memory-infra: Start disentangling tracing from memory-infra

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 <inttypes.h>
 #include <stdio.h>
 
 #include <algorithm>
@@ skipping 17 matching lines @@
 #include "base/trace_event/heap_profiler_allocation_context_tracker.h"
 #include "base/trace_event/heap_profiler_event_filter.h"
 #include "base/trace_event/heap_profiler_stack_frame_deduplicator.h"
 #include "base/trace_event/heap_profiler_type_name_deduplicator.h"
 #include "base/trace_event/malloc_dump_provider.h"
 #include "base/trace_event/memory_dump_provider.h"
 #include "base/trace_event/memory_dump_scheduler.h"
 #include "base/trace_event/memory_dump_session_state.h"
 #include "base/trace_event/memory_infra_background_whitelist.h"
 #include "base/trace_event/memory_peak_detector.h"
+#include "base/trace_event/memory_tracing_observer.h"
 #include "base/trace_event/process_memory_dump.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "build/build_config.h"
 
 #if defined(OS_ANDROID)
 #include "base/trace_event/java_heap_dump_provider_android.h"
 #endif
 
 namespace base {
 namespace trace_event {
 
 namespace {
 
-const int kTraceEventNumArgs = 1;
-const char* kTraceEventArgNames[] = {"dumps"};
-const unsigned char kTraceEventArgTypes[] = {TRACE_VALUE_TYPE_CONVERTABLE};
-
 StaticAtomicSequenceNumber g_next_guid;
 MemoryDumpManager* g_instance_for_testing = nullptr;
 
 // The list of names of dump providers that are blacklisted from strict thread
 // affinity check on unregistration. These providers could potentially cause
 // crashes on build bots if they do not unregister on right thread.
 // TODO(ssid): Fix all the dump providers to unregister if needed and clear the
 // blacklist, crbug.com/643438.
 const char* const kStrictThreadCheckBlacklist[] = {
     "ClientDiscardableSharedMemoryManager",
@@ skipping 125 matching lines @@
 
   // At this point the command line may not be initialized but we try to
   // enable the heap profiler to capture allocations as soon as possible.
   EnableHeapProfilingIfNeeded();
 
   strict_thread_check_blacklist_.insert(std::begin(kStrictThreadCheckBlacklist),
                                         std::end(kStrictThreadCheckBlacklist));
 }
 
 MemoryDumpManager::~MemoryDumpManager() {
-  TraceLog::GetInstance()->RemoveEnabledStateObserver(this);
 }
 
 void MemoryDumpManager::EnableHeapProfilingIfNeeded() {
   if (heap_profiling_enabled_)
     return;
 
   if (!CommandLine::InitializedForCurrentProcess() ||
       !CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableHeapProfiling))
     return;
@@ skipping 70 matching lines @@
 
     TraceConfig::EventFilters filters;
     filters.push_back(heap_profiler_filter_config);
     TraceConfig filtering_trace_config;
     filtering_trace_config.SetEventFilters(filters);
 
     TraceLog::GetInstance()->SetEnabled(filtering_trace_config,
                                         TraceLog::FILTERING_MODE);
   }
 
-  // If tracing was enabled before initializing MemoryDumpManager, we missed the
-  // OnTraceLogEnabled() event. Synthetize it so we can late-join the party.
-  // IsEnabled is called before adding observer to avoid calling
-  // OnTraceLogEnabled twice.
-  bool is_tracing_already_enabled = TraceLog::GetInstance()->IsEnabled();
-  TraceLog::GetInstance()->AddEnabledStateObserver(this);
-  if (is_tracing_already_enabled)
-    OnTraceLogEnabled();
+  trace_log_observer_ =
+      MakeUnique<MemoryTracingObserver>(TraceLog::GetInstance(), this);
 }
 
 void MemoryDumpManager::RegisterDumpProvider(
     MemoryDumpProvider* mdp,
     const char* name,
     scoped_refptr<SingleThreadTaskRunner> task_runner,
     MemoryDumpProvider::Options options) {
   options.dumps_on_single_thread_task_runner = true;
   RegisterDumpProviderInternal(mdp, name, std::move(task_runner), options);
 }
@@ skipping 428 matching lines @@
 
   TRACE_EVENT0(kTraceCategory, "MemoryDumpManager::FinalizeDumpAndAddToTrace");
 
   // The results struct to fill.
   // TODO(hjd): Transitional until we send the full PMD. See crbug.com/704203
   MemoryDumpCallbackResult result;
 
   for (const auto& kv : pmd_async_state->process_dumps) {
     ProcessId pid = kv.first;  // kNullProcessId for the current process.
     ProcessMemoryDump* process_memory_dump = kv.second.get();
-    std::unique_ptr<TracedValue> traced_value(new TracedValue);
-    process_memory_dump->AsValueInto(traced_value.get());
-    traced_value->SetString("level_of_detail",
-                            MemoryDumpLevelOfDetailToString(
-                                pmd_async_state->req_args.level_of_detail));
-    const char* const event_name =
-        MemoryDumpTypeToString(pmd_async_state->req_args.dump_type);
 
-    std::unique_ptr<ConvertableToTraceFormat> event_value(
-        std::move(traced_value));
-    TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_PROCESS_ID(
-        TRACE_EVENT_PHASE_MEMORY_DUMP,
-        TraceLog::GetCategoryGroupEnabled(kTraceCategory), event_name,
-        trace_event_internal::kGlobalScope, dump_guid, pid,
-        kTraceEventNumArgs, kTraceEventArgNames,
-        kTraceEventArgTypes, nullptr /* arg_values */, &event_value,
-        TRACE_EVENT_FLAG_HAS_ID);
+    MemoryTracingObserver::MaybeAddDumpToTrace(&pmd_async_state->req_args, pid,

[Primiano Tucci (use gerrit), 2017/04/21 10:10:26]

I'd call this AddDumpToTraceIf(Tracing)Enabled to make it sound a bit less
mysterious. I know that there is an extra subtlety about the max_dump_level, but
at least AddDumpToTraceIf(Tracing)Enabled gives a hint about the general use
case.

