[cleanup] Change CounterMap to use unordered map.

Trying to reduce use of our self-baked data structures.

Bug: v8:7570
Change-Id: Ie4257911b388d320e4c5da5108cd763d3ab9299f
Reviewed-on: https://chromium-review.googlesource.com/1032555Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52840}

src/d8.cc

@@ -480,12 +480,6 @@ ArrayBuffer::Allocator* Shell::array_buffer_allocator;
 ShellOptions Shell::options;
 base::OnceType Shell::quit_once_ = V8_ONCE_INIT;
 
-bool CounterMap::Match(void* key1, void* key2) {
-  const char* name1 = reinterpret_cast<const char*>(key1);
-  const char* name2 = reinterpret_cast<const char*>(key2);
-  return strcmp(name1, name2) == 0;
-}
-
 // Dummy external source stream which returns the whole source in one go.
 class DummySourceStream : public v8::ScriptCompiler::ExternalSourceStream {
  public:
@@ -1629,25 +1623,15 @@ void Shell::MapCounters(v8::Isolate* isolate, const char* name) {
   isolate->SetAddHistogramSampleFunction(AddHistogramSample);
 }
 
-
-int CounterMap::Hash(const char* name) {
-  int h = 0;
-  int c;
-  while ((c = *name++) != 0) {
-    h += h << 5;
-    h += c;
-  }
-  return h;
-}
-
-
 Counter* Shell::GetCounter(const char* name, bool is_histogram) {
-  Counter* counter = counter_map_->Lookup(name);
+  auto map_entry = counter_map_->find(name);
+  Counter* counter =
+      map_entry != counter_map_->end() ? map_entry->second : nullptr;
 
   if (counter == nullptr) {
     counter = counters_->GetNextCounter();
     if (counter != nullptr) {
-      counter_map_->Set(name, counter);
+      (*counter_map_)[name] = counter;
       counter->Bind(name, is_histogram);
     }
   } else {
@@ -2083,15 +2067,13 @@ void Shell::OnExit(v8::Isolate* isolate) {
   isolate->Dispose();
 
   if (i::FLAG_dump_counters || i::FLAG_dump_counters_nvp) {
-    int number_of_counters = 0;
-    for (CounterMap::Iterator i(counter_map_); i.More(); i.Next()) {
-      number_of_counters++;
-    }
+    const int number_of_counters = static_cast<int>(counter_map_->size());
     CounterAndKey* counters = new CounterAndKey[number_of_counters];
     int j = 0;
-    for (CounterMap::Iterator i(counter_map_); i.More(); i.Next(), j++) {
-      counters[j].counter = i.CurrentValue();
-      counters[j].key = i.CurrentKey();
+    for (auto map_entry : *counter_map_) {
+      counters[j].counter = map_entry.second;
+      counters[j].key = map_entry.first;
+      j++;
     }
     std::sort(counters, counters + number_of_counters);
 

src/d8.h

@@ -9,10 +9,10 @@
 #include <map>
 #include <memory>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 #include "src/allocation.h"
-#include "src/base/hashmap.h"
 #include "src/base/platform/time.h"
 #include "src/utils.h"
 
@@ -56,41 +56,26 @@ class CounterCollection {
   Counter counters_[kMaxCounters];
 };
 
-
-class CounterMap {
- public:
-  CounterMap(): hash_map_(Match) { }
-  Counter* Lookup(const char* name) {
-    base::HashMap::Entry* answer =
-        hash_map_.Lookup(const_cast<char*>(name), Hash(name));
-    if (!answer) return nullptr;
-    return reinterpret_cast<Counter*>(answer->value);
-  }
-  void Set(const char* name, Counter* value) {
-    base::HashMap::Entry* answer =
-        hash_map_.LookupOrInsert(const_cast<char*>(name), Hash(name));
-    DCHECK_NOT_NULL(answer);
-    answer->value = value;
+struct StringHasher {
+  std::size_t operator()(const char* name) const {
+    size_t h = 0;
+    size_t c;
+    while ((c = *name++) != 0) {
+      h += h << 5;
+      h += c;
+    }
+    return h;
   }
-  class Iterator {
-   public:
-    explicit Iterator(CounterMap* map)
-        : map_(&map->hash_map_), entry_(map_->Start()) { }
-    void Next() { entry_ = map_->Next(entry_); }
-    bool More() { return entry_ != nullptr; }
-    const char* CurrentKey() { return static_cast<const char*>(entry_->key); }
-    Counter* CurrentValue() { return static_cast<Counter*>(entry_->value); }
-   private:
-    base::CustomMatcherHashMap* map_;
-    base::CustomMatcherHashMap::Entry* entry_;
-  };
+};
 
- private:
-  static int Hash(const char* name);
-  static bool Match(void* key1, void* key2);
-  base::CustomMatcherHashMap hash_map_;
+struct StringEquals {
+  bool operator()(const char* name1, const char* name2) const {
+    return strcmp(name1, name2) == 0;
+  }
 };
 
+typedef std::unordered_map<const char*, Counter*, StringHasher, StringEquals>
+    CounterMap;
 
 class SourceGroup {
  public: