Add ability to retrieve a thread_name given a thread_id.

base/threading/thread_id_name_manager.cc

Index: base/threading/thread_id_name_manager.cc
diff --git a/base/threading/thread_id_name_manager.cc b/base/threading/thread_id_name_manager.cc
new file mode 100644
index 0000000000000000000000000000000000000000..405cc32d8a5e7729716fb61dba5f068ff840fee2
--- /dev/null
+++ b/base/threading/thread_id_name_manager.cc
@@ -0,0 +1,75 @@
+// Copyright (c) 2012 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/threading/thread_id_name_manager.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "base/string_util.h"
+
+namespace base {
+namespace {
+
+static const char kDefaultName[] = "";
+static std::string* g_default_name;
+
+typedef std::map<PlatformThreadId, std::string*>::iterator
+    ThreadIdToInternedNameIterator;
+typedef std::map<std::string, std::string*>::iterator
+    NameToInternedNameIterator;
+}
+
+ThreadIdNameManager::ThreadIdNameManager() {
+  g_default_name = new std::string(kDefaultName);

[jar (doing other things), 2013/01/25 03:13:25]

nit: probably AutoLock locked(lock_); before writing to the map.

You could trust protection from the singleton... but it is good to consistently
use the lock.

[dsinclair, 2013/01/25 14:54:43]

Done.

+  name_to_interned_name_[kDefaultName] = g_default_name;
+}
+
+ThreadIdNameManager::~ThreadIdNameManager() {
+}
+
+ThreadIdNameManager* ThreadIdNameManager::GetInstance() {
+  return Singleton<ThreadIdNameManager,
+      LeakySingletonTraits<ThreadIdNameManager> >::get();
+}
+
+const char* ThreadIdNameManager::GetDefaultInternedString() {
+  return g_default_name->c_str();
+}
+
+void ThreadIdNameManager::SetName(PlatformThreadId id, const char* name) {
+  std::string str_name(name);
+
+  AutoLock locked(lock_);
+  NameToInternedNameIterator iter = name_to_interned_name_.find(str_name);
+  if (iter != name_to_interned_name_.end()) {
+    thread_id_to_interned_name_[id] = iter->second;
+    return;
+  }
+
+  std::string* leaked_str = new std::string(str_name);
+  name_to_interned_name_[str_name] = leaked_str;
+  thread_id_to_interned_name_[id] = leaked_str;

[jar (doing other things), 2013/01/25 03:13:25]

nit: I think this code went back and forth.  I thought it might be cleaner to
replace lines 48-55 with:
std::string* leaked_str = NULL;
if (iter != name_to_interned_name_.end()) {
  leaked_string = iter->second;
} else {
  leaked_string = new std::string(str_name);
  thread_id_to_interned_name[id] = leaked_string;
}
thread_id_to_interned_name_[id] = leaked_string;

...but they are both the same length.... so perhaps yours is as good.

I'll let you decide.  I'm ok with either.

[dsinclair, 2013/01/25 14:54:43]

Sorry about that, juggled it around again when I was fixing up the leaking.


On 2013/01/25 03:13:25, jar wrote:

+}
+
+const char* ThreadIdNameManager::GetName(PlatformThreadId id) {
+  AutoLock locked(lock_);
+  ThreadIdToInternedNameIterator iter = thread_id_to_interned_name_.find(id);
+  DCHECK(iter != thread_id_to_interned_name_.end());
+  return iter->second->c_str();
+}
+
+void ThreadIdNameManager::RemoveName(PlatformThreadId id) {
+  if (id == kInvalidThreadId)
+    return;
+
+  AutoLock locked(lock_);
+  ThreadIdToInternedNameIterator iter = thread_id_to_interned_name_.find(id);
+  DCHECK((iter != thread_id_to_interned_name_.end()));
+  thread_id_to_interned_name_.erase(iter);
+}
+
+}  // namespace base