Add analyzer support for multiple processes.

base/debug/activity_analyzer.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.
 
 #include "base/debug/activity_analyzer.h"
 
+#include <algorithm>
+
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/memory_mapped_file.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 
 namespace base {
 namespace debug {
 
+namespace {
+// An empty snapshot that can be returned when there otherwise is none.
+LazyInstance<ActivityUserData::Snapshot>::Leaky g_empty_user_data_snapshot;
+}  // namespace
+
 ThreadActivityAnalyzer::Snapshot::Snapshot() {}
 ThreadActivityAnalyzer::Snapshot::~Snapshot() {}
 
 ThreadActivityAnalyzer::ThreadActivityAnalyzer(
     const ThreadActivityTracker& tracker)
     : activity_snapshot_valid_(tracker.CreateSnapshot(&activity_snapshot_)) {}
 
 ThreadActivityAnalyzer::ThreadActivityAnalyzer(void* base, size_t size)
     : ThreadActivityAnalyzer(ThreadActivityTracker(base, size)) {}
 
@@ skipping 13 matching lines @@
   if (!IsValid())
     return;
 
   // User-data is held at the global scope even though it's referenced at the
   // thread scope.
   activity_snapshot_.user_data_stack.clear();
   for (auto& activity : activity_snapshot_.activity_stack) {
     // The global GetUserDataSnapshot will return an empty snapshot if the ref
     // or id is not valid.
     activity_snapshot_.user_data_stack.push_back(global->GetUserDataSnapshot(
-        activity.user_data_ref, activity.user_data_id));
+        activity_snapshot_.process_id, activity.user_data_ref,
+        activity.user_data_id));
   }
 }
 
 GlobalActivityAnalyzer::GlobalActivityAnalyzer(
     std::unique_ptr<PersistentMemoryAllocator> allocator)
     : allocator_(std::move(allocator)), allocator_iterator_(allocator_.get()) {}
 
 GlobalActivityAnalyzer::~GlobalActivityAnalyzer() {}
 
 #if !defined(OS_NACL)
 // static
 std::unique_ptr<GlobalActivityAnalyzer> GlobalActivityAnalyzer::CreateWithFile(
     const FilePath& file_path) {
   // Map the file read-write so it can guarantee consistency between
   // the analyzer and any trackers that my still be active.
   std::unique_ptr<MemoryMappedFile> mmfile(new MemoryMappedFile());
   mmfile->Initialize(file_path, MemoryMappedFile::READ_WRITE);
   if (!mmfile->IsValid())
     return nullptr;
 
   if (!FilePersistentMemoryAllocator::IsFileAcceptable(*mmfile, true))
     return nullptr;
 
   return WrapUnique(
       new GlobalActivityAnalyzer(MakeUnique<FilePersistentMemoryAllocator>(
           std::move(mmfile), 0, 0, base::StringPiece(), true)));
 }
 #endif  // !defined(OS_NACL)
 
-ThreadActivityAnalyzer* GlobalActivityAnalyzer::GetFirstAnalyzer() {
+int64_t GlobalActivityAnalyzer::GetFirstProcess() {
   PrepareAllAnalyzers();
+  return GetNextProcess();
+}
+
+int64_t GlobalActivityAnalyzer::GetNextProcess() {
+  if (process_ids_.empty())
+    return 0;
+  int64_t pid = process_ids_.back();
+  process_ids_.pop_back();
+  return pid;
+}
+
+ThreadActivityAnalyzer* GlobalActivityAnalyzer::GetFirstAnalyzer(int64_t pid) {
   analyzers_iterator_ = analyzers_.begin();
   if (analyzers_iterator_ == analyzers_.end())
     return nullptr;
+  int64_t create_stamp;
+  if (analyzers_iterator_->second->GetProcessId(&create_stamp) == pid &&
+      create_stamp <= analysis_stamp_) {
+    return analyzers_iterator_->second.get();
+  }
+  return GetNextAnalyzer(pid);
+}
+
+ThreadActivityAnalyzer* GlobalActivityAnalyzer::GetNextAnalyzer(int64_t pid) {
+  DCHECK(analyzers_iterator_ != analyzers_.end());
+  int64_t create_stamp;
+  do {
+    ++analyzers_iterator_;
+    if (analyzers_iterator_ == analyzers_.end())
+      return nullptr;
+  } while (analyzers_iterator_->second->GetProcessId(&create_stamp) != pid &&
+           create_stamp <= analysis_stamp_);

