Update from https://crrev.com/316786

base/metrics/stats_table.cc

Index: base/metrics/stats_table.cc
diff --git a/base/metrics/stats_table.cc b/base/metrics/stats_table.cc
deleted file mode 100644
index 0986395dd9841d87ddb1230715ffbc6adcf66227..0000000000000000000000000000000000000000
--- a/base/metrics/stats_table.cc
+++ /dev/null
@@ -1,617 +0,0 @@
-// Copyright (c) 2011 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/metrics/stats_table.h"
-
-#include "base/logging.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/shared_memory.h"
-#include "base/process/process_handle.h"
-#include "base/strings/string_piece.h"
-#include "base/strings/string_util.h"
-#include "base/strings/utf_string_conversions.h"
-#include "base/threading/platform_thread.h"
-#include "base/threading/thread_local_storage.h"
-
-namespace base {
-
-// The StatsTable uses a shared memory segment that is laid out as follows
-//
-// +-------------------------------------------+
-// | Version | Size | MaxCounters | MaxThreads |
-// +-------------------------------------------+
-// | Thread names table                        |
-// +-------------------------------------------+
-// | Thread TID table                          |
-// +-------------------------------------------+
-// | Thread PID table                          |
-// +-------------------------------------------+
-// | Counter names table                       |
-// +-------------------------------------------+
-// | Data                                      |
-// +-------------------------------------------+
-//
-// The data layout is a grid, where the columns are the thread_ids and the
-// rows are the counter_ids.
-//
-// If the first character of the thread_name is '\0', then that column is
-// empty.
-// If the first character of the counter_name is '\0', then that row is
-// empty.
-//
-// About Locking:
-// This class is designed to be both multi-thread and multi-process safe.
-// Aside from initialization, this is done by partitioning the data which
-// each thread uses so that no locking is required.  However, to allocate
-// the rows and columns of the table to particular threads, locking is
-// required.
-//
-// At the shared-memory level, we have a lock.  This lock protects the
-// shared-memory table only, and is used when we create new counters (e.g.
-// use rows) or when we register new threads (e.g. use columns).  Reading
-// data from the table does not require any locking at the shared memory
-// level.
-//
-// Each process which accesses the table will create a StatsTable object.
-// The StatsTable maintains a hash table of the existing counters in the
-// table for faster lookup.  Since the hash table is process specific,
-// each process maintains its own cache.  We avoid complexity here by never
-// de-allocating from the hash table.  (Counters are dynamically added,
-// but not dynamically removed).
-
-// In order for external viewers to be able to read our shared memory,
-// we all need to use the same size ints.
-COMPILE_ASSERT(sizeof(int)==4, expect_4_byte_ints);
-
-namespace {
-
-// An internal version in case we ever change the format of this
-// file, and so that we can identify our table.
-const int kTableVersion = 0x13131313;
-
-// The name for un-named counters and threads in the table.
-const char kUnknownName[] = "<unknown>";
-
-// Calculates delta to align an offset to the size of an int
-inline int AlignOffset(int offset) {
-  return (sizeof(int) - (offset % sizeof(int))) % sizeof(int);
-}
-
-inline int AlignedSize(int size) {
-  return size + AlignOffset(size);
-}
-
-}  // namespace
-
-// The StatsTable::Internal maintains convenience pointers into the
-// shared memory segment.  Use this class to keep the data structure
-// clean and accessible.
-class StatsTable::Internal {
- public:
-  // Various header information contained in the memory mapped segment.
-  struct TableHeader {
-    int version;
-    int size;
-    int max_counters;
-    int max_threads;
-  };
-
-  // Construct a new Internal based on expected size parameters, or
-  // return NULL on failure.
-  static Internal* New(const StatsTable::TableIdentifier& table,
-                       int size,
-                       int max_threads,
-                       int max_counters);
-
-  SharedMemory* shared_memory() { return shared_memory_.get(); }
-
-  // Accessors for our header pointers
-  TableHeader* table_header() const { return table_header_; }
-  int version() const { return table_header_->version; }
-  int size() const { return table_header_->size; }
-  int max_counters() const { return table_header_->max_counters; }
-  int max_threads() const { return table_header_->max_threads; }
-
-  // Accessors for our tables
-  char* thread_name(int slot_id) const {
-    return &thread_names_table_[
-      (slot_id-1) * (StatsTable::kMaxThreadNameLength)];
-  }
-  PlatformThreadId* thread_tid(int slot_id) const {
-    return &(thread_tid_table_[slot_id-1]);
-  }
-  int* thread_pid(int slot_id) const {
-    return &(thread_pid_table_[slot_id-1]);
-  }
-  char* counter_name(int counter_id) const {
-    return &counter_names_table_[
-      (counter_id-1) * (StatsTable::kMaxCounterNameLength)];
-  }
-  int* row(int counter_id) const {
-    return &data_table_[(counter_id-1) * max_threads()];
-  }
-
- private:
-  // Constructor is private because you should use New() instead.
-  explicit Internal(SharedMemory* shared_memory)
-      : shared_memory_(shared_memory),
-        table_header_(NULL),
-        thread_names_table_(NULL),
-        thread_tid_table_(NULL),
-        thread_pid_table_(NULL),
-        counter_names_table_(NULL),
-        data_table_(NULL) {
-  }
-
-  // Create or open the SharedMemory used by the stats table.
-  static SharedMemory* CreateSharedMemory(
-      const StatsTable::TableIdentifier& table,
-      int size);
-
-  // Initializes the table on first access.  Sets header values
-  // appropriately and zeroes all counters.
-  void InitializeTable(void* memory, int size, int max_counters,
-                       int max_threads);
-
-  // Initializes our in-memory pointers into a pre-created StatsTable.
-  void ComputeMappedPointers(void* memory);
-
-  scoped_ptr<SharedMemory> shared_memory_;
-  TableHeader* table_header_;
-  char* thread_names_table_;
-  PlatformThreadId* thread_tid_table_;
-  int* thread_pid_table_;
-  char* counter_names_table_;
-  int* data_table_;
-
-  DISALLOW_COPY_AND_ASSIGN(Internal);
-};
-
-// static
-StatsTable::Internal* StatsTable::Internal::New(
-    const StatsTable::TableIdentifier& table,
-    int size,
-    int max_threads,
-    int max_counters) {
-  scoped_ptr<SharedMemory> shared_memory(CreateSharedMemory(table, size));
-  if (!shared_memory.get())
-    return NULL;
-  if (!shared_memory->Map(size))
-    return NULL;
-  void* memory = shared_memory->memory();
-
-  scoped_ptr<Internal> internal(new Internal(shared_memory.release()));
-  TableHeader* header = static_cast<TableHeader*>(memory);
-
-  // If the version does not match, then assume the table needs
-  // to be initialized.
-  if (header->version != kTableVersion)
-    internal->InitializeTable(memory, size, max_counters, max_threads);
-
-  // We have a valid table, so compute our pointers.
-  internal->ComputeMappedPointers(memory);
-
-  return internal.release();
-}
-
-// static
-SharedMemory* StatsTable::Internal::CreateSharedMemory(
-    const StatsTable::TableIdentifier& table,
-    int size) {
-#if defined(OS_POSIX)
-  // Check for existing table.
-  if (table.fd != -1)
-    return new SharedMemory(table, false);
-
-  // Otherwise we need to create it.
-  scoped_ptr<SharedMemory> shared_memory(new SharedMemory());
-  if (!shared_memory->CreateAnonymous(size))
-    return NULL;
-  return shared_memory.release();
-#elif defined(OS_WIN)
-  scoped_ptr<SharedMemory> shared_memory(new SharedMemory());
-  if (table.empty()) {
-    // Create an anonymous table.
-    if (!shared_memory->CreateAnonymous(size))
-      return NULL;
-  } else {
-    // Create a named table for sharing between processes.
-    if (!shared_memory->CreateNamedDeprecated(table, true, size))
-      return NULL;
-  }
-  return shared_memory.release();
-#endif
-}
-
-void StatsTable::Internal::InitializeTable(void* memory, int size,
-                                           int max_counters,
-                                           int max_threads) {
-  // Zero everything.
-  memset(memory, 0, size);
-
-  // Initialize the header.
-  TableHeader* header = static_cast<TableHeader*>(memory);
-  header->version = kTableVersion;
-  header->size = size;
-  header->max_counters = max_counters;
-  header->max_threads = max_threads;
-}
-
-void StatsTable::Internal::ComputeMappedPointers(void* memory) {
-  char* data = static_cast<char*>(memory);
-  int offset = 0;
-
-  table_header_ = reinterpret_cast<TableHeader*>(data);
-  offset += sizeof(*table_header_);
-  offset += AlignOffset(offset);
-
-  // Verify we're looking at a valid StatsTable.
-  DCHECK_EQ(table_header_->version, kTableVersion);
-
-  thread_names_table_ = reinterpret_cast<char*>(data + offset);
-  offset += sizeof(char) *
-            max_threads() * StatsTable::kMaxThreadNameLength;
-  offset += AlignOffset(offset);
-
-  thread_tid_table_ = reinterpret_cast<PlatformThreadId*>(data + offset);
-  offset += sizeof(int) * max_threads();
-  offset += AlignOffset(offset);
-
-  thread_pid_table_ = reinterpret_cast<int*>(data + offset);
-  offset += sizeof(int) * max_threads();
-  offset += AlignOffset(offset);
-
-  counter_names_table_ = reinterpret_cast<char*>(data + offset);
-  offset += sizeof(char) *
-            max_counters() * StatsTable::kMaxCounterNameLength;
-  offset += AlignOffset(offset);
-
-  data_table_ = reinterpret_cast<int*>(data + offset);
-  offset += sizeof(int) * max_threads() * max_counters();
-
-  DCHECK_EQ(offset, size());
-}
-
-// TLSData carries the data stored in the TLS slots for the
-// StatsTable.  This is used so that we can properly cleanup when the
-// thread exits and return the table slot.
-//
-// Each thread that calls RegisterThread in the StatsTable will have
-// a TLSData stored in its TLS.
-struct StatsTable::TLSData {
-  StatsTable* table;
-  int slot;
-};
-
-// We keep a singleton table which can be easily accessed.
-StatsTable* global_table = NULL;
-
-StatsTable::StatsTable(const TableIdentifier& table,
-                       int max_threads,
-                       int max_counters)
-    : internal_(NULL),
-      tls_index_(SlotReturnFunction) {
-  int table_size =
-    AlignedSize(sizeof(Internal::TableHeader)) +
-    AlignedSize((max_counters * sizeof(char) * kMaxCounterNameLength)) +
-    AlignedSize((max_threads * sizeof(char) * kMaxThreadNameLength)) +
-    AlignedSize(max_threads * sizeof(int)) +
-    AlignedSize(max_threads * sizeof(int)) +
-    AlignedSize((sizeof(int) * (max_counters * max_threads)));
-
-  internal_ = Internal::New(table, table_size, max_threads, max_counters);
-
-  if (!internal_)
-    DPLOG(ERROR) << "StatsTable did not initialize";
-}
-
-StatsTable::~StatsTable() {
-  // Before we tear down our copy of the table, be sure to
-  // unregister our thread.
-  UnregisterThread();
-
-  // Return ThreadLocalStorage.  At this point, if any registered threads
-  // still exist, they cannot Unregister.
-  tls_index_.Free();
-
-  // Cleanup our shared memory.
-  delete internal_;
-
-  // If we are the global table, unregister ourselves.
-  if (global_table == this)
-    global_table = NULL;
-}
-
-StatsTable* StatsTable::current() {
-  return global_table;
-}
-
-void StatsTable::set_current(StatsTable* value) {
-  global_table = value;
-}
-
-int StatsTable::GetSlot() const {
-  TLSData* data = GetTLSData();
-  if (!data)
-    return 0;
-  return data->slot;
-}
-
-int StatsTable::RegisterThread(const std::string& name) {
-  int slot = 0;
-  if (!internal_)
-    return 0;
-
-  // Registering a thread requires that we lock the shared memory
-  // so that two threads don't grab the same slot.  Fortunately,
-  // thread creation shouldn't happen in inner loops.
-  // TODO(viettrungluu): crbug.com/345734: Use a different locking mechanism.
-  {
-    SharedMemoryAutoLockDeprecated lock(internal_->shared_memory());
-    slot = FindEmptyThread();
-    if (!slot) {
-      return 0;
-    }
-
-    // We have space, so consume a column in the table.
-    std::string thread_name = name;
-    if (name.empty())
-      thread_name = kUnknownName;
-    strlcpy(internal_->thread_name(slot), thread_name.c_str(),
-            kMaxThreadNameLength);
-    *(internal_->thread_tid(slot)) = PlatformThread::CurrentId();
-    *(internal_->thread_pid(slot)) = GetCurrentProcId();
-  }
-
-  // Set our thread local storage.
-  TLSData* data = new TLSData;
-  data->table = this;
-  data->slot = slot;
-  tls_index_.Set(data);
-  return slot;
-}
-
-int StatsTable::CountThreadsRegistered() const {
-  if (!internal_)
-    return 0;
-
-  // Loop through the shared memory and count the threads that are active.
-  // We intentionally do not lock the table during the operation.
-  int count = 0;
-  for (int index = 1; index <= internal_->max_threads(); index++) {
-    char* name = internal_->thread_name(index);
-    if (*name != '\0')
-      count++;
-  }
-  return count;
-}
-
-int StatsTable::FindCounter(const std::string& name) {
-  // Note: the API returns counters numbered from 1..N, although
-  // internally, the array is 0..N-1.  This is so that we can return
-  // zero as "not found".
-  if (!internal_)
-    return 0;
-
-  // Create a scope for our auto-lock.
-  {
-    AutoLock scoped_lock(counters_lock_);
-
-    // Attempt to find the counter.
-    CountersMap::const_iterator iter;
-    iter = counters_.find(name);
-    if (iter != counters_.end())
-      return iter->second;
-  }
-
-  // Counter does not exist, so add it.
-  return AddCounter(name);
-}
-
-int* StatsTable::GetLocation(int counter_id, int slot_id) const {
-  if (!internal_)
-    return NULL;
-  if (slot_id > internal_->max_threads())
-    return NULL;
-
-  int* row = internal_->row(counter_id);
-  return &(row[slot_id-1]);
-}
-
-const char* StatsTable::GetRowName(int index) const {
-  if (!internal_)
-    return NULL;
-
-  return internal_->counter_name(index);
-}
-
-int StatsTable::GetRowValue(int index) const {
-  return GetRowValue(index, 0);
-}
-
-int StatsTable::GetRowValue(int index, int pid) const {
-  if (!internal_)
-    return 0;
-
-  int rv = 0;
-  int* row = internal_->row(index);
-  for (int slot_id = 1; slot_id <= internal_->max_threads(); slot_id++) {
-    if (pid == 0 || *internal_->thread_pid(slot_id) == pid)
-      rv += row[slot_id-1];
-  }
-  return rv;
-}
-
-int StatsTable::GetCounterValue(const std::string& name) {
-  return GetCounterValue(name, 0);
-}
-
-int StatsTable::GetCounterValue(const std::string& name, int pid) {
-  if (!internal_)
-    return 0;
-
-  int row = FindCounter(name);
-  if (!row)
-    return 0;
-  return GetRowValue(row, pid);
-}
-
-int StatsTable::GetMaxCounters() const {
-  if (!internal_)
-    return 0;
-  return internal_->max_counters();
-}
-
-int StatsTable::GetMaxThreads() const {
-  if (!internal_)
-    return 0;
-  return internal_->max_threads();
-}
-
-int* StatsTable::FindLocation(const char* name) {
-  // Get the static StatsTable
-  StatsTable *table = StatsTable::current();
-  if (!table)
-    return NULL;
-
-  // Get the slot for this thread.  Try to register
-  // it if none exists.
-  int slot = table->GetSlot();
-  if (!slot)
-    slot = table->RegisterThread(std::string());
-  if (!slot)
-    return NULL;
-
-  // Find the counter id for the counter.
-  std::string str_name(name);
-  int counter = table->FindCounter(str_name);
-
-  // Now we can find the location in the table.
-  return table->GetLocation(counter, slot);
-}
-
-void StatsTable::UnregisterThread() {
-  UnregisterThread(GetTLSData());
-}
-
-void StatsTable::UnregisterThread(TLSData* data) {
-  if (!data)
-    return;
-  DCHECK(internal_);
-
-  // Mark the slot free by zeroing out the thread name.
-  char* name = internal_->thread_name(data->slot);
-  *name = '\0';
-
-  // Remove the calling thread's TLS so that it cannot use the slot.
-  tls_index_.Set(NULL);
-  delete data;
-}
-
-void StatsTable::SlotReturnFunction(void* data) {
-  // This is called by the TLS destructor, which on some platforms has
-  // already cleared the TLS info, so use the tls_data argument
-  // rather than trying to fetch it ourselves.
-  TLSData* tls_data = static_cast<TLSData*>(data);
-  if (tls_data) {
-    DCHECK(tls_data->table);
-    tls_data->table->UnregisterThread(tls_data);
-  }
-}
-
-int StatsTable::FindEmptyThread() const {
-  // Note: the API returns slots numbered from 1..N, although
-  // internally, the array is 0..N-1.  This is so that we can return
-  // zero as "not found".
-  //
-  // The reason for doing this is because the thread 'slot' is stored
-  // in TLS, which is always initialized to zero, not -1.  If 0 were
-  // returned as a valid slot number, it would be confused with the
-  // uninitialized state.
-  if (!internal_)
-    return 0;
-
-  int index = 1;
-  for (; index <= internal_->max_threads(); index++) {
-    char* name = internal_->thread_name(index);
-    if (!*name)
-      break;
-  }
-  if (index > internal_->max_threads())
-    return 0;  // The table is full.
-  return index;
-}
-
-int StatsTable::FindCounterOrEmptyRow(const std::string& name) const {
-  // Note: the API returns slots numbered from 1..N, although
-  // internally, the array is 0..N-1.  This is so that we can return
-  // zero as "not found".
-  //
-  // There isn't much reason for this other than to be consistent
-  // with the way we track columns for thread slots.  (See comments
-  // in FindEmptyThread for why it is done this way).
-  if (!internal_)
-    return 0;
-
-  int free_slot = 0;
-  for (int index = 1; index <= internal_->max_counters(); index++) {
-    char* row_name = internal_->counter_name(index);
-    if (!*row_name && !free_slot)
-      free_slot = index;  // save that we found a free slot
-    else if (!strncmp(row_name, name.c_str(), kMaxCounterNameLength))
-      return index;
-  }
-  return free_slot;
-}
-
-int StatsTable::AddCounter(const std::string& name) {
-  if (!internal_)
-    return 0;
-
-  int counter_id = 0;
-  {
-    // To add a counter to the shared memory, we need the
-    // shared memory lock.
-    SharedMemoryAutoLockDeprecated lock(internal_->shared_memory());
-
-    // We have space, so create a new counter.
-    counter_id = FindCounterOrEmptyRow(name);
-    if (!counter_id)
-      return 0;
-
-    std::string counter_name = name;
-    if (name.empty())
-      counter_name = kUnknownName;
-    strlcpy(internal_->counter_name(counter_id), counter_name.c_str(),
-            kMaxCounterNameLength);
-  }
-
-  // now add to our in-memory cache
-  {
-    AutoLock lock(counters_lock_);
-    counters_[name] = counter_id;
-  }
-  return counter_id;
-}
-
-StatsTable::TLSData* StatsTable::GetTLSData() const {
-  TLSData* data =
-    static_cast<TLSData*>(tls_index_.Get());
-  if (!data)
-    return NULL;
-
-  DCHECK(data->slot);
-  DCHECK_EQ(data->table, this);
-  return data;
-}
-
-#if defined(OS_POSIX)
-SharedMemoryHandle StatsTable::GetSharedMemoryHandle() const {
-  if (!internal_)
-    return SharedMemory::NULLHandle();
-  return internal_->shared_memory()->handle();
-}
-#endif
-
-}  // namespace base