[memory-infra] Implement PollFastMemoryTotal in ProcessMetricsMemoryD…

…umpProvider.

For fast polling the dump provider keeps the /proc/<pid>/statm files
open during the tracing session.

BUG=607533

Review-Url: https://codereview.chromium.org/2568313004
Cr-Commit-Position: refs/heads/master@{#439405}

components/tracing/common/process_metrics_memory_dump_provider.cc

@@ -155,6 +155,18 @@ uint32_t ReadLinuxProcSmapsFile(FILE* smaps_file,
   }
   return num_valid_regions;
 }
+
+bool GetResidentSizeFromStatmFile(int fd, uint64_t* resident_pages) {
+  lseek(fd, 0, SEEK_SET);
+  char line[kMaxLineSize];
+  int res = read(fd, line, kMaxLineSize - 1);
+  if (res <= 0)
+    return false;
+  line[res] = '\0';
+  int num_scanned = sscanf(line, "%*s %" SCNu64, resident_pages);
+  return num_scanned == 1;
+}
+
 #endif  // defined(OS_LINUX) || defined(OS_ANDROID)
 
 std::unique_ptr<base::ProcessMetrics> CreateProcessMetrics(
@@ -183,6 +195,9 @@ uint64_t ProcessMetricsMemoryDumpProvider::rss_bytes_for_testing = 0;
 // static
 FILE* ProcessMetricsMemoryDumpProvider::proc_smaps_for_testing = nullptr;
 
+// static
+int ProcessMetricsMemoryDumpProvider::fast_polling_statm_fd_for_testing = -1;
+
 bool ProcessMetricsMemoryDumpProvider::DumpProcessMemoryMaps(
     const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* pmd) {
@@ -211,6 +226,7 @@ void ProcessMetricsMemoryDumpProvider::RegisterForProcess(
       new ProcessMetricsMemoryDumpProvider(process));
   base::trace_event::MemoryDumpProvider::Options options;
   options.target_pid = process;
+  options.is_fast_polling_supported = true;
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
       metrics_provider.get(), "ProcessMemoryMetrics", nullptr, options);
   bool did_insert =
@@ -229,9 +245,8 @@ void ProcessMetricsMemoryDumpProvider::RegisterForProcess(
 void ProcessMetricsMemoryDumpProvider::UnregisterForProcess(
     base::ProcessId process) {
   auto iter = g_dump_providers_map.Get().find(process);
-  if (iter == g_dump_providers_map.Get().end()) {
+  if (iter == g_dump_providers_map.Get().end())
     return;
-  }
   base::trace_event::MemoryDumpManager::GetInstance()
       ->UnregisterAndDeleteDumpProviderSoon(std::move(iter->second));
   g_dump_providers_map.Get().erase(iter);
@@ -322,4 +337,40 @@ bool ProcessMetricsMemoryDumpProvider::DumpProcessTotals(
   return true;
 }
 
+void ProcessMetricsMemoryDumpProvider::PollFastMemoryTotal(
+    uint64_t* memory_total) {
+  *memory_total = 0;
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+  int statm_fd = fast_polling_statm_fd_for_testing;
+  if (statm_fd == -1) {
+    if (!fast_polling_statm_fd_.is_valid()) {
+      std::string name = "/proc/" + (process_ == base::kNullProcessId
+                                         ? "self"
+                                         : base::IntToString(process_)) +
+                         "/statm";
+      fast_polling_statm_fd_.reset(open(name.c_str(), O_RDONLY));
+      DCHECK(fast_polling_statm_fd_.is_valid());
+    }
+    statm_fd = fast_polling_statm_fd_.get();
+  }
+  if (statm_fd == -1)
+    return;
+
+  uint64_t rss_pages = 0;
+  if (!GetResidentSizeFromStatmFile(statm_fd, &rss_pages))
+    return;
+
+  static size_t page_size = base::GetPageSize();
+  *memory_total = rss_pages * page_size;
+#else
+  *memory_total = process_metrics_->GetWorkingSetSize();
+#endif
+}
+
+void ProcessMetricsMemoryDumpProvider::SuspendFastMemoryPolling() {
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+  fast_polling_statm_fd_.reset();
+#endif
+}
+
 }  // namespace tracing

components/tracing/common/process_metrics_memory_dump_provider.h

@@ -7,6 +7,7 @@
 
 #include <memory>
 
+#include "base/files/scoped_file.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/process/process_handle.h"
@@ -33,11 +34,15 @@ class TRACING_EXPORT ProcessMetricsMemoryDumpProvider
   // MemoryDumpProvider implementation.
   bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                     base::trace_event::ProcessMemoryDump* pmd) override;
+  void PollFastMemoryTotal(uint64_t* memory_total) override;
+  void SuspendFastMemoryPolling() override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest,
                            ParseProcSmaps);
   FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest, DumpRSS);
+  FRIEND_TEST_ALL_PREFIXES(ProcessMetricsMemoryDumpProviderTest,
+                           TestPollFastMemoryTotal);
 
   ProcessMetricsMemoryDumpProvider(base::ProcessId process);
 
@@ -50,6 +55,9 @@ class TRACING_EXPORT ProcessMetricsMemoryDumpProvider
 
 #if defined(OS_LINUX) || defined(OS_ANDROID)
   static FILE* proc_smaps_for_testing;
+  static int fast_polling_statm_fd_for_testing;
+
+  base::ScopedFD fast_polling_statm_fd_;
 #endif
 
   base::ProcessId process_;

components/tracing/common/process_metrics_memory_dump_provider_unittest.cc

@@ -9,6 +9,8 @@
 #include <memory>
 
 #include "base/files/file_util.h"
+#include "base/memory/ptr_util.h"
+#include "base/process/process_metrics.h"
 #include "base/trace_event/process_memory_dump.h"
 #include "base/trace_event/process_memory_maps.h"
 #include "base/trace_event/process_memory_totals.h"
@@ -107,15 +109,16 @@ const char kTestSmaps2[] =
     "Locked:                0 kB\n"
     "VmFlags: rd wr mr mw me ac sd\n";
 
-void CreateAndSetSmapsFileForTesting(const char* smaps_string,
-                                     base::ScopedFILE& file) {
+const char kTestStatm[] = "200 100 20 2 3 4";
+
+void CreateTempFileWithContents(const char* contents, base::ScopedFILE* file) {
   base::FilePath temp_path;
   FILE* temp_file = CreateAndOpenTemporaryFile(&temp_path);
-  file.reset(temp_file);
+  file->reset(temp_file);
   ASSERT_TRUE(temp_file);
 
-  ASSERT_TRUE(base::WriteFileDescriptor(fileno(temp_file), smaps_string,
-                                        strlen(smaps_string)));
+  ASSERT_TRUE(
+      base::WriteFileDescriptor(fileno(temp_file), contents, strlen(contents)));
 }
 
 }  // namespace
@@ -182,7 +185,7 @@ TEST(ProcessMetricsMemoryDumpProviderTest, ParseProcSmaps) {
   base::trace_event::ProcessMemoryDump pmd_1(nullptr /* session_state */,
                                              dump_args);
   base::ScopedFILE temp_file1;
-  CreateAndSetSmapsFileForTesting(kTestSmaps1, temp_file1);
+  CreateTempFileWithContents(kTestSmaps1, &temp_file1);
   ProcessMetricsMemoryDumpProvider::proc_smaps_for_testing = temp_file1.get();
   pmmdp->OnMemoryDump(dump_args, &pmd_1);
   ASSERT_TRUE(pmd_1.has_process_mmaps());
@@ -215,7 +218,7 @@ TEST(ProcessMetricsMemoryDumpProviderTest, ParseProcSmaps) {
   base::trace_event::ProcessMemoryDump pmd_2(nullptr /* session_state */,
                                              dump_args);
   base::ScopedFILE temp_file2;
-  CreateAndSetSmapsFileForTesting(kTestSmaps2, temp_file2);
+  CreateTempFileWithContents(kTestSmaps2, &temp_file2);
   ProcessMetricsMemoryDumpProvider::proc_smaps_for_testing = temp_file2.get();
   pmmdp->OnMemoryDump(dump_args, &pmd_2);
   ASSERT_TRUE(pmd_2.has_process_mmaps());
@@ -234,4 +237,36 @@ TEST(ProcessMetricsMemoryDumpProviderTest, ParseProcSmaps) {
 }
 #endif  // defined(OS_LINUX) || defined(OS_ANDROID)
 
+TEST(ProcessMetricsMemoryDumpProviderTest, TestPollFastMemoryTotal) {
+  ProcessMetricsMemoryDumpProvider mdp(base::kNullProcessId);
+
+  uint64_t total1, total2;
+  mdp.PollFastMemoryTotal(&total1);
+  ASSERT_GT(total1, 0u);
+  size_t kBufSize = 16 * 1024 * 1024;
+  auto buf = base::MakeUnique<char[]>(kBufSize);
+  for (size_t i = 0; i < kBufSize; i++)
+    buf[i] = *((volatile char*)&buf[i]) + 1;
+  mdp.PollFastMemoryTotal(&total2);
+  ASSERT_GT(total2, 0u);
+  EXPECT_GT(total2, total1 + kBufSize / 2);
+
+#if defined(OS_LINUX) || defined(OS_ANDROID)
+  EXPECT_GE(mdp.fast_polling_statm_fd_.get(), 0);
+
+  base::ScopedFILE temp_file;
+  CreateTempFileWithContents(kTestStatm, &temp_file);
+  mdp.fast_polling_statm_fd_for_testing = fileno(temp_file.get());
+  size_t page_size = base::GetPageSize();
+  uint64_t value;
+  mdp.PollFastMemoryTotal(&value);
+  EXPECT_EQ(100 * page_size, value);
+
+  mdp.SuspendFastMemoryPolling();
+  EXPECT_FALSE(mdp.fast_polling_statm_fd_.is_valid());
+#else
+  mdp.SuspendFastMemoryPolling();
+#endif
+}
+
 }  // namespace tracing