[manzagop (departed), 2017/03/21 21:10:05]

Not sure I follow this condition. Should it be "while 1) not the right process
OR 2) the process was created after analysis began" (ie || create_stamp >=
analysis_stamp)?

Might be worth adding a test with multiple processes.

[bcwhite, 2017/03/29 22:00:51]

Done.
That's pretty complicated and shouldn't be necessary since it doesn't really
behave any differently than standard multi-threading except for the PID value
that gets stored.

Instead, I'll let the PID be override-able during construction which should
allow it to be tested even in a single thread.

   return analyzers_iterator_->second.get();
 }
 
-ThreadActivityAnalyzer* GlobalActivityAnalyzer::GetNextAnalyzer() {
-  DCHECK(analyzers_iterator_ != analyzers_.end());
-  ++analyzers_iterator_;
-  if (analyzers_iterator_ == analyzers_.end())
-    return nullptr;
-  return analyzers_iterator_->second.get();
-}
-
 ThreadActivityAnalyzer* GlobalActivityAnalyzer::GetAnalyzerForThread(
     const ThreadKey& key) {
   auto found = analyzers_.find(key);
   if (found == analyzers_.end())
     return nullptr;
   return found->second.get();
 }
 
 ActivityUserData::Snapshot GlobalActivityAnalyzer::GetUserDataSnapshot(
+    int64_t pid,
     uint32_t ref,
     uint32_t id) {
   ActivityUserData::Snapshot snapshot;
 
   void* memory = allocator_->GetAsArray<char>(
       ref, GlobalActivityTracker::kTypeIdUserDataRecord,
       PersistentMemoryAllocator::kSizeAny);
   if (memory) {
     size_t size = allocator_->GetAllocSize(ref);
     const ActivityUserData user_data(memory, size);
     user_data.CreateSnapshot(&snapshot);
-    if (user_data.id() != id) {
+    ProcessId process_id;
+    int64_t create_stamp;
+    if (!ActivityUserData::GetOwningProcessId(memory, &process_id,
+                                              &create_stamp) ||
+        process_id != pid || user_data.id() != id) {
       // This allocation has been overwritten since it was created. Return an
       // empty snapshot because whatever was captured is incorrect.
       snapshot.clear();
     }
   }
 
   return snapshot;
 }
 
-ActivityUserData::Snapshot GlobalActivityAnalyzer::GetGlobalUserDataSnapshot() {
-  ActivityUserData::Snapshot snapshot;
+const ActivityUserData::Snapshot&
+GlobalActivityAnalyzer::GetProcessDataSnapshot(int64_t pid) {
+  auto iter = process_data_.find(pid);
+  if (iter == process_data_.end())
+    return g_empty_user_data_snapshot.Get();
+  if (iter->second.create_stamp > analysis_stamp_)
+    return g_empty_user_data_snapshot.Get();
+  DCHECK_EQ(pid, iter->second.process_id);
+  return iter->second.data;
+}
+
+const ActivityUserData::Snapshot&
+GlobalActivityAnalyzer::GetGlobalDataSnapshot() {
+  global_data_snapshot_.clear();
 
   PersistentMemoryAllocator::Reference ref =
       PersistentMemoryAllocator::Iterator(allocator_.get())
           .GetNextOfType(GlobalActivityTracker::kTypeIdGlobalDataRecord);
   void* memory = allocator_->GetAsArray<char>(
       ref, GlobalActivityTracker::kTypeIdGlobalDataRecord,
       PersistentMemoryAllocator::kSizeAny);
   if (memory) {
     size_t size = allocator_->GetAllocSize(ref);
     const ActivityUserData global_data(memory, size);
-    global_data.CreateSnapshot(&snapshot);
+    global_data.CreateSnapshot(&global_data_snapshot_);
   }
 
