Reland of [tracing] Dump child processes' memory metrics in browser

base/trace_event/process_memory_maps_dump_provider.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/process_memory_maps_dump_provider.h"
-
-#include <stdint.h>
-
-#include "base/files/scoped_file.h"
-#include "base/format_macros.h"
-#include "base/logging.h"
-#include "base/strings/string_util.h"
-#include "base/trace_event/process_memory_dump.h"
-#include "base/trace_event/process_memory_maps.h"
-
-namespace base {
-namespace trace_event {
-
-// static
-FILE* ProcessMemoryMapsDumpProvider::proc_smaps_for_testing = nullptr;
-
-namespace {
-
-const uint32_t kMaxLineSize = 4096;
-
-bool ParseSmapsHeader(const char* header_line,
-                      ProcessMemoryMaps::VMRegion* region) {
-  // e.g., "00400000-00421000 r-xp 00000000 fc:01 1234  /foo.so\n"
-  bool res = true;  // Whether this region should be appended or skipped.
-  uint64_t end_addr = 0;
-  char protection_flags[5] = {0};
-  char mapped_file[kMaxLineSize];
-
-  if (sscanf(header_line, "%" SCNx64 "-%" SCNx64 " %4c %*s %*s %*s%4095[^\n]\n",
-             &region->start_address, &end_addr, protection_flags,
-             mapped_file) != 4)
-    return false;
-
-  if (end_addr > region->start_address) {
-    region->size_in_bytes = end_addr - region->start_address;
-  } else {
-    // This is not just paranoia, it can actually happen (See crbug.com/461237).
-    region->size_in_bytes = 0;
-    res = false;
-  }
-
-  region->protection_flags = 0;
-  if (protection_flags[0] == 'r') {
-    region->protection_flags |=
-        ProcessMemoryMaps::VMRegion::kProtectionFlagsRead;
-  }
-  if (protection_flags[1] == 'w') {
-    region->protection_flags |=
-        ProcessMemoryMaps::VMRegion::kProtectionFlagsWrite;
-  }
-  if (protection_flags[2] == 'x') {
-    region->protection_flags |=
-        ProcessMemoryMaps::VMRegion::kProtectionFlagsExec;
-  }
-
-  region->mapped_file = mapped_file;
-  TrimWhitespaceASCII(region->mapped_file, TRIM_ALL, &region->mapped_file);
-
-  return res;
-}
-
-uint64_t ReadCounterBytes(char* counter_line) {
-  uint64_t counter_value = 0;
-  int res = sscanf(counter_line, "%*s %" SCNu64 " kB", &counter_value);
-  DCHECK_EQ(1, res);
-  return counter_value * 1024;
-}
-
-uint32_t ParseSmapsCounter(char* counter_line,
-                           ProcessMemoryMaps::VMRegion* region) {
-  // A smaps counter lines looks as follows: "RSS:  0 Kb\n"
-  uint32_t res = 1;
-  char counter_name[20];
-  int did_read = sscanf(counter_line, "%19[^\n ]", counter_name);
-  DCHECK_EQ(1, did_read);
-
-  if (strcmp(counter_name, "Pss:") == 0) {
-    region->byte_stats_proportional_resident = ReadCounterBytes(counter_line);
-  } else if (strcmp(counter_name, "Private_Dirty:") == 0) {
-    region->byte_stats_private_dirty_resident = ReadCounterBytes(counter_line);
-  } else if (strcmp(counter_name, "Private_Clean:") == 0) {
-    region->byte_stats_private_clean_resident = ReadCounterBytes(counter_line);
-  } else if (strcmp(counter_name, "Shared_Dirty:") == 0) {
-    region->byte_stats_shared_dirty_resident = ReadCounterBytes(counter_line);
-  } else if (strcmp(counter_name, "Shared_Clean:") == 0) {
-    region->byte_stats_shared_clean_resident = ReadCounterBytes(counter_line);
-  } else if (strcmp(counter_name, "Swap:") == 0) {
-    region->byte_stats_swapped = ReadCounterBytes(counter_line);
-  } else {
-    res = 0;
-  }
-
-  return res;
-}
-
-uint32_t ReadLinuxProcSmapsFile(FILE* smaps_file, ProcessMemoryMaps* pmm) {
-  if (!smaps_file)
-    return 0;
-
-  fseek(smaps_file, 0, SEEK_SET);
-
-  char line[kMaxLineSize];
-  const uint32_t kNumExpectedCountersPerRegion = 6;
-  uint32_t counters_parsed_for_current_region = 0;
-  uint32_t num_valid_regions = 0;
-  ProcessMemoryMaps::VMRegion region;
-  bool should_add_current_region = false;
-  for (;;) {
-    line[0] = '\0';
-    if (fgets(line, kMaxLineSize, smaps_file) == nullptr)
-      break;
-    DCHECK_GT(strlen(line), 0u);
-    if (isxdigit(line[0]) && !isupper(line[0])) {
-      region = ProcessMemoryMaps::VMRegion();
-      counters_parsed_for_current_region = 0;
-      should_add_current_region = ParseSmapsHeader(line, &region);
-    } else {
-      counters_parsed_for_current_region += ParseSmapsCounter(line, &region);
-      DCHECK_LE(counters_parsed_for_current_region,
-                kNumExpectedCountersPerRegion);
-      if (counters_parsed_for_current_region == kNumExpectedCountersPerRegion) {
-        if (should_add_current_region) {
-          pmm->AddVMRegion(region);
-          ++num_valid_regions;
-          should_add_current_region = false;
-        }
-      }
-    }
-  }
-  return num_valid_regions;
-}
-
-}  // namespace
-
-// static
-ProcessMemoryMapsDumpProvider* ProcessMemoryMapsDumpProvider::GetInstance() {
-  return Singleton<ProcessMemoryMapsDumpProvider,
-                   LeakySingletonTraits<ProcessMemoryMapsDumpProvider>>::get();
-}
-
-ProcessMemoryMapsDumpProvider::ProcessMemoryMapsDumpProvider() {
-}
-
-ProcessMemoryMapsDumpProvider::~ProcessMemoryMapsDumpProvider() {
-}
-
-// Called at trace dump point time. Creates a snapshot of the memory maps for
-// the current process.
-bool ProcessMemoryMapsDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,
-                                                 ProcessMemoryDump* pmd) {
-  // Snapshot of memory maps is not taken for light dump requests.
-  if (args.level_of_detail == MemoryDumpLevelOfDetail::LIGHT)
-    return true;
-
-  uint32_t res = 0;
-  if (UNLIKELY(proc_smaps_for_testing)) {
-    res = ReadLinuxProcSmapsFile(proc_smaps_for_testing, pmd->process_mmaps());
-  } else {
-    ScopedFILE smaps_file(fopen("/proc/self/smaps", "r"));
-    res = ReadLinuxProcSmapsFile(smaps_file.get(), pmd->process_mmaps());
-  }
-
-  if (res > 0) {
-    pmd->set_has_process_mmaps();
-    return true;
-  }
-  return false;
-}
-
-}  // namespace trace_event
-}  // namespace base