[memory-infra] Make MemoryDumpScheduler non-thread safe singleton

base/trace_event/memory_dump_manager.cc

 // Copyright 2015 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/trace_event/memory_dump_manager.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/allocator/features.h"
@@ skipping 400 matching lines @@
 
 void MemoryDumpManager::RegisterPollingMDPOnDumpThread(
     scoped_refptr<MemoryDumpManager::MemoryDumpProviderInfo> mdpinfo) {
   AutoLock lock(lock_);
   dump_providers_for_polling_.insert(mdpinfo);
 
   // Notify ready for polling when first polling supported provider is
   // registered. This handles the case where OnTraceLogEnabled() did not notify
   // ready since no polling supported mdp has yet been registered.
   if (dump_providers_for_polling_.size() == 1)
-    dump_scheduler_->NotifyPollingSupported();
+    MemoryDumpScheduler::GetInstance()->EnablePollingIfNeeded();
 }
 
 void MemoryDumpManager::UnregisterPollingMDPOnDumpThread(
     scoped_refptr<MemoryDumpManager::MemoryDumpProviderInfo> mdpinfo) {
   mdpinfo->dump_provider->SuspendFastMemoryPolling();
 
   AutoLock lock(lock_);
   dump_providers_for_polling_.erase(mdpinfo);
   DCHECK(!dump_providers_for_polling_.empty())
       << "All polling MDPs cannot be unregistered.";
@@ skipping 73 matching lines @@
     pmd_async_state.reset(new ProcessMemoryDumpAsyncState(
         args, dump_providers_, session_state_, callback,
         dump_thread_ ? dump_thread_->task_runner() : nullptr));
 
     // Safety check to prevent reaching here without calling RequestGlobalDump,
     // with disallowed modes. If |session_state_| is null then tracing is
     // disabled.
     CHECK(!session_state_ ||
           session_state_->IsDumpModeAllowed(args.level_of_detail));
 
-    if (dump_scheduler_)
-      dump_scheduler_->NotifyDumpTriggered();
+    MemoryDumpScheduler::GetInstance()->NotifyDumpTriggered();
   }
 
   TRACE_EVENT_WITH_FLOW0(kTraceCategory, "MemoryDumpManager::CreateProcessDump",
                          TRACE_ID_MANGLE(args.dump_guid),
                          TRACE_EVENT_FLAG_FLOW_OUT);
 
   // Start the process dump. This involves task runner hops as specified by the
   // MemoryDumpProvider(s) in RegisterDumpProvider()).
   SetupNextMemoryDump(std::move(pmd_async_state));
 }
@@ skipping 292 matching lines @@
         MakeUnique<SessionStateConvertableProxy<StackFrameDeduplicator>>(
             session_state, &MemoryDumpSessionState::stack_frame_deduplicator));
 
     TRACE_EVENT_API_ADD_METADATA_EVENT(
         TraceLog::GetCategoryGroupEnabled("__metadata"), "typeNames",
         "typeNames",
         MakeUnique<SessionStateConvertableProxy<TypeNameDeduplicator>>(
             session_state, &MemoryDumpSessionState::type_name_deduplicator));
   }
 
-  std::unique_ptr<MemoryDumpScheduler> dump_scheduler(
-      new MemoryDumpScheduler(this, dump_thread->task_runner()));
-  DCHECK_LE(memory_dump_config.triggers.size(), 3u);
-  for (const auto& trigger : memory_dump_config.triggers) {
-    if (!session_state->IsDumpModeAllowed(trigger.level_of_detail)) {
-      NOTREACHED();
-      continue;
-    }
-    dump_scheduler->AddTrigger(trigger.trigger_type, trigger.level_of_detail,
-                               trigger.min_time_between_dumps_ms);
-  }
-
   {
     AutoLock lock(lock_);
 
     DCHECK(delegate_);  // At this point we must have a delegate.
     session_state_ = session_state;
 
     DCHECK(!dump_thread_);
     dump_thread_ = std::move(dump_thread);
-    dump_scheduler_ = std::move(dump_scheduler);
 
     subtle::NoBarrier_Store(&memory_tracing_enabled_, 1);
 
     dump_providers_for_polling_.clear();
     for (const auto& mdpinfo : dump_providers_) {
       if (mdpinfo->options.is_fast_polling_supported)
         dump_providers_for_polling_.insert(mdpinfo);
     }
+
+    MemoryDumpScheduler* dump_scheduler = MemoryDumpScheduler::GetInstance();
+    dump_scheduler->Setup(this, dump_thread_->task_runner());
+    DCHECK_LE(memory_dump_config.triggers.size(), 3u);
+    for (const auto& trigger : memory_dump_config.triggers) {
+      if (!session_state_->IsDumpModeAllowed(trigger.level_of_detail)) {
+        NOTREACHED();
+        continue;
+      }
+      dump_scheduler->AddTrigger(trigger.trigger_type, trigger.level_of_detail,
+                                 trigger.min_time_between_dumps_ms);
+    }
+
     // Notify polling supported only if some polling supported provider was
     // registered, else RegisterPollingMDPOnDumpThread() will notify when first
     // polling MDP registers.
     if (!dump_providers_for_polling_.empty())
-      dump_scheduler_->NotifyPollingSupported();
+      dump_scheduler->EnablePollingIfNeeded();
 
     // Only coordinator process triggers periodic global memory dumps.
     if (delegate_->IsCoordinator())
-      dump_scheduler_->NotifyPeriodicTriggerSupported();
+      dump_scheduler->EnablePeriodicTriggerIfNeeded();
   }
 
 }
 
 void MemoryDumpManager::OnTraceLogDisabled() {
   // There might be a memory dump in progress while this happens. Therefore,
   // ensure that the MDM state which depends on the tracing enabled / disabled
   // state is always accessed by the dumping methods holding the |lock_|.
   if (!subtle::NoBarrier_Load(&memory_tracing_enabled_))
     return;
   subtle::NoBarrier_Store(&memory_tracing_enabled_, 0);
   std::unique_ptr<Thread> dump_thread;
-  std::unique_ptr<MemoryDumpScheduler> scheduler;
   {
     AutoLock lock(lock_);
     dump_thread = std::move(dump_thread_);
     session_state_ = nullptr;
-    scheduler = std::move(dump_scheduler_);
+    MemoryDumpScheduler::GetInstance()->DisableAllTriggers();
   }
-  scheduler->DisableAllTriggers();
 
   // Thread stops are blocking and must be performed outside of the |lock_|
   // or will deadlock (e.g., if SetupNextMemoryDump() tries to acquire it).
   if (dump_thread)
     dump_thread->Stop();
 
   // |dump_providers_for_polling_| must be cleared only after the dump thread is
   // stopped (polling tasks are done).
   {
     AutoLock lock(lock_);
@@ skipping 64 matching lines @@
   if (iter == process_dumps.end()) {
     std::unique_ptr<ProcessMemoryDump> new_pmd(
         new ProcessMemoryDump(session_state, dump_args));
     iter = process_dumps.insert(std::make_pair(pid, std::move(new_pmd))).first;
   }
   return iter->second.get();
 }
 
 }  // namespace trace_event
 }  // namespace base