-  return snapshot;
+  return global_data_snapshot_;
 }
 
 std::vector<std::string> GlobalActivityAnalyzer::GetLogMessages() {
   std::vector<std::string> messages;
   PersistentMemoryAllocator::Reference ref;
 
   PersistentMemoryAllocator::Iterator iter(allocator_.get());
   while ((ref = iter.GetNextOfType(
               GlobalActivityTracker::kTypeIdGlobalLogMessage)) != 0) {
     const char* message = allocator_->GetAsArray<char>(
@@ skipping 25 matching lines @@
 
   return modules;
 }
 
 GlobalActivityAnalyzer::ProgramLocation
 GlobalActivityAnalyzer::GetProgramLocationFromAddress(uint64_t address) {
   // TODO(bcwhite): Implement this.
   return { 0, 0 };
 }
 
+GlobalActivityAnalyzer::UserDataSnapshot::UserDataSnapshot() {}
+GlobalActivityAnalyzer::UserDataSnapshot::UserDataSnapshot(
+    const UserDataSnapshot& rhs) = default;
+GlobalActivityAnalyzer::UserDataSnapshot::UserDataSnapshot(
+    UserDataSnapshot&& rhs) = default;
+GlobalActivityAnalyzer::UserDataSnapshot::~UserDataSnapshot() {}
+
 void GlobalActivityAnalyzer::PrepareAllAnalyzers() {
+  // Record the time when analysis started.
+  analysis_stamp_ = base::Time::Now().ToInternalValue();
+
   // Fetch all the records. This will retrieve only ones created since the
   // last run since the PMA iterator will continue from where it left off.
   uint32_t type;
   PersistentMemoryAllocator::Reference ref;
   while ((ref = allocator_iterator_.GetNext(&type)) != 0) {
     switch (type) {
       case GlobalActivityTracker::kTypeIdActivityTracker:
       case GlobalActivityTracker::kTypeIdActivityTrackerFree:
-        // Free or not, add it to the list of references for later analysis.
-        tracker_references_.insert(ref);
+      case GlobalActivityTracker::kTypeIdProcessDataRecord:
+      case GlobalActivityTracker::kTypeIdProcessDataRecordFree:
+      case PersistentMemoryAllocator::kTypeIdTransitioning:
+        // Active, free, or transitioning: add it to the list of references
+        // for later analysis.
+        memory_references_.insert(ref);
         break;
     }
   }
 
-  // Go through all the known references and create analyzers for them with
+  // Clear out any old information.
+  analyzers_.clear();
+  process_data_.clear();
+  process_ids_.clear();
+  std::set<int64_t> seen_pids;
+
+  // Go through all the known references and create objects for them with
   // snapshots of the current state.
-  analyzers_.clear();
-  for (PersistentMemoryAllocator::Reference tracker_ref : tracker_references_) {
+  for (PersistentMemoryAllocator::Reference memory_ref : memory_references_) {
     // Get the actual data segment for the tracker. This can fail if the
     // record has been marked "free" since the type will not match.

[manzagop (departed), 2017/03/21 21:10:05]

Update comment: retrieval of kTypeIdAny can't fail?

[bcwhite, 2017/03/29 22:00:51]

Done.

-    void* base = allocator_->GetAsArray<char>(
-        tracker_ref, GlobalActivityTracker::kTypeIdActivityTracker,
-        PersistentMemoryAllocator::kSizeAny);
+    void* const base = allocator_->GetAsArray<char>(
+        memory_ref, 0, PersistentMemoryAllocator::kSizeAny);

[manzagop (departed), 2017/03/21 21:10:05]

Is 0 the same as kTypeIdAny?

[bcwhite, 2017/03/29 22:00:51]

Done.

+    const size_t size = allocator_->GetAllocSize(memory_ref);
     if (!base)
       continue;
 
-    // Create the analyzer on the data. This will capture a snapshot of the
-    // tracker state. This can fail if the tracker is somehow corrupted or is
-    // in the process of shutting down.
-    std::unique_ptr<ThreadActivityAnalyzer> analyzer(new ThreadActivityAnalyzer(
-        base, allocator_->GetAllocSize(tracker_ref)));
-    if (!analyzer->IsValid())
-      continue;
-    analyzer->AddGlobalInformation(this);
+    switch (allocator_->GetType(memory_ref)) {
+      case GlobalActivityTracker::kTypeIdActivityTracker: {
+        // Create the analyzer on the data. This will capture a snapshot of the
+        // tracker state. This can fail if the tracker is somehow corrupted or
+        // is in the process of shutting down.
+        std::unique_ptr<ThreadActivityAnalyzer> analyzer(
+            new ThreadActivityAnalyzer(base, size));
+        if (!analyzer->IsValid())
+          continue;
+        analyzer->AddGlobalInformation(this);
 
-    // Add this analyzer to the map of known ones, indexed by a unique thread
-    // identifier.
-    DCHECK(!base::ContainsKey(analyzers_, analyzer->GetThreadKey()));
-    analyzer->allocator_reference_ = ref;
-    analyzers_[analyzer->GetThreadKey()] = std::move(analyzer);
+        // Track PIDs.
+        int64_t pid = analyzer->GetProcessId();
+        if (seen_pids.find(pid) == seen_pids.end()) {
+          process_ids_.push_back(pid);
+          seen_pids.insert(pid);
+        }
+
+        // Add this analyzer to the map of known ones, indexed by a unique
+        // thread
+        // identifier.
+        DCHECK(!base::ContainsKey(analyzers_, analyzer->GetThreadKey()));
+        analyzer->allocator_reference_ = ref;
+        analyzers_[analyzer->GetThreadKey()] = std::move(analyzer);
+      } break;
+
+      case GlobalActivityTracker::kTypeIdProcessDataRecord: {

[manzagop (departed), 2017/03/21 21:10:05]

Looks like a process that had no threads won't be added to process_ids_.

[bcwhite, 2017/03/29 22:00:51]

Done.

+        // Get the PID associated with this data record.
+        ProcessId process_id;
+        int64_t create_stamp;
+        ActivityUserData::GetOwningProcessId(base, &process_id, &create_stamp);
+
+        // Create a snapshot of the data. This can fail if the data is somehow
+        // corrupted or the process shutdown and the memory being released.
+        UserDataSnapshot& snapshot = process_data_[process_id];
+        snapshot.process_id = process_id;
+        snapshot.create_stamp = create_stamp;
+        const ActivityUserData process_data(base, size);
+        if (!process_data.CreateSnapshot(&snapshot.data))
+          break;
+
+        // Check that nothing changed. If it did, forget what was recorded.
+        ActivityUserData::GetOwningProcessId(base, &process_id, &create_stamp);
+        if (process_id != snapshot.process_id ||
+            create_stamp != snapshot.create_stamp) {
+          process_data_.erase(process_id);
+        }
+      } break;
+    }
   }
+
+  // Reverse the list of PIDs so that they get popped in the order found.

[manzagop (departed), 2017/03/21 21:10:05]

Is the order important? We don't seem to care about it for threads. Could we
just drop the pid vector?

[bcwhite, 2017/03/29 22:00:51]

There has to be some list of PIDs though it could be the (merged?) keys of any
map.

But I think it's worth keeping the order because then the first process (i.e.
the Browser) will be the first one returned and that might be useful during
analysis.

[manzagop (departed), 2017/03/30 18:13:24]

The retrieval by creation order sounds worth adding to the comments for
Get*Process().

[bcwhite, 2017/03/30 22:20:51]

Done.

+  std::reverse(process_ids_.begin(), process_ids_.end());
 }
 
 }  // namespace debug
 }  // namespace base