry->process_state, entry->is_focused,
-                             entry->last_activity_time);
-      // |entry->packages| is provided only when process.mojom's verion is >=4.
-      if (entry->packages) {
-        for (const auto& package : entry->packages) {
-          arc_process.packages().push_back(package.get());
-        }
-      }
-      ret_processes->push_back(std::move(arc_process));
-    }
-  }
-}
-
-// Computes a map from PID in ARC namespace to PID in system namespace.
-// The returned map contains ARC processes only.
-void ArcProcessService::UpdateNspidToPidMap() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  TRACE_EVENT0("browser", "ArcProcessService::UpdateNspidToPidMap");
-
-  // NB: Despite of its name, ProcessIterator::Snapshot() may return
-  // inconsistent information because it simply walks procfs. Especially
-  // we must not assume the parent-child relationships are consistent.
-  const base::ProcessIterator::ProcessEntries& entry_list =
-      base::ProcessIterator(nullptr).Snapshot();
-
-  // System may contain many different namespaces so several different
-  // processes may have the same nspid. We need to get the proper subset of
-  // processes to create correct nspid -> pid map.
-
-  // Construct the process tree.
-  // NB: This can contain a loop in case of race conditions.
-  map<ProcessId, vector<ProcessId> > process_tree;
-  for (const base::ProcessEntry& entry : entry_list)
-    process_tree[entry.parent_pid()].push_back(entry.pid());
-
-  // Find the ARC init process.
-  ProcessId arc_init_pid = kNullProcessId;
-  for (const base::ProcessEntry& entry : entry_list) {
-    // TODO(nya): Add more constraints to avoid mismatches.
-    std::string process_name =
-        !entry.cmd_line_args().empty() ? entry.cmd_line_args()[0] : "";
-    if (process_name == "/init") {
-      arc_init_pid = entry.pid();
-      break;
-    }
-  }
-
-  // Enumerate all processes under ARC init and create nspid -> pid map.
-  if (arc_init_pid != kNullProcessId) {
-    std::queue<ProcessId> queue;
-    std::set<ProcessId> visited;
-    queue.push(arc_init_pid);
-    while (!queue.empty()) {
-      ProcessId pid = queue.front();
-      queue.pop();
-      // Do not visit the same process twice. Otherwise we may enter an infinite
-      // loop if |process_tree| contains a loop.
-      if (!visited.insert(pid).second)
-        continue;
-
-      ProcessId nspid = base::Process(pid).GetPidInNamespace();
-
-      // All ARC processes should be in namespace so nspid is usually non-null,
-      // but this can happen if the process has already gone.
-      // Only add processes we're interested in (those appear as keys in
-      // |nspid_to_pid_|).
-      if (nspid != kNullProcessId &&
-          nspid_to_pid_.find(nspid) != nspid_to_pid_.end())
-        nspid_to_pid_[nspid] = pid;
-
-      for (ProcessId child_pid : process_tree[pid])
-        queue.push(child_pid);
-    }
-  }
-}
+inline ArcProcessService::NSPidToPidMap::~NSPidToPidMap() {}
 
 }  // namespace arc