[hjd, 2017/04/21 11:51:57]

Done.

+                                               process_memory_dump);
 
     // TODO(hjd): Transitional until we send the full PMD. See crbug.com/704203
     // Don't try to fill the struct in detailed mode since it is hard to avoid
     // double counting.
     if (pmd_async_state->req_args.level_of_detail ==
         MemoryDumpLevelOfDetail::DETAILED)
       continue;
 
     // TODO(hjd): Transitional until we send the full PMD. See crbug.com/704203
     if (pid == kNullProcessId) {
@@ skipping 10 matching lines @@
           GetDumpsSumKb("partition_alloc/partitions/*", process_memory_dump);
       result.chrome_dump.blink_gc_total_kb =
           GetDumpsSumKb("blink_gc", process_memory_dump);
       FillOsDumpFromProcessMemoryDump(process_memory_dump, &result.os_dump);
     } else {
       auto& os_dump = result.extra_processes_dump[pid];
       FillOsDumpFromProcessMemoryDump(process_memory_dump, &os_dump);
     }
   }
 
-  bool tracing_still_enabled;
-  TRACE_EVENT_CATEGORY_GROUP_ENABLED(kTraceCategory, &tracing_still_enabled);
-  if (!tracing_still_enabled) {
-    pmd_async_state->dump_successful = false;
-    VLOG(1) << kLogPrefix << " failed because tracing was disabled before"
-            << " the dump was completed";
-  }
-
   if (!pmd_async_state->callback.is_null()) {
     pmd_async_state->callback.Run(dump_guid, pmd_async_state->dump_successful);
     pmd_async_state->callback.Reset();
   }
 
   TRACE_EVENT_NESTABLE_ASYNC_END0(kTraceCategory, "ProcessMemoryDump",
                                   TRACE_ID_LOCAL(dump_guid));
 }
 
-void MemoryDumpManager::OnTraceLogEnabled() {
-  bool enabled;
-  TRACE_EVENT_CATEGORY_GROUP_ENABLED(kTraceCategory, &enabled);
-  if (!enabled)
-    return;
-
+void MemoryDumpManager::Enable(
+    const TraceConfig::MemoryDumpConfig& memory_dump_config) {

[Primiano Tucci (use gerrit), 2017/04/21 10:10:26]

okay for the moment, but I think that in the next CL we should rip this out
(i.e. the TraceConfig argument) and move the IsDumpModeAllowed to the observer.

[hjd, 2017/04/21 11:51:57]

Acknowledged.

   // Initialize the TraceLog for the current thread. This is to avoid that the
   // TraceLog memory dump provider is registered lazily in the PostTask() below
   // while the |lock_| is taken;
   TraceLog::GetInstance()->InitializeThreadLocalEventBufferIfSupported();

[Primiano Tucci (use gerrit), 2017/04/21 10:10:26]

I think this should also be moved to the MTO

[hjd, 2017/04/21 11:51:57]

Done.

 
   // Spin-up the thread used to invoke unbound dump providers.
   std::unique_ptr<Thread> dump_thread(new Thread("MemoryInfra"));
   if (!dump_thread->Start()) {
     LOG(ERROR) << "Failed to start the memory-infra thread for tracing";
     return;
   }
 
-  const TraceConfig& trace_config =
-      TraceLog::GetInstance()->GetCurrentTraceConfig();
-  const TraceConfig::MemoryDumpConfig& memory_dump_config =
-      trace_config.memory_dump_config();
   scoped_refptr<MemoryDumpSessionState> session_state =
       new MemoryDumpSessionState;
   session_state->SetAllowedDumpModes(memory_dump_config.allowed_dump_modes);
   session_state->set_heap_profiler_breakdown_threshold_bytes(
       memory_dump_config.heap_profiler_options.breakdown_threshold_bytes);
   if (heap_profiling_enabled_) {
     // If heap profiling is enabled, the stack frame deduplicator and type name
     // deduplicator will be in use. Add a metadata events to write the frames
     // and type IDs.
     session_state->SetStackFrameDeduplicator(
@@ skipping 64 matching lines @@
     }
   }
 
   // Only coordinator process triggers periodic global memory dumps.
   if (delegate_->IsCoordinator() && !periodic_config.triggers.empty()) {
     MemoryDumpScheduler::GetInstance()->Start(periodic_config,
                                               dump_thread_->task_runner());
   }
 }
 
-void MemoryDumpManager::OnTraceLogDisabled() {
+void MemoryDumpManager::Disable() {
   // 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;
   {
     AutoLock lock(lock_);
     MemoryDumpScheduler::GetInstance()->Stop();
@@ skipping 